JP2009063459A - Component analysis method and ion chromatograph apparatus using ion chromatograph - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion chromatographic device capable of shortening analysis intervals and performing continuous measurements, without being affected by components not to be measured despite its simple system, and to provide a measuring method that uses the same. <P>SOLUTION: Components to be measured in a sample concentrated in a concentrating column are introduced into a separation column by an eluent, then separated sequentially, and measured in the measuring method of the ion chromatograph. When a sample containing non-measurement components and requiring separation in a time longer than those of the components to be measured is measured, introduction of the non-measurement components from the concentrating column to the separation column is blocked, after the components to be measured are separated from the concentrating column. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a component analysis method using an ion chromatograph that is used as a gas monitor in a clean room or the like in which a semiconductor manufacturing apparatus is installed, and an ion chromatograph apparatus, and aims to reduce the length of an analysis interval caused by carbon dioxide gas. The present invention relates to a component analysis method using an ion chromatograph and an ion chromatograph apparatus.

  Analyzing ions by ion chromatography or high-performance liquid chromatography is an extremely excellent analytical method and has been rapidly spreading in recent years. Ion chromatography is an analytical method that applies HPLC. Usually, after separation by ion-exchange chromatography, detection by electrical conductivity detection method or indirect absorbance detection method realizes both high sensitivity and high selectivity. Yes.

  The following documents are known as prior art relating to a component analysis method and an ion chromatograph apparatus using such an ion chromatograph.

Japanese Patent Laid-Open No. 08-304363 JP 11-160300 A JP 2007-033322 A “Measurement of trace amounts of organic acids using the concentrated column method” on pages 124-127, published by Yokogawa Electric at the 7th IC Forum held on November 8-9, 1990 and “Ion Chromatography” Analysis of polyvalent anions used "

FIG. 3 is a block diagram showing the main part of an analysis system for a clean room gas monitor using a conventional ion chromatograph apparatus.
As shown in FIG. 3, the clean room gas monitor includes a gas collection unit (A) and an ion chromatography unit (B). And the gas collection unit part is comprised by the flow-path switching part (C) and the impinger part (D).

  In the figure, reference numeral 1 denotes a flow path switching valve connected to a plurality of pipes 2, which switches samples flowing in from a plurality of pipes 2 and sequentially sends them to the impeller section (D). The gas switching pump 3 operates the flow path valve 4 connected to each pipe 2 to suck the gas to be measured next before the measurement of one kind of gas is completed. Prepare for a smooth gas supply.

  Here, the tip of the pipe 2 is arranged in a plurality of gas atmospheres, for example, 50 m ahead, and the gas replacement pump 3 sucks the gas in each place and fills the pipe 2 with the gas in each atmosphere. To wait.

  The gas selected by the flow path switching valve 1 is sent to the impeller section D. The sample that has flowed into the impeller portion D is bubbled in pure water supplied from the pure water supply port E, for example, by entering the first impeller 6a by switching the three-way valves 5a to 5d. The sample gas bubbled by the first impeller 6a and absorbed in the pure water is transported to the pure water and moves to the ion chromatography unit part B side, and the concentration column made of ion exchange resin through the sample pump 7 and the concentration valve 8 9 flows in.

  When the gas to be measured is, for example, hydrofluoric acid or organic acid, the concentration column 9 contains a cation exchange resin, and the anion component in the sample is captured by the cation exchange resin and concentrated. Water and cation components are discharged without being captured by the concentration column 9.

  After the first sample has moved to the ion chromatography unit B side, the second impinger 6b is introduced with the gas to be measured next from the flow path switching valve 1 side and supplied from the pure water supply port E. Bubbled underwater.

  Further, the flow path valves 4b to 4e and the three-way valves 5a to 5d, which are components of the impeller portion D, are operated, and a small amount of gas remaining in the first impeller 6a is discharged by the gas collection pump 10, and then the cleaning is performed. For this purpose, pure water is supplied from the pure water supply port E and discharged by the cleaning liquid discharge pump 11. That is, in the impinger section D, preparations are alternately performed in a state where the sample supplied to the ion chromatography unit section B side is not contaminated by the immediately preceding sample.

  4A and 4B are explanatory views showing the operation of the ion chromatography unit B section. In FIG. 4A, the sample exiting the impinger 6 enters the 6-way concentration valve 8 via the sample pump 7, and the measurement component is concentrated on the concentration column 9 through the path indicated by the thick solid line M.

  Next, after a predetermined time has elapsed, as shown in FIG. 4B, the six-way concentration valve 8 is switched to the path indicated by the thick solid line M ′. As a result, the sample concentrated in the concentration column 9 is conveyed by the eluent in the eluent tank 13 sucked by the eluent pump 12 and flows into the separation column 14.

  In the separation column 14, the time for separation varies depending on the measurement component. The separated measurement component is measured by, for example, the conductivity detector 15 disposed in the subsequent stage. Reference numeral 16 denotes a suppressor disposed in front of the conductivity detector 15. The separation column 14, the suppressor 16, and the conductivity measuring device are disposed in a thermostatic chamber (an oven in the figure).

