Discharge ionization current detector

Abstract

A discharge ionization current detector using a low-frequency barrier discharge is provided to improve the linearity of detection sensitivity with respect to a sample introduction amount. From a lower end of a lower gas passage 10 connected to a lower end of an upper gas passage 4, a dilution gas is supplied upward against a downward flow of a plasma gas. A gas discharge passage 15 for discharging a plasma gas, the dilution gas and a sample gas is arranged between an ion-collecting electrode 11 and a bias voltage application electrode 12. The sample gas introduced through a capillary tube 16 is mixed with the plasma gas and the dilution gas due to a disturbed flow generated by collision of the plasma gas and the dilution gas. The sample component is efficiently ionized by light from the plasma without undergoing light-shielding effect of concentrated sample components. Furthermore, since an ion generation area is close to the electrodes 11 and 12, ions can quickly move the short distance due to the action of a direct current electric field. Therefore, the ions can reach the ion-collecting electrode 11 before their lifetime terminates.

Description

technical field [0001] The present invention relates to a discharge ionization current detector suitable primarily as a gas chromatography (GC) detector, and more particularly to a discharge ionization current detector using a low frequency barrier discharge. Background technique [0002] As gas chromatography detectors, such as thermal conductivity cell detector (TCD), electron capture detector (ECD), flame ionization detector (FID), flame photometric detector (FPD) and flame thermionic detector have been practically used (FTD), etc. of various types of detectors. Among these detectors, the FID is the most widely used, especially for the detection of organic substances. FID is a device that uses a hydrogen flame to ionize the sample components in the sample gas and detects the resulting ion current. The FID can achieve a wide dynamic range of about 6 orders of magnitude. However, FID has the following defects: (1) the ionization efficiency of FID is low, which makes the ...

AI Technical Summary

Problems solved by technology

However, FID has the following defects: (1) the ionization efficiency of FID is low, which makes the minimum detectable amount of FID not low enough; (2) the ionization efficiency of FID for alcohols, aromatic substances and chlorine-containing substances is low; ( 3) FID needs hydrogen as a highly dangerous substance, so it must be equipped with explosion-proof equipment or similar special equipment, which makes the whole system more difficult to operate

Significant drop in sensitivity especially in areas of high sample concentration

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