JP7379278B2 - Analysis method for phthalate esters - Google Patents

Description

Embodiments of the present invention relate to a method for analyzing phthalate esters.

As environmental issues increase, electrical and electronic products are also required to be manufactured in an environmentally friendly manner. In 2006, the European Union enacted the RoHS Directive (Restriction for the use of certain hazardous substances in electrical and electronic equipment). As described above, regulations on chemical substances have become stricter in recent years, and as companies that manufacture electrical and electronic equipment, it has become extremely important to manage chemical substances in the constituent materials used in products.

Under the revised RoHS Directive, which has been applied since July 2019, four types of phthalate esters (PAE), which are used as plasticizers in resin and rubber materials, have been added to the list of restricted substances, and their thresholds are It is 0.1wt% (1000 ppm).

As methods for screening phthalate esters, thermal desorption gas chromatography mass spectrometry, ion attachment mass spectrometry, and solvent extraction-gas chromatography mass spectrometry are known. However, these analyzes require dedicated expensive equipment and specialized techniques, and it is not easy to analyze components of a wide variety of electrical and electronic devices from an equipment and technical standpoint.

Japanese Patent Application Publication No. 2019-197006

Embodiments of the present invention provide a quick and easy method for analyzing phthalate esters.

The phthalate ester analysis method of the embodiment is a method of thin layer chromatography analysis of phthalate esters, which includes extracting a plasticizer contained in a resin or rubber material, and fixing the extract obtained by the extraction. attaching a standard solution containing phthalate esters of known concentration to the first analysis starting point and a second analysis starting point of the phase; and adhering a standard solution containing phthalate esters of known concentration to the second analysis starting point; The moving distance of the mobile phase from the first analysis starting point is B1, the moving distance of the phthalate spot from the first analysis starting point is A1, and the moving distance of the mobile phase from the second analysis starting point is B2. , where A2 is the moving distance of the spot of phthalate esters with known concentration from the second analysis starting point, A2/B2 of one or more compounds among the phthalate esters contained in the standard solution is the substance-specific Rf value. If it is not 0.93 times or more and 1.03 times or less of including determining the type of.

FIG. 3 is a diagram showing a procedure of an analysis method according to an embodiment. FIG. 2 is a diagram illustrating a detailed procedure of FIG. 1; 1 is a table of Rf values of phthalate esters and substitute compounds for phthalate esters according to embodiments. An image of the results of thin layer chromatography analysis of a solution containing phthalate esters and a substitute compound for phthalate esters according to an embodiment. FIG. 3 is a schematic diagram of analysis results of thin layer chromatography according to an embodiment. An example of a graph showing an approximate formula for determining the concentration of a plasticizer according to an embodiment An image of the analysis results of Example 1.

Hereinafter, a preferred embodiment will be described in detail with reference to the drawings.
(First embodiment)
The analysis method of the first embodiment includes a procedure for extracting a plasticizer from a resin material or a rubber material (S1) and a thin layer chromatography analysis procedure S2, as shown in the diagram of FIG. 1 showing the procedure related to the embodiment. FIG. 2 is a diagram showing a detailed procedure of the procedure shown in FIG.

Preferably, the extraction procedure S1 includes extracting the plasticizer contained in the resin material or rubber material using acetonitrile, ethyl acetate, or isopropanol as an extraction solvent (procedure). Further, the thin layer chromatography analysis procedure S2 may include thin layer chromatography analysis (procedure) in which the extract obtained by the extraction is attached to an analysis starting point of a stationary phase and the extract is developed with a mobile phase. preferable.

The object of analysis is a resin material or a rubber material. In the analysis method of the embodiment, a qualitative analysis or a qualitative analysis and a quantitative analysis of a plasticizer contained in a resin material or a rubber material is performed. If it is unclear whether the object to be analyzed is a resin material or a rubber material, it is preferable to use acetonitrile as the extraction solvent. The analysis target may include additives such as lubricants in addition to plasticizers, resins, and rubbers. When acetonitrile is used as an extraction solvent, the extraction time is preferably 30 minutes or more and 3 hours or less.

When the object to be analyzed is a rubber material, it is preferable to use ethyl acetate or isopropanol. When ethyl acetate is used as an extraction solvent, the extraction time is preferably 3 minutes or more and 10 minutes or less, or 3 minutes or more and 5 minutes or less. Since ethyl acetate is easily absorbed by rubber materials, it is not preferable to extract it for a long time. Since ethyl acetate can extract the plasticizer in a very short time, the analysis can be performed more quickly than the analysis in the first embodiment. When used as an extraction solvent for isopropanol, the extraction time is preferably 1 hour or more and 3 hours or less.

The resin contained in the resin material is not particularly limited. Specific resins contained in the resin material include, for example, polyvinyl chloride, polyethylene, polypropylene, polyester, urethane, vinyl acetate, acrylic resin, epoxy resin, and nitrocellulose. be. A resin material is typically a material in which 50 wt% or more of the sample is resin.

The rubber contained in the rubber material is not particularly limited. Specific rubbers contained in the rubber material include nitrile butadiene rubber, chloroprene rubber, etc. Rubber material is typically a material in which 50 wt% or more of the sample is rubber.

