An automated gas chromatographic system was constructed to easily adapt either the cryogenic trap or chemical sorbent trap for preconcentrating ambient levels of volatile organic compounds. Remarkable similarity in chromatograms from C-3 to C-10 was found between these two enrichment methods, except that the sorbent trap did not quantitatively trap the C-2-hydrocarbons, In contrast to cryogenic trapping, the chromatographic conditions for more volatile compounds were substantially improved using the sorbent trap. Water interference on the porous-layer open tubular column was also better managed using the sorbent trap for the continuous analysis of humid room air. The similarity in peak profiles between the GC-flame ionization detection (FID) and a commercial GC-MS system, regardless of concentration levels, facilitated compound identification on the FID chromatograms based on a field mission involving analysis of 106 air samples. (C) 1999 Elsevier Science BN. All rights reserved.