WINDOWLESS PULSED-DISCHARGE PHOTOIONIZATION DETECTOR - APPLICATION TOQUALITATIVE-ANALYSIS OF VOLATILE ORGANIC-COMPOUNDS

The effluent from a gas chromatograph was split and directed to four i dentical windowless photoionization detectors. These detectors use pur e helium, helium with Ar (0.64%), Ar (4.15%) and Kr (0.58%) as the dis charge gas. The relative ionization cross-sections can be obtained fro m the ratio of the normalized response using an internal standard. Thi s value is characteristic of the compound and could be used for qualit ative analysis. These ratios for 47 compounds encompassing 13 function al groups have been determined and are reported. The values have an av erage relative standard deviation of 2% for the majority of the compou nds. The long-term reproducibility of a smaller set of compounds has b een determined and was 0.78-2% relative standard deviation for the Ar detector and 5.6-11.3% (worse cases) where the response of the krypton detector is low.