JP3221020B2 - Ion analysis method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention provides a method for analyzing ions.

[0002]

2. Description of the Prior Art In ion exchange chromatography, highly ionized ionic species are separated by an ion exchange resin and quantitatively detected by, for example, an electric conductivity detector.

[0003] The first system of this type was the Big Bolt [Z.
al. Chem., 132, 401 (1951)], but no liquid pump was used and the efficiency of the packed column was poor.
Moreover, it has disadvantages such as low sensitivity. After that,
The ion chromatograph developed by Le [Anal. Chem., 47, 1801] has achieved high-sensitivity analysis of ions by incorporating high-performance liquid chromatography technology, in particular by using a deion exchange column.

Further, an ion exchange tube is used instead of a deion exchange column, and an eluate from the separation column is passed through the tube to extract counter ions outward through the wall of the tube. The method of analyzing the ions that are generated is disclosed in
No. 6,135,156 and Japanese Patent Laid-Open No. 58-58464.

[0005]

In the method using a deion exchange column, when a large amount of ions are retained in the deion exchange column, the analysis is temporarily stopped in order to switch them to another flow path and regenerate them. Then, it is necessary to sequentially feed the regenerating solution and the washing solution, which complicates the configuration of the analyzer, and further has the disadvantage that a large amount of acid or alkali is required for regeneration.

In the method using an ion exchange tube instead of a deion exchange column, a reagent such as sulfuric acid or dodecylbenzenesulfonic acid has a property of leaking inward through the wall of the ion exchange tube. Therefore, these reagents are not suitable for use at a high concentration, and therefore require a means for constantly sending low-concentration reagents, such as a pump and its piping system, and further require acid or alkali for regeneration. Has the disadvantage that a large amount of is required. In addition, such a device requires a deionization device, and thus the analysis device becomes large and complicated.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to improve these drawbacks. As a result, particularly, the analysis of ions which can measure trace amounts of ions present in an aqueous solution with high sensitivity and good reproducibility. The method is completed.

That is, according to the present invention, after a sample solution containing ions is passed through a separation column to separate the ions, a reaction containing a counter ion exchanger having a molecular weight of 1,000,000 or more or a particle size of 1.0 μm or less is performed. An ion analysis method characterized by reacting with a solution and measuring the ions with an electric conductivity detector.

[0009]

Hereinafter, the present invention will be described in detail.

The counter ion exchanger used in the present invention is for removing eluted components and cations present in the eluate, and for quantifying the desired anion component with high sensitivity and reproducibility.

The counter ion exchanger referred to in the present invention is an ion exchanger having a cation exchange group for removing cations, such as polystyrene sulfonic acid, polyvinyl sulfonic acid, polyacrylic acid, lignin sulfonic acid, formalin and naphthalene. Sulfonic acid condensate, polymethacrylic acid,
Polymers having a unit structure of a low molecular electrolyte such as alginic acid, carboxymethyl cellulose, cellulose sulfate, and starch sulfate, styrene / divinylbenzene gel, polyacrylate gel, crosslinked cellulose gel, silica gel, car
An ion exchanger having a cation exchange group on the surface of a substrate such as Bongel is exemplified.

For removing anions, it is an ion exchanger having an anion exchange group, and uses a low molecular electrolyte such as glyco-leuktosan, alkylglycol-lektosan, polyvinylpyridinium, aminated starch, aminated cellulose or polyethyleneimine as a unit. Polymer or styrene
Examples thereof include an ion exchanger having an anion exchange group on the surface of a substrate such as divinylbenzene gel, polyacrylate gel, crosslinked cellulose gel, silica gel, and carbon gel.

What is important in the present invention is that these counter ion exchangers have a molecular weight of 1,000,000 or more or a particle size of 1.0.
It needs to be less than μm. In the case of a polymer having a low molecular electrolyte as a unit structure, the counter ion exchanger is a stable reaction solution having a molecular weight of 1,000,000 or more and no precipitation even when adjusted to a concentration of 0.1 to 5%, When the surface of a base material such as a gel has ion-exchange groups, the particle size is 1.
Even when the concentration is adjusted to 0.1 to 5% at 0 μm or less, a stable colloid solution which does not cause precipitation is obtained.

If the molecular weight is less than 1,000,000, the mobility of the counter ion exchanger increases, and the background electric conductivity does not decrease. If the particle size exceeds 1.0 μm, it does not exist as a stable colloid solution. It is not preferable because the concentration is not sent and the piping is clogged.

A characteristic feature of the use of a reaction solution containing these counter ion exchangers is that the regeneration solution can be used without using a deionization column or an ion exchange membrane device which has been conventionally used. Without using the same, it is possible to measure even a small amount of ions with sufficiently high sensitivity and reproducibility.

Of course, a special deionization device is not required, but by devising the confluence of the colloid liquid containing the eluate and the counter ion exchanger, the shape of the pipe to the detector, the length of the pipe, etc. It is also possible to increase the rate of ion exchange.

