JP7645776B2 - Albumin Measurement Test Strips - Google Patents

Description

The present disclosure relates to a test strip for measuring albumin, and in particular to a test strip for measuring albumin using the improved bromocresol purple (BCP) method and a method for measuring albumin using the same.

Methods for measuring albumin in biological samples include an immunological assay that uses anti-albumin serum to measure the scattering intensity from an antigen-antibody complex, and a dye-binding method that uses dyes such as bromocresol green (BCG) and BCP, and the dye-binding method is widely used in routine testing. In recent years, the improved BCP method has been widely used as a method that is highly correlated with the immunological assay method (Patent Document 1). The improved BCP method involves converting reduced albumin to oxidized albumin using a protein denaturant and a sulfhydryl reagent (SH reagent), and then reacting it with BCP.

Japanese Patent Application Publication No. 10-232233

The improved BCP method is highly specific to albumin and is widely used as described above, but the mainstream is a liquid-based albumin measurement reagent in which a solution (liquid reagent) containing BCP, a protein denaturant, and an SH reagent is mixed with a biological sample to react albumin with BCP. There was no dry-based albumin measurement reagent in which a dry reagent containing BCP, a protein denaturant, and an SH reagent is directly mixed with a biological sample to react albumin with BCP. In other words, there was no test strip for albumin measurement using the improved BCP method that contains BCP, a protein denaturant, and an SH reagent.
Therefore, the present disclosure provides a test strip for measuring albumin that is based on the improved BCP method and is capable of measuring albumin with high sensitivity, and preferably provides a test strip for measuring albumin that is capable of measuring albumin with high accuracy.

In one aspect, the present disclosure relates to a test strip for measuring albumin in a sample, the test strip having a support and a reagent holding layer provided on the support and onto which a sample is applied, the reagent holding layer containing a protein denaturant (component A), an SH reagent (component B), BCP (component C), and a nonionic surfactant (component D), the weight ratio (D/C) of component D to component C in the reagent holding layer being 0.3 to 13, the content of component C relative to the amount of the sample applied being 0.4 μg/μL to 5.4 μg/μL, and the content of component D relative to the amount of the sample applied being 25 μg/μL or less.

In another aspect, the present disclosure relates to a test strip for measuring albumin in a sample, the test strip having a support and a reagent holding layer provided on the support and onto which a sample is applied, the reagent holding layer containing a protein denaturant (component A), an SH reagent (component B), BCP (component C), and polyoxyethylene (23) lauryl ether (component D), the weight ratio (D/C) of component D to component C in the reagent holding layer being 1.3 to 13, the content of component C relative to the amount of the sample applied being 0.4 μg/μL to 5 μg/μL, and the content of component D relative to the amount of the sample applied being 20 μg/μL or less.

In another aspect, the present disclosure relates to a method for measuring the amount of albumin in a sample based on the measured optical properties of BCP in the presence of a protein denaturant and an SH reagent, the method comprising: spotting a predetermined amount of sample on a reagent retention layer of a test strip having a reagent retention layer containing a protein denaturant (component A), an SH reagent (component B), BCP (component C), and a nonionic surfactant (component D) to prepare a mixture of the sample and the components A, B, C, and D; in the mixture, the weight ratio (D/C) of component D to component C is 0.3 to 13, the concentration of component C is 0.4 μg/μL to 5.4 μg/μL, and the concentration of component D is 25 μg/μL or less.

In another aspect, the present disclosure relates to a method for measuring the amount of albumin in a sample based on the measured value of the optical properties of BCP in the presence of a protein denaturant and an SH reagent, the method comprising: spotting a predetermined amount of sample on a reagent retention layer of a test strip having a reagent retention layer containing a protein denaturant (component A), an SH reagent (component B), BCP (component C), and polyoxyethylene (23) lauryl ether (component D) to prepare a mixture of the sample and the components A, B, C, and D, in which the weight ratio (D/C) of component D to component C is 1.3 to 13, the concentration of component C is 0.4 μg/μL to 5 μg/μL, and the concentration of component D is 20 μg/μL or less.

According to the present disclosure, it is possible to provide a test strip for measuring albumin that is based on the principle of the improved BCP method and is capable of measuring albumin with high sensitivity, preferably a dry test strip for measuring albumin that is capable of measuring albumin with high accuracy.

FIG. 1 shows the configuration of a test strip for measuring albumin according to embodiment 1 of the present disclosure, where FIG. 1(a) is a perspective view and FIG. 1(b) is a longitudinal sectional view taken along line AA. FIG. 2 shows the ratio (D/C) of the content of BCP (component C) and polyoxyethylene (23) lauryl ether (Brij35) (component D) relative to the amount of sample applied in the measurement of an albumin measurement test strip based on an embodiment, and the evaluation thereof. FIG. 3 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene (23) lauryl ether (Brij35) (component D) per unit area of the sample application surface (surface where the sample is applied) of the reagent holding layer in the measurement of an albumin measurement test strip based on an embodiment, and its evaluation. FIG. 4 is a graph showing an example of the results of a correlation test between the test strip of Example 5 and a liquid reagent of the improved BCP method. FIG. 5 shows the ratio (D/C) of the content of BCP (component C) and polyoxyethylene distyrenated phenyl ether (Emulgen A90) (component D) relative to the amount of sample applied in the measurement of an albumin measurement test strip based on an embodiment, and the evaluation thereof. FIG. 6 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene distyrenated phenyl ether (Emulgen A90) (component D) per unit area of the sample application surface (surface on which the sample is applied) of the reagent holding layer in the measurement of an albumin measurement test strip based on an embodiment, and its evaluation. FIG. 7 shows the ratio (D/C) of the content of BCP (component C) and polyoxyethylene (13) oleyl ether (Emulgen 420) (component D) to the amount of sample applied in the measurement of an albumin measurement test strip based on the embodiment, and the evaluation thereof. FIG. 8 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene (13) oleyl ether (EMULGEN 420) (component D) per unit area of the sample application surface (surface where the sample is applied) of the reagent holding layer in the measurement of an albumin measurement test strip based on an embodiment, and its evaluation. FIG. 9 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene polyoxypropylene alkyl ether (Emulgen LS110) (component D) relative to the amount of sample applied in the measurement of an albumin measurement test strip based on an embodiment, and the evaluation thereof. FIG. 10 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene polyoxypropylene alkyl ether (Emulgen LS110) (component D) per unit area of the sample application surface (surface where the sample is applied) of the reagent holding layer in the measurement of an albumin measurement test strip based on an embodiment, and its evaluation. FIG. 11 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene (20) sorbitan monolaurate (Tween 20) (component D) relative to the amount of sample spotted in the measurement of an albumin measurement test strip based on an embodiment, and the evaluation thereof. FIG. 12 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene (20) sorbitan monolaurate (Tween 20) (component D) per unit area of the sample application surface (surface on which the sample is applied) of the reagent holding layer in the measurement of an albumin measurement test strip based on an embodiment, and its evaluation. FIG. 13 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene (12) lauryl ether (EMULGEN 120) (component D) relative to the amount of sample applied in the measurement of an albumin measurement test strip based on an embodiment, and the evaluation thereof. FIG. 14 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene (12) lauryl ether (Emulgen 120) (component D) per unit area of the sample application surface (surface where the sample is applied) of the reagent holding layer in the measurement of an albumin measurement test strip based on an embodiment, and its evaluation. FIG. 15 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene (20) sorbitan monooleate (Tween 80) (component D) relative to the amount of sample spotted in the measurement of an albumin measurement test strip based on an embodiment, and the evaluation thereof. FIG. 16 shows the content ratio (D/C) of BCP (component C) and polyoxyethylene (20) sorbitan monooleate (Tween 80) (component D) per unit area of the sample application surface (surface where the sample is applied) of the reagent holding layer in the measurement of an albumin measurement test strip based on an embodiment, and its evaluation.

The improved BCP method involves oxidizing reduced albumin in a specimen to oxidized albumin in the presence of a protein denaturant such as SDS and an SH reagent, and then measuring changes in the optical properties of BCP, such as changes in absorbance, caused by binding the oxidized albumin to BCP. Specifically, the absorbance is measured at wavelengths of 570 to 660 nm.
In the case of dry-system measurements such as test strips, the properties and optical characteristics of the sample itself greatly affect the measurement results because the dry reagent is dissolved by the liquid sample. In particular, when the sample is serum or plasma, the sample may contain hemoglobin eluted from red blood cells due to hemolysis. Hemoglobin has absorption at a wavelength of about 610 nm, and since the measurement wavelength of the improved BCP method is also about 610 nm, the presence of hemoglobin greatly affects the measurement of albumin. For this reason, it is possible to perform correction or calibration to eliminate the influence of hemoglobin, but in the case of dry-system measurements, correction or calibration is very difficult and complicated compared to liquid systems.

This disclosure is based on the finding that albumin can be measured with high sensitivity, preferably with high accuracy while suppressing the influence of coexisting substances such as hemoglobin in serum. The number in parentheses for polyoxyethylene (23) lauryl ether indicates the number of moles of oxyethylene groups added. The number in parentheses for polyoxyethylene (23) lauryl ether indicates the number of moles of oxyethylene groups added. The number in parentheses for polyoxyethylene (23) lauryl ether indicates the number of moles of oxyethylene groups added.

According to the present disclosure, it is possible to provide a dry test strip for measuring albumin based on the improved BCP method. According to the present disclosure, it is possible to provide a dry test strip for measuring albumin based on the improved BCP method, which is capable of measuring albumin with high sensitivity. According to the present disclosure, in one or more embodiments, even if the sample contains hemoglobin, it is preferable to be able to measure albumin in the sample with high accuracy.

[Albumin measurement test strip]
The albumin measurement test strip of the present disclosure has a support and a reagent holding layer provided on the support, and is a test strip for measuring albumin based on the improved BCP method. The reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), BCP (component C) and a nonionic surfactant (component D), the weight ratio (D/C) of component D to component C in the reagent holding layer is 0.3 to 13, the content of component C relative to the amount of sample applied to the reagent holding layer is 0.4 μg/μL to 5.4 μg/μL, and the content of component D relative to the amount of sample applied to the reagent holding layer is 25 μg/μL or less.

The reagent holding layer contains a reagent used in measuring albumin, and is the site where the sample is applied, and in one or more embodiments, is made of a porous material or the like, as described below. When a predetermined amount of sample is applied to this reagent holding layer, in one or more embodiments, the sample spreads over the entire reagent holding layer and is held in the reagent holding layer, and the entire reagent holding layer is immersed in the sample. This predetermined amount of sample applied can also be called the sample holding capacity of the reagent holding layer. The amount of sample applied and the sample holding capacity of the reagent holding layer are substantially the same. The predetermined amount of sample (sample application amount) can be determined appropriately, and in one or more embodiments, is about 1 to 20 μL.

In one or more embodiments, the reagent retention layer in the test strip of the present disclosure contains a reagent in a dry state (dry reagent). In one or more embodiments, the dry reagent contains a protein denaturant (component A), an SH reagent (component B), BCP (component C), and a nonionic surfactant (component D) in a dry state. In the present disclosure, "dry" or "dry reagent" refers to a reagent that is substantially free of water and is in a solid state.

[Component C]
In one or more embodiments, BCP (component C) may be a commercially available product. BCP is also called bromocresol purple or bromocresol purple. The chemical name of BCP is 5,5'-dibromo-o-cresolsulfonephthalein (CAS No. 115-40-2).

The ratio of component D to component C in the reagent holding layer (D/C, weight ratio) is 0.3 to 13, and a ratio of 1.3 to 13 is preferable because it enables highly accurate measurement while suppressing the effects of hemoglobin in the sample.

The content of component C in the reagent holding layer relative to the amount of sample spotted is 0.4 μg/μL to 5.4 μg/μL, and 0.4 μg/μL to 5 μg/μL is preferable because it allows for highly accurate measurement while suppressing the effects of hemoglobin in the sample.

The content of component C in the reagent holding layer is 5.8 μg/cm ² to 77.2 μg/cm ² , and preferably 5.8 μg/cm ² to 71.5 μg/cm ² because this enables highly accurate measurement while suppressing the effects of hemoglobin in the sample. Note that the content (μg/cm ² ) in the reagent holding layer in the present disclosure refers to the content per unit area on the sample application surface (surface where the sample is applied) of the reagent holding layer.