The analysis of the embodiment can perform simple screening of plasticizers in resin materials or rubber materials. The plasticizer of the embodiment is preferably a phthalate ester or a phthalate ester substitute. In the analysis method of the embodiment, the analysis target is a resin material or a rubber material containing a plasticizer of 0.05 wt% or more and 50 wt% or less, 0.7% or more and 50 wt% or less, or 0.1 wt% or more and 50 wt% or less. .

Plasticizers contained in resin materials or rubber materials include dibutyl phthalate (DBP), butylbenzyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP), diisobutyl phthalate (DIBP), and diisononyl phthalate (DINP). ), diisodecyl phthalate (DIDP), di-n-octyl phthalate (DNOP), dicyclohexyl phthalate (DCHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), bis-2-ethylhexyl isophthalate (DOIP) ), tris-2-ethylhexyl terephthalate (DOTP), di-n-hexyl phthalate (DnHP), tris-2-ethylhexyl trimellitate (TOTM) and bis-2-ethylhexyl adipate (DOA). It is preferable that one or more types are used.

Among the plasticizers, dibutyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl phthalate, diisobutyl phthalate, diisononyl phthalate, diisodecyl phthalate, di-n-octyl phthalate, dicyclohexyl phthalate, dimethyl phthalate, Diethyl phthalate, bis-2-ethylhexyl isophthalate, tris-2-ethylhexyl terephthalate and di-n-hexyl phthalate are phthalate esters.

Among these, dibutyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl phthalate, and diisobutyl phthalate are regulated substances under RoHS regulations. The analysis method of the embodiment can quickly and easily analyze whether dibutyl phthalate, benzyl butyl phthalate, di-2-ethylhexyl phthalate, and diisobutyl phthalate are contained in a resin material or a rubber material. . If the regulated conditions change, the phthalate esters of the regulated substances in the embodiment also change.

Trimeth acids and adipic acids are alternative compounds for phthalates. Examples of trimellitic acids include tris-2-ethylhexyl trimellitate (TOTM), trinormalalkyl trimellitate, and triisodecyl trimellitate. Examples of adipate esters include bis-2-ethylhexyl adipate (DOA), diisononyl adipate, and diisodecyl adipate.

Note that the regulated amount under RoHS regulations is 0.1 wt% or more. Therefore, it is preferable as the analysis method of the embodiment to detect regulated phthalate esters of 0.05 wt % below the regulation value or 0.07 wt % or more.

It is preferable to use acetonitrile as the extraction solvent for extracting the plasticizer from the resin material or rubber material. By using acetonitrile as an extraction solvent, it is possible to perform extraction to an extent detectable by thin layer chromatography analysis in a relatively short time, regardless of whether the object to be analyzed is a resin material or a rubber material. By using acetonitrile as an extraction solvent, even if only trace amounts of phthalate esters are contained, the plasticizer can be extracted in a relatively short time of 30 minutes or more and less than 3 hours. Although conditions such as temperature also influence the extraction time, a more preferable extraction time is 1 hour or more and 2 hours or less. The solution in which the plasticizer is eluted into the extraction solvent is referred to as the extraction liquid.

Even if it is uncertain whether the target to be analyzed is a resin material or a rubber material, screening can be performed under the same conditions by using acetonitrile as the extraction solvent. There is no problem if the material of the object to be analyzed is clear, but the printed material may not match the actual material. Therefore, from the viewpoint of more reliable screening, it is preferable to use acetonitrile as the extraction solvent. When it is specified that the target to be analyzed is a rubber material, the plasticizer can be extracted in a short time or a relatively short time by using ethyl acetate or isopropanol as an extraction solvent, as described above.

When acetonitrile is used as the extraction solvent, a solvent other than acetonitrile can be included, but it is preferably 100% acetonitrile. When ethyl acetate is used as the extraction solvent, a solvent other than ethyl acetate may be included, but it is preferably 100% ethyl acetate. When isopropanol is used as the extraction solvent, a solvent other than isopropanol can be included, but it is preferably 100% isopropanol.

It is not preferable to use a solvent such as ethanol as an extraction solvent because it takes several tens of hours or more to extract a low concentration of plasticizer to a detectable extent. Furthermore, acetone can extract plasticizers in a short time. However, acetone, which dissolves resins such as polyvinyl chloride, is not preferred as an extraction solvent. Further, toluene and hexane do not dissolve resins or rubbers, but have a low extraction rate of plasticizers, so they are unsuitable for short-term extraction. Isopropanol can also detectably extract low concentrations of plasticizer in a short period of time.

Preferably, it is extracted from small resin or rubber materials. It is preferable to shred or crush the resin material or rubber material so that the longest side is 4 mm or less. Since extraction from a large member results in poor extraction efficiency, it is preferable to extract from a small member.

When extracting a resin material or rubber material with an extraction solvent, the volume of the extraction solvent (mL) with respect to the mass (mg) of the resin material or rubber material is [volume of extraction solvent (mL)]/[volume of the resin material or rubber material] Mass (mg)] is preferably 1/250 mL/mg or more and 1/1000 mL/mg or less. [Volume of extraction solvent (mL)]/[Mass of resin material or rubber material (mg)] is more preferably 1/500. Further, in extraction, heating can shorten the extraction time. Note that the extraction is preferably performed in a closed container. Further, it is preferable that the resin material or rubber material is immersed in the extraction solvent, and the amount of extraction solvent is not too large. When a large amount of extraction solvent is used, the concentration of plasticizer in the extraction solvent becomes relatively low. By reducing the amount of extraction solvent used, it is possible to increase the plasticizer concentration of the extract to such an extent that it can be directly analyzed by thin layer chromatography without concentrating the solvent after extraction.