FIG. 1 shows an embodiment of an analyzer for carrying out the method of the present invention. The main parts of FIG. 1 are an eluent storage tank 1, an eluent feed pump 2, a sample injection valve 3, a separation column 4, a column thermostat 5, an electric conductivity detector 6, an integrator 7, a reaction solution storage tank 8, and a reaction. Solution feeding pump 9
The reaction solution is a device for analyzing ions introduced into the eluent flow path between the separation column 4 and the electric conductivity detector 6.

[0018]

FIG.

[0019]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 As a high-performance liquid chromatograph, a column thermostat having a sample injection part in a dual pump (CCPM type, manufactured by Tohso Corporation) for sending an eluent and a reaction solution and having an electric conductivity detector built therein. (Toso-IC-8010), an anion analysis column having a length of 5 cm and an inner diameter of 4.6 mm was installed as a separation column, and a length of 2 cm was used between the analysis column and the electric conductivity detector.
A chromatographic analyzer was used in which a Teflon pipe having a diameter of 0.5 mm and an inner diameter of 0.5 mm was provided, and a T-shaped Teflon pipe for introducing a reaction solution containing a counter ion exchanger was provided at an intermediate position.

The reaction solution was prepared by converting an acid-type polystyrene sulfonic acid ion exchanger into a 10% solution with a 2N HCl solution, filtering through a 1.0 μm microfilter, and filtering the filtrate. Using a ultrafiltration membrane having a molecular weight cutoff of 1,000,000, low molecular substances were removed, and the resultant was repeatedly washed with ultrapure water. The molecular weight of the polystyrene sulfonic acid ion exchanger in this reaction solution was 1,000,000 to 3,000,000.

A mixed aqueous solution of 2.6 mM NaHCO ₃ and 1.0 mM Na ₂ CO ₃ was passed as eluent at a flow rate of 1.0 ml / min.
When the solution was passed at 0 ml / min, the background conductivity of the electric conductivity detector was 392 μS / cm.

Example 2 The background conductivity was measured in the same manner as in Example 1 except that a polyvinyl sulfonic acid ion exchanger having a molecular weight of 1,000,000 to 2.5 million was used instead of the polystyrene sulfonic acid ion exchanger. 433 μS / cm.

Example 3 The background conductivity was measured in the same manner as in Example 1 except that a polyacrylic acid ion exchanger having a molecular weight of 1,000,000 to 2.5 million was used instead of the polystyrenesulfonic acid ion exchanger. It was 425 μS / cm.

Example 4 In the same manner as in Example 1 except that a sulfonic acid type polystyrene gel ion exchanger having a molecular weight of 1,000,000 to 2.5 million and an average particle diameter of 0.1 μm was used instead of the polystyrenesulfonic acid ion exchanger. The measured background conductivity was 15 μS / cm. FIG. 2 shows chromatograms obtained when analysis was performed using seven types of standard ions.

[0026]

FIG. 2

Example 5 Same as Example 1 except that a carboxylic acid type polyacrylate gel ion exchanger having a molecular weight distribution of 1,000,000 to 2.5 million and an average particle diameter of 0.1 μm was used instead of the polystyrenesulfonic acid ion exchanger. The measured background conductivity was 28 μS / cm.

COMPARATIVE EXAMPLE 1 The same procedure as in Example 1 was repeated except that a low-molecular-weight cation exchanger such as nitric acid, sulfuric acid, or dodecylbenzenesulfonic acid was used instead of the reaction solution used in Example 1. The conductivity was measured. As a result, for nitric acid, 610
0 μS / cm, sulfuric acid showed high conductivity of 5200 μS / cm, and dodecylbenzenesulfonic acid showed high conductivity of 4200 μS / cm. The background was high on the chromatogram, and measurement with standard ions could not be performed.

[0029]

As described above in detail, according to the analysis method of the present invention, a reaction solution containing a counter ion exchanger is merged in order to efficiently remove an elution component and a counter ion in an eluent. Simply by doing so, the target ion can be quantified with high sensitivity and high reproducibility.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of an analyzer for performing the method of the present invention.

FIG. 2 is a chromatogram of seven standard ions obtained in Example 4.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 30/02 G01N 27/08

Claims (1)

(57) [Claims] 1. A sample solution containing ions is supplied to a separation column, and the ions are separated and eluted by supplying an eluent to the surface of a polymer having a unit structure of a low molecular electrolyte having a molecular weight of 1,000,000 or more. The reaction solution containing the counter ion exchanger into which the ion exchange group is introduced, or the reaction solution containing the counter ion exchanger into which the counter ion exchange group is introduced into the base material having a particle size of 1.0 μm or less is eluted into the eluate. A method for analyzing ions, comprising adding and mixing the mixture, and supplying the mixture to an electric conductivity detector to detect the ions.