[Component D]
In one or more embodiments, the nonionic surfactant in the present disclosure is a nonionic surfactant having a polyoxyethylene group. In one or more embodiments, the nonionic surfactant having a polyoxyethylene group may include polyoxyethylene alkyl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene polyoxypropylene alkyl ether, and fatty acid ester. In one or more embodiments, the polyoxyethylene alkyl ether may include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene myristyl ether. In one or more embodiments, the fatty acid ester may include polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monooleate.
In one or more embodiments, examples of the nonionic surfactant include polyoxyethylene (23) lauryl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene (13) oleyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (12) lauryl ether, and polyoxyethylene (20) sorbitan monooleate.
In one or more embodiments, the nonionic surfactant may be one type or multiple types.

In one or more embodiments, the average number of moles of ethyleneoxy groups added in the nonionic surfactant of the present disclosure is 10, 11, 12, or 13 or more, or 25, 24, or 23 or less.

In one or more embodiments, the HLB of the nonionic surfactant in this disclosure is 13 to 17, or 13.4 to 16.9. HLB in this disclosure refers to the Griffin HLB value. The Griffin HLB value is defined in the publication J. Soc. Cosm. Chem. 1954 (Vol. 5), pp. 249-256.

The content of component D in the reagent holding layer relative to the amount of sample dispensed is 25 μg/μL or less, and 20 μg/μL or less is preferable because this allows for highly accurate measurement while suppressing the effects of hemoglobin in the sample.

The content of component D in the reagent holding layer is 357 μg/cm ² or less, and preferably 300 μg/cm ² or less, since this enables highly accurate measurement while suppressing the influence of hemoglobin in the sample.

The protein denaturant (component A), SH reagent (component B), and BCP (component C) contained in the reagent retention layer of the test strip disclosed herein are essential components for measuring albumin based on the improved BCP method.

[Component A]
In one or more embodiments, the protein denaturant (component A) may include anionic surfactants, amphoteric surfactants, urea, guanidine salts, inorganic salts, and thiocyanates. In one or more embodiments, component A may be used alone or in combination of two or more types. In one or more embodiments, the protein denaturant (component A) is substantially free of the nonionic surfactant used as component D, and preferably is substantially free of the nonionic surfactant. In the present disclosure, "substantially free" means that the content of the nonionic surfactant in the protein denaturant (component A) is 3% by mass or less, 1% by mass or less, or 0.1% by mass or less, and preferably 0% by mass, i.e., not contained, in one or more embodiments.

In one or more embodiments, the guanidine salts include guanidine hydrochloride and guanidine sulfate. In one or more embodiments, the inorganic salts include sodium fluoride, sodium azide, sodium chloride, potassium chloride, and the like. In one or more embodiments, the thiocyanates include ammonium thiocyanate, potassium thiocyanate, and sodium thiocyanate, and the like.

In one or more embodiments, component A is preferably an anionic surfactant. In one or more embodiments, the anionic surfactant may be an alkyl sulfate ester surfactant, a polyoxyethylene alkyl phenyl ether sulfate salt, a polyoxyethylene alkyl ether sulfate salt, or an alkyl benzene sulfonate salt. In one or more embodiments, the alkyl sulfate ester surfactant may be sodium lauryl sulfate (SDS) or sodium cetyl sulfate. In one or more embodiments, the polyoxyethylene alkyl phenyl ether sulfate salt may be sodium polyoxyethylene alkyl phenyl ether sulfate. In one or more embodiments, the polyoxyethylene alkyl ether sulfate salt may be sodium polyoxyethylene alkyl ether sulfate or triethanolamine polyoxyethylene alkyl ether sulfate. In one or more embodiments, the alkyl benzene sulfonate salt may be sodium lauryl benzene sulfonate or sodium cetyl benzene sulfonate.

In one or more embodiments, SDS and sodium laurylbenzenesulfonate are preferred as component A.

In one or more embodiments, the content of component A in the reagent holding layer relative to the amount of sample applied is 0.1 μg/μL to 15 μg/μL. From the viewpoint of obtaining even higher sensitivity to albumin and enabling albumin to be measured with higher accuracy even in hemolyzed samples, the content is more preferably 0.1 μg/μL to 5 μg/μL.

In one or more embodiments, the content of component A in the reagent holding layer is 1 μg/cm ² to 215 μg/cm ^2. From the viewpoint of obtaining even higher sensitivity to albumin and enabling albumin to be measured with higher accuracy even in a hemolyzed sample, the content is preferably 1 μg/cm ² to 72 μg/cm ² .

[Component B]
In one or more embodiments, the SH reagent (component B) may be a disulfide, an oxidizing agent, an alkylating agent, maleimide and its derivatives, thiophthalimide, etc. In one or more embodiments, component B may be used alone or in combination of two or more kinds.

In one or more embodiments, examples of disulfides include 5'-dithiobis(2-nitrobenzoic acid) (DTNB), 2,2'-dithiobis(5-nitropyridine) (NPDS), 2,2'-dithiodipyridine (2-PDS), 4,4'-dithiodipyridine (4-PDS), 4,4'-dithiobis(1-azidobenzene) (DTBPA), and oxidized glutathione. In one or more embodiments, examples of oxidizing agents include iodine, ferricyanide, iodosobenzoic acid, iodates, chlorites, mercury, and zinc. In one or more embodiments, examples of alkylating agents include iodoacetic acid, chloroacetic acid, iodoacetamide, and chloroacetophenone. In one or more embodiments, examples of maleimide derivatives include N-methylmaleimide, N-ethylmaleimide, and N,N'-p-phenylenedimaleimide.

In one or more embodiments, component B is preferably a disulfide such as DTNB, 2-PDS, or 4-PDS, maleimide, or a maleimide derivative such as N-ethylmaleimide.

In one or more embodiments, the content of component B in the reagent holding layer relative to the amount of sample applied is 0.0004 μg/μL to 8 μg/μL. From the viewpoint of obtaining even higher sensitivity to albumin and enabling albumin to be measured with higher accuracy even in hemolyzed samples, the content is preferably 1.5 μg/μL to 2 μg/μL.

In one or more embodiments, the content of component B in the reagent holding layer is 0.01 μg/cm ² to 115 μg/cm ^2. From the viewpoint of obtaining even higher sensitivity to albumin and enabling albumin to be measured with higher accuracy even in a hemolyzed sample, the content is preferably 20 μg/cm ² to 30 μg/cm ² .

In one or more embodiments, the reagent holding layer may further contain a buffer and/or a preservative, etc.

In one or more embodiments, the buffer may be acetate, citrate, phosphate, succinate, malate, Good's buffer, etc. In one or more embodiments, the Good's buffer may be 3-(N-morpholino)ethanesulfonic acid (MES), Bis-Tris, etc. Preferably, it is citrate, malate, succinate, or 3-(N-morpholino)ethanesulfonic acid (MES). In one or more embodiments, the pKa of the buffer is 4.5 to 6.0, preferably 5.0 to 5.5. In order to obtain a strong color development of BCP when a sample containing albumin is measured and to suppress the color development of BCP when a sample not containing albumin is measured, it is preferable to contain a buffer in the reagent holding layer so that the pH of the sample (mixture of sample and reagent) applied to the reagent holding layer is 4.5 to 6.0, preferably 5.0 to 5.5.

In one or more embodiments, the reagent holding layer may be a reagent holding member impregnated with a reagent liquid containing the above-mentioned reagents (components A, B, C, and D, etc.) and dried, or a reagent liquid directly placed on a support and dried. The reagent holding member is not limited to a specific member as long as it is a member capable of holding the reagent used in measuring albumin. The sample (specimen) spotted on the reagent holding layer spreads in the reagent holding layer and is mixed with the reagent. In one or more embodiments, a porous material, a fibrous material, etc. can be used as the reagent holding member. In one or more embodiments, the reagent holding member may be in the form of a sheet or a film. In one or more embodiments, the reagent holding member may be a paper-like material, a foam (foam), a woven material, a nonwoven material, a knitted material, etc. In one or more embodiments, materials for forming the reagent holding member include cotton, hemp, cellulose, nitrocellulose, cellulose acetate, rock wool, glass fiber, silica fiber, carbon fiber, boron fiber, polyamide, aramid, polyvinyl alcohol, polyvinyl acetate, rayon, polyester, nylon, polyacrylic acid, polyacrylic acid ester, polyolefin, etc. The shape of the reagent holding layer is not particularly limited, and in one or more embodiments, examples include a rectangle, an elongated rectangle, a circle, etc.

In one or more embodiments, the support is preferably made of a material that is not permeable to liquids. In one or more embodiments, examples of the material for the support include paper, plastic (synthetic resin), and metal.

Below, one embodiment of the test piece of the present disclosure is described.

[Component D: Polyoxyethylene (23) lauryl ether]
In one aspect, the test strip of the present disclosure contains polyoxyethylene (23) lauryl ether as component D. In one or more embodiments, Brij (registered trademark) 35 (product name: Polyoxyethylene 23 Lauryl Ether, molecular weight: 1225) can be used as the polyoxyethylene (23) lauryl ether.

In this embodiment, the ratio of component D to component C in the reagent holding layer (D/C, weight ratio) is preferably 1.3 to 13, since this allows for highly accurate measurement while suppressing the effects of hemoglobin in the sample, and is preferably 1.5 to 9.3, since this allows for even higher accuracy while further suppressing the effects of hemoglobin in the sample. A more preferred ratio is 1.5 to 2.9, since this provides even higher sensitivity to albumin and allows for more accurate measurement of albumin even in hemolyzed samples.

In this embodiment, the content of component C relative to the amount of sample spotted on the reagent holding layer is preferably 0.4 μg/μL to 5 μg/μL, since this allows for highly accurate measurement while suppressing the effects of hemoglobin in the sample, and is preferably 0.5 μg/μL to 4.3 μg/μL, since this allows for even more accurate measurement while further suppressing the effects of hemoglobin in the sample. It is more preferably 1.6 μg/μL to 3.8 μg/μL, since this provides even higher sensitivity to albumin and allows for more accurate measurement of albumin even in hemolyzed samples.

In this embodiment, the content of component D relative to the amount of sample spotted on the reagent holding layer is preferably 20 μg/μL or less, since this allows for highly accurate measurement while suppressing the effects of hemoglobin in the sample, and is preferably 1.3 μg/μL to 20 μg/μL, since this allows for even more accurate measurement while further suppressing the effects of hemoglobin in the sample. It is more preferably 3.8 μg/μL to 8.8 μg/μL, since this provides even higher sensitivity to albumin and allows for more accurate measurement of albumin even in hemolyzed samples.

[Component D: Polyoxyethylene distyrenated phenyl ether]
In one aspect, the test strip of the present disclosure contains polyoxyethylene distyrenated phenyl ether as component D. In one or more embodiments, the polyoxyethylene distyrenated phenyl ether may be Emulgen A90 (manufactured by Kao Corporation, HLB: 14.5).

In this embodiment, the ratio of component D to component C in the reagent holding layer (D/C, weight ratio) is preferably 1.2 to 10.6, since this allows for more precise measurement while further suppressing the effects of hemoglobin in the sample. It is more preferably 1.2 to 2.3, since this provides even higher sensitivity to albumin and allows for more precise measurement of albumin even in hemolyzed samples.

In this embodiment, the content of component C relative to the amount of sample spotted on the reagent holding layer is preferably 0.5 μg/μL to 5.4 μg/μL, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample. It is more preferably 2.2 μg/μL to 5.4 μg/μL, since this provides even higher sensitivity to albumin and allows for more accurate measurement of albumin even in hemolyzed samples.

In this embodiment, the content of component D in the reagent holding layer relative to the amount of sample spotted is preferably 23.0 μg/μL or less, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample. From the viewpoint of obtaining even higher sensitivity to albumin and allowing for more accurate measurement of albumin even in hemolyzed samples, it is more preferable that the content is 12.5 μg/μL or less, and even more preferable that it is 3.8 μg/μL to 12.5 μg/μL.

[Component D: Polyoxyethylene (13) oleyl ether]
In one aspect, the test strip of the present disclosure contains polyoxyethylene (13) oleyl ether as component D. In one or more embodiments, the polyoxyethylene (13) oleyl ether may be Emulgen 420 (manufactured by Kao Corporation, HLB: 13.6).

In this embodiment, the ratio of component D to component C in the reagent holding layer (D/C, weight ratio) is preferably 0.9 to 9.3, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample. From the viewpoint of obtaining even higher sensitivity to albumin, the ratio is more preferably 0.9 to 2.3.

In this embodiment, the content of component C relative to the amount of sample spotted on the reagent holding layer is preferably 0.5 μg/μL to 5.4 μg/μL, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample. From the viewpoint of obtaining even higher sensitivity, the content is more preferably 2.2 μg/μL to 5.4 μg/μL.

