JPH0385448A - Ion analyser - Google Patents

Abstract

PURPOSE:To enhance concn. efficiency and analytical sensitivity by providing a pH control means for allowing a speciman solution to approach neutrality at the position on the upstream side of the concn. means in the flow passage of the specimen solution. CONSTITUTION:In an analyser, an ion exchanger 11 is newly provided between the pump in a specimen supply system and the change-over valve on the upstream side of a concn. means. This exchanger 11 is constituted by providing an ion exchange memberane 13 in a container 12 in concentric relation to a supply pipe 2. When a specimen solution with pH of about 1.0 is introduced into the exchanger 11 by 0.2N hydrochloric acid containing metal ions and a neutralizing solution is supplied from a supply pipeline 14, ion exchange is performed through the exchange member 13. That is, when an alkaline neutralizing solution, for example, 0.1 - 1N tetramethylammonium hydroxide solution is used, chlorine ions transfer from the specimen solution to the neutralizing solution and hydroxyl ions move from the neutralizing solution to the specimen solution to perform ion exchange. Therefore, the hydrogen ions in the specimen solution decrease and pH rises to approach neutrality.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to an analyzer using ion chromatography,
In particular, the present invention relates to an ion analyzer suitable for use in ion analysis of samples other than neutral (pH 7), such as strongly acidic sample solutions.

"Prior Art" In the conventional ion chromatography analysis method, as shown in FIG. Supply pipe 2
．． The sample liquid is sent through the flow path of the switching valve 3 to a concentration column 4 filled with ion exchange resin, which serves as a concentration means, to capture ions in the sample liquid, and after the ions have been captured, the water is removed. He is trying to discharge from the drainage channel 6 via the switching valve 5.

After supplying the sample liquid to the concentration column 4 for a certain period of time, it is stopped, and the flow paths of the switching valves 3 and 5 are switched.
By operating the eluent pump 7, the switching valve 3 is removed from the eluent tank 8.
The eluent is caused to flow in through the channel, and the ions captured in the concentration column 4 are released into the eluent, and then sent through the channel in the desorption switching valve 5 to the separation column 9 as a separation means. In the separation column 9, ions flow out in time series according to the ion type due to the flow of the eluent. the result,
From the detector IO, an output IJ< as shown in FIG. 7 is obtained. The type of ion can be determined from the time from the start of elution until the peak (P1~ps) appears, as well as the area and height (H
, ~H,) can determine the amount of ions.

``Problems to be Solved by the Invention'' However, in the analysis of the above-mentioned prior art, when the sample solution containing the ions to be analyzed is significantly deviated from neutrality (pH 7), for example, hydrochloric acid (pH around 1) When attempting to analyze metal ions in the ion exchange resin, the amount of analyte ions remaining on the surface of the ion-exchange resin for concentration is reduced because ion capture and acid desorption occur simultaneously in the concentrating column 4 in a competitive manner. Since the amount of ions is smaller than the amount of ions actually contained in the supplied sample liquid, the analysis of metal ions becomes uncertain as a result. In addition, immediately after the start of concentration, a large amount of H° ions (hydrogen ions) contained in the sample solution actively adheres to the ion exchange resin in the concentration column 4, and its exchange capacity is quickly saturated. There was a problem in that the target ions could not be sufficiently concentrated, resulting in a decrease in analytical sensitivity.

The present invention was proposed in view of the above circumstances, and an object of the present invention is to provide an analyzer capable of measuring ion concentration with high precision and high sensitivity regardless of the pH of a sample liquid.

"Means for Solving the Problems" In order to solve the above problems, the present invention provides a supply means for supplying a sample liquid containing ions to be analyzed, and a temporary storage of ions in the sample liquid supplied from the supply means. a concentration means for
an eluent supply means for supplying an eluent to the concentration means to release ions; a separation means for eluting ions separated from the concentration means into ion types in time series by a flow of the eluent; The analyzer is equipped with a detection means for detecting each type, and a pH adjustment means for bringing the sample liquid close to neutrality is provided at a position on the upstream side of the concentration means in the flow path of the sample liquid.

