JPH0616053B2 - Flow injection analysis method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a quantitative analysis method for quantitatively knowing a chemical composition of a substance, more specifically, a flow injection analysis method (hereinafter referred to as FIA). It is about improvement.

That is, a small amount of sample solution and reagent solution are made to flow into a corrosion-resistant tube such as a Teflon tube to react with each other, and the reaction product is measured in a flow cell by utilizing physical or chemical characteristics (generally, an absorption The present invention relates to the improvement of an analytical technique for quantifying a target chemical component in the sample.

(B) Background Art As the wet chemical analysis methods for quantifying the amounts of the constituent substances that compose the sample, there are mainly a gravimetric method, a volumetric method and an absorptiometric method.

The gravimetric method separates the target component as a 100% insoluble precipitate, and weighs this to perform quantification. The volumetric analysis method and the absorptiometric method use a reagent solution of known concentration as a solution of the target component. The content of the target component is calculated by determining the equivalent point or the absorbance at which 100% of the components are reacted.

In the absorptiometric analysis method, it is necessary that the reaction proceeds quantitatively without any side reaction, that the end of the reaction can be known quickly and clearly, and that the reaction rate is fast.

In this absorption spectrophotometric analysis, the target component is 100%.
% As a completely colored compound, its absorbance is measured and quantified.

In this way, the fundamental idea of quantitative analysis is to limit the number of target components to 1
It is an essential condition to quantify after reacting near to 00%.

However, FIA is simple in analytical operation and suitable for the analysis of multiple samples. For example, a reaction product is produced by mixing and reacting a reagent solution with a reagent solution in an ultrafine Teflon tube. Has a short residence time and is therefore a very short reaction, so in most cases the reaction is
The present situation is that complete quantitative analysis is not completed because the reaction is not completely completed at 00% and is often in the middle of reaction.

In view of such problems of the conventional FIA, the present invention aims to make the reaction rate of the FIA infinitely close to 100%, keep the reaction conditions constant, and even if the reaction rate does not reach 100%, a constant reaction close to 100%. It is developed as a fundamental design concept that the rate is obtained.

(C) Disclosure of the Invention The present invention solves the above-mentioned problems of FIA and provides an application technique for assembling a flow line that enables more accurate quantification, and provides a sample solution and a sample solution, respectively. Flow of sample solution and sample solution in a flow injection analysis method in which a small amount of both solutions are alternately sent to the mixing flow line and mixed and reacted after passing through independent flow lines. The inner diameter of each line should be 0.25 mm or more and 1.0 mm or less,
Further, by using a pulseless double plunger type metering pump, the discharge amount per stroke of the both liquids alternately delivered is set to 1.25 μ or more and 20 μ or less to improve the mixing ratio of the both liquids. Furthermore, the reaction cell in the mixing flow line is installed in a constant temperature bath to keep the reaction temperature constant to increase the reaction rate, and a back pressure coil is arranged at the rear of the flow cell provided at the end of the mixing flow line. The present invention relates to a flow injection analysis method which is installed to adjust the internal pressure of all flow lines to prevent generation of bubbles and to obtain a stable steady flow without pulsation.
That is, the present invention has been improved according to the following concept.

(a) A sample solution and a reagent solution are alternately sent in small amounts, and both solutions are in a thin reaction tube so that they have a large surface area and are in liquid-liquid contact with each other to allow sufficient mixing to increase the reaction rate.

(b) The reaction rate is kept constant by keeping the flow rates of the reagent solution and the sample solution constant and the reaction temperature constant.

Therefore, in the method of the present invention, the sample solution and the reagent solution are caused to flow through independent flow lines, respectively, and thereafter, both liquids are alternately fed to the mixing flow line in small amounts of predetermined amounts to be mixed and reacted. .

Further, by installing the reaction cell in the mixing flow line in a thermostat, the reaction temperature of the reaction system is kept constant to increase the reaction rate and make it constant, and further, the flow cell provided at the end of the mixing flow line. By disposing a back pressure coil in the rear part, it is possible to adjust the internal pressure of all flow lines to prevent the generation of bubbles and to obtain a stable steady flow without pulsation.

It is preferable that the amount of sample solution and reagent solution sent is as small as possible. However, due to various factors such as the flow rate accuracy of the solution sending pump, the viscosity of the reagent and sample solution, and the accuracy of the inner diameter of the reaction tube,
Naturally, the optimum range of the inner diameter of the flow line and the liquid transfer amount is limited.

That is, if the inner diameter of the tube in the flow line is less than 0.25 mm, not only the inner wall of the tube and the flow resistance of the solution become high and the inner pressure becomes high, but also the mixing of the sample solution and the reagent solution becomes insufficient. Also, if the inner diameter exceeds 1.0 mm, the flow resistance in the tube will decrease, and at the same time, the internal pressure will also decrease, making the device manufacturing and handling easier, but consuming more reagents and samples than necessary, and reducing costs. It becomes high.