Further, during extraction, it is preferable to set the temperature of the extraction solvent to 40°C to 70°C. The extraction rate can be increased by increasing the temperature of the extraction solvent. Moreover, it is preferable to apply ultrasonic waves during extraction. The extraction speed can also be increased by ultrasonic irradiation. Further, during extraction, it is preferable to perform the extraction in a closed container. This method is preferable because it prevents solvent volatilization and allows quantitative analysis of plasticizers.

Under these extraction conditions, the error caused by extraction is small (RSD (relative standard deviation) 10% or less), so highly reliable analysis can be performed.

In the thin layer chromatography analysis of the embodiment, it is preferable to use a plate for reversed phase chromatography (reversed phase plate) using a column (stationary phase) with low polarity. Plasticizers can be analyzed using plates for normal phase chromatography using highly polar columns (stationary phase), but when analyzing phthalate esters, analysis accuracy can be improved by using a reversed phase plate. can.

The reverse phase plate is preferably one in which a stationary phase such as silica gel is laminated on a support. Examples of the support include glass, aluminum sheet, and plastic sheet. Moreover, it is preferable that the silica gel is chemically modified. Chemical modifications to silica gel include octadecyl group (C18), octyl group (C8), and dimethylsilyl group (Si(CH ₃ ) ₂ ). As a chemical modification to silica gel, an octadecyl group (C18) is preferred in the analysis of phthalate esters using acetonitrile as a mobile phase.

The analysis method will be described below with reference to the diagram of FIG. 2 showing the procedure. The diagram showing the procedure in Figure 2 includes extracting the plasticizer from the resin material or rubber material (procedure) (S1), spotting the extract onto the stationary phase (procedure) (S2A), and fixing the standard solution. Spotting onto the phase (procedure) (S2B), developing the extract and standard solution in the mobile phase (S2C), measuring the Rf value of each spot (S2D), determining the type of plasticizer from the Rf value What to do (procedure) (S2E), and if it does not match the Rf value of phthalate esters, terminate the analysis (S2F), or if it matches the Rf value of phthalate esters, perform concentration analysis. The flow for precise analysis (S2G) is described. Concentration analysis and precision analysis can be omitted in the analysis method of the embodiment.

Hereinafter, the procedures after S2A, which are thin layer chromatography analysis procedures, will be explained. First, the extract obtained by extraction is spotted (S2A) on a stationary phase (reversed phase plate), and the extract is attached to the analysis starting point of the stationary phase. The extract solution is spotted on both the first analysis starting point where the standard solution is not spotted and the second analysis starting point where the standard solution is spotted. In order to be able to detect even a low concentration of plasticizer in a resin material or rubber material, it is preferable to spot a small amount of the extract multiple times. For example, it is preferable that one spotting volume is 0.5 μL or more and 1.5 μL or less, and the spotting is performed 5 times or more and 10 times or less. A capillary tube or pipettor is used for spotting. To give a specific example, if a plasticizer is extracted from a resin or rubber material containing 0.07 wt% of regulated phthalate esters, 1 μL can be spotted 5 times to perform thin layer chromatography analysis. Can be detected. Therefore, it is preferable to spot 1 μL five or more times. If the plasticizer concentration is high, it is preferable to dilute the extract or perform analysis by reducing the number of spottings.

Even when only the extract is spotted, it is often possible to analyze what kind of plasticizer is contained in the sample based on the Rf value specific to the substance. However, if an adipic acid ester used as a plasticizer is included, the Rf value may shift. If a plasticizer whose Rf value shifts is included, if only the extract is spotted and analyzed, the presence or absence of a regulated plasticizer may be incorrectly determined, and qualitative analysis of the plasticizer may not be possible.

By spotting a standard solution containing a plasticizer with a known concentration on the spot where the extract was spotted, it is possible to determine whether or not the Rf value of a specific plasticizer has shifted. Then, even if the Rf value is shifted, qualitative analysis of the plasticizer contained in the sample can be performed with high reliability. When using a standard solution, analysis can be performed even if the Rf value does not shift, so analysis can be performed regardless of whether or not adipic acid ester, etc., which causes a shift in the Rf value, is contained. In addition, if there is no plasticizer corresponding to the Rf value obtained by analysis without using the standard solution (analysis using the procedure excluding spotting the standard solution on the stationary phase (procedure) (S2B)), spotting the standard solution By doing so, highly reliable analysis can be performed even when the Rf value has shifted.

When the extract contains an adipic acid ester, the Rf value of the plasticizer having an Rf value in the range of 0.40 to more than 0.60 tends to shift. As the concentration of adipate ester increases, the amount of shift in the Rf value tends to increase, making qualitative analysis difficult in some cases. In such cases, by including a plasticizer with an original Rf value of 0.40 to over 0.60 in the standard solution, highly reliable qualitative analysis can be performed even if the Rf value has shifted. be able to. Adipate esters do not absorb even when irradiated with UV, so if a shift in Rf value is confirmed from the plate after development, in other words, a spot with an Rf value that does not correspond to the Rf value of the known plasticizer will occur. This indicates that a plasticizer that does not absorb UV is contained.

