RU4830U1 - RADIOACTIVE IONIZATION DETECTOR FOR GAS CHROMATOGRAPHY - Google Patents

Abstract

1. A radioactive ionization detector for gas chromatography, comprising a flow chamber with inlet and outlet fittings with a radiation source and a collector electrode and an electrometer, characterized in that an additional variable-area electrode made of a material whose electron work function is placed in the detector chamber differs from the electron work function of the collector electrode material, the additional electrode being electrically connected to the collector electrode. 2. The detector according to claim 1, characterized in that the additional electrode is made in the form of a metal screw.

Description

Known radioactive ionization detectors containing flow-through working and comparative chambers with radiation sources located in them, electrodes to which voltages are supplied from stabilized high-voltage power sources, and an electrometer for measuring current (G. Shai. Theoretical Foundations of Gas Chromatography. M., Ed. Foreign Lit., 1963, S.326-328).

The principle of operation of radioactive ionization detectors is to ionize the gas mixture - or - by radiation. The resulting gas ions are collected by the collector, and the current arising in the circuit is measured by an electrometer, moreover, the comparative cell serves to compensate for the initial detector current

The disadvantage of these detectors is the need to use stabilized high-voltage power sources, which complicates the design and operation of the device.

Known radioactive ionization detector containing a flow chamber with inlet and outlet fittings with radiation sources and a collector electrode and an electrometer Farzan N.G., Nlyasov L.V., Azim-Zade A. K). Automatic

gas and liquid detectors. M., Energoatomizdat, 1983, S. 49-51). During gas ionization in the chamber, the detector signal is generated without a power source, i.e. the detector is in generator mode.

The disadvantage of this detector is that when it is used in differential circuits, due to the difference in the activity of the radiation sources in the measuring and comparative cells, there is a significant initial current and the associated zero-signal drift, which reduces the accuracy of measuring the concentrations of the detected components.

Utility Model Essence

The task of creating a utility model is to increase the accuracy of measuring component concentrations by a radioactive ionization detector.

EFFECT: creation of a radioactive ionization detector with a tunable value of the initial current. The technical result is achieved in that in the chamber of a radioactive ionization detector containing a flow chamber with inlet and outlet fittings with a radiation source and a collector electrode and an electrometer, an additional variable-area electrode made of a material whose electron work function differs from the work function is placed electrons of the material of the collector electrode, moreover, the additional electrode is electrically connected to the collector electrode. The additional electrode is made in the form of a metal screw. Compared with the prototype of the claimed design has a distinctive feature in the combination of elements and their relative position.

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Brief Description of the Drawings

Figure 1 shows a diagram of a radioactive ionization detector

The best option for implementing a utility model

The radioactive ionization detector for gas chromatography contains a flow chamber 1, equipped with an inlet 2 and an outlet 3 fittings, with a tritium radiation source 4 placed therein, a collector electrode 5 and an additional electrode 6. The chamber 1 is separated from the housing 7 by an insulator S. The collector electrode 5 and an additional the electrode 6 is electrically interconnected, and the tritium radiation source 4 and the collector electrode 5 are connected to the electrometer 9. The additional electrode 6 is made in the form of a screw, moreover, part of the electrode I is introduced into the chamber 1 of the detector is made of metal with an electron work function that is different from the electron work function of the material of the collecting electrode 5, and another portion 10 of the additional electrode 6 is made of a dielectric material, e.g., Teflon.

The operation of the detector is as follows. The carrier gas stream with the separated components of the gas mixture from the chromatographic column through the nozzle 2 enters the chamber i of the detector. - In the detector chamber, particles emitted from the tritium radiation source 4 ionize the molecules of the gas mixture. The resulting gas ions are collected by the collector electrode 5 and an ionization current flows in the input circuit of the electrometer 9. The value of this current depends on the concentration of the detected components of the gas mixture and the contact potential difference between the tritium sources

lump of radiation 4 and collector electrode 5, as well as the nature of the detected components and carrier gas.

When using the detector in differential circuits, adjustment of the initial current value and elimination of the zero signal drift associated with it is carried out by changing the area of the additional electrode 6 ,. which is carried out by changing the angle of rotation of the screw and changing the degree of arrangement of the metal part of the additional electrode in the chamber 1 of the detector from the complete introduction of the metal part to its replacement by the Fluoroplastic part 10.

Experimental studies of the described radioactive ionization detector were performed on a standard chromatographic analyzer LHM-8MD, in the analytical unit of which this detector was installed. The area of the collector and additional electrodes was 80 mm and 7 mm, respectively. Distance

between them was 0.32 mm. The collector electrode material is stainless steel, the additional electrode was made of red copper and Ftoroplast. With the complete introduction of the metal part of the additional electrode into the detector chamber, the value of the initial detector current decreases by its nominal value, which confirms the possibility of changing the initial current signal of the detector.

The advantage of the proposed utility model is: - higher accuracy of measuring the concentration of the components of the gas mixture;

- ease of setting the initial current when using the detector in differential circuits.

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Industrial applicability

A radioactive ionization detector can be implemented on the basis of a generator radioactive ionization detector with a slight change in the design of its collector electrode.

The proposed detector can be used both in packed and capillary gas chromatography.

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Claims (2)

1. A radioactive ionization detector for gas chromatography, comprising a flow chamber with inlet and outlet fittings with a radiation source and a collector electrode and an electrometer, characterized in that an additional variable-area electrode made of a material whose electron work function is placed in the detector chamber differs from the electron work function of the collector electrode material, the additional electrode being electrically connected to the collector electrode. 2. The detector according to claim 1, characterized in that the additional electrode is made in the form of a metal screw.