JPS6324154A - Method and instrument for gradient analysis of ion chromatograph - Google Patents

Abstract

PURPOSE:To enable a gradient analysis by using two kinds of eluants which are different in ion species and are equal in electric conductivity and changing the mixing ratios of both the eluants in such a manner that elution power increases with lapse of time. CONSTITUTION:A pump 6 and a pump 8 are operated and a sample is injected from an injector 13 according to the program set in a pump driving control part 24. The eluant which is mixed by a mixer 10 and is fed to a column 12 through an injector 13 is first higher in the fraction of the eluate A having the small elution power but the fraction of the eluant B of the large elution power increases gradually with lapse of time. The elution of the samples from the samples having the small retention power and short retention time up to the samples having the large retention power and the long retention time is thereby enabled in a suitable time.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an analysis method using ion chromatography, particularly a gradient analysis method in which elution power is changed over time;
The present invention relates to an ion chromatograph used in the analysis method.

(Prior Art) In ion chromatography analysis, the background level of the eluent is high, so when the concentration of the eluent is changed, the baseline fluctuates greatly, making analysis impossible. Therefore, in ion chromatography analysis, only equiconcentration elution is possible, and when analyzing a sample with a short retention time and a sample with a long retention time, it is necessary to exchange the eluent for both samples.

(Problems to be Solved by the Invention) The present invention provides a method and apparatus for performing gradient analysis in ion chromatography analysis to simultaneously analyze samples with short retention times and samples with long retention times. The purpose is to

(Means for Solving the Problems) In the analysis method of the present invention, two types of eluents with different ion types and equal electrical conductivity are used, and the elution power is increased over time. , the mixing ratio of both hot and synergistic liquids is changed.

In addition, in the ion chromatograph of the present invention, two pumps are provided to send two types of eluents having different ion types and the same electrical conductivity, and the eluents sent from both pumps are mixed in a mixer. At the same time, the two pumps are programmed to change the mixing ratio of the two hot separation liquids so that the elution power becomes stronger over time. A department was established.

(Example) The figure shows an example in which the present invention is applied to a non-suppressor type ion chromatograph.

A first eluent A and a second eluent B are prepared as eluents. The first eluent A is contained in the container 2, and the second eluent B is contained in the container 4. 6 and 8 are pumps for feeding eluents A and B, respectively.

Eluent A and eluent B are adjusted to have the same electrical conductivity. The elution power of eluent B is assumed to be stronger than that of eluent A.

As such eluents, for example, benzoic acid can be used as eluent A, and phthalic acid can be used as eluent B.

Eluent A was pumped by pump 6.8.

B is mixed in mixer 10 and sent to column 12.

An injector 13 is provided between the mixer 10 and the column 12, and a measurement sample is injected from the injector 13. Effluent from column 12 is discharged through detection cell 14 to drain 16 . The detection cell 14 is, for example, an electrical conductivity detection cell, and the detection signal of this detection cell 14 is recorded on the recorder 20 via the controller 18.

The column 12 and the detection cell 14 are housed in the column oven 22 in order to keep the temperature constant. 624 is a pump drive control unit that controls the amount of liquid sent by the pumps 6 and 8. Zunawachi.

While keeping the sum of the amount of eluent A sent by pump 6 and the amount of eluent B sent by pump 8 constant, as time passes, the ratio of eluent A is initially high and gradually increases. A program is implemented to operate the pump 6.8 so that the ratio of eluent B becomes higher.

In this embodiment, the pump 6 and the pump 8 are operated according to a program set in the pump drive control section 24, and the sample is injected from the injector 13. The eluent mixed in the mixer 10 and sent to the column 12 via the injector 13 initially has a high proportion of eluent A, which has a low elution power, but as time passes, the proportion of eluent B, which has a large elution power, increases. It's getting higher. This makes it possible to elute from a sample with a small retention force and a short retention time to a sample with a large retention force and a long retention time in an appropriate time.

The electrical conductivity of eluent A and eluent B was measured using an electrical conductivity meter, and the electrical conductivity of eluent A and eluent B was adjusted to be equal.
and the concentration of eluent B are adjusted in advance.

The combination of eluent A and eluent B is not limited to the combination of benzoic acid and phthalic acid mentioned in the example, but may also be a combination of two other eluents with different elution powers while maintaining the same electrical conductivity. can be used.

Furthermore, although the examples illustrate a non-suppressor type ion chromatograph, the present invention can also be applied to a suppressor type ion chromatograph. In that case,
Sodium borate as a combination of eluent A and eluent B;
Any two of sodium bicarbonate and sodium carbonate can be used.

(Effect of the invention) In the present invention, two
Different types of eluents are used, and the mixing ratio of both i8 synergists is changed so that the elution power becomes stronger over time, so the eluent's electrical conductivity does not change over time. Only the elution power can be changed accordingly. Therefore, although in the past it was impossible to perform gradient analysis due to too large baseline fluctuations, the present invention makes it possible to perform gradient analysis, and allows samples with short retention times to be used with samples with long retention times. Samples can be analyzed simultaneously.

[Brief explanation of drawings]

The figure is a flow path diagram showing one embodiment of the present invention. 2.4... Eluent, 6.8...Pump, 10...Mixer. 12... Column, 14...detection cell, 24...Pump drive control section.

Claims (2)

[Claims] (1) Using two types of eluents with different ion species and equal electrical conductivity, the mixing ratio of both eluents is changed so that the elution power becomes stronger over time. Chromatographic gradient analysis method. (2) Two pumps are provided to send two types of eluents with different ionic species and the same electrical conductivity, and the eluents sent from both pumps are mixed in a mixer and sent to the column. An ion chromatograph in which the two pumps are provided with a pump drive control unit programmed to change the mixing ratio of both eluents so that the elution power becomes stronger over time.