On the other hand, if the inner diameter of the tube is determined, the optimum flow rate is naturally limited to a certain range. Particularly, in order to keep the reaction rate high and constant by alternately feeding a small amount of liquid to the mixing / reacting ly with high accuracy, If the batch feed amount is less than 1.25μ, the feeding precision is poor, and if it exceeds 20μ, the mixing of the reagent solution and the reagent solution becomes insufficient.

Therefore, the inner diameters of the independent flow lines of the sample solution and the reagent solution are also 0.25 mm or more and 1.0 mm or less, and the discharge amount per stroke of the both solutions alternately delivered by the infinite flow metering pump is set. Both are 1.25 μl or more and 20 μl or less.

Next, one embodiment of the method of the present invention will be described in detail with reference to the drawings.

(D) Example FIG. 1 shows an example of a flow path diagram in the present invention, and FIG. 2 shows a liquid feeding state of a mixing flow line.

As described above, according to the method of the present invention, the sample solution C ₁ ′ and the reagent solution C ₂ ′ are alternately fed in small amounts as shown in FIG. ₂ into the mixed flow line by the independent flow lines C ₁ and C ₂ , respectively. Increase the contact area of both solutions and mix.

Therefore, as the pump P to be used, a non-pulsating double-plunger type pump is suitable, and the discharge liquid amount per stroke without synchronizing the plunger for sample solution line C ₁ and the plunger for reagent solution line C ₂ . Is adjusted to about 5 μ. This is a volume equivalent to a liquid length of about 25 mm in the case of a Teflon tube having an inner diameter of 0.5 mm. In order to obtain a constant flow rate without pulsation, a different phase double plunger type pump is preferable, for example, a stroke length of 1 mm, a stroke discharge amount of about 5 μ, and a plunger diameter of about 2 to 3 mm.

In the figure, B is a hexagonal injection valve for sample injection provided in the sample solution line C ₁ , in which the sample S is pressed into the carrier liquid.

RC is a reaction coil in which both liquids are mixed and reacted. In this case, the reaction coil RC is installed in the constant temperature bath HB so that the reaction temperature of both liquids C ₁ ′ and C ₂ ′ is kept constant to increase the reaction rate and keep the reaction rate constant.

Next, after completion of the reaction in which the reaction coil RC in the mixed flow line is sufficiently reacted, the liquid is sent to the flow cell FC and measured by an absorptiometry method, and the measured value is stored in the recorder R.

On the other hand, the liquid after measurement is back pressure coil BPC.
Discard outside the line through (for example, 0.20 to 0.50 mm inner diameter). The waste liquid W is discharged after being subjected to pollution prevention processing.

The back pressure coil BPC can prevent the generation of bubbles in the entire flow line and can obtain a stable steady flow without pulsation.

Generally, a peristaltic pump may be used to keep the flow line free of pulsation, but this type of pump has poor durability. , It also uses a pulseless double plunger type pump.

The present invention can be applied not only to the flow injection analysis method but also to many other flow line analysis methods.

(E) Effect of the Invention According to the present invention, the reaction rate of FIA can be made almost 100%, and further, the reaction rate can be constantly kept constant, so that extremely highly accurate quantitative analysis can be performed quickly. Since it can be carried out and the amount of expensive reagents used is very small, it is very economical, and the waste liquid can be easily treated for pollution, which greatly contributes to environmental protection.

[Brief description of drawings]

FIG. 1 is an example of a flow path diagram based on the method of the present invention, and FIG. 2 is an explanatory diagram showing a liquid layer state diagram in a mixing flow line in the method of the present invention. Symbol Description C ₁ …… Sample solution line C ₂ …… Reagent solution line C ₁ ′ ... Sample solution C ₂ ′ ... Reagent solution P …… Pulseless double plunger pump S …… Sample B …… Hex injection valve M: mixing joint RC: reaction coil FC: flow cell R: recorder W: waste liquid, HB: constant temperature bath

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-36053 (JP, A) JP-A-59-3336 (JP, A) Actual development: JP-A-62-143263 (JP, U) JP-A-59- 77360 (JP, A)

Claims (1)

[Claims] 1. A sample solution and a reagent solution are caused to flow through independent flow lines, respectively, and thereafter, a small amount of each solution is alternately sent to a mixing flow line to be mixed and reacted, and then detected by a flow cell. In the flow injection analysis method, the inner diameters of both the sample solution and reagent solution flow lines are set to 0.
Both liquids are set to 25 mm or more and 1.0 mm or less, and the discharge amount per stroke of the above two liquids alternately delivered by using a non-pulsating double plunger type metering pump is set to 1.25μ or more and 20μ or less. The reaction cell in the mixing flow line is installed in a constant temperature bath to keep the reaction temperature constant to increase the reaction rate, and the rear part of the flow cell provided at the end of the mixing flow line. A flow injection analysis method characterized in that a back pressure coil is installed in the chamber to control the internal pressure of all flow lines to prevent the generation of bubbles and to obtain a stable steady flow without pulsation.