In this embodiment, the content of component D in the reagent holding layer relative to the amount of sample dispensed is preferably 12.5 μg/μL or less, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample. From the viewpoint of obtaining even higher sensitivity to albumin and allowing for more accurate measurement of albumin even in hemolyzed samples, the content is more preferably 3.8 μg/μL to 12.5 μg/μL.

[Component D: Polyoxyethylene polyoxypropylene alkyl ether]
In one aspect, the test strip of the present disclosure contains a polyoxyethylene polyoxypropylene alkyl ether as component D. In one or more embodiments, the polyoxyethylene polyoxypropylene alkyl ether may be Emulgen LS110 (manufactured by Kao Corporation, HLB: 13.4).

In this embodiment, the ratio of component D to component C in the reagent holding layer (D/C, weight ratio) is preferably 1.2 to 2.3, since this allows for more accurate measurement while further suppressing the effect of hemoglobin in the sample.

In this embodiment, the content of component C relative to the amount of sample spotted on the reagent holding layer is preferably 2.2 μg/μL to 5.4 μg/μL, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample.

In this embodiment, the content of component D in the reagent holding layer relative to the amount of sample applied is preferably 12.5 μg/μL or less, and more preferably 3.8 μg/μL to 12.5 μg/μL, in order to enable more accurate measurement while further suppressing the effects of hemoglobin in the sample.

[Component D: Polyoxyethylene (20) sorbitan monolaurate]
In one aspect, the test strip of the present disclosure contains polyoxyethylene (20) sorbitan monolaurate as component D. As the polyoxyethylene (20) sorbitan monolaurate, in one or more embodiments, Tween 20 (HLB: 16.7) can be used.

In this embodiment, the ratio of component D to component C in the reagent holding layer (D/C, weight ratio) is preferably 1.7 to 2.3, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample.

In this embodiment, the content of component C relative to the amount of sample spotted on the reagent holding layer is preferably 2.2 μg/μL to 4.3 μg/μL, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample.

In this embodiment, the content of component D in the reagent holding layer relative to the amount of sample applied is preferably 10.0 μg/μL or less, and more preferably 3.8 μg/μL to 10.0 μg/μL, in order to enable more accurate measurement while further suppressing the effects of hemoglobin in the sample.

[Component D: Polyoxyethylene (12) lauryl ether]
In one aspect, the test strip of the present disclosure contains polyoxyethylene (12) lauryl ether as component D. In one or more embodiments, the polyoxyethylene (12) lauryl ether may be Emulgen 120 (manufactured by Kao Corporation, HLB: 15.3).

In this embodiment, the ratio of component D to component C in the reagent holding layer (D/C, weight ratio) is preferably 1.2 to 2.3, since this allows for more precise measurement while further suppressing the effect of hemoglobin in the sample, and more preferably 1.2 to 1.4, since this provides even higher sensitivity to albumin and allows for more precise measurement of albumin even in hemolyzed samples.

In this embodiment, the content of component C relative to the amount of sample spotted on the reagent holding layer is preferably 2.2 μg/μL to 4.3 μg/μL, since this allows for more precise measurement while further suppressing the effects of hemoglobin in the sample, and more preferably 2.2 μg/μL to 3.1 μg/μL, since this provides even higher sensitivity to albumin and allows for more precise measurement of albumin even in hemolyzed samples.

In this embodiment, the content of component D relative to the amount of sample spotted in the reagent holding layer is preferably 5.0 μg/μL or less, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample, and more preferably 1.3 μg/μL to 3.8 μg/μL, since this provides even higher sensitivity to albumin and allows for more accurate measurement of albumin even in hemolyzed samples.

[Component D: Polyoxyethylene (20) sorbitan monooleate]
In one aspect, the test strip of the present disclosure contains polyoxyethylene (20) sorbitan monooleate as component D. In one or more embodiments, Tween 80 (HLB: 15.0) can be used as the polyoxyethylene (20) sorbitan monooleate.

In this embodiment, the ratio of component D to component C in the reagent holding layer (D/C, weight ratio) is preferably 1.2 to 13.9 or 1.2 to 10.6, since this allows for more precise measurement while further suppressing the effect of hemoglobin in the sample, and more preferably 1.2 to 2.3, since this provides even higher sensitivity to albumin and allows for more precise measurement of albumin even in hemolyzed samples.

In this embodiment, the content of component C relative to the amount of sample spotted on the reagent holding layer is preferably 0.5 μg/μL to 5.4 μg/μL, since this allows for more precise measurement while further suppressing the effects of hemoglobin in the sample, and more preferably 2.2 μg/μL to 5.4 μg/μL, since this provides even higher sensitivity to albumin and allows for more precise measurement of albumin even in hemolyzed samples.

The test strip of the present disclosure, which contains polyoxyethylene (20) sorbitan monooleate as component D, is capable of measuring albumin with high accuracy even when the content of component D relative to the amount of sample spotted in the reagent holding layer exceeds 25 μg/μL, for example, 30 μg/μL.
In this embodiment, the content of component D in the reagent holding layer relative to the amount of sample spotted is preferably 30 μg/μL or less, 25 μg/μL or less, or 23 μg/μL or less, from the viewpoint of further suppressing the effect of hemoglobin in the sample while enabling more accurate measurement, and is more preferably 12.5 μg/μL or less, and even more preferably 2.5 μg/μL to 12.5 μg/μL, from the viewpoint of obtaining even higher sensitivity to albumin and enabling more accurate measurement of albumin even in a hemolyzed sample.

Therefore, in another aspect, the present disclosure relates to a test strip for measuring albumin contained in a sample, the test strip having a support and a reagent holding layer provided on the support and onto which a sample is applied, the reagent holding layer containing a protein denaturant (component A), an SH reagent (component B), BCP (component C), and polyoxyethylene (20) sorbitan monooleate (component D), the weight ratio (D/C) of component D to component C in the reagent holding layer is 1.2 to 13.9, the content of component C relative to the amount of the sample applied is 0.5 μg/μL to 5.4 μg/μL, and the content of component D relative to the amount of the sample applied is 30 μg/μL or less.

In one or more embodiments, the test strip of the present disclosure can be used to measure albumin in a biological sample, and in particular, can be used to suitably measure albumin in serum or plasma, even in hemolyzed samples.

[Method of measuring albumin]
In another aspect, the present disclosure relates to a method for measuring the amount of albumin in a specimen based on the measured value of the optical properties of BCP in the presence of a protein denaturant and an SH reagent. The measurement method of the present disclosure includes spotting a predetermined amount of specimen on a reagent holding layer of a test strip having a reagent holding layer containing a protein denaturant (component A), an SH reagent (component B), BCP (component C), and a nonionic surfactant (component D) to prepare a mixture of the specimen and the components A, B, C, and D, wherein in the mixture, the ratio of component D to component C (D/C, weight ratio) is 0.3 to 13, the concentration of component C is 0.4 μg/μL to 5.4 μg/μL, and the concentration of component D is 25 μg/μL or less.

In one or more embodiments of the present disclosure, the specimen is a liquid specimen, and examples of the specimen include biological samples such as serum and plasma. In one or more embodiments of the measurement method of the present disclosure, when the specimen (liquid) is spotted (dropped) onto a reagent holding layer provided on a test piece, the specimen spreads in the reagent holding layer, and the reagent contained in the reagent holding layer dissolves in the specimen, forming a mixture of the specimen and the reagent.

The concentration of component C in the mixture is 0.4 μg/μL to 5.4 μg/μL.

The concentration of component D in the mixture is 25 μg/μL or less.

The ratio of component D to component C in the mixture (D/C, weight ratio) is the same as that of the test specimen of the present disclosure.

In one or more embodiments, the concentration of component A in the mixture is 0.1 μg/μL to 15 μg/μL. From the viewpoint of obtaining even higher sensitivity to albumin and enabling albumin to be measured with higher accuracy even in hemolyzed samples, the concentration is more preferably 0.1 μg/μL to 5 μg/μL.

In one or more embodiments, the concentration of component B in the mixture is 0.0004 μg/μL to 8 μg/μL. From the viewpoint of obtaining even higher sensitivity to albumin and enabling albumin to be measured with higher accuracy even in hemolyzed samples, the concentration is more preferably 1.5 μg/μL to 2 μg/μL.

In one or more embodiments, the mixed solution may further contain a buffering agent. The concentration of the buffering agent in the mixed solution may be any concentration that can maintain the mixed solution at a predetermined pH. For example, in one or more embodiments, the concentration of the buffering agent in the mixed solution is 300 mmol/L to 500 mmol/L. In one or more embodiments, the reagent holding layer preferably contains a buffering agent such that the pH of the reagent holding layer (mixed solution) after application of the sample is 4.5 to 6.0, preferably 5.0 to 5.5.

In the present disclosure, when a measurement is performed using the test strip of the present disclosure, the concentration of each drug in the mixed solution can be calculated by multiplying the content (μg/ ^cm2 ) of each drug in the test strip (reagent holding layer) by the area ( ^cm2 ) of the reagent holding layer and dividing the result by the amount of sample dropped onto the reagent holding layer.
(Concentration in mixed solution)=Drug content in reagent holding layer (μg/cm ² )×Area of reagent holding layer (cm ² )÷Amount of sample (μL)

The components A, B, C, and D and the buffer in the measurement method of the present disclosure are the same as those in the test specimen of the present disclosure. The ratio of component D to component C (D/C) in the test specimen and the contents of components A, B, C, and D are the same as those in the test specimen of the present disclosure.

Below, one embodiment of the measurement method disclosed herein is described.

[Component D: Polyoxyethylene (23) lauryl ether]
In one embodiment, the measurement method of the present disclosure uses polyoxyethylene (23) lauryl ether as component D.
Thus, in another aspect, the present disclosure relates to a method for measuring the amount of albumin in a specimen based on the measured value of the optical properties of BCP in the presence of a protein denaturant and an SH reagent. The measurement method of the present disclosure includes spotting a predetermined amount of specimen on a reagent holding layer of a test piece having a reagent holding layer containing a protein denaturant (component A), an SH reagent (component B), BCP (component C), and polyoxyethylene (23) lauryl ether (component D) to prepare a mixture of the specimen and the components A, B, C, and D, wherein in the mixture, the ratio of component D to component C (D/C, weight ratio) is 1.3 to 13, the concentration of component C is 0.4 μg/μL to 5 μg/μL, and the concentration of component D is 20 μg/μL or less.
In this embodiment, the concentration of component C in the mixture is preferably 0.4 μg/μL to 5 μg/μL in order to enable highly accurate measurement while suppressing the influence of hemoglobin in the sample, and is preferably 0.5 μg/μL to 4.3 μg/μL in order to enable more accurate measurement while further suppressing the influence of hemoglobin in the sample. More preferably, the concentration is 1.6 μg/μL to 3.8 μg/μL in order to obtain even higher sensitivity to albumin and enable more accurate measurement of albumin even in a hemolyzed sample.

In this embodiment, the concentration of component D in the mixed solution is preferably 20 μg/μL or less, since this allows for highly accurate measurement while suppressing the effects of hemoglobin in the sample, and is preferably 1.3 μg/μL to 20 μg/μL, since this allows for even more accurate measurement while further suppressing the effects of hemoglobin in the sample. It is more preferably 3.8 μg/μL to 8.8 μg/μL, since this provides even higher sensitivity to albumin and allows for more accurate measurement of albumin even in hemolyzed samples.

In this embodiment, the ratio of component D to component C in the mixed solution (D/C, weight ratio) and its preferred range are the same as those of the test strip containing polyoxyethylene (23) lauryl ether as component D. In this embodiment, the concentrations of components A and B in the mixed solution are as described above.

[Component D: Polyoxyethylene distyrenated phenyl ether]
In one embodiment of the measurement method of the present disclosure, polyoxyethylene distyrenated phenyl ether is used as component D. In this embodiment, the concentration of component C in the mixed solution is preferably 0.5 μg/μL to 5.4 μg/μL, since it enables measurement with higher accuracy while further suppressing the influence of hemoglobin in the sample. It is more preferably 2.2 μg/μL to 5.4 μg/μL, since it provides even higher sensitivity to albumin and enables albumin to be measured with higher accuracy even in a hemolyzed sample.

In this embodiment, the concentration of component D in the mixture is preferably 23.0 μg/μL or less, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample. From the viewpoint of obtaining even higher sensitivity to albumin and allowing for more accurate measurement of albumin even in hemolyzed samples, the concentration is more preferably 12.5 μg/μL or less, and even more preferably 3.8 μg/μL to 12.5 μg/μL.

In this embodiment, the ratio of component D to component C in the mixed solution (D/C, weight ratio) and its preferred range are the same as those of the test piece containing polyoxyethylene distyrenated phenyl ether as component D described above. In this embodiment, the concentrations of components A and B in the mixed solution are as described above.

