A plasma reactor has been developed, which is inserted into a gas-chromatographic flow system so that any effluent emerging from the first column can be routed through the plasma and the resulting products separated in a second column. Plasma processing is based, typically, on a weak,β-stimulated argon discharge, and a variety of doping gases can be added to provide different chemical environments. The resulting product patterns are characteristic of the compounds processed and can serve analytical or physiochemical ends.