Detection of negative ions from a conventional analytical glow discharge source using argon as the working gas is reported. The negative ions are recorded using a pulsed discharge source coupled with a time-of-flight mass spectrometer. A considerable enhancement in the "afterglow" region of the negative ion signal for halogens and halogenated molecules and reduction in background is observed. This is the first time when negative ions have been reported for halogen containing materials and we illustrate our findings with results from the polytetrafluoroethene polymer (PTFE).