Atomic emission from a 350-kHz helium plasma was evaluated for the calculation of C/Cl and C/Br ratios in compounds separated by capillary gas chromatography. When the plasma was sustained inside the end of a 0.32 mm I.D. fused-silica GC column in 2 ml/min of GC carrier gas + 18 ml/min of make-up gas (helium), 94% of the elemental ratios obtained deviated by less than 20% from the theoretical values. These results with the on-column r.f. discharge were comparable to data obtained with a commercial GC-atomic emission detection system based on a microwave-induced plasma.