By the way, in the measurement of hydrofluoric acid and organic acid, NaOH is used as an eluent, and analysis is performed using an anion separation column.
At this time, CO ₂ in the air dissolves in the sample as carbonate ions, so that the carbonate ions are detected by the conductivity detector 15 and the peak appears in the chromatogram.

This carbonate ion peak elutes very slowly, and it takes 1 hour or more for the carbonate ion to finish.
FIG. 5 is a diagram showing the relationship between peak intensity (vertical axis) and time (horizontal axis). This indicates that the carbonate ion peak does not appear unless a time close to 5000 seconds (83 minutes) elapses.

  Therefore, after the elution of hydrofluoric acid and organic acid, for example, after about 30 minutes, if the analysis of the next sample is performed continuously in order to shorten the time, the influence of carbonate ions remaining in the separation column will appear and the next sample There was a problem that normal analysis (measurement) was not possible.

Further, in the ion chromatograph system described in Japanese Patent Application Laid-Open No. 11-160300 shown as the prior art, the hydrofluoric acid and organic acid necessary for removing carbonate ions are trapped in order to remove impurities in the column in advance. Analysis becomes impossible.
Furthermore, in the “measurement of trace organic acids using the concentration column method” shown as a non-patent document, carbonate ions can be cut, but two high-pressure eluent pumps are required, resulting in high costs. was there.

  Accordingly, the present invention prevents the influence of carbonate ions from affecting the sensitive analysis of hydrofluoric acid and organic acid, shortens the analysis interval (for example, within 30 minutes) and enables continuous measurement. It is an object of the present invention to realize an ion chromatogram apparatus and a measuring method using the same.

The present invention was made to solve the above problems, and in the invention of the component analysis method using an ion chromatograph according to claim 1,
In the ion chromatograph measurement method, in which the measurement component in the sample concentrated in the concentration column is introduced into the separation column by the eluent, and separated and measured sequentially, it is a non-measurement component and is separated longer than the measurement component. When measuring a sample containing a necessary component, after the measurement component is separated from the concentration column, introduction of the non-measurement component from the concentration column to the separation column is prevented.

In claim 2, in the component analysis method using the ion chromatograph according to claim 1,
The measurement component contains hydrofluoric acid and organic acid, and the non-measurement component is a sample solution containing carbonate ions, and NaOH is used as an eluent.

In claim 3, in the ion chromatograph apparatus,
In the ion chromatograph device that introduces the measurement components in the sample concentrated in the concentration column into the separation column using the eluent and sequentially separates and measures them, the non-measurement components that require longer separation than the measurement components In the measurement of a sample containing, a concentration liquid introduction blocking means for blocking the introduction of the non-measurement component from the concentration column to the separation column after the measurement component is separated from the concentration column, To do.

As is apparent from the above description, according to claims 1 to 3 of the present invention, the following effects can be obtained.
After the hydrofluoric acid and the organic acid are separated from the concentration column, the concentration liquid introduction blocking means for blocking the introduction of the concentrated solution from the concentration column to the separation column is provided, so that the analysis time can be shortened. .

  FIG. 1 shows an example of an embodiment of the present invention, which is different from the conventional example shown in FIG. 3 only in that a concentrated liquid introduction blocking portion F is provided between a sample pump 7 and a concentration valve. The other parts are the same as in FIG.

  In FIG. 1, the discharge port of the sample pump 7 is connected to the connection port a of the 6-way switching valve 20 via the piping p1 that constitutes the concentrated liquid introduction preventing portion F, and the connection port b of the switching valve 20 is connected to the piping p2. Are connected to the connection port a ′ of the six-way concentration valve 8. Further, the connection port d of the switching valve 20 is connected to the suction port of the pure water drainage pump 21 through the pipe p3, and the connection port e of the switching valve 20 is immersed in the eluent in the eluent tank 13 through the pipe p4. Has been.

The connection ports f and c of the switching valve 20 are connected by an eluent holding loop (pipe) 22 having a pipe capacity of about 10 ml.
The pure water drain pump 21 is a simple membrane pump that operates at low pressure, and the switching valve 20 is a six-way valve that can withstand high pressure.

In the above configuration,
1) At first (0 seconds), the concentration valve 8 is turned ON to make the path indicated by the solid line conductive. Also, the pure water drain pump 21 is activated to suck the eluent in the eluent tank 13 and put it into the eluent holding loop 22 of the switching valve 20 (this eluent is pure in a state where the eluent holding loop 22 is filled). It is discharged from the discharge port of the water drain pump 21). The amount of the eluent in the eluent holding loop 22 is about 10 ml. Meanwhile, the sample pump 7 sends pure water (or sample liquid) to the concentration column 9 via the path indicated by the solid lines of the switching valve 20 and the concentration valve 8 (this pure water (or sample liquid) is connected to the concentration valve 8). It is discharged through the mouth e → f).