A standard solution is a solution containing a plasticizer of known concentration. From the perspective of determining the presence or absence of regulated plasticizers, the plasticizers included in the standard solution include regulated plasticizers dibutyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl phthalate, and diisobutyl phthalate. It is preferable that one or more types selected from the group consisting of these phthalate esters are included, and it is preferable that all of these four types of phthalate esters are included.

The analysis starting point, where spotting is performed, is preferably separated from the lower end of the stationary phase by, for example, about 1 cm or more and 2 cm or less. It is preferable for the mobile phase development distance to be 7 cm or more for analysis of phthalate esters. Therefore, the distance from the upper end of the stationary phase to the analysis starting point is preferably longer than 7 cm. The longer the deployment distance, the easier the analysis, but the longer the analysis time, so the deployment distance is preferably 7 cm or more and 25 cm or less, 7 cm or more and 20 cm or less, or 7 cm or more and 17 cm or less. Since the size of commercially available plates is 10 cm or 20 cm, the deployment distance is preferably 7 cm or 17 cm. If the deployment distance is short, it will be difficult to separate, so the deployment distance is preferably 17 cm.

Next, the standard solution is spotted onto the second analysis starting point (S2B) to adhere the standard solution to the second analysis starting point of the stationary phase. The standard solution contains each plasticizer at a concentration of 1 mg/L or more and 5 mg/L or less. The solvent for the standard solution is not particularly limited, but it is typically preferable to use acetonitrile, tetrahydrofuran, acetone, and methanol. It is preferable to carry out spotting an appropriate number of times depending on the concentration of the plasticizer in the standard solution.

A third analysis starting point is provided, and only the standard solution is spotted on the third analysis starting point, and a spot developed from the second analysis starting point where the extract solution and the standard solution are spotted and a spot developed from the third analysis starting point are separated. By comparing, it can be determined whether the extract contains a substance that shifts the Rf value.

Next, the extract and standard solution are developed with a mobile phase (S2C). Specifically, the lower end of a stationary phase (reversed phase plate) on which the extract and standard solution are attached by spotting the extract at the analysis starting point is immersed in a developing solvent, which is a mobile phase. Then, the extract solution and standard solution are developed by the mobile phase, and a spot appears. When developing the extract and the standard solution, it is preferable to carry out the development in a space that contains a developing solvent as a mobile phase and is filled with the vapor of the developing solvent. As the mobile phase, it is preferable to use acetonitrile. It does not matter if the acetonitrile contains an additive for pH adjustment or the like. By using the same acetonitrile as the extraction solvent and the developing solvent, one type of solvent is used in the analysis, which improves the convenience of the analysis and is also preferable from the viewpoint of waste liquid treatment. From the same point of view, it is preferable that the solvent of the standard solution is also the same as the extraction solvent and the developing solvent.

Next, the Rf value of each spot is measured (S2D). The moving distance of the mobile phase from the first analysis starting point is defined as B1, and the moving distance from the first analysis starting point to a spot (specifically, a spot of phthalate esters) generated by development of the extract solution is defined as A1. The Rf value of phthalate esters contained in the extract is determined from A1/B1. In addition, the moving distance of the mobile phase from the second analysis starting point is defined as B2, and the moving distance from the second analysis starting point to the spot generated by the development of the standard solution (specifically, the known spot of phthalate ester) Assuming that A2 is A2, the Rf value of phthalate esters whose concentration is known and is contained in the standard solution can be found from A2/B2.

First, take out the stationary phase (reversed phase plate) that has been immersed in the developing solvent, which is the mobile phase, and mark the position where the developing solvent has risen. The mark is, for example, a straight line indicating the position where the developing solvent has risen. The distance between the mark placed at the position where the developing solvent has risen and the analysis starting point is the moving distance B of the mobile phase from the analysis starting point. Next, a UV lamp (wavelength: 254 nm) is irradiated to mark a spot that emits fluorescence. The distance between the spot mark and the analysis starting point is the distance A from the analysis starting point to the spot generated by the expansion of the extract.

The Rf value is a value specific to a substance. FIG. 3 shows a table of Rf values of phthalate esters and substitute compounds for phthalate esters. Moreover, FIG. 4 is an image showing the results of thin layer chromatography analysis of a solution containing phthalate esters and a substitute compound for phthalate esters. Although some phthalate esters have close Rf values and are difficult to identify, it is possible to determine the possibility that regulated phthalate esters are contained using the analysis method of the embodiment. The resulting image in FIG. 4 is the result obtained under the condition that the Rf value does not shift, and the development distance is 17 cm. When the development distance is 17 cm, it is also possible to separate di-2-ethylhexyl phthalate (DEHP) and di-n-octyl phthalate (DNOP), which have similar Rf values.