[Component D: Polyoxyethylene (13) oleyl ether]
In one embodiment of the measurement method of the present disclosure, polyoxyethylene (13) oleyl ether is used as component D. In this embodiment, the concentration of component C in the mixed solution is preferably 0.5 μg/μL to 5.4 μg/μL, from the viewpoint of enabling measurement with higher accuracy while further suppressing the influence of hemoglobin in the sample. It is more preferably 2.2 μg/μL to 5.4 μg/μL, from the viewpoint of obtaining even higher sensitivity to albumin and enabling albumin measurement with higher accuracy even in a hemolyzed sample.

In this embodiment, the concentration of component D in the mixture is preferably 12.5 μg/μL or less, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample. It is more preferably 3.8 μg/μL to 12.5 μg/μL, since this provides even higher sensitivity to albumin and allows for more accurate measurement of albumin even in hemolyzed samples.

In this embodiment, the ratio of component D to component C in the mixed solution (D/C, weight ratio) and its preferred range are the same as those of the test strip containing polyoxyethylene (13) oleyl ether as component D. In this embodiment, the concentrations of components A and B in the mixed solution are as described above.

[Component D: Polyoxyethylene polyoxypropylene alkyl ether]
In one embodiment of the measurement method of the present disclosure, a polyoxyethylene polyoxypropylene alkyl ether is used as component D. In this embodiment, the concentration of component C in the mixed solution is preferably 2.2 μg/μL to 5.4 μg/μL, since this enables measurement with higher accuracy while further suppressing the influence of hemoglobin in the sample.

In this embodiment, the concentration of component D in the mixture is preferably 12.5 μg/μL or less, and more preferably 3.8 μg/μL to 12.5 μg/μL, in order to enable more accurate measurement while further suppressing the effect of hemoglobin in the sample.

In this embodiment, the ratio of component D to component C in the mixed solution (D/C, weight ratio) and its preferred range are the same as those of the test strip containing polyoxyethylene polyoxypropylene alkyl ether as component D. In this embodiment, the concentrations of components A and B in the mixed solution are as described above.

[Component D: Polyoxyethylene (20) sorbitan monolaurate]
In one embodiment of the measurement method of the present disclosure, polyoxyethylene (20) sorbitan monolaurate is used as component D. In this embodiment, the concentration of component C in the mixed solution is preferably 2.2 μg/μL to 4.3 μg/μL, since this enables measurement with higher accuracy while further suppressing the influence of hemoglobin in the sample.

In this embodiment, the concentration of component D in the mixture is preferably 10.0 μg/μL or less, and more preferably 3.8 μg/μL to 10.0 μg/μL, in order to enable more accurate measurement while further suppressing the effect of hemoglobin in the sample.

In this embodiment, the ratio of component D to component C in the mixture (D/C, weight ratio) and its preferred range are the same as those of the test strip containing polyoxyethylene (20) sorbitan monolaurate as component D. In this embodiment, the concentrations of components A and B in the mixture are as described above.

[Component D: Polyoxyethylene (12) lauryl ether]
In one embodiment of the measurement method of the present disclosure, polyoxyethylene (12) lauryl ether is used as component D. In this embodiment, the concentration of component C in the mixed solution is preferably 2.2 μg/μL to 4.3 μg/μL from the viewpoint of enabling measurement with higher accuracy while further suppressing the influence of hemoglobin in the sample, and more preferably 2.2 μg/μL to 3.1 μg/μL from the viewpoint of obtaining even higher sensitivity to albumin and enabling albumin to be measured with higher accuracy even in a hemolyzed sample.

In this embodiment, the concentration of component D in the mixture is preferably 5.0 μg/μL or less, since this allows for more accurate measurement while further suppressing the effects of hemoglobin in the sample, and more preferably 1.3 μg/μL to 3.8 μg/μL, since this provides even higher sensitivity to albumin and allows for more accurate measurement of albumin even in hemolyzed samples.

In this embodiment, the ratio of component D to component C in the mixed solution (D/C, weight ratio) and its preferred range are the same as those of the test strip containing polyoxyethylene (12) lauryl ether as component D. In this embodiment, the concentrations of components A and B in the mixed solution are as described above.

[Component D: Polyoxyethylene (20) sorbitan monooleate]
In one embodiment of the measurement method of the present disclosure, polyoxyethylene (20) sorbitan monooleate is used as component D. In this embodiment, the concentration of component C in the mixed solution is preferably 0.5 μg/μL to 5.4 μg/μL from the viewpoint of enabling measurement with higher accuracy while further suppressing the influence of hemoglobin in the sample, and more preferably 2.2 μg/μL to 5.4 μg/μL from the viewpoint of obtaining even higher sensitivity to albumin and enabling measurement of albumin with higher accuracy even in a hemolyzed sample.

When measurements are performed using a test strip of the present disclosure that contains polyoxyethylene (20) sorbitan monooleate as component D, even when the content of component D relative to the amount of sample spotted in the reagent holding layer exceeds 25 μg/μL, for example, 30 μg/μL, component C can be sufficiently dissolved in the sample and albumin can be measured with high accuracy.
In this embodiment, the concentration of component D in the mixed solution is preferably 30 μg/μL or less, 25 μg/μL or less, or 23.0 μg/μL or less, from the viewpoint of enabling measurement with higher accuracy while further suppressing the effect of hemoglobin in the sample, and is more preferably 12.5 μg/μL or less, and even more preferably 2.5 μg/μL to 12.5 μg/μL, from the viewpoint of obtaining even higher sensitivity to albumin and enabling measurement of albumin with higher accuracy even in a hemolyzed sample.

In another aspect, the present disclosure relates to a method for measuring the amount of albumin in a specimen based on the measured value of the optical properties of BCP in the presence of a protein denaturant and an SH reagent. The measurement method of the present disclosure includes spotting a predetermined amount of specimen on a reagent retention layer of a test strip having a reagent retention layer containing a protein denaturant (component A), an SH reagent (component B), BCP (component C), and polyoxyethylene (20) sorbitan monooleate (component D) to prepare a mixture of the specimen and the components A, B, C, and D, in which the ratio of component D to component C (D/C, weight ratio) is 1.2 to 13.9, the concentration of component C is 0.5 μg/μL to 5.4 μg/μL, and the concentration of component D is 30 μg/μL or less.

In this embodiment, the ratio of component D to component C in the mixture (D/C, weight ratio) and its preferred range are the same as those of the test strip containing polyoxyethylene (20) sorbitan monooleate as component D. In this embodiment, the concentrations of components A and B in the mixture are as described above.

[Method of manufacturing test strip for measuring albumin]
In another aspect, the present disclosure relates to a method for producing a test strip for measuring albumin of the present disclosure. In one or more embodiments, the method for producing the present disclosure includes mixing a protein denaturant (component A), an SH reagent (component B), BCP (component C), and a nonionic surfactant (component D) to prepare an impregnating liquid, impregnating a reagent holding member with the impregnating liquid, drying the impregnating liquid impregnated into the reagent holding member, and attaching the reagent holding member impregnated with the impregnating liquid to a support, and includes preparing the impregnating liquid such that the ratio of component D to component C (D/C, weight ratio) is 0.3 to 13, the concentration of component C relative to the amount of sample applied during use is 0.4 μg/μL to 5.4 μg/μL, and the concentration of component D relative to the amount of sample applied during use is 25 μg/μL or less.

The concentrations and preferred ranges of components C and D relative to the amount of sample applied when used in the manufacturing method of the present disclosure are the same as the concentrations in the mixed solution in the measurement method of the present disclosure. The ratio of component D to component C (D/C) and the preferred range in the manufacturing method of the present disclosure are the same as the test strip of the present disclosure.

In another aspect, the present disclosure relates to a method for manufacturing the test strip for measuring albumin of the present disclosure. In one or more embodiments, the manufacturing method of the present disclosure includes mixing a protein denaturant (component A), an SH reagent (component B), BCP (component C), and polyoxyethylene (23) lauryl ether (component D) to prepare an impregnation liquid, impregnating a reagent holding member with the impregnation liquid, drying the impregnation liquid impregnated into the reagent holding member, and attaching the reagent holding member impregnated with the impregnation liquid to a support, and includes preparing the impregnation liquid such that the ratio of component D to component C (D/C, weight ratio) is 1.3 to 13, the concentration of component C relative to the amount of sample applied during use is 0.4 μg/μL to 5 μg/μL, and the concentration of component D relative to the amount of sample applied during use is 20 μg/μL or less.

In one or more embodiments, the manufacturing method of the present disclosure may include preparing the impregnation amount in such a way that the concentration of component A relative to the amount of sample applied at the time of use is 0.1 μg/μL to 15 μg/μL. In one or more embodiments, the manufacturing method of the present disclosure may include preparing the impregnation amount in such a way that the concentration of component B relative to the amount of sample applied at the time of use is 0.0004 μg/μL to 8 μg/μL.

In one or more embodiments, the manufacturing method of the present disclosure may further include mixing components A, B, C, and D with a buffer in preparing the impregnation solution. In one or more embodiments, the buffer is preferably mixed with components A, B, C, and D so that the pH of the reagent holding layer after application of the sample during use is 4.5 to 6.0, preferably 5.0 to 5.5.

[First embodiment]
As shown in Fig. 1(a), the albumin measurement test strip 1 according to the first embodiment is composed of a long and narrow rectangular support 2 and a reagent holding layer 3 formed on one end of the support 2. As shown in Fig. 1(b), the reagent holding layer 3 is disposed on the support 2 by being adhered with an adhesive (not shown) or the like.

The albumin measurement test strip 1 according to the first embodiment can be prepared as follows. In the first embodiment, the embodiment will be described using an example in which polyoxyethylene (23) lauryl ether is used as component D.

First, the support 2 is prepared. The support 2 is prepared by cutting a PET sheet into a long and thin piece having a predetermined dimension. In one or more embodiments, the width and length of the support 2 can be appropriately determined according to the amount of sample used in the measurement. In one or more embodiments, the width of the support 2 is about 5 mm to 1 cm when the amount of sample applied is about 5 μL. In one or more embodiments, the length of the support 2 is about 5 cm to 15 cm.

Next, the reagent holding layer 3 is prepared. First, an impregnating solution to be impregnated into the reagent holding layer is prepared. BCP (component C), polyoxyethylene (23) lauryl ether (product name: Brij35) (component D), 1M succinic acid/NaOH buffer pH 5.5, SDS (component A) and DTNB (component B) are added to distilled water in this order, and the mixture is stirred and dispersed to prepare the impregnating solution. At this time, the ratio of component D to component C in the impregnating solution (D/C, weight ratio) is adjusted to 1.3 to 13, the concentration of component C relative to the amount of sample applied when in use is adjusted to 0.4 μg/μL to 5 μg/μL, and the concentration of component D relative to the amount of sample applied when in use is adjusted to 20 μg/μL or less. In addition, the succinic acid/NaOH buffer is added to the impregnation solution so that the pH of the reaction solution (mixture of the sample and the reagent) after the sample is dispensed is 4.5 to 6.0, preferably 5.0 to 5.5.

The prepared impregnating liquid is absorbed into a reagent holding member made of a liquid-permeable material such as a woven fabric, and the reagent contained in the impregnating liquid is dispersed in the reagent holding member. The reagent holding layer 3 is then prepared by drying to remove moisture and cutting to a predetermined size. The size of the reagent holding layer 3 can be appropriately determined depending on the width of the support 2 and the amount of sample used in the measurement. When the test amount of the sample is about 5 μL, the size of the reagent holding layer 3 is about 5 mm to 10 mm x 5 mm to 10 mm in one or more embodiments. The thickness of the reagent holding layer 3 is about 100 μm to 500 μm.

Next, the reagent holding layer 3 is placed on the support 2. In one or more embodiments, the reagent holding layer 3 can be adhered to the support 2 by an adhesive or a pressure sensitive adhesive.

In this way, the test strip 1 for measuring albumin can be produced.

Albumin measurement using the albumin measurement test strip 1 according to the present embodiment 1 can be performed as follows.

A predetermined amount of serum (e.g., about 5 μL) is dropped onto the reagent holding layer 3 (5 mm x 7 mm, thickness: 235 μm). The liquid specimen instantly diffuses throughout the reagent holding layer 3, unifying all the reagents, and a mixture (reaction liquid) in which the reagents are dissolved in the specimen is prepared inside the reagent holding layer 3. The concentration of component C in the mixture is 0.4 μg/μL to 5 μg/μL, and the concentration of component D is 20 μg/μL or less.

