Simplified flame ionization detector for gas chromatography

Abstract

Impedance conversion circuit, which consists of two 6AU6 MT valves, for use with a single flame detector in the gas chromatograph was presented. With this simplified circuit, designed to have a very high input resistance and a low output resistance together with a high degree of linearity between input and output, the detector exhibited high signal to noise ratio and also high sensitivity, as 4.8×105mV ml/mg for benzene with a background of less than 0.01 mV. The linear relationship between peak height and weight was maintained over the range of 10~0.1γ for benzene, 10~0.2γ for toluene and 10~0.5γ for xylene. The least detectable amounts of them were 0.05γ for benzene, 0.1γ for toluene and 0.25γ for xylene with the signal to noise ratio 2:1. Under a constant mains voltage, the short term drift was within 100 μV, the maximum deviation was within 2 mV/hour and the amplification was 0.4. © 1962, The Japan Society for Analytical Chemistry. All rights reserved.