SU1749826A1 - Device for entry of sample to chromatograph - Google Patents

Abstract

Use: analytical equipment, where it is required to accurately enter the sample into the system under pressure or vacuum using a syringe or other analytical device and monitor the tightness of the system over time. SUMMARY OF THE INVENTION: The device has a body, two membranes separated by a sleeve, a gas supply line between the membranes and a carrier gas supply line. In the gas supply line between the membranes, a gas source is introduced that is different in its physical and chemical; triggers from a carrier gas, a variable pneumatic resistance included at the inlet of the line, pressure indicators switched on before and after the pneumatic resistance, and a pressure regulator to maintain a constant pressure at the inlet line. 1 il.

Description

The invention relates to chromatography, in particular, to devices for introducing a sample into a chromatograph, which can also be used in other analytical equipment, where accurate injection of a sample into a system under pressure or discharge using a syringe or other analytical device and monitoring the tightness of the system over time is carried out. .

A device is known for introducing a sample into a chromatograph comprising an evaporator housing with a socket for mounting a sealing membrane, sealing the membrane and pressing. Such a device is used in almost all gas chromatographs produced in the USSR and abroad. The device provides the ability to enter liquid samples in the chromatograph using

microsyringe However, a significant disadvantage of this device is that when extracting the needle of the syringe from the evaporator, there is a partial release into the atmosphere of the vapors of the analyzed sample introduced into the chromatograph. Such an ejection of a part of the sample reduces the accuracy of the chromatographic analysis, since the accuracy of the input sample decreases both in size and composition.

Closest to the invention is a device for introducing a sample into a chromatograph comprising an evaporator housing, membranes separated by a sleeve forming a cavity between them, a gas supply line between the membranes, and a carrier gas supply line to the evaporator. This device, in order to increase the reproducibility of the sample inlet, is equipped with a pneumatic repeater connected to the line |

4 О 00 Ю О

Achie carrier gas and with intermembrane cavity.

This device reduces the possibility of carrier gas leaking from the evaporation region in the event of an internal sealing membrane leaking due to the equality of pressures in the intermembrane cavity and in the evaporation region.

However, in case of leakage of the outer membrane; which, apparently, will break out of the building temporarily from the inside, the carrier gas will be ejected from the evaporation and intermembrane regions and some of the sample vapor will be entrained. This feature is a significant disadvantage, which leads to a decrease in the accuracy of the analysis. Loss of tightness is not monitored and can be detected only by changing the retention time of the components, but when analyzing samples with different composition of components that have different exit times, detection; Leaks are complicated.

The purpose of the invention is to improve the accuracy of the analysis.

The goal is achieved by the fact that, in a sample inlet device for a chromatograph containing a housing, membranes separated by a sleeve forming a cavity between them, a gas supply line between the membranes and a carrier gas supply line, a gas source is introduced that is different in nature from the carrier gas, variable pneumatic resistance included at the inlet of the additional gas line; pressure indicator connected before and after the pneumatic resistance. pressure regulator to maintain a constant pressure at the inlet of the line of this gas.

Entering an additional gas source with a pressure regulator and pneumatic resistance ensures the creation and maintenance of an overpressure, as compared to the pressure at the inlet of the chromatographic column, a gas that differs in nature from the carrier gas in the space between the sealing membranes. Excessive pressure in this area, on the one hand, prevents vapor of the sample being analyzed when the needle of the syringe is removed from the evaporator, on the other hand, if there is a minor leakage of the membrane located on the side of the evaporator, additional gas flows into the flow of the carrier gas. is exposed from the carrier gas and upon entry and the detector allows, based on its readings

instantly detect leakage. Pressure indicators on the additional gas line allow detection of external leakage

membranes.

The drawing shows the input device of the sample in the chromatograph, section.

The input device of the sample in the chromatograph contains the evaporator 1, sealing

membranes 2 and 3, sleeve 4, line 5 of additional gas, pressure indicators 6 and 7, variable pneumatic resistance 8, pressure nut on the evaporator 9. pressure 10, source 11 of additional gas with pressure regulator.

The input device of the sample in the chromatograph works as follows.

At the entrance of the line 5, additional gas is supplied with a constant pressure from the source

11 additional gas, exceeding the pressure of the carrier gas. If the membranes 2 and 3 are sealed, then the gas flow in line 5 is absent and the indications of pressure indicators 6 and 7 are the same. At loss of tightness

in the area between the membranes 2 and 3 due to the pressure drop at the pneumatic resistance 8, the indication of the indicator 7 decreases, which indicates to the operator that one or both sealing leaks

membranes 2 and 3. If the additional gas enters the evaporator 1, then the chromatograph detecting device (not shown) signals this by changing the zero signal, which means that

membrane 2 has lost tightness.

The sample injection device in the chromatograph provides continuous monitoring by the operator of the evaporator tightness, which ensures high accuracy of qualitative and quantitative chromatographic analysis and allows you to work for a long time without replacing the sealing membranes, fully using their life.

The proposed device can be easily used with any chromatograph.

Claims (1)

The invention of the input device samples in the chromatograph, comprising a housing, membranes separated by a sleeve, forming a cavity between them, a gas supply line between the membranes and a carrier gas supply line, so that, in order to increase the accuracy of the analysis, a source of additional gas, different in physico-chemical properties, recorded by the detector, from a carrier gas, was introduced into the gas supply line between the membranes, the variable pneumatic resistance included at the inlet pressure indicators connected to pressure to maintain constant and after pneumatic resistance, and a pressure regulator at the inlet of the line. f