BCP (component C) tends to develop color more easily with oxidized albumin than with reduced albumin. For this reason, in the mixed solution, SDS (component A) denatures albumin, and DTNB (component B) forms disulfide bonds with the denatured albumin and reduced albumin in the specimen to turn them into oxidized albumin. BCP binds to albumin (oxidized albumin) to form a BCP-albumin complex, and the color of the mixed solution changes from yellow to green. Therefore, the color of the reagent holding layer 3 containing the mixed solution changes from yellow to green depending on the concentration of albumin in the specimen.

Then, the reagent holding layer 3 is irradiated with light, and the intensity of the light reflected from the reagent holding layer or the light that has passed through the reagent holding layer is measured. In one or more embodiments, the measurement can be performed 120 to 300 seconds, preferably 180 seconds, after the sample is applied. The wavelength may be any wavelength that allows the color tone of the BCP-albumin complex to be measured, and in one or more embodiments, the wavelength is 570 nm to 660 nm, and preferably 600 nm to 630 nm or around 610 nm. In one or more embodiments, the temperature during measurement is 15°C to 37°C.

The degree of coloration (K/S value) may be calculated by irradiating reagent holding layer 3 with light and receiving the light reflected from reagent holding layer 3. The K/S value can be calculated by the following Kubelka-Munk equation, where R is the reflectance of visible light.
K/S=(1-R) ² /2R

The light intensity can be measured using a commercially available optical analysis device. In one or more embodiments, the optical analysis device may be SPOTCHEM (registered trademark) (manufactured by ARKRAY, Inc.).

According to the albumin measurement test strip of the present embodiment 1, since the reagent holding layer 3 contains component C (BCP) and component D (polyoxyethylene (23) lauryl ether, Brij35) in a predetermined ratio, even if the serum contains hemoglobin that has the property of absorbing near the measurement wavelength of 610 nm, for example, the influence of hemoglobin can be suppressed without performing a separate correction process. Therefore, albumin in serum can be measured with high accuracy, and preferably quantified.

In the first embodiment, the embodiment using polyoxyethylene (23) lauryl ether as component D is described as an example, but component D in the present disclosure is not limited to this, and the composition can be produced and measured in the same manner even when other components D (nonionic surfactants) are used.

In the first embodiment, a woven fabric material is used as the reagent holding member, but the material of the reagent holding member is not limited to this, and various materials capable of holding reagents can be used, including fibrous materials such as filter paper.

In the first embodiment, an example has been described in which a reagent holding member impregnated with an impregnation liquid is disposed on the support 2 as the reagent holding layer 3, but the method of forming the reagent holding layer 3 is not limited to this. In one or more embodiments, the reagent holding layer 3 may be formed directly on the support 2 by dropping the impregnation liquid directly onto the support 2 and drying it, without impregnating the reagent holding member with the impregnation liquid. In this case (when the reagent holding layer 3 does not contain a reagent holding member), the support 2 may be subjected to a hydrophobic treatment or a depression may be provided on the support 2 so that the impregnation liquid or the sample dropped on the support 2 remains and is held within a predetermined area range.

In the first embodiment, an example has been described in which the amount of sample dropped onto the reagent holding layer 3 is about 5 μL, but the amount of sample is not limited to this. Furthermore, the method of supplying the sample to the reagent holding layer 3 is not limited to dropping the sample onto the reagent holding layer 3. The sample may be spotted onto the reagent holding layer 3, or the sample in a container may be dipped into the reagent holding layer 3 to impregnate the reagent holding layer 3 with the sample.

In the first embodiment, an example is described in which the color tone of the BCP is measured using the reflectance of light irradiated onto the reagent holding layer 3, but the method for measuring the color tone of the BCP is not limited to this, and it may also be measured using transmitted light.

The present disclosure may relate to one or more of the following non-limiting embodiments.
[1] A support;
A reagent holding layer is provided on the support and onto which a sample is applied.
A test strip for measuring albumin contained in the sample, comprising:
The reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and a nonionic surfactant (component D),
In the reagent holding layer,
a weight ratio (D/C) of the component D to the component C is 0.3 to 13;
The content of the component C relative to the amount of the sample spotted is 0.4 μg/μL to 5.4 μg/μL,
A test strip for measuring albumin, in which the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[2] The weight ratio (D/C) of the component D to the component C is 1.3 to 13,
The content of the component C relative to the amount of the sample spotted is 0.4 μg/μL to 5 μg/μL,
The test strip according to [1], wherein the content of component D relative to the amount of the sample applied is 20 μg/μL or less.
[3] The test strip according to [1] or [2], wherein the nonionic surfactant is a nonionic surfactant having a polyoxyethylene group.
[4] The test piece according to any one of [1] to [3], wherein the HLB value of the nonionic surfactant is 13.4 to 16.9.
[5] The test strip according to any one of [1] to [4], wherein the nonionic surfactant is one or more nonionic surfactants selected from the group consisting of polyoxyethylene (23) lauryl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene (13) oleyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (12) lauryl ether, and polyoxyethylene (20) sorbitan monooleate.
[6] A support,
A reagent holding layer is provided on the support and onto which a sample is applied.
A test strip for measuring albumin contained in the sample, comprising:
the reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene (23) lauryl ether (component D);
In the reagent holding layer,
a weight ratio (D/C) of the component D to the component C is 1.3 to 13;
The content of the component C relative to the amount of the sample spotted is 0.4 μg/μL to 5 μg/μL,
A test strip for measuring albumin, in which the content of component D relative to the amount of the sample applied is 20 μg/μL or less.
[7] The test strip according to [6], wherein the weight ratio (D/C) of the component D to the component C is 1.5 to 9.3, and the content of the component C relative to the amount of the sample applied is 0.5 μg/μL to 4.3 μg/μL.
[8] The test strip according to [6], wherein the weight ratio (D/C) of the component D to the component C is 1.5 to 2.9, and the content of the component C relative to the amount of the sample applied is 1.6 μg/μL to 3.8 μg/μL.
[9] A support;
A reagent holding layer is provided on the support and onto which a sample is applied.
A test strip for measuring albumin contained in the sample, comprising:
The reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene distyrenated phenyl ether (component D),
In the reagent holding layer,
a weight ratio (D/C) of the component D to the component C is 1.2 to 10.6;
The content of the component C relative to the amount of the sample spotted is 0.5 μg/μL to 5.4 μg/μL,
A test strip for measuring albumin, in which the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[10] A support;
A reagent holding layer is provided on the support and onto which a sample is applied.
A test strip for measuring albumin contained in the sample, comprising:
the reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene (13) oleyl ether (component D);
In the reagent holding layer,
a weight ratio (D/C) of the component D to the component C is 0.9 to 9.3;
The content of the component C relative to the amount of the sample spotted is 0.5 μg/μL to 5.4 μg/μL,
A test strip for measuring albumin, in which the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[11] A support;
A reagent holding layer is provided on the support and onto which a sample is applied.
A test strip for measuring albumin contained in the sample, comprising:
the reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and a polyoxyethylene polyoxypropylene alkyl ether (component D);
In the reagent holding layer,
The weight ratio (D/C) of the component D to the component C is 1.2 to 2.3;
The content of the component C relative to the amount of the sample spotted is 2.2 μg/μL to 5.4 μg/μL,
A test strip for measuring albumin, in which the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[12] A support;
A reagent holding layer is provided on the support and onto which a sample is applied.
A test strip for measuring albumin contained in the sample, comprising:
the reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene (20) sorbitan monolaurate (component D),
In the reagent holding layer,
the weight ratio (D/C) of the component D to the component C is 1.7 to 2.3;
The content of the component C relative to the amount of the sample spotted is 2.2 μg/μL to 4.3 μg/μL,
A test strip for measuring albumin, in which the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[13] A support;
A reagent holding layer is provided on the support and onto which a sample is applied.
A test strip for measuring albumin contained in the sample, comprising:
the reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene (12) lauryl ether (component D);
In the reagent holding layer,
The weight ratio (D/C) of the component D to the component C is 1.2 to 2.3;
The content of the component C relative to the amount of the sample spotted is 2.2 μg/μL to 4.3 μg/μL,
A test strip for measuring albumin, in which the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[14] A support;
A reagent holding layer is provided on the support and onto which a sample is applied.
A test strip for measuring albumin contained in the sample, comprising:
the reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene (20) sorbitan monooleate (component D);
In the reagent holding layer,
a weight ratio (D/C) of the component D to the component C is 1.2 to 13.9; a content of the component C relative to the amount of the sample spotted is 0.5 μg/μL to 5.4 μg/μL;
A test strip for measuring albumin, in which the content of component D relative to the amount of the sample applied is 30 μg/μL or less.
[15] The test strip according to any one of [1] to [14], wherein the protein denaturant is an anionic surfactant.
[16] The test strip according to any one of [1] to [15], for measuring albumin in a biological sample.
[17] The test strip according to [16], wherein the biological sample is serum or plasma.
[18] A method for measuring an amount of albumin in a sample based on a measured value of optical properties of bromocresol purple in the presence of a protein denaturant and an SH reagent, comprising:
The method includes spotting a predetermined amount of a specimen on a reagent holding layer of a test piece, the reagent holding layer including a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and a nonionic surfactant (component D), to prepare a mixed solution of the specimen, the components A, B, C, and D;
In the mixed solution,
a weight ratio (D/C) of the component D to the component C is 0.3 to 13;
The concentration of the component C is 0.4 μg/μL to 5.4 μg/μL,
The measurement method, wherein the concentration of component D is 25 μg/μL or less.
[19] A method for measuring an amount of albumin in a sample based on a measured value of optical properties of bromocresol purple in the presence of a protein denaturant and an SH reagent, comprising:
The method includes spotting a predetermined amount of a specimen on a reagent holding layer of a test piece, the reagent holding layer including a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene (23) lauryl ether (component D), to prepare a mixture of the specimen, the components A, B, C, and D;
In the mixed solution,
a weight ratio (D/C) of the component D to the component C is 1.3 to 13;
The content of the component C relative to the amount of the sample spotted is 0.4 μg/μL to 5 μg/μL,
A measurement method, wherein the content of component D relative to the amount of the sample applied is 20 μg/μL or less.
[20] A method for measuring an amount of albumin in a sample based on a measurement value of optical properties of bromocresol purple in the presence of a protein denaturant and an SH reagent, comprising:
The method includes spotting a predetermined amount of a specimen on a reagent holding layer of a test piece, the reagent holding layer including a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene distyrenated phenyl ether (component D), to prepare a mixed solution in which the specimen, the components A, B, C, and D are mixed together;
In the mixed solution,
The weight ratio (D/C) of the component D to the component C is 1.2 to 10.6;
The content of the component C relative to the amount of the sample spotted is 0.5 μg/μL to 5.4 μg/μL,
A measurement method, wherein the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[21] A method for measuring an amount of albumin in a sample based on a measured value of optical properties of bromocresol purple in the presence of a protein denaturant and an SH reagent, comprising:
The method includes spotting a predetermined amount of a specimen on a reagent holding layer of a test piece, the reagent holding layer including a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene (13) oleyl ether (component D), to prepare a mixed solution of the specimen, the components A, B, C, and D;
In the mixed solution,
a weight ratio (D/C) of the component D to the component C is 0.9 to 9.3;
The content of the component C relative to the amount of the sample spotted is 0.5 μg/μL to 5.4 μg/μL,
A measurement method, wherein the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[22] A method for measuring an amount of albumin in a sample based on a measurement of optical properties of bromocresol purple in the presence of a protein denaturant and an SH reagent, comprising:
The method includes spotting a predetermined amount of a specimen on a reagent holding layer of a test piece, the reagent holding layer including a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and a polyoxyethylene polyoxypropylene alkyl ether (component D), to prepare a mixture of the specimen, the components A, B, C, and D,
The weight ratio (D/C) of the component D to the component C is 1.2 to 2.3;
The content of the component C relative to the amount of the sample spotted is 2.2 μg/μL to 5.4 μg/μL,
A measurement method, wherein the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[23] A method for measuring an amount of albumin in a sample based on a measured value of optical properties of bromocresol purple in the presence of a protein denaturant and an SH reagent, comprising:
The method includes spotting a predetermined amount of a specimen on a reagent holding layer of a test piece, the reagent holding layer including a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene (20) sorbitan monolaurate (component D), to prepare a mixed solution of the specimen, the components A, B, C, and D;
In the mixed solution,
The weight ratio (D/C) of the component D to the component C is 1.7 to 2.3;
The content of the component C relative to the amount of the sample spotted is 2.2 μg/μL to 4.3 μg/μL,
A measurement method, wherein the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[24] A method for measuring an amount of albumin in a sample based on a measurement of optical properties of bromocresol purple in the presence of a protein denaturant and an SH reagent, comprising:
The method includes spotting a predetermined amount of a specimen on a reagent holding layer of a test piece, the reagent holding layer including a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene (12) lauryl ether (component D), to prepare a mixture of the specimen, the components A, B, C, and D;
In the mixed solution,
The weight ratio (D/C) of the component D to the component C is 1.2 to 2.3;
The content of the component C relative to the amount of the sample spotted is 2.2 μg/μL to 4.3 μg/μL,
A measurement method, wherein the content of component D relative to the amount of the sample applied is 25 μg/μL or less.
[25] A method for measuring an amount of albumin in a sample based on a measurement of optical properties of bromocresol purple in the presence of a protein denaturant and an SH reagent, comprising:
The method includes spotting a predetermined amount of a specimen on a reagent holding layer of a test piece, the reagent holding layer including a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and polyoxyethylene (20) sorbitan monooleate (component D), to prepare a mixed solution of the specimen, the components A, B, C, and D;
In the mixed solution,
a weight ratio (D/C) of the component D to the component C is 1.2 to 13.9; a content of the component C relative to the amount of the sample spotted is 0.5 μg/μL to 5.4 μg/μL;
A measurement method, wherein the content of component D relative to the amount of the sample applied is 30 μg/μL or less.
[26] The measurement method according to any one of [18] to [25], wherein the test piece is the test piece according to any one of [1] to [17].
[27] The method according to any one of [18] to [26], wherein the protein denaturant is an anionic surfactant.
[28] The measurement method according to any one of [18] to [27], wherein the specimen is a biological sample.
[29] The method according to [28], wherein the biological sample is serum or plasma.

