The effect of make-up gas was studied for capillary gas chromatography (GC) coupled with on-column atomic emission spectrometric detection (AED), where a 350 kHz plasma was sustained inside the end of a 0.32 mm i.d. capillary GC column. For selective detection of Cl and Br both the plasma background characteristics and elemental responses were stabilized during temperature programmed analysis when 10-15 ml min^-1 of helium were added as a make-up gas. In addition, Chromatographic peaks were protected against tailing, while Cl and Br were detected at the 4 pg s^-1 level.