"Function" With the above configuration, the pH of the sample liquid is brought close to neutrality by the pH adjustment means prior to concentration, and subsequent capture of ions by the concentration means is ensured.

"Embodiment" An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. In the figure, parts common to the conventional example are given the same reference numerals to simplify the explanation.

FIG. 1 shows an analyzer according to the present invention, in which an ion exchanger 11 is connected between a pump l and a switching valve 3 in a sample supply system of a conventional ion chromatography analyzer.
It has a new configuration.

Next, the specific structure of the ion exchanger 12 will be explained with reference to FIG. Reference numeral 12 denotes a hollow container, and an ion exchange membrane 13 formed in a cylindrical shape concentric with the supply pipe 2 is provided inside the container 12, and both ends of the ion exchange membrane 13 are connected to the supply pipe 2. 2 to receive the supply of sample liquid.

Further, a liquid supply pipe 14 and a drain liquid pipe 15 are connected to a space outside the ion exchange membrane 13 in the container 12, and a pump 17 is connected to the liquid supply pipe 14 from a neutralization liquid tank 16. The neutralizing liquid sucked up by the tank is supplied. That is, the interior of the chamber 612 is divided into a sample flow path 18 and a neutralizing liquid flow path 19 by the ion exchange membrane 13.

Furthermore, the color former sucked by the pump 21 from the color former 20 is supplied to the conduit between the separation column 9 and the detector 10 of the analyzer.

Next, analysis of an acidic solution of transition metal ions (hereinafter simply referred to as metal ions) according to an example of the present invention will be described.

For example, if a sample solution is hydrochloric acid with an O62 standard containing metal ions, this sample solution is as strong as p)(t,O), and cannot be sufficiently captured and concentrated using the ion exchange resin of a normal concentration column for metal ions. Can not.

When such a sample liquid is introduced into the ion exchanger 11 using an anion exchange membrane and a neutralizing liquid is supplied from the supply pipe 14, ion exchange can be performed via the ion exchange membrane 13. That is, an alkaline neutralizing solution, e.g.
When a 1N tetramethylammonium hydroxide solution is used, chloride ions <Ca-> move from the sample solution into the neutralization solution, and hydroxide ions (OH-) move from the neutralization solution into the sample solution.
In other words, ion exchange occurs, and in the sample solution, 2H"+OH-→HtO In the neutralizing solution, Na++CQ-→NaCg, both of which produce neutral water and neutral salts. .

In this way, the hydrogen ion concentration in the sample solution decreases, and the pH increases, approaching neutrality.

The degree of neutralization is determined by the exchange capacity of the ion exchange membrane;
Furthermore, it is greatly influenced by the acidity strength of the sample solution, the alkalinity strength of the neutralizing solution, and the flow rate of each solution.

In the actual analysis of metal ions, it is preferable to adjust the pH to a weak acidity, that is, within a pH range of 2 to 7.

It is also possible to directly inject alkali into the acidic sample solution without performing ion exchange for neutralization, but in this case, alkali metal ions (Na"K') etc. will be generated and have a negative impact on the analysis. In addition, hydrogen ions in the sample solution may be adsorbed using an ion exchange resin, but in practice this is difficult to solve problems such as saturation of the ion exchange resin and analyte ions being adsorbed. It becomes necessary.

The sample solution containing metal ions that has been ion-neutralized in this way is sent from the ion exchanger 11 to the concentration column 4, while the neutralized solution is passed through the drain pipe 15 to a drain reservoir tank (as shown in the diagram). ).

After the concentration column 4 performs the same concentration as in normal ion chromatography, the eluent is passed through the separation column 9 to separate each ion species, and these ions are passed through the separation column 9 in chronological order. It is eluted from. Then, a coloring agent (P A R = pyridylazoresorcin) is added to the eluted sample solution by the coloring agent supply pump 21, and by supplying this coloring agent, the degree to which the degree of coloring increases or decreases with the metal ion concentration is determined. When detected by the absorbing liquid detector 10, a chromatogram similar to that shown in FIG. 4 is obtained.

