The efficiencies of various carbon sorbents in the preconcentration of volatile organic substances from a stream of humid air for their subsequent gas-chromatographic determination are compared. A hybrid procedure for rapid analysis including the sorption preconcentration of analytes on a selected carbon–fluoroplastic composite sorbent and their one-stage thermal desorption in the injector of a chromatograph with a capillary column and a flame-ionization detector is proposed. This procedure makes it possible to determine lower alcohols and ketones in air saturated with water vapor for 5–10 min with determination limits at a level of several μg/m ³.