Next, the type of plasticizer is determined based on the Rf value determined from each spot (S2E). In this determination, it is determined whether the Rf value (Rf _n ) specific to the phthalate ester substance matches or the Rf value of the phthalate ester obtained from the standard solution. More specifically, the plasticizer contained in the extract attached to the first analysis starting point is one selected from the group consisting of dibutyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl phthalate, and diisobutyl phthalate. It is determined whether or not the above is included. The Rf value of each compound shown in FIG. 3 and the Rf value determined from each spot are compared. Let the Rf value of the regulated object shown in Figure 3 be Rf _n , and when the Rf value obtained from the spot satisfies 0.93Rf _n or more and 1.03 Rf _n or less, the Rf value obtained from the spot and the regulated phthalate ester It is determined that the Rf values (Rf _n ) match. That is, the Rf value determined from the spot allows an error of ±3%. For example, the Rf value of the spot is 0.41 or more and 0.43 or less (bis(2-ethylhexyl) phthalate), 0.78 or more and 0.82 or less (butylbenzyl phthalate), or 0.73 or more and 0.77 or less. (dibutyl phthalate) and 0.74 or more and 0.78 or less (diisobutyl phthalate), it is determined that the plasticizer is a regulated phthalate ester. As a quick and simple analysis method, it is sufficient to be able to screen whether the plasticizer is a regulated phthalate ester. Even considering the error, the Rf values of the plasticizers shown in the table in Figure 3 are the same as those for regulated phthalate esters (bis(2-ethylhexyl phthalate (0.41 or more and 0.43 or less)), butylbenzyl phthalate, etc. (0.78 or more and 0.82 or less), dibutyl phthalate (0.73 or more and 0.77 or less), diisobutyl phthalate (0.74 or more and 0.78 or less)) and non-regulated plasticizers (diisononyl phthalate). (0.32 to 0.34), diisodecyl phthalate (0.26 to 0.28), di-n-octyl phthalate (0.36 to 0.38), dicyclohexyl phthalate (0.60 0.64 or more), dimethyl phthalate (0.86 or more and 0.92 or less), diethyl phthalate (0.83 or more and 0.89 or less), bis-2-ethylhexyl isophthalate (0.27 or more and 0.29 (below), tris-2-ethylhexyl terephthalate (0.26 or more and 0.28 or less), and tris(2-ethylhexyl) trimetate (0.17 or more and 0.19 or less)). Therefore, practical screening of phthalate esters and alternative materials can be performed using a quick and simple analysis method called thin layer chromatography analysis. In addition, the results can be used to perform concentration analysis, and precise analysis by thermal desorption gas chromatography mass spectrometry, ion attachment mass spectrometry, solvent extraction-gas chromatography mass spectrometry, etc.

In addition, if the Rf value determined from the spot does not satisfy the range of 0.97Rfn _or more and _1.03Rfn or less, the Rf value determined from the spot and the Rf value ( _Rfn ) of the regulated phthalate ester do not match. judge. When the Rf value obtained from the spot and the Rf value (Rf _n ) of the regulated phthalate esters do not match, it is assumed that the analyzed resin material or rubber material does not contain the regulated phthalate esters. , the analyzed resin or rubber material contains regulated phthalate esters, but the Rf value shifts due to adipate ester, making it impossible to determine whether it contains regulated phthalate esters. There are cases. In such a situation, the Rf value (=A1/B1) of the spot starting from the first analysis and the Rf value (=A2/B2) of the spot starting from the second analysis are compared to determine the phthalate ester contained in the extract. Determine the type of class. More specifically, the Rf value (=A1/B1) of the spot starting from the first analysis is in the range from 0.95 times to 1.05 times the Rf value (=A2/B2) of the spot starting from the second analysis. If they match, it can be determined whether the phthalate esters in the standard solution, the type of which is known in advance, are included in the phthalate esters contained in the extract. In this way, by comparing the spots generated by development from the first analysis starting point and the spots generated by development from the second analysis starting point, it can be determined whether it is one of the above two cases. After comparing the Rf values and performing qualitative analysis, the spot area with a migration distance of A1 and the spot area with a migration distance of A2 are compared, and the extract solution is determined based on the concentration of phthalate esters contained in the standard solution. The concentration of phthalate esters contained in can be quantitatively analyzed.

Here, the analysis method in the above case will be explained using the schematic diagram of the analysis results of thin layer chromatography shown in FIG. FIG. 5 shows the results developed from six analysis starting points from α to ζ. In FIG. 5, analysis is performed on one plate, but analysis may be performed on multiple plates. The x in FIG. 5 is the analysis starting point and is the spot where the extract and standard solution are spotted. The developing solvent has moved to the thin solid line in FIG. 5, and the distance from the x point to the thin solid line is the moving distance (B) of the mobile phase. Further, the distance (A) from x is determined for each spot, and the Rf value of each spot is determined. The standard solution contains benzyl butyl phthalate, dibutyl phthalate and diisobutyl phthalate, and di-2-ethylhexyl phthalate.

α in FIG. 5 is the result of spotting and analyzing the standard solution once. When spotting an extract solution and a standard solution on the same analysis starting point, the standard solution contains 3 times as much water as the extract solution in order to easily distinguish whether the spot originates from the extract solution or the standard solution. From the above, it is preferable to use a solution with a concentration about 20 times higher. In addition, when spotting a volume of the standard solution equal to or larger than that of the extract, the shift in the Rf value that occurs in the extract due to dropping a large amount of the standard solution at the starting point of analysis is caused by spotting the extract and the standard solution. The shift of is easy to change. Therefore, when spotting both the standard solution and the extract, the spotting capacity of the standard solution is less than or equal to the spotting capacity of the extract, preferably 1/2 or less of the spotting capacity of the extract. More preferably, it is 1/5 or less of the spotting capacity. The effect of the shift in Rf value is that a higher concentration of plasticizer is dissolved in the standard solution than in the extract solution.