In the examples, transition metal ions were the ions to be detected, but the detection targets of the present invention are not limited thereto, and other metal ions and other ions can be detected. Of course.

Furthermore, instead of using an ion exchange membrane as in the previous embodiment as an ion exchanger, the ion exchanger shown in FIGS.
As shown in the figure, a hollow fiber material made of ion exchange phase resin called hollow fiber or hollow fiber or a semipermeable ion-permeable membrane may be used.

That is, as shown in FIG. 3, an ion exchanger is constructed by housing a large number of hollow fibers 30 in a container 31, and, for example, the inside of the hollow fibers 30 is connected to the supply pipe 2 to control the sample liquid flow. Alternatively, the outer side of the hollow fiber 30 may be connected to a neutralizing liquid supply pipe line to be used as a neutralizing liquid flow path 19.

In this case, since each hollow fiber 30 functions as an ion exchange membrane, the area of the ion exchange membrane can be increased.

In the above example, since the pH of the sample liquid was low, an alkaline solution was used as the neutralizing liquid, but if the pH of the sample i(?D) is high, an acid may be used as the neutralizing liquid.

Further, the installation position of the ion exchanger is not limited to the above embodiment, and it goes without saying that the ion exchanger may be installed at any position upstream of the concentration column in the piping through which the sample flows.

"Effects of the Invention" As is clear from the above description, the present invention has the following effects.

a3 Expansion of analysis concentration range (1) Since the pH of the sample solution can be kept within a certain range, the ability of the concentration column 4 is fully demonstrated, and therefore,
Concentration efficiency can be increased and analytical sensitivity can be improved by 10 to 100 times.

(ii) Since saturation is unlikely to occur and concentration and elution do not occur simultaneously, a direct relationship can be shown between the amount of ion capture and the concentration time even over a wide range of concentration times.

b9 Expansion of liquid properties to be analyzed In addition to neutral aqueous solutions, acidic solutions and alkaline solutions,
It is possible to perform ion chromatography analysis of trace amounts of metals, alkali metals, alkaline earth metals, etc. contained in hydrochloric acid, sulfuric acid, hydrofluoric acid, etc., which are currently becoming a problem in semiconductor manufacturing processes.

Stabilization of C0 analysis performance For example, in a method that uses an ion exchange membrane as a specific pH and I adjustment means, a neutralizing solution containing ions to be exchanged is replenished, so it can be used for a long period of time without replacing the membrane itself. Stable neutralization becomes possible, and analytical functions are also stabilized.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention,
Fig. 1 is a piping diagram of the analyzer, Fig. 2 is a vertical sectional view of the ion exchanger, Figs. 3 to 5 show other embodiments of the present invention, and Fig. 3 is a diagram of the ion exchanger. 4 is an enlarged cross-sectional view of the hollow fiber portion, FIG. 5 is an enlarged longitudinal sectional view of the hollow fiber portion, and FIG. 6 is a piping diagram of a conventional analyzer.
FIG. 7 is a diagram of the output waveform of the detector. l...Sample liquid pump, 2...Sample liquid supply pipe, 3...Switching valve, 4...Concentration column, 5...Switching valve , 6... Eluent container, 7... Eluent pump, 9... Separation column, 10... Detector, 11...
Ion exchanger, 12... Container, 13...
・Ion exchange membrane, 18...Sample liquid flow path, 19.
..... Neutralizing liquid flow path, 20 ..... Coloring liquid tank, 2
1...Coloring liquid supply pump.

Claims (1)

[Scope of Claims] Supply means for supplying a sample liquid containing ions to be analyzed;
a concentration means for temporarily retaining ions in the sample solution supplied from the supply means; an eluent supply means for supplying an eluent to the concentration means to remove the ions; In an analyzer equipped with a separation means for eluting ion types in time series by flow, and a detection means for detecting the eluted ions according to ion type, the sample liquid is placed at a position on the upstream side of the concentrating means in the sample liquid flow path. An ion analyzer characterized by being provided with a pH adjusting means for bringing the pH value closer to neutrality.