The objective of the study was to evaluate the Photovac 10S50 portable photoionization gas chromatograph as a monitor for fourteen selected toxic organic vapors in ambient air. These included benzene, toluene, bromo- and chloro-benzene, o-xylene, and nine halo-methanes, ethanes, and ethylenes. Such analyses have usually been done by gas chromatography using a mass spectrometer as detector (GC/MS). The procedure is inefficient in collection and delivery of analytes to the GC/MS system and limits GC/MS analysis of organic vapors in air to being a semiquantitative method which may produce misleading results. A portable chromatograph with a detector sensitive enough to detect pollutants without preconcentration could avoid these shortcomings and supplement or complement data obtained by preconcentration/GC/MS.