The present disclosure will be explained in more detail below with reference to examples and comparative examples, but these are merely illustrative and the present disclosure is not limited to these examples.

[Preparation of test strips for albumin measurement 1]
An impregnation solution was prepared by sequentially adding BCP, Brij35 (Polyoxyethylene 23 Lauryl Ether, nonionic surfactant, HLB: 16.9), 1M succinic acid/NaOH buffer (pH 5.5), SDS (protein denaturant), and DTNB (5,5'-Dithiobis (2-nitrobenzoic acid), SH reagent) to distilled water. The prepared impregnation solution was uniformly impregnated into the entire cloth (thickness: 235 μm) woven from composite yarn of polyester and nylon. The succinic acid/NaOH buffer was added to the impregnation solution so that the pH of the reaction solution (mixture of the sample and the reagent) after the sample was spotted on the reagent holding layer was 5.5.
The impregnated cloth was dried at 50°C for 10 minutes and cut to 5mm x 7mm to prepare a reagent holding layer. The prepared reagent holding layer 3 was attached to a white PET plate 2 measuring 70mm in length x 5mm in width with an adhesive to obtain a test strip 1 for measuring albumin as shown in Figure 1. The content of the reagent contained in the obtained test strip (reagent holding layer) is shown in Table 1 below. The concentration of the mixed liquid (at the time of measurement) in Table 1 refers to the concentration in the reaction liquid after the sample is spotted on the reagent holding layer.

[Sample preparation]
The following reagents were mixed appropriately to prepare samples 1 to 6 shown in Table 2 below.
Frozen pooled serum (3.9 g/dL albumin, 0 g/dL hemoglobin; Consela®, Nissui Pharmaceutical Co., Ltd.)
・Saline ・Human serum albumin (Sigma-Aldrich)
- Hemolyzed hemoglobin (Interference Check A Plus, Sysmex Corporation)

[Creating a calibration curve]
Using Samples 1 to 3, the K/S values were measured and a calibration curve was prepared according to the following procedure.
5 μL of sample was spotted on the reagent holding layer of the albumin measurement test strip. 180 seconds after spotting, light with a wavelength of 610 nm was irradiated onto the reagent holding layer, the intensity of the reflected light with a wavelength of 610 nm was measured, and the reflectance R, which is the ratio of the measured intensity of the reflected light to the intensity of the irradiated light, was calculated. The degree of coloration of the reagent holding layer (K/S value) was calculated from the reflectance R and the Kubelka-Munk formula, and a calibration curve was obtained. The obtained K/S value and calibration curve are shown in Table 3 below.
The reflectance was measured using SPOTCHEM (registered trademark) D-Concept (manufactured by Arkray, Inc.) under the following conditions.
[Measurement parameters]
Dominant wavelength: 610 nm
Sub wavelength: 810 nm
Measurement completion time: 180 seconds Measurement method: endpoint assay Sample volume: 5 μL
(Kubelka-Munk formula) K/S=(1-R) ² /2R

Calibration curve: y = ^0.2118x2 + 2.3002x-0.2768
y: Albumin concentration [g / dL]
x: K/S value

[Measurement of serum albumin of unknown concentration]
Using sample 5 (albumin concentration: 3.5 g/dL), the measurement was performed by the method described above, and the K/S value was calculated. The albumin concentration was calculated using the calculated K/S value and the above calibration curve. As a result, the albumin concentration was calculated to be 3.4 g/dL, with an error of within ±3%, and the measurement was performed with high accuracy.

[Preparation of test strips for albumin measurement 2]
Test strips for measuring albumin (Examples 1 to 21 and Reference Examples 1 to 3) were prepared having the contents of Brij35 and BCP and the ratios thereof shown in Table 4 below. The test strips were prepared in the same manner as in Preparation 1 of Test Strips for Measuring Albumin.

[Evaluation of test strips for measuring albumin]
Based on the following three items, albumin measurement test strips having different contents (content relative to the amount of sample applied) of BCP (component C) and Brij35 (component D) shown in Table 4 below were evaluated.
Item 1) Concentration linearity Item 2) Measurement sensitivity Item 3) Accuracy (precision) when measuring hemolyzed samples
The contents of the buffer (1 M succinic acid/NaOH buffer (pH 5.5)), SDS (component A) and DTNB (component B) in the test strips in Table 4 below are the same as those in Preparation 1 of the test strip for measuring albumin (Table 1).

Item (1) Concentration Linearity For the test strips in Table 4, measurements were performed using Samples 1 to 3 by the method described above, and the K/S values were calculated. A calibration curve was created using the calculated K/S values and the albumin concentrations of Samples 1 to 3. The albumin concentrations of Samples 2 and 3 were calculated from the obtained calibration curve and the K/S values of Samples 2 and 3. Using the obtained albumin concentrations, evaluation was performed according to the following evaluation criteria, and the concentration linearity of each test strip was evaluated.
The above measurements and evaluations were carried out for each of the test pieces shown in Table 4 below. The results are shown in Table 4 below. The K/S values shown in Table 4 are K/S values calculated from the measured values of Sample 3.
<Evaluation criteria>
Good: Albumin concentration calculated from the measured value of sample 2 is within 3.9 g/dL ± 15%.
And the albumin concentration calculated from the measured value of sample 3 is within 6.5 g/dL ± 15%.

Item (2) Measurement sensitivity The above measurement was performed three times using sample 1 (albumin concentration: 0 g/dL) to calculate the K/S value, and the average value and standard deviation (SD) were obtained. Furthermore, the above measurement was performed three times using sample 4 (albumin concentration: 1 g/dL) to calculate the K/S value, and the average value and standard deviation (SD) were obtained. Using the obtained average value and standard deviation (SD) of the K/S value, evaluation was performed according to the following evaluation criteria to evaluate the measurement sensitivity of each test piece.
The above measurements and evaluations were carried out on each of the test pieces shown in Table 4 below. The results are shown in Table 4 below.
<Evaluation criteria>
Good: There is no overlap between the range of (K/S value 1) + 3 x standard deviation (SD1) and the range of (K/S value 4) - 3 x standard deviation (SD4). Bad: There is an overlap between the range of (K/S value 1) + 3 x standard deviation (SD1) and the range of (K/S value 4) - 3 x standard deviation (SD4). K/S value 1: Average value of the K/S values of sample 1. K/S value 4: Average value of the K/S values of sample 4. SD1: Standard deviation (SD) of sample 1.
SD4: Standard deviation (SD) of sample 4

Item (3) Accuracy (precision) when measuring hemolyzed samples
Using the above samples 1 to 3, the K/S values were determined by the method described in [Creating a calibration curve] above, and a calibration curve was created.
Next, measurements were performed in the same manner using samples 5 and 6 (both albumin concentrations: 3.5 g/dL) to calculate the K/S value. The albumin concentrations of samples 5 and 6 were calculated from the obtained K/S values of samples 5 and 6 and the calibration curves prepared using each of samples 1 to 3. The calculated albumin concentrations of samples 5 and 6 were used to calculate the deviation rate (%) according to the following formula, and the obtained deviation rate (%) was used to evaluate the accuracy of the measurement of the hemolyzed sample for each test strip according to the following evaluation criteria. The hemoglobin concentration of sample 6 was 0.5 g/dL, which is the recommended concentration in CLSI (Clinical and Laboratory Standards Institute) EP07-A2.
Deviation rate (%) = {(albumin concentration 6) - (albumin concentration 5)} / (albumin concentration 5) x 100
Albumin concentration 5: Albumin concentration calculated from the K/S value of sample 5 Albumin concentration 6: Albumin concentration calculated from the K/S value of sample 6 <Evaluation criteria>
Good: Deviation rate is within 15% Bad: Deviation rate exceeds 15%

FIG. 2 shows the evaluation of the albumin test strip shown in Table 4, plotted with the BCP content (μg/μL) relative to the amount of sample applied on the horizontal axis and the Brij35 content (μg/μL) relative to the amount of sample applied on the vertical axis. FIG. 3 shows the same evaluation plotted with the BCP content (μg/cm ² ) per unit area of the reagent holding layer on the horizontal axis and the Brij35 content (μg/cm ² ) per unit area of the reagent holding layer on the vertical axis. In FIG. 2 and FIG. 3, the areas corresponding to the test strips that were evaluated as ◎ in Table 4 above are plotted in black, and the cells corresponding to the test strips that were evaluated as ◯ are plotted in gray. The numbers in each cell indicate the ratio of the Brij35 content to the BCP content (D/C, weight ratio). The evaluation in Table 4 was as follows.
⊚: All of the evaluation items (1) to (3) were satisfactory. ◯: The evaluation items (1) and (2) were satisfactory. ×: Only the evaluation item (1) was satisfactory, or all of the evaluation items (1) to (3) were unsatisfactory. From the results of the above evaluation and Figs. 2 and 3, it was confirmed that, as long as the dry test strip satisfies the conditions below, the albumin concentration can be measured with high accuracy, even when measuring serum containing hemoglobin.
D/C (Brij35/BCP, weight ratio): 1.5 to 9.3
BCP concentration: 0.5 to 4.3 μg/μL (content: 7.7 to 61.7 μg/cm ² ) Brij35 concentration: 20 μg/μL or less (content: 285.7 μg/cm ² or less)
In Figures 2 and 3, the test strips of the examples that satisfy the conditions underlined for the D/C value show a K/S value of 2.2 or more when measuring sample 3 with an albumin concentration of 6.5 g/dL (hemoglobin concentration: 0 g/dL). These test strips (Examples 1 to 5, 8, 9, and 11) show high K/S values for albumin among the test strips of Examples 1 to 21. The fact that the K/S value is high even when samples with the same albumin concentration are measured means that the test strips with the underlined D/C have high sensitivity to albumin, and even if the K/S value changes, the change in the albumin measurement value (albumin concentration calculated from the K/S value) is small. Therefore, the test strips that satisfy the underlined conditions below can measure albumin with higher accuracy even in serum containing a large amount of hemoglobin.
D/C (Brij35/BCP, weight ratio): 1.5 to 2.9
BCP concentration: 1.6-3.8μg/μL
Brij35 concentration: 3.8-8.8μg/μL

[Correlation test with liquid reagent of improved BCP method]
Serum collected from 48 patients who provided their informed consent was measured using a liquid reagent of the BCP improved method, which is an existing product, and the test strip of Example 5. Measurements using the liquid reagent were performed according to the package insert that came with the product. Measurements using the test strip of Example 5 were performed according to the method described above, and K/S values were obtained. [Liquid Reagent]
Albumin kit for blood testing L-type Wako ALB-BCP (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
(Measurement principle: BCP improvement method)
[Test piece]
Test piece of Example 5

Figure 4 shows the correlation between the measured values of the liquid reagent of the improved BCP method and the K/S value of the test piece of Example 5. The K/S value of the test piece of Example 5 showed a good correlation with the measured values of the liquid reagent of the improved BCP method. This shows that the test piece of the present disclosure has good performance.