β is the result of spotting and analysis of extract A obtained by extracting the plasticizer from sample A containing adipic acid ester as a plasticizer. γ is the result of spotting analysis of extract A and standard solution. δ is the result of spotting and analyzing twice the amount of standard solution as γ. ε is the result of spotting and analysis of extract B obtained by extracting plasticizer from sample B which does not contain adipic acid ester. ζ is the result of spotting analysis of extract B and standard solution. Although it depends on the concentration of the compound that shifts the Rf value, the Rf value shifts by about 0.25 at most. If a spot with an Rf value in the range of 0.40 to 0.65 (or 0.62) is confirmed, the Rf value may have shifted because the extract contains adipic acid ester, etc. . Qualitative analysis using a standard solution is performed when spots with Rf values in the range of 0.40 to 0.65 (or 0.62) are confirmed, thereby increasing the reliability of the analysis. In addition, if the Rf value is shifted by another compound, there is a possibility that the Rf value will shift by about 0.25 at most outside the range of Rf value from 0.40 to 0.65 (or 0.62). However, with the analysis method of the embodiment, a highly reliable analysis can be quickly performed even if the Rf value shifts in any range. In the case of adipic acid ester, there is almost no shift if it is contained in a trace amount, but a shift in the Rf value is confirmed when it is contained at about 10 wt%, and when it is contained at about 20 wt%, the Rf value of di-2-ethylhexyl phthalate is about 0. .20 shift.

First, when looking at the standard solution of α, spots where the calculated Rf value is around 0.42, 0.76, and 0.80 have been confirmed, and the Rf value of the regulated plasticizer contained in the standard solution is confirmed. Match. When only β extract A is spotted, spots with calculated Rf values of around 0.27, 0.50, 0.76, and 0.80 are confirmed. Referring to the table in Figure 3, the spot with an Rf value of 0.27 is derived from bis(2-ethylhexyl) isophthalate or bis(2-ethylhexyl) terephthalate, and the spot with an Rf value of 0.76 is derived from dibutyl phthalate. Alternatively, spots with an Rf value of 0.80 originate from diisobutyl phthalate, but spots with an Rf value of 0.50 do not have the corresponding plasticizer.

Comparing only the α and β analysis results in Figure 5, it is unclear which spot has an Rf value of 0.50 in the β analysis result, but the γ analysis result obtained by spotting both the standard solution and extract A is Qualitative analysis becomes possible when this is taken into account. When spotting γ extract A and standard solution, spots with calculated Rf values of around 0.27, 0.50, 0.76, and 0.80 are confirmed. In the analysis results for γ, as with the analysis results for β, for spots with an Rf value of 0.50, there is no corresponding plasticizer even when examined based on the Rf value specific to the substance. In the α analysis results obtained by spotting only the standard solution, the Rf value did not shift, and a large-area spot was confirmed with an Rf value of 0.42 indicating the presence of a high concentration of di-2-ethylhexyl phthalate. In the analysis results for γ, there is no spot with an Rf value of 0.42, and a spot with an Rf value of 0.50 with an area comparable to or larger than the analysis results for α is confirmed, indicating that extract A contains phthalic acid. There is a compound that shifts the Rf value of di-2-ethylhexyl, and it can be determined that extract A contains di-2-ethylhexyl phthalate. In other words, using the correspondence between the types of phthalate esters and the Rf value determined from the analysis results of γ, the phthalate esters contained in extract A are determined from the Rf value determined from the analysis results of extract A. can be specified.

In addition to the γ analysis results, the plasticizer can be quantitatively analyzed from the spot area of the β analysis results. For example, from the spot area with an Rf value of 0.50 in the analysis of γ, the area of the spot with the Rf value of 0.42 in the analysis of α, or the area of the spot with the Rf value of 0.50 in the analysis of β, The amount (mass or number of moles) of di-2-ethylhexyl phthalate is determined. Considering the amount of extract A used in the analysis of γ, the concentration of di-2-ethylhexyl phthalate in extract A can be determined. An approximate formula may be used for this calculation. FIG. 6 shows an example of a graph showing an approximate formula for determining the concentration of plasticizer. In the graph of the approximate equation in FIG. 6, the horizontal axis represents the concentration (mg/ml) of the plasticizer to be analyzed contained in the standard solution spotted and added to the analysis starting point, and the vertical axis represents the spot area. FIG. 6 shows the concentration of di-2-ethylhexyl phthalate. Determine the spot area of di-2-ethylhexyl phthalate in β analysis by spotting extract A. Here, the obtained spot area is assumed to be S1. Then, as shown in the graph of FIG. 6, the results of the analysis of β are plotted (P _β ) where the horizontal axis is zero and the vertical axis is S1. Next, the spot area of di-2-ethylhexyl phthalate in the γ analysis by spotting the extract A and the standard solution is determined. Here, the obtained spot area is assumed to be S2. When the amount of di-2-ethylhexyl phthalate added in the analysis of γ is M2, as shown in the graph of Figure 6, the results of the analysis of δ are plotted where the horizontal axis is M2 and the vertical axis is S2 (P _γ ). An approximate expression is found from the two plots P _β and P _γ . The approximation formula is, for example, a linear approximation formula. By extending the approximate formula in the negative direction of the horizontal axis, the absolute value of the value when the approximate formula crosses the horizontal axis (M0: concentration when the spot area of the approximate formula becomes zero) is the phthalic acid in extract A. This is the concentration of di-2-ethylhexyl. Therefore, when an approximate formula is obtained from the plot of two points, the approximate formula is y = ((S2-S1)/M2)x+S1, and the concentration of di-2-ethylhexyl phthalate in extract A is |(-S1・M2)/(S2-S1)| The concentration of the plasticizer in the sample is determined from the concentration of the plasticizer in the extract A and the conditions for obtaining the extract from the sample. In order to increase the reliability of quantitative analysis, it is preferable to conduct an analysis in which the number of spottings of extract A or standard solution is different from γ. For example, the spot area for δ analysis is determined by doubling the number of spottings of the standard solution as for γ analysis. Then, an approximate formula is calculated to determine the amount of di-2-ethylhexyl phthalate according to the area from the spot area of analysis from β to δ, and the number of spots for extract A is further taken into consideration. The concentration of di-2-ethylhexyl can be determined.

