JP6879058B2 - Liquid chromatograph analysis method - Google Patents

Description

The present invention relates to an analysis method using a liquid chromatograph device.

The detector of the liquid chromatograph device produces an output depending on the amount, concentration or physical characteristics of the fluid flowing through the pipe connected to the detector. If the sensitivity setting of the detector can be specified by the user of the liquid chromatograph device, it is necessary to set the sensitivity so that all the signals for detection can be contained within the detection area of the detector. For example, when the detector is set to low sensitivity, when the concentration of the object to be measured in the sample is low, the peak of the object to be measured is small and the intensity of the noise signal is high, so the ratio of the signal to noise (S / N). Ratio) is low. For this reason, the quantitative accuracy and measurement reproducibility are deteriorated, and it is difficult to calculate the accurate concentration. In addition, when the detector is set to high sensitivity, when the concentration of the object to be measured in the sample is high, the peak of the object to be measured exceeds the detection range of the detector, so that the peak cannot be acquired correctly and is accurate. It becomes difficult to calculate the concentration.

For example, in Patent Document 1, an optical waveguide is provided so as to detect light after passing through a sample after light is incident on a flow path of a sample formed in a single flow cell from a plurality of different directions. A technique for forming and expanding the dynamic range of a detector for a liquid chromatograph is disclosed.

However, this technique is limited to those that can be applied only to optical detectors, and there is no problem if all of these peaks are within the dynamic range in a sample in which two or more types of measurement objects are mixed, but even one type is dynamic. If it is out of the range, it cannot be measured accurately once and remeasurement is required.

Japanese Unexamined Patent Publication No. 2014-32098

An object of the present invention is to provide an analysis method using a liquid chromatograph device that can obtain an accurate value with a small number of measurements regardless of the concentration of an object to be measured.

As a result of diligent studies, the present inventors have found that remeasurement can be reduced by using a liquid chromatograph device in which two or more electric conductivity detectors are arranged in series in a column oven. The invention was completed. Hereinafter, the present invention will be described in detail.

The present invention is an analysis method using a liquid chromatograph device in which two or more electric conductivity detectors are arranged in series in a column oven, and the detection sensitivities of the detectors are set to be different from each other. It is a feature.

FIG. 1 is a configuration diagram of a general ion chromatograph analyzer. By driving the liquid feed pump 103, the eluent 101 is sent to the guard column 105 and then to the separation column 106 after passing through the degassing device 102. The sample is injected from the autosampler 104 and sent to the guard column 105 and then to the separation column 106. Then, each component is eluted in the separation column 106. After that, it is sequentially sent to the suppressor rotary valve 107 and the electric conductivity detector 108, measures the electric conductivity for each component, is taken into the data processing device 110, is calculated, and is output. The guard column 105, the separation column 106, and the electrical conductivity detector 108 are temperature-controlled by the column oven 109. Further, the suppressor gel 113 is filled in the suppressor rotary valve 107 by the distilled water 111 and the filling pump 112.

FIG. 2 is a configuration diagram of the ion chromatograph analyzer used in the present invention. Unlike a general ion chromatograph analyzer as shown in FIG. 1, the electric conductivity detectors 208A, 208B, and 208C in the column oven 209 are arranged in series in the flow path. The term "arranged in series" as used herein means connecting a plurality of electric conductivity detectors via a connector, or using a pipe made of a metal such as stainless steel or a polymer material such as PEEK or PTFE to connect a flow path. To connect.

There is no problem if the number of electrical conductivity detectors arranged in series in the column oven of the liquid chromatograph device is two or more, but as the number of electrical conductivity detectors increases, the peak of the chromatogram spreads, and the column Considering the size of the oven, it is preferably set to 4 or less, and it is preferable to select the electric conductivity detector as small as possible.

The electrical conductivity data from each detector is taken into the data processing device 210, then individually calculated and output. There is no problem if the output signal is transmitted as a chromatogram to a computer such as a PC using the display attached to the device or a communication means and displayed on the display of the computer such as a PC. Considering the convenience of operation, it is preferable that all signals are displayed on the same screen.