[Preparation of test strips for albumin measurement 3]
Dry test strips for albumin measurement were prepared in the same manner as in Preparation 1 of Test Strips for Albumin Measurement, except that polyoxyethylene distyrenated phenyl ether (manufactured by Kao Corporation, Emulgen A90, HLB: 14.5) was used instead of Brij35, and the contents and ratios of Emulgen A90 and BCP were as shown in Table 5 below. The prepared test strips were evaluated in the above items (1) to (3). The results are shown in Table 5 below. The K/S values in Table 5 are the K/S values calculated from the measured values of Sample 3, and the evaluations in Table 5 were as follows:
◎: All evaluation items (1) to (3) are good. ◯: Both evaluation items (1) and (2) are good. ×: Only evaluation item (1) is good, or all evaluation items (1) to (3) are bad.

The evaluation of the albumin test strip shown in Table 5 is plotted as the BCP content (μg/μL) relative to the amount of sample applied on the horizontal axis and the Emulgen A90 content (μg/μL) relative to the amount of sample applied on the vertical axis in FIG. 5. The same evaluation is plotted as the BCP content (μg/cm ² ) per unit area of the reagent holding layer on the horizontal axis and the Emulgen A90 content (μg/cm ² ) per unit area of the reagent holding layer on the vertical axis in FIG. 6. In FIG. 5 and FIG. 6, the areas corresponding to the test strips that were evaluated as ◎ in Table 5 are plotted in black, the areas corresponding to the test strips that were evaluated as ◯ are plotted in gray, and the areas corresponding to the test strips that were evaluated as × are plotted in light gray. The numbers in each cell indicate the ratio (D/C, weight ratio) of the Emulgen A90 content to the BCP content. In addition, in Figs. 5 and 6, the test pieces of the examples which satisfy the conditions indicated by the underlined D/C values exhibit a K/S value of 2.2 or more when Sample 3 is measured.

As shown in Table 5 and Figures 5 and 6, in the dry test strips containing Emulgen A90 as component D, the test strips of all Examples were evaluated favorably in both evaluation items (1) and (2), and it was confirmed that albumin can be measured with high sensitivity. Furthermore, it was found that albumin can be measured with high accuracy because it showed high linearity.
As shown in Table 5 above, it was confirmed that, in dry test strips containing Emulgen A90 as component D, test strips (Examples 1-1 to 1-10) that satisfy the following conditions can measure albumin concentration with high accuracy even when measuring serum containing hemoglobin. D/C (Emulgen A90/BCP, weight ratio): 1.2 to 10.6
BCP concentration: 0.5 to 5.4 μg/μL (content: 7.7 to 77.2 μg/cm ² ) Emulgen A90 concentration: 23 μg/μL or less (content: 328.6 μg/cm ² or less)
The dry test strips of Examples 1-2 to 1-5, 1-7, and 1-9 showed a K/S value of 2.2 or more when measuring Sample 3 with an albumin concentration of 6.5 g/dL (hemoglobin concentration: 0 g/dL). Therefore, the test strips that satisfy the following conditions can measure albumin with higher accuracy even in serum containing a large amount of hemoglobin.
D/C (Emulgen A90/BCP, weight ratio): 1.2-2.3
BCP concentration: 2.2-5.4μg/μL
Emulgen A90 concentration: 12.5μg/μL or less

[Preparation of test strips for albumin measurement 4]
Dry test strips for albumin measurement were prepared in the same manner as in Preparation 1 of test strips for albumin measurement, except that polyoxyethylene (13) oleyl ether (manufactured by Kao Corporation, Emulgen 420, HLB: 13.6) was used instead of Brij35, and the contents and ratios of Emulgen 420 and BCP were as shown in Table 6 below. The prepared test strips were evaluated in the above items (1) to (3). The results are shown in Table 6 below. The K/S values in Table 6 are K/S values calculated from the measured values of Sample 3, and the evaluation criteria in Table 6 were the same as those in Preparation 3 of test strips for albumin measurement.

The evaluation of the albumin test strip shown in Table 6 is plotted as the BCP content (μg/μL) relative to the amount of sample applied on the horizontal axis and the Emulgen 420 content (μg/μL) relative to the amount of sample applied on the vertical axis in FIG. 7. The same evaluation is plotted as the BCP content (μg/cm ² ) per unit area of the reagent holding layer on the horizontal axis and the Emulgen 420 content (μg/cm ² ) per unit area of the reagent holding layer on the vertical axis in FIG. 8. In FIG. 7 and FIG. 8, the areas corresponding to the test strips that were evaluated as ⊚ in Table 6 are plotted in black, the areas corresponding to the test strips that were evaluated as ◯ are plotted in gray, and the areas corresponding to the test strips that were evaluated as × are plotted in light gray. The numbers in each cell indicate the ratio (D/C, weight ratio) of the Emulgen 420 content to the BCP content. In addition, in Figs. 7 and 8, the test pieces of the examples which satisfy the conditions indicated by the underlined D/C values exhibit a K/S value of 2.2 or more when Sample 3 is measured.

As shown in Table 6 and Figures 7 and 8, in the dry test strips containing Emulgen 420 as component D, the test strips of all Examples were evaluated favorably in both evaluation items (1) and (2), and it was confirmed that albumin can be measured with high sensitivity. Furthermore, it was found that albumin can be measured with high accuracy because it showed high linearity.
As shown in Table 6 above, it was confirmed that, in dry test strips containing Emulgen 420 as component D, test strips (Examples 2-1 to 2-10) that satisfy the following conditions can measure albumin concentration with high accuracy even when measuring serum containing hemoglobin. D/C (Emulgen 420/BCP, weight ratio): 0.9 to 9.3
BCP concentration: 0.5 to 5.4 μg/μL (content: 7.7 to 77.2 μg/cm ² ) Emulgen 420 concentration: 12.5 μg/μL or less (content: 178.6 μg/cm ² or less)
The dry test strips of Examples 2-2 to 2-5 and 2-7 to 2-10 showed a K/S value of 2.2 or more when measuring Sample 3 with an albumin concentration of 6.5 g/dL (hemoglobin concentration: 0 g/dL). Therefore, with test strips that satisfy the following conditions, albumin can be measured with higher accuracy even in serum containing a large amount of hemoglobin.
D/C (Emulgen 420/BCP, weight ratio): 0.9-2.3
BCP concentration: 2.2-5.4μg/μL
Emulgen 420 concentration: 3.8-12.5 μg/μL

[Preparation of test strips for albumin measurement 5]
Dry test strips for albumin measurement were prepared in the same manner as in Preparation 1 of test strips for albumin measurement, except that polyoxyethylene polyoxypropylene alkyl ether (manufactured by Kao Corporation, Emulgen LS110, HLB: 13.4) was used instead of Brij35, and the contents and ratios of Emulgen LS110 and BCP were as shown in Table 7 below. The prepared test strips were evaluated in the above items (1) to (3). The results are shown in Table 7 below. The K/S values in Table 7 are K/S values calculated from the measured values of Sample 3, and the evaluation criteria in Table 7 were the same as those in Preparation 3 of test strips for albumin measurement.

FIG. 9 shows the evaluation of the albumin test strips shown in Table 7, plotted as the BCP content (μg/μL) relative to the amount of sample applied on the horizontal axis and the Emulgen LS110 content (μg/μL) relative to the amount of sample applied on the vertical axis. FIG. 10 shows the same evaluation plotted as the BCP content (μg/cm ² ) per unit area of the reagent holding layer on the horizontal axis and the Emulgen LS110 content (μg/cm ² ) per unit area of the reagent holding layer on the vertical axis. In FIG. 9 and FIG. 10, the areas corresponding to the test strips that were evaluated as ⊚ in Table 7 are plotted in black, the areas corresponding to the test strips that were evaluated as ◯ are plotted in gray, and the areas corresponding to the test strips that were evaluated as × are plotted in light gray. The numbers in each cell indicate the ratio (D/C, weight ratio) of the Emulgen LS110 content to the BCP content. In addition, in Figs. 9 and 10, the test pieces of the examples which satisfy the conditions indicated by the underlined D/C values exhibit a K/S value of 2.2 or more when Sample 3 is measured.

As shown in Table 7, Figures 9 and 10, in the dry test strips containing Emulgen LS110 as component D, the test strips of all the Examples were evaluated favorably in both evaluation items (1) and (2), and it was confirmed that albumin can be measured with high sensitivity. Furthermore, it was found that albumin can be measured with high accuracy because it showed high linearity.
As shown in Table 7 above, it was confirmed that in dry test strips containing Emulgen LS110 as component D, test strips (Examples 3-1 to 3-6) that satisfy the following conditions can measure albumin concentration with high accuracy even when measuring serum containing hemoglobin.
D/C (Emulgen LS110/BCP, weight ratio): 1.2-2.3
BCP concentration: 2.2 to 5.4 μg/μL (content: 30.9 to 77.2 μg/cm ² )
Emulgen LS110 concentration: 12.5 μg/μL or less (content: 178.6 μg/cm ² or less)
The test strips that satisfied the above conditions showed a K/S value of 2.2 or more or close to 2.2 when measuring Sample 3 with an albumin concentration of 6.5 g/dL (hemoglobin concentration: 0 g/dL). Therefore, the test strips that satisfied the above conditions can measure albumin with higher accuracy even in serum containing a large amount of hemoglobin.

[Preparation of test strips for albumin measurement 6]
Dry test strips for albumin measurement were prepared in the same manner as in Preparation 1 of test strips for albumin measurement, except that polyoxyethylene (20) sorbitan monolaurate (Tween 20, HLB: 16.7) was used instead of Brij 35, and the contents and ratios of Tween 20 and BCP were as shown in Table 8 below. The prepared test strips were evaluated in the above items (1) to (3). The results are shown in Table 8 below. The K/S values in Table 8 are K/S values calculated from the measured values of Sample 3, and the evaluation criteria in Table 8 were the same as those in Preparation 3 of test strips for albumin measurement.

FIG. 11 shows the evaluation of the albumin test strip shown in Table 8, plotted with the BCP content (μg/μL) relative to the amount of sample applied on the horizontal axis and the Tween 20 content (μg/μL) relative to the amount of sample applied on the vertical axis. FIG. 12 shows the same evaluation plotted with the BCP content (μg/cm ² ) per unit area of the reagent holding layer on the horizontal axis and the Tween 20 content (μg/cm ² ) per unit area of the reagent holding layer on the vertical axis. In FIG. 11 and FIG. 12, the areas corresponding to the test strips that were evaluated as ⊚ in Table 8 are plotted in black, the areas corresponding to the test strips that were evaluated as ◯ are plotted in gray, and the areas corresponding to the test strips that were evaluated as × are plotted in light gray. The numbers in each cell indicate the ratio (D/C, weight ratio) of the Tween 20 content to the BCP content. In addition, in Figs. 11 and 12, the test pieces of the examples which satisfy the conditions indicated by the underlined D/C values exhibit a K/S value of 2.2 or more when Sample 3 is measured.

As shown in Table 8 and Figures 11 and 12, in the dry test strips containing Tween 20 as component D, the test strips of all Examples were evaluated as being good in both evaluation items (1) and (2), and it was confirmed that albumin could be measured with high sensitivity. Furthermore, it was found that albumin could be measured with high accuracy because it showed high linearity.
As shown in Table 8 above, it was confirmed that, in the dry test strips containing Tween 20 as component D, the test strips (Examples 4-1 and 4-2) that satisfy the following conditions can measure albumin concentration with high accuracy even when measuring serum containing hemoglobin.
D/C (Tween20/BCP, weight ratio): 1.7 to 2.3
BCP concentration: 2.2 to 4.3 μg/μL (content: 30.9 to 61.7 μg/cm ² )
Tween20 concentration: 10.0 μg/μL or less (content: 142.9 μg/cm ² or less)

[Preparation of test strips for albumin measurement 7]
Dry test strips for albumin measurement were prepared in the same manner as in Preparation 1 of test strips for albumin measurement, except that polyoxyethylene (12) lauryl ether (manufactured by Kao Corporation, Emulgen 120, HLB: 15.3) was used instead of Brij35, and the contents and ratios of Emulgen 120 and BCP were as shown in Table 9 below. The prepared test strips were evaluated in the above items (1) to (3). The results are shown in Table 9 below. The K/S values in Table 9 are K/S values calculated from the measured values of Sample 3, and the evaluation criteria in Table 9 were the same as those in Preparation 3 of test strips for albumin measurement.

