Characterization of an element selective GC plasma detector based on diode laser atomic absorption spectrometry

An element-selective GC-plasma detector consisting of a modulated low-pressure microwave-induced plasma and a laser detection system based on Wavelength Modulation Diode Laser Atomic Absorption Spectroscopy (WM-DLAAS) was investigated. The influence on the plasma conditions and the fragmentation capability of different types of organic compounds, such as alkanes, alkenes, alkynes and aromatics, was studied by measurements of the element ratios of C, H and Cl, and the population density of the metastable 1s(5) level of Kr added as a trace to the plasma gas (He or Ar). Deviations from the expected stoichiometrical ratios were found to be insignificant. Therefore, calibration and determination of the sum formula of analyte species is possible if an internal standard is used. Furthermore, the correlation between the metastable density in the microwave-induced plasma and the total dissociation energy of the analytes was studied. (C) 1998 Elsevier Science B.V.