2) Next, for example, after 60 seconds have elapsed, the switching valve 20 is turned on to bring the path indicated by the dotted line into a conductive state.
As a result, the pure water (or sample liquid) sent from the sample pump flows into the eluent holding loop 22 through the switching valve a → f → c → b, thereby entering the eluent holding loop 22. The eluted liquid is sent to the concentration column 9 via the connection port a ′ → b ′ of the concentration valve 8 via the pipe p2, and flows to the drain via the connection port e → f.
As a result, carbonic acid or the like that has been in the concentration column 9 is pushed out of the concentration column by 10 ml of the eluent. About 6 ml (3 minutes) is enough to eliminate carbonate ions etc. in the concentration column 9 but it is 10 ml with a margin (in short, non-measurement components concentrated in the concentration column 9 do not affect the measurement) Any amount that can be washed to a certain extent).

3) Next, for example, after 240 seconds have elapsed, the switching valve 20 is turned off and the path indicated by the solid line is turned on so that the liquid from the first or second ping pin 6 (6a or 6b) is sent to the concentration column 9. To do. The sample liquid from the impinger 6 enters the concentration column 9 through the path indicated by the solid line of the concentration valve 8 and the sample is concentrated (trapped).

4) Next, for example, after 840 seconds have elapsed, the concentration valve 8 is turned OFF. As a result, the path indicated by the dotted line of the concentration valve 8 becomes conductive, and the eluent from the eluent layer 13 sucked by the eluent pump 12 flows into the sample that has entered (trapped) the concentration valve 8, and the separation column. It flows out to 14.
At this time, the flow direction of the sample during concentration is the same as the flow direction of the eluent.

5) Since the cation exchange resin is contained in the concentration column 9 (the same resin as the separation column 14, but the amount of the resin is small), simple anions are separated.
6) Next, for example, after 990 seconds, the concentration valve 8 is turned ON again. This time is set in the concentration column until the sparse separation of hydrofluoric acid and organic acid is completed and carbonic acid is produced. As a result, the path indicated by the solid line in the concentration valve 8 becomes conductive, and the carbonate ion does not enter the separation column 14 and remains in the concentration column 9.

7) Accordingly, since carbonate ions do not enter the separation column 14, the conductivity detector 15 does not detect carbonate ions, and therefore no carbonate ion peak appears in the chromatogram.
FIG. 2 is a diagram showing the relationship between peak intensity (vertical axis) and time (horizontal axis). This shows that no carbonate ion peak appears even after 5000 seconds.
The actual measurement is completed in about 15 minutes, for example, and the next sample is measured.

The carbonate ions remaining without flowing out to the concentration column 9 are not affected because they are pushed out first by the implementation of the above items 1) and 2) when the next sample is measured.
Although omitted in the present embodiment, it is assumed that the activation of each pump and the opening and closing of the three-way valve and the six-way valve are controlled in sequence by a computer (not shown).

The foregoing description is merely illustrative of certain preferred embodiments for purposes of explanation and illustration of the invention. For example, in the examples, the measurement component is hydrofluoric acid or organic acid, but other components may be used. Further, in the examples, the non-measurement component is carbonate ion. However, when measuring chlorine other than carbon dioxide, it is affected by what elutes later than chlorine to be measured, such as SO ₄ and NO ₃ present in the air. It can be considered not to. In the embodiment, a conductivity detector is used as a detector, but an indirect absorbance detector may be used.
Therefore, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

It is a principal part block diagram which shows an example of embodiment of the ion chromatograph apparatus of this invention. It is a figure which shows the relationship between the intensity | strength of the peak of the measurement component measured using the ion chromatograph apparatus of this invention, and elution time. It is a principal part block diagram which shows an example of the conventional ion chromatograph apparatus. It is explanatory drawing which shows operation | movement of an ion chromatography unit part. It is a figure which shows the relationship between the intensity | strength of the peak of the measurement component measured using the conventional ion chromatograph apparatus, and elution time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flow path switching valve 2, p1-p4 piping 3 Gas exchange pump 4 Flow path valve 5 3-way valve 6 Impinger 7 Sample pump 8 Concentration valve 9 Concentration column 10 Gas collection pump 11 Washing liquid discharge pump 12 Eluent pump 13 Elution Liquid tank 14 Separation column 15 Conductivity detector 20 Switching valve 21 Pure water drain pump 22 Eluent holding loop

Claims (3)

  In the ion chromatograph measurement method, in which the measurement component in the sample concentrated in the concentration column is introduced into the separation column by the eluent, and separated and measured sequentially, it is a non-measurement component and is separated longer than the measurement component. When measuring a sample containing a necessary component, an ion chromatograph is used which prevents introduction of the non-measurement component from the concentration column to the separation column after the measurement component is separated from the concentration column. Component analysis method.   The ion chromatograph according to claim 1, wherein the measurement component includes hydrofluoric acid and an organic acid, and the non-measurement component is a sample solution containing carbonate ions, and NaOH is used as an eluent. Component analysis method.   In the ion chromatograph device that introduces the measurement components in the sample concentrated in the concentration column into the separation column using the eluent and sequentially separates and measures them, the non-measurement components that require longer separation than the measurement components In the measurement of a sample containing, a concentration liquid introduction blocking means for blocking the introduction of the non-measurement component from the concentration column to the separation column after the measurement component is separated from the concentration column, Ion chromatograph device.