Note that when extract B is spotted and qualitatively analyzed, the results of ε and ζ in FIG. 5 are obtained. Since the spot of the standard solution did not shift even when both extract B and the standard solution were spotted, it can be seen that extract B does not contain a compound that causes the spot to shift. Since the Rf values of neither the ε spot nor the ζ spot have shifted, qualitative analysis is possible from the analysis results of ε, and the concentration of plasticizer in extract B can be determined by considering the analysis results of ε and ζ. You can ask for it.

If it is determined that the spot area of each regulated plasticizer in the standard solution of α analysis has not increased in the analysis of γ, δ, and ζ, the regulated phthalate esters are the resin materials or rubbers analyzed. It is determined that it is not included in the material, and the analysis is ended (S2F).

When it is determined that the Rf value obtained from the spot and the Rf value (Rf _n ) of phthalate esters match, the concentration analysis of phthalate esters (for example, the above-mentioned quantitative analysis) is performed based on the results of thin layer chromatography analysis. analysis) or precise analysis (S2G). Note that the S2F analysis procedure is an arbitrary analysis procedure as described above, and can be omitted as a quick and simple analysis method.

Note that the Rf value of each spot can be determined by visually observing an image taken by irradiating with a UV lamp or by using image processing software. An example of the image processing software is Just TLC.

Concentration analysis is performed using image processing software. The compound concentration of each spot can be determined by analyzing the image taken by irradiating with a UV lamp using image processing software. Examples of precise analysis include thermal desorption gas chromatography mass spectrometry and ion attachment mass spectrometry.

Note that if a series of analysis conditions including sample processing are unified, the type of plasticizer can be determined from the distance A from the analysis starting point to the spot created by the expansion of the extract.

According to this embodiment, even if the Rf value shifts, phthalate esters can be analyzed quickly and easily. The analytical method can be applied to concentrations from below the minimum regulatory limit of very small amounts to high concentrations, and is preferred as a primary screening method for a wide variety of products. For example, even if the sample is labeled as PVC but is made of rubber, analysis of phthalate esters can be performed, so the analysis method of the embodiment is excellent in reliability. Thin layer chromatography analysis is preferable for primary screening where testing of all samples is required, as it allows multiple analyzes to be performed simultaneously. The analysis method of the embodiment is preferable as a primary screening method for a wide variety of products because it does not require expensive equipment or advanced technology. The quick and easy analysis of embodiments can prevent distribution of products containing regulated phthalates.

Hereinafter, the analysis method of this embodiment will be explained in more detail with reference to Examples.
(Example 1)
Example 1 is an experiment in which the possibility of detecting regulated phthalate esters was investigated by thin layer chromatography analysis using samples (samples A and B) in which the type and concentration of plasticizer were known in advance. Sample A is polyvinyl chloride (resin material) containing about 20 wt% of adipate ester. Sample B is polyvinyl chloride without adipate ester. Sample A and Sample B are samples prepared for Examples, and each contains diisobutyl phthalate, dibutyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl phthalate, dicyclohexyl phthalate, diisononyl phthalate, diisodecyl phthalate, and diisobutyl phthalate. Each contains 1000 mg/kg of di-n-hexyl phthalate. The two samples were cut into pieces with scissors so that the long sides were 4 mm or less, and 250 mg of each was measured and placed in separate 2 mL crimp vials. Then, add 0.5 mL of acetonitrile as an extraction solvent to the crimp vial and seal it with a lid. Then, while performing ultrasonic irradiation at 60° C., the plasticizer contained in the sample was extracted to obtain an extract. The extraction time for samples A and B was 1 hour. The obtained extract was added 5 times with 1 μL each to 20 cm x 20 cm Merck RP-18F254s (reversed phase plate) at 3 locations each (first analysis starting point, second analysis starting point). , third analysis starting point) was spotted. A standard solution was also spotted at the second analysis starting point and the third analysis starting point of each sample. The standard solution contains 2.5 g/mL each of diisobutyl phthalate, dibutyl phthalate, benzyl butyl phthalate, and di-2-ethylhexyl phthalate. 1 μL was spotted once on the second analysis starting point, and 1 μL was spotted twice on the third analysis starting point. Spotting was performed so that the analysis starting point was 2 cm from the bottom edge of the reversed phase plate.

Acetonitrile is added in advance to a container that can accommodate a 20 cm x 20 cm plate, and the container is filled with vaporized acetonitrile. At this time, the liquid level height of acetonitrile was set to about 1 cm. Place the spotted reversed-phase plate into the container so that the lower end of the spotted reversed-phase plate is immersed in acetonitrile, and when the development distance (the height of the acetonitrile from the analysis starting point, which is the spotting point) reaches 17 cm, remove the plate from the container. The reverse phase plate was taken out.