The present invention is characterized in that the detection sensitivities of the detectors are set to different settings. There is no problem if the detection sensitivity settings of the detectors are different, but in order to reduce the spread of the peak generated by the flow path volume, the samples are detected in order from the detector with the high sensitivity setting. It is desirable to. For example, when there are three electrical conductivity detectors arranged in series in the column oven as shown in FIG. 2, the detection sensitivity of the detector 208A installed at the position where the flow path length from the separation column is the shortest is the highest. It is preferable to set it higher and set it lower in the order of 208B and 208C, that is, set the detection sensitivity of the detector lower as the flow path length from the separation column becomes longer. As a specific setting value of the detection sensitivity, if the setting value of the detector installed at the position where the flow path length from the separation column is the shortest is used as the standard value, the setting value of the detector installed at the second shortest position is used. For example, the set value of the detector installed at the third shortest position, which is 5 to 30 times the standard value, is 50 to 300 times the standard value.

According to the present invention, the number of measurements can be reduced even when an unknown sample is measured.

It is a block diagram in a general ion chromatograph analyzer. It is a block diagram in the ion chromatograph analyzer of this invention. It is a figure which showed the chromatogram which made the detection sensitivity 50 μS. It is a figure which showed the chromatogram which made the detection sensitivity 500 μS. It is a figure which showed the chromatogram which made the detection sensitivity 5000 μS.

The present invention will be specifically shown below by way of examples, but the present invention is not limited thereto.

Using the ion chromatograph analyzer having the configuration shown in FIG. 2, the detection sensitivity of the electrical conductivity detector was set to 50 μS for 208A, 500 μS for 208B, and 5000 μS for 208C, and 36.5 ppm chloride ion was used. Ion chromatographic analysis was performed on a sample containing 1000.0 ppm nitrate ion and 7000.0 ppm sulfate ion.

The chromatogram from the detector 208A is shown in FIG. The peak at 1.5 minutes could be detected, but the peaks at 2.5 minutes and 3.5 minutes were saturated, and an accurate value could not be calculated.

The chromatogram from the detector 208B is shown in FIG. The peak at 2.5 minutes could be detected, but the peak at 1.5 minutes was too weak and the peak at 3.5 minutes was saturated, making it impossible to calculate an accurate value.

The chromatogram from the detector 208C is shown in FIG. The peaks at 2.5 minutes and 3.5 minutes could be detected, but the peaks at 1.5 minutes were too weak to be buried in noise, and accurate values could not be calculated.

In this case, the 1.5 minute peak is from the detector 208A or 208B, the 2.5 minute peak is from the detector 208B or 208C, and the 3.5 minute peak is from the detector 208C. The concentration may be calculated based on the chromatogram of.

In the conventional method (only one detector), it is not possible to calculate the accurate values of the three components by one measurement, but by using a plurality of detectors having different sensitivities based on the present invention, once. It was possible to calculate the accurate values of the three components with greatly different concentrations by the measurement of.

101, 201. Eluent 102, 202. Degassing device 103, 203. Liquid transfer pumps 104, 204. Autosampler 105, 205. Guard columns 106, 206. Separation columns 107, 207. Suppressor rotary valve 108, 208. Electrical conductivity detector 109, 209. Column oven 110, 210. Data processing devices 111, 211. Distilled water 112, 212. Filling pump 113, 213. Suppressor gel

Claims (2)

This is an analysis method using a liquid chromatograph device in which two or more electric conductivity detectors are arranged in series in a column oven.
The detection sensitivity of the detector is set to a different setting.
The analysis method. For the detector, the detection sensitivity of the detector installed at the position where the flow path length from the separation column is the shortest is set to the highest, and the other detectors detect the detector as the flow path length from the separation column becomes longer. The analysis method according to claim 1, wherein the sensitivity is set low.

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