Abstract: In this paper, a microwave plasma torch （MPT） ionization detector for gas chromatography is studied while argon（Ar） is used as the plasma support gas. The response characteristics and the ionization mechanism when O₂ and N₂ were, respectively, used as the sheath gas of ArMPT are evaluated. It shows better response characteristics when oxygen is used as sheathing ArMPT than that when nitrogen is used. than nitrogen. The detection limit of organic compounds was also investigated. The detector could stably and easily work under the atmospheric pressure, with a lower cost, a lower power and a lower gas flow-rate, moreover, the maximum e ndurance capacity of ArMPT to various organic compounds is superior to the simil ar detectors such as surfatron and TM₀₁₀, thus it is helpful to th e detection of the trace component in the complex mixtures.

Key words: gas chromatography, microwave plasma torch, ionization detector