The removed reverse phase plate was irradiated with a 254 nm UV lamp and photographed with a digital camera under strobe non-emission conditions. The captured images were analyzed using Just TLC, a thin layer chromatography analysis software. FIG. 7 shows an image of the analysis results of sample A of Example 1. FIG. 7 shows spots developed from the first analysis starting point, the second analysis starting point, and the third analysis starting point in order from the left. The Rf value of each spot of each sample was determined visually and using image processing software, and the type of plasticizer contained in the sample was investigated. The type of plasticizer determined from the Rf value of the sample containing no adipate ester matched the previously known type of plasticizer. On the other hand, in the sample containing adipic acid ester, the Rf value determined from the spot of di-2-ethylhexyl phthalate inside the dashed line in Figure 7 was shifted; Since the Rf value of the spot of di-2-ethylhexyl phthalate developed from the starting point was similarly shifted, it was possible to identify the type of plasticizer contained in the extract even in the sample containing adipic acid ester. The Rf value of di-2-ethylhexyl phthalate, for which the Rf value of sample A has shifted, is generally the same for spots developed from any of the first to third analysis starting points, and even when spotting a standard solution, extraction is not possible. The Rf value shifted as in the case where only the liquid was spotted. If the shift amount of the Rf value in the spots developed from the first analysis starting point and the third analysis starting point changes enough to affect the qualitative analysis, the reliability of the analysis will be low, but the results of Example 1 It was confirmed that in the analysis method of the embodiment, the variation in the shift amount of the Rf value is small, and the reliability of the analysis is high from this point of view as well. In the analysis of sample B, the Rf value of each spot all matched the Rf value specific to the substance, so the plasticizer in sample B could be identified without considering the spot that was the starting point of the second analysis where the standard solution was spotted. I was able to do that. Similar results were obtained both visually and by software analysis. Then, the concentration of plasticizer was analyzed from each spot area using Just TLC. Since the concentration of each plasticizer in the standard solution is known, the concentration of the plasticizer in the extract can be easily determined. Approximate formula for the concentration determined from the areas of spots developed from the first analysis starting point, second analysis starting point, and third analysis starting point and the area of only the spots developed from the first analysis starting point and second analysis starting point The concentration approximation equations obtained from the above were generally in agreement, and the plasticizer concentration obtained from either approximation equation had a concentration error of less than 10% from the sample concentration of 1000 mg/kg.

Example 1 shows that it is possible to detect phthalate esters at a level around the regulatory value both in cases in which adipate esters are included and in cases in which they are not included. Since both visual inspection and analysis using image processing software can be performed quickly and easily, Example 1 shows that the analysis method of the embodiment is highly reliable as a primary screening.

Example 1 was evaluated using a sample prepared for the example in order to evaluate the influence of adipate ester. A sample can also be analyzed in the same way.

Furthermore, the analysis method of the embodiment is a reliable screening method in that it is possible to analyze the type and concentration of plasticizer by performing image analysis even when it is developed in a line rather than a spot. It shows.

Although the explanation has mainly been given to determining whether or not a regulated plasticizer is contained, the analysis method of the embodiment can analyze not only regulated plasticizers. The practical analysis method is a quick and reliable screening method that includes the plasticizer to be analyzed in the standard price.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

Claims (4)

A method for thin layer chromatography analysis of phthalate esters, the method comprising:
Extracting the plasticizer contained in the resin or rubber material,
attaching the extract obtained by the extraction to a first analysis starting point and a second analysis starting point of the stationary phase;
attaching a standard solution containing phthalate esters of known concentration to the second analysis starting point;
Developing the extract and standard solution in a mobile phase;
The moving distance of the mobile phase from the first analysis starting point is B1, the moving distance of the phthalate spot from the first analysis starting point is A1, the moving distance of the mobile phase from the second analysis starting point is B2, and the moving distance of the mobile phase from the second analysis starting point is B2. Assuming that the moving distance of the spot of the phthalate ester with a known concentration from the second analysis starting point is A2, A2/B2 of one or more compounds among the phthalate esters contained in the standard solution is Rf specific to the substance. If the value is not 0.93 times or more and 1.03 times or less, the Rf value specific to the substance and A1/B1 are not compared, but the A1/B1 and A2/B2 are compared to determine the phthalate contained in the extract. A method for analyzing phthalate esters, including determining the type of acid esters. Compare the spot area with the moving distance A1 and the spot area with the moving distance A2 to determine the concentration of phthalate esters contained in the extract based on the concentration of phthalate esters contained in the standard solution. The method for analyzing phthalate esters according to claim 1, which includes quantitative analysis. The method for analyzing phthalate esters according to claim 1 or 2, comprising a spot where the A1/B1 is from 0.40 to 0.65. attaching the standard solution to a third analysis starting point of the stationary phase without attaching the extract obtained by the extraction and developing the standard solution with the mobile phase;
The moving distance of the mobile phase from the third analysis starting point is B3, and the moving distance of the phthalate spot from the first analysis starting point is A3,
The phthalate according to any one of claims 1 to 3, wherein the shift of A1/B1 or/and A2/B2 and A3/B3 is confirmed by comparing A1/B1 or/and A2/B2 and A3/B3. Analysis method for acid esters.