SU1370554A1 - Gas chromatograph - Google Patents

Abstract

The invention relates to gas chromatography and can be used for the analysis of pesticides. The aim of the invention is to increase the reliability of identification and to expand the dynamic range detected11. The chromatograph contains a series-connected flow control gas carrier, a sample introduction device, a separation column and a gas flow divider. In series with each of the pneumatic resistances of the three arms, the gas flow divider 4 is additionally installed with one resistance, and the channels connecting the pneumatic resistances are connected to the channels for supplying additional gas flows through lines 11, 12, 13 from the flow regulators. By varying the flow rates of additional gases, it is possible to promptly redistribute the flow of carrier gas between the detectors, using the analysis as one of the detectors, and all of them simultaneously. 1 hp f-ly, 1 ill. with S (L

Description

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The invention relates to gas chromatography and can be applied for the analysis of pesticides.

The aim of the invention is to increase the reliability of identification and to expand the dynamic range of detection.

The drawing shows the structural scheme of the chromatograph.

Chromatograph contains serially connected regulator 1 of flow of carrier gas, device 2 of sample introduction, separating column.

3 and a gas flow divider A consisting of three parallel arms, each of which has two pneumatic resistances in series: 5 and 6 in the first arm, 7 and 8 in the second arm, 9 and

.10 - in the third shoulder, and the channels connecting between pneumatic resistances 5 and 6, 7 and 8, 9 and 10 are connected to channels 11, 12, 13, respectively, through which additional gas flows Oj, Q 4, Q 5 are formed; tors 14-16 gas consumption. The outlets of the latter are connected respectively to the channels 11-13, and the inputs to the source of the carrier gas or the outlet of the regulator 1 of the carrier gas flow. An electron-capture detector (ECD) 17, a flame ionization detector P1Sch 18, a flame photometric detector PFD 19 are connected to the outputs of the arms of the divider 4 gas flow divider.

The device works as follows.

from detectors depends on the ratio of the magnitudes of the pneumatic resistances 5–10 and the flow rates of additional gases in the channels 11–13. In order to eliminate the fractionation effect of the analyzed substances, simplify the manufacturing process and set up the detection system, and also simplify

The 1Q calculation formulas by which the amount of carrier gas flowing into each detector is calculated, the magnitudes of the pneumatic resistances of the arms of the divider 4 flow are equal to 5, and the ratio of the magnitudes of the pneumatic resistances in the same arm are also chosen to be the same.

In this case, with equal or no flow rates Q-, Q ,, Q additional gases in the channels 11, 12, 13, the flow of carrier gas coming out of the separation column 3 is divided into three equal parts, i.e. each detector receives an equal

25 amount of analyte. The magnitude of the flow rates of additional gases Q, Q, Qj can vary from zero to the maximum gas flow rate through the separation column 3. At the same time, regardless of the combination of flow rates QI QJ QJ, the gas flow rate at the output of each detector will be

35 o Q5 3

Using various combinations of additional gas flow rates, In the sample introduction device 2, the number of incoming detectors can be varied, depending on the ratio of the pneumatic resistance values 5 to 10 and the flow rates of additional gases in the channels 11-13. In order to eliminate the fractionation effect of the analyzed substances, simplify the manufacturing process and setup of the detection system, as well as to simplify

The Q calculation formulas by which the amount of carrier gas entering each of the detectors is calculated, the magnitudes of the pneumatic resistances of the arms of the divider 4 flow are the same5, and the ratio of the magnitudes of the pneumatic resistances in the same arm is also chosen the same.

In this case, with equal or no flow rates Q-, Q ,, Q, the additional gases in the channels 11, 12, 13, the flow of carrier gas coming out of the separation column 3 is divided into three equal parts, i.e. each detector receives an equal

5 amount of analyte. The magnitude of the flow rates of additional gases Q, Q, Qj can vary from zero to the maximum gas flow rate through the separation column 3. At the same time, regardless of the combination of the flow rates QI QJ QJ, the gas flow rate at the exit of each detector will be

5 about Q5 3

Dates the evaporation and mixing of the analyzed mixture with a carrier gas, the flow of which Q is formed by the regulator 1 of the flow rate of the carrier gas. Ana-

Lysing the mixture with the Q flow; the linear dynamic range of the detector enters the separation tirovat of each of the detectors on column 3, in which two orders of magnitude occur, and second, to carry out the matographic separation of the analyzed mixture. From separation coanalysis using both one of the detectors and all detectors