The evaluation of the albumin test strips shown in Table 9 is plotted as the BCP content (μg/μL) relative to the amount of sample applied on the horizontal axis and the Emulgen 120 content (μg/μL) relative to the amount of sample applied on the vertical axis in FIG. 13. The same evaluation is plotted as the BCP content (μg/cm ² ) per unit area of the reagent holding layer on the horizontal axis and the Emulgen 120 content (μg/cm ² ) per unit area of the reagent holding layer on the vertical axis in FIG. 14. In FIG. 13 and FIG. 14, the areas corresponding to the test strips that were evaluated as ⊚ in Table 9 are plotted in black, the areas corresponding to the test strips that were evaluated as ◯ are plotted in gray, and the areas corresponding to the test strips that were evaluated as × are plotted in light gray. The numbers in each cell indicate the ratio (D/C, weight ratio) of the Emulgen 120 content to the BCP content. In addition, in Figs. 13 and 14, the test pieces of the examples which satisfy the conditions indicated by the underlined D/C values exhibit a K/S value of 2.2 or more when Sample 3 is measured.

As shown in Table 9 and Figures 13 and 14, in the dry test strips containing Emulgen 120 as component D, the test strips of all Examples were evaluated favorably in both evaluation items (1) and (2), and it was confirmed that albumin can be measured with high sensitivity. Furthermore, it was found that albumin can be measured with high accuracy because it showed high linearity.
As shown in Table 9 above, it was confirmed that in dry test strips containing Emulgen 120 as component D, test strips satisfying the following conditions (Examples 5-1 to 5-4) can measure albumin concentration with high accuracy even when measuring serum containing hemoglobin.
D/C (Emulgen 120/BCP, weight ratio): 1.2-2.3
BCP concentration: 2.2 to 4.3 μg/μL (content: 7.7 to 77.2 μg/cm ² ) Emulgen 120 concentration: 5.0 μg/μL or less (content: 71.4 μg/cm ² or less)
In Table 9 above, the dry test strip of Example 5-2 showed a K/S value of 2.2 or more when measuring Sample 3 with an albumin concentration of 6.5 g/dL (hemoglobin concentration: 0 g/dL). Therefore, with a test strip that satisfies the following conditions, albumin can be measured with higher accuracy even in serum containing a large amount of hemoglobin.
D/C (Emulgen 120/BCP, weight ratio): 1.2-1.4
BCP concentration: 2.2-3.1μg/μL
Emulgen 120 concentration: 1.3-3.8 μg/μL

[Preparation of test strips for albumin measurement 8]
Dry test strips for albumin measurement were prepared in the same manner as in Preparation 1 of test strips for albumin measurement, except that polyoxyethylene (20) sorbitan monooleate (Tween 80, HLB: 15.0) was used instead of Brij 35, and the contents and ratios of Tween 80 and BCP were as shown in Table 10 below. The prepared test strips were evaluated in the above items (1) to (3). The results are shown in Table 10 below. The K/S values in Table 10 are K/S values calculated from the measured values of Sample 3, and the evaluation criteria in Table 10 were the same as those in Preparation 3 of test strips for albumin measurement.

FIG. 15 shows the evaluation of the albumin test strips shown in Table 10, plotted with the BCP content (μg/μL) relative to the amount of sample applied on the horizontal axis and the Tween 80 content (μg/μL) relative to the amount of sample applied on the vertical axis. FIG. 16 shows the same evaluation plotted with the BCP content (μg/cm ² ) per unit area of the reagent holding layer on the horizontal axis and the Tween 80 content (μg/cm ² ) per unit area of the reagent holding layer on the vertical axis. In FIG. 15 and FIG. 16, the areas corresponding to the test strips that were evaluated as ⊚ in Table 10 are plotted in black, the areas corresponding to the test strips that were evaluated as ◯ are plotted in gray, and the areas corresponding to the test strips that were evaluated as × are plotted in light gray. The numbers in each cell indicate the ratio (D/C, weight ratio) of the Tween 80 content to the BCP content. In addition, in Figs. 15 and 16, the test pieces of the examples which satisfy the conditions indicated by the underlined D/C values exhibit a K/S value of 2.2 or more when Sample 3 is measured.

As shown in Table 10 and Figures 15 and 16, in the dry test strips containing Tween 80 as component D, the test strips of all Examples were evaluated favorably in both evaluation items (1) and (2), and it was confirmed that albumin could be measured with high sensitivity. Furthermore, it was found that albumin could be measured with high accuracy because it showed high linearity.
As shown in Table 10 above, it was confirmed that, in dry test strips containing Tween 80 as component D, test strips (Examples 6-1 to 6-11) that satisfy the following conditions can measure albumin concentration with high accuracy even when measuring serum containing hemoglobin. D/C (Tween 80/BCP, weight ratio): 1.2 to 13.9
BCP concentration: 0.5 to 5.4 μg/μL (content: 7.7 to 77.2 μg/cm ² ) Tween 80 concentration: 30 μg/μL or less (content: 428.6 μg/cm ² or less)
The dry test strips of Examples 6-2 to 6-4, 6-6, 6-8, and 6-9 showed a K/S value of 2.2 or more when measuring Sample 3 with an albumin concentration of 6.5 g/dL (hemoglobin concentration: 0 g/dL). Therefore, with test strips that satisfy the following conditions, albumin can be measured with higher accuracy even in serum containing a large amount of hemoglobin.
D/C (Tween80/BCP, weight ratio): 1.2 to 2.3
BCP concentration: 2.2-5.4μg/μL
Tween80 concentration: 12.5μg/μL or less

As is clear from the above evaluation results, the test strips using the following seven types of nonionic surfactants as component D and satisfying the following condition A were evaluated as good in both evaluation items (1) and (2). Therefore, it was found that the test strips using a nonionic surfactant as component D and satisfying the following condition A can measure albumin with high sensitivity. Furthermore, it was found that the test strips exhibit high linearity and can measure albumin with high accuracy. Furthermore, the test strips satisfying the following condition B were also evaluated as good in evaluation item (3). Therefore, it was found that the test strips using a nonionic surfactant as component D and satisfying the following condition B can measure the albumin concentration in serum containing hemoglobin with even higher accuracy.
Component D:
Polyoxyethylene (23) lauryl ether (Brij35, HLB value: 16.9)
Polyoxyethylene distyrenated phenyl ether (Kao Corporation, Emulgen A90, HLB: 14.5)
Polyoxyethylene (13) oleyl ether (Kao Corporation, Emulgen 420, HLB: 13.6)
Polyoxyethylene polyoxypropylene alkyl ether (Kao Corporation, Emulgen LS110, HLB: 13.4)
Polyoxyethylene (20) sorbitan monolaurate (Tween 20, HLB: 16.7)
Polyoxyethylene (12) lauryl ether (Kao Corporation, Emulgen 120, HLB: 15.3)
Polyoxyethylene (20) sorbitan monooleate (Tween 80, HLB: 15.0)
Condition A:
D/C (BCP/nonionic surfactant, weight ratio): 0.3 to 13
Component C (BCP) concentration: 0.4 to 5.4 μg/μL (content: 5.7 to 77.2 μg/cm ² )
Component D (nonionic surfactant) concentration: 25 μg/μL or less (content: 357.1 μg/cm ² or less)
Condition B:
D/C (BCP/nonionic surfactant, weight ratio): 1.3 to 13
Component C (BCP) concentration: 0.4 to 5 μg/μL (content: 5.7 to 71.4 μg/cm ² )
Component D (nonionic surfactant) concentration: 20 μg/μL or less (content: 285.7 μg/cm ² or less)

Claims (16)

A support;
A reagent holding layer is provided on the support and onto which a sample is applied.
A test strip for measuring albumin contained in the sample, comprising:
The reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and a nonionic surfactant (component D),
The nonionic surfactant (component D) is a nonionic surfactant having an HLB value of 13 to 17 selected from the group consisting of polyoxyethylene alkyl ethers, polyoxyethylene distyrenated phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene sorbitan monolaurate, and polyoxyethylene sorbitan monooleate;
In the reagent holding layer,
a weight ratio (D/C) of the component D to the component C is 0.3 to 13;
The content of the component C relative to the amount of the sample spotted is 0.4 μg/μL to 5.4 μg/μL,
The content of the component D relative to the amount of the sample applied is 25 μg/μL or less,
A test strip for measuring albumin , wherein the sample is serum or plasma . a weight ratio (D/C) of the component D to the component C is 1.3 to 13;
The content of the component C relative to the amount of the sample spotted is 0.4 μg/μL to 5 μg/μL,
The test strip according to claim 1 , wherein the content of said component D relative to the amount of said sample applied is 20 μg/μL or less. 3. The test strip according to claim 1, wherein the average number of moles of ethyleneoxy groups added to the nonionic surfactant (component D) is 10 or more and 23 or less. The test strip according to any one of claims 1 to 3, wherein the HLB value of the nonionic surfactant (component D) is 13.4 to 16.9. 5. The test strip of claim 1, wherein the nonionic surfactant (component D) is one or more nonionic surfactants selected from the group consisting of polyoxyethylene (23) lauryl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene (13) oleyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (12) lauryl ether, and polyoxyethylene (20) sorbitan monooleate. The component D is polyoxyethylene (23) lauryl ether,
a weight ratio (D/C) of the component D to the component C is 1.3 to 13;
The content of the component C relative to the amount of the sample spotted is 0.4 μg/μL to 5 μg/μL,
The test strip according to claim 1 , wherein the content of said component D relative to the amount of said sample applied is 20 μg/μL or less. said component D being polyoxyethylene distyrenated phenyl ether;
The weight ratio (D/C) of the component D to the component C is 1.2 to 10.6;
The test strip according to claim 1, wherein the content of component C relative to the amount of the sample spotted is 0.5 μg/μL to 5.4 μg/μL. The component D is polyoxyethylene (13) oleyl ether,
a weight ratio (D/C) of the component D to the component C is 0.9 to 9.3;
The test strip according to claim 1, wherein the content of component C relative to the amount of the sample spotted is 0.5 μg/μL to 5.4 μg/μL. Component D is a polyoxyethylene polyoxypropylene alkyl ether,
The weight ratio (D/C) of the component D to the component C is 1.2 to 2.3;
The test strip according to claim 1, wherein the content of component C relative to the amount of the sample spotted is 2.2 μg/μL to 5.4 μg/μL. The component D is polyoxyethylene (20) sorbitan monolaurate,
The weight ratio (D/C) of the component D to the component C is 1.7 to 2.3;
The test strip according to claim 1, wherein the content of component C relative to the amount of the sample applied is 2.2 μg/μL to 4.3 μg/μL. The component D is polyoxyethylene (12) lauryl ether,
The weight ratio (D/C) of the component D to the component C is 1.2 to 2.3;
The test strip according to claim 1, wherein the content of component C relative to the amount of the sample applied is 2.2 μg/μL to 4.3 μg/μL. A support;
A reagent holding layer is provided on the support and onto which a sample is applied.
A test strip for measuring albumin contained in the sample, comprising:
The reagent holding layer contains a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and a nonionic surfactant (component D),
Component D is polyoxyethylene (20) sorbitan monooleate,
In the reagent holding layer,
a weight ratio (D/C) of the component D to the component C is 1.2 to 13.9;
The content of the component C relative to the amount of the sample spotted is 0.5 μg/μL to 5.4 μg/μL,
The content of the component D relative to the amount of the sample applied is 30 μg/μL or less,
A test strip for measuring albumin , wherein the sample is serum or plasma . The test strip according to any one of claims 1 to 12, wherein the protein denaturant is an anionic surfactant. 1. A method for measuring the amount of albumin in a sample based on a measurement of optical properties of bromocresol purple in the presence of a protein denaturant and an SH reagent, comprising:
The method includes spotting a predetermined amount of a specimen on a reagent holding layer of a test piece, the reagent holding layer including a protein denaturant (component A), an SH reagent (component B), bromocresol purple (component C), and a nonionic surfactant (component D), to prepare a mixed solution of the specimen, the components A, B, C, and D;
The nonionic surfactant (component D) is a nonionic surfactant having an HLB value of 13 to 17 selected from the group consisting of polyoxyethylene alkyl ethers, polyoxyethylene distyrenated phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene sorbitan monolaurate, and polyoxyethylene sorbitan monooleate;
In the mixed solution,
a weight ratio (D/C) of the component D to the component C is 0.3 to 13;
The concentration of the component C is 0.4 μg/μL to 5.4 μg/μL,
The concentration of the component D is 25 μg/μL or less,
A measurement method , wherein the sample is serum or plasma . The method of claim 14, wherein the nonionic surfactant (component D) is one or more nonionic surfactants selected from the group consisting of polyoxyethylene (23) lauryl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene (13) oleyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (12) lauryl ether, and polyoxyethylene (20) sorbitan monooleate. The measurement method according to claim 14 or claim 15 , wherein the test piece is a test piece according to any one of claims 1 to 3 .