The use of mercuric oxide reduction gas detection (RGD) for the passive sampling and capillary gas chromatographic determination of low concentrations of volatile organic compounds (C6) in ambient air is described. Sampling times are significantly reduced, compared with those required by the use of a flame ionization detector, due to the high sensitivity of RGD. The RGD signal due to the build-up of artifacts on polymeric sampling matrices during storage has also been investigated for Tenax-TA, Tenax-GR, Carbotrap and Chromosorb 106. The problem is at a minimum with Tenax-TA and GR, is more acute with Carbotrap, and is so severe with Chromosorb 106 that it prevents the use of this material for this application.