3 component) of the analyzed mixture with a carrier gas through the splitter 4 flow enters the EZD 17, FID 18, PFD 19, Pneumatic resistance 8 splitter 4 flow is not installed

before, and after the EZD 17, in order to disperse the analyzes, as well as the direct penetration of oxygen from the atmosphere during the analysis, while the spheres enter the EZD chamber 17. The number of hectares of sensitivity and quenching

3a-HocvtTe-jiH with the components of the allysi-flame detectors does not occur, so

flowable mixture and flow into each, as the flow of gases through the detectors

go to each detector of the carrier gas leaving the separation column 3, in the range from 0 to 100%. This allows, firstly, to expand the

linear detection range of each detector by two orders of magnitude, secondly, to conduct

analyzes using one of the detectors as well as all detectors

detection systems at the same time.

The redistribution of the carrier gas exiting the separation column 3 between the detectors of the detection system can be done as

always constant. Such a mode of operation significantly enlarges the possibilities of the chromatics rafa and allows, firstly, to increase the reliability of the quantitative analysis and identification of multicomponent mixtures with a low content of the desired components of different composition in the sample, secondly, to determine the amount of solvent in the introduced sample not only during operation. using several detectors, but also when working with one PID 18 and, thirdly, working with large volumes of input samples. Improving the accuracy and reliability of the analysis occurs by redistributing during the analysis of the gas flow with the desired components in the detectors with high sensitivity to the desired components. When forming the gas redistribution algorithm, data on the retention time of the desired component is taken into account. When determining the amount of solvent in the injected sample and working with a large volume of injected sample, at the time the solvent exits in PID 18 and PFD 19, 1–2% of the carrier gas exiting from column 3 is fed. Through EZD 17, the main part of the solvent is discharged. at the same time, the flame of the PVD 18 and PFD 19 is not quenched with a solvent, and the curiiaji of the PVD 18 does not go beyond the limits of the linear detection region. After the solvent exits, the carrier gas stream is redistributed in the required proportion between the detectors of the detection system.

In the detection system, another set of detectors can be used, and their number is reduced to two or increased to four or more. To do this, it is necessary to install an appropriate number of additional gas regulators, and the flow of the flow must have a corresponding number of outlets. The principle of the chromatograph is similar to that described above.

The amplitudes of the proposed chromatograph can be expanded by installing an additional detector on the outflow: ECD 17. As this detector ;. Any of the well known gas chromatography detectors can be used. The principle of operation of the detection system and chromatograph in

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Overall, it remains the same as described above.

As gas flow regulators 1, 1A, 15, 16, high-speed electronic gas flow regulators are used, which ensure the establishment of a predetermined gas flow rate when the driver action changes within three to five seconds. The internal volume of the gas lines connecting the outputs of the flow regulators 14, 15, 16 to the additional gas flow, and the channels 11-13 of the detection system should be minimal.

Most modern chromatographs use microcomputers to control the instrument and process the results of the analysis. In the proposed microcomputer chromatograph, the functions of calculating the values of the required gas flow rates, controlling the gas flow controllers, and automatically optimizing the detection conditions can be assigned, which will significantly improve the accuracy and reliability of the qualitative and quantitative analysis. Optimization of the detection conditions is achieved by adjusting the algorithm for redistributing the flow of eluent between the detectors and selecting the optimal-) 1k amounts of the element entering the detection system in each process during the analysis. Automatic optimization allows reducing the influence on the accuracy and reliability of transient analysis arising from the redistribution of eluent, provides optimal detection modes and matching the values of the output signals of the detectors with amplification devices and signal processing of the detectors.

Claims (2)

1. A gas chromatograph containing a series-connected flow control gas carrier, a sample introduction device, a separation column, a gas flow divider, to the outlets of which are connected an electron-capture detector, flame ionization and flame photometric detectors, characterized in that the purpose of increasing the 51370354 fidelity of identification and expansion of the gas from the additional linear dynamic range of gas flow regulators. detection sequentially with 2. The chromatograph according to claim 1, about tl and - each of the pyresistances is hinged by the fact that the inputs of the gas flow divider of the additional flow controllers are installed one pneumatic counter-gas one, and the channels connecting the pneumatic the flow rate of the carrier gas, and the outlets - to the resistivity among themselves, the connecting channels for the supply of additional yen with the channels and the supply of additional supplementary gas.