SU1723516A1 - Device for sampling and injecting vapor phase to gas chromatograph - Google Patents

Abstract

The invention relates to a technique for the investigation and analysis of substances in a dissolved or distributed state in a matrix (in a liquid or in a solid). The purpose of the invention is to increase the reproducibility of the measurement by equalizing the pressure when the sample is introduced. A device for sampling and introducing a vapor phase sample into a gas chromatograph contains a sample introduction unit, a thermostat, a sample container with a sealed lid, connected via a tap switch to a chromatograph, a channel for transferring the vapor phase from the tank to the chromatograph, a channel for resetting the vapor phase to atmosphere and channel for carrier gas supply. The sample introduction unit and the carrier gas supply channel are combined into a single circulation loop, and the sample container is equipped with a compensation chamber with elastic membranes on both sides of the chamber. The method can be used to analyze contaminants in wastewater, drinking water, and also in biological fluids. 1 il. (Ls

Description

The invention relates to the research and analysis of substances in a dissolved or distributed state in a liquid or solid using chromatography.

The invention can be used in the chemical and microbiological industry, as well as in medicine for analyzing contaminants in wastewater, drinking water, food products, and biological fluids, such as blood plasma, saline, and the like.

A device for taking and introducing samples of the vapor phase into a gas chromatograph is known.

The device includes a thermostat, a tank for sealing, sealed with an elastic membrane and connected with a chromatograph channel to the tap. The tank is also provided with a carrier gas discharge channel to the atmosphere, an overpressure inlet channel with throttle gauges and a turret.

The drawback of the device is the inability to equalize the pressure when the sample is injected. When a sample is introduced, a pressure jump occurs in the chromatograph, which leads to the formation of a false peak.

Closest to the proposed technical entity is a device for sampling and introducing a sample of the vapor phase into a gas chromatograph containing a sample insertion unit with a needle and a sample container sealed with an elastic membrane, a crane switch connecting the sample introduction unit to the chromatograph, a channel for transferring the vapor phase from the tank to the chromatograph with a manometer installed on it, a channel for discharge of the vapor phase into the atmosphere with an adjustable throttle and a channel for supplying a carrier gas.

The disadvantage of the prototype is the introduction of an additional cylinder with a carrier gas and the absence of a compensation chamber. ..

The described disadvantages are also inherent in this device. A pressure surge in this device also leads to a decrease in the measurement performance.

The purpose of the invention is to increase the reproducibility of the measurement by equalizing the pressure when the sample is introduced.

The goal is achieved by the fact that the device for sampling and introducing a sample of the vapor phase into a gas chromatograph is additionally equipped with a gas line connecting the entrance to the chromatograph with the output of an adjustable throttle so that the sample introduction unit and the channel for supplying the carrier gas are combined into a closed circulation loop , moreover, the sample container is equipped with an additional membrane, which, together with the first membrane, forms a compensation chamber.

The invention allows to increase the reproducibility of the measurement and to obtain stable results when conducting research.

The drawing shows the device for the selection and input of samples of the vapor phase in a gas chromatograph.

The device for selecting and introducing the vapor phase is intended for use with a gas chromatograph 1, which contains an evaporator 2, chromatographic column 3, detector 4. It includes an input unit with a needle 5 and a container 6 with a sample sealed by an elastic membrane 7, a tap switch 8, a connection a sample input unit with a needle 5 with a chromatograph 1, a channel 9 for transferring the vapor phase from the tank 6 to the chromatograph 1 with a pressure gauge 10 installed on it, a channel 11 for resetting the vapor phase to atmosphere with an adjustable throttle 12 and a channel 13 for supplying gas to the nose ate. The device is additionally equipped with a gas line 14 connecting the entrance to the chromatograph 1 with the input of an adjustable throttle 12. The sample introduction unit with the needle 5 and the channel 13 for supplying the carrier gas are combined into a closed circulation loop. The container 6 is equipped with an additional membrane 14, which together with the membrane 7 forms a compensation chamber.

The device is equipped with a cylinder 15 with a carrier gas, a gearbox 16, a control valve 17 and a carrier gas flow regulator 18. Channel 9 steam transfer

phase is equipped with a pressure gauge 19 and valve 20.

The device works as follows.

Initial pressure from gas cylinder

0 15 with a gearbox 16 is fed to the inlet of the evaporator 2 through the flow controller 18, and through the valve 17 to the inlet of the circulation circuit. The valve 17 in the circulation circuit sets the required

5, the overpressure relative to the pressure in the chromatograph 1 by the pressure gauge 10. Moving down the needles 5, the elastic membranes 7 and 14 of the compensation chamber of the container 6 are pierced, and the overpressure is supplied to the container 6. Then the pressure gauge 19 is cut off from the circulation circuit by closing the valve 20. The needle 5 is inserted into the compensation chamber. Crane switch 8 is switched to a neutral position at which all channels are locked. At this time, the sample in the tank 6 is in equilibrium with the vapor liquid depending on the volatility of the analyzed substances. Then, the crane 8 is moved to another position,

0, the needle 5 is brought into the container 6 and the sample under excessive pressure is fed to the evaporator 2 of the chromatograph 1.

Next, the sample is separated into a chromatographic column 3 and the component is registered with detector 4.

When separating a sample of fatty acids using a prototype, the peak of the solvent along with the peak resulting from a pressure surge of 0.025 MPa,

0 masks the peaks of the acids and does not allow for their quantitative analysis.

The proposed device for taking and introducing a sample of the vapor phase into a gas chromatograph allows to obtain clear

5 chromatograms and the most accurate measurement of the concentrations of contaminants in matrices (water, soil, biological fluid, etc.).

The proposed device will be used to control the level of environmental pollution (water, soil, air), food products, biotechnological media (culture liquid), and in the study of biological substances. The use of this device eliminates the time-consuming and error-making stage of sample preparation.

Claims (1)

Formula and acquisitions A device for sampling and introducing a sample of the vapor phase into a gas chromatograph containing a sample introduction unit, including a needle for introducing samples to a sample vessel sealed with an elastic membrane, a tap switch connecting the sample introduction unit to the chromatograph, a channel for transferring the vapor phase from the tank to a chromatograph with a manometer installed on it, a channel for discharge of the vapor phase into the atmosphere with an adjustable throttle and a channel for supplying a carrier gas, so that, in order to increase 0 reproducibility of the measurement by equalizing the pressure when the sample is injected, it is equipped with an additional gas line connecting the input to the chromatograph with the output of the adjustable throttle, so that the sample introduction unit and the channel for supplying the carrier gas are combined in a closed circulation loop additional membrane, forming together with the first membrane compensation chamber.