Sorption/desorption gas analysis apparatus

Abstract

A sorption/desorption gas analysis apparatus includes a sorption/desorption bed having a thin layer of sorption material fixed to an outside surface of a first and a second adjacent tapered bed element arranged in a mutually mating configuration. The bed elements are further arranged to be selectively moved with respect to each other to produce a first flow volume therebetween past the sorptive material during a sorption mode of operation and a second substantially smaller flow volume past the sorptive material during a desorption mode of operation. The sorption/desorption bed is used in the gas analysis apparatus by first exposing the sorption bed to an impinging flow of a sample gas containing the constituent of interest which is sorbed by the sorptive material in the sorption mode of operation. During the desorption mode of operation, the first and second bed elements are displaced toward each other by a bed drive while flow directing elements are used to direct the flow of a desorbed sample from the sorption bed. Finally, the sorptive material is heated to desorb the sorbed sample and which is directed to an inlet of a detector, e.g., a gas chromatograph. The flow volume reduction provided by the volume of the flow path across the sorptive material during the desorption operation compared to the cumulative volume of impinging gas flow during the sorption operation produces a very high accumulation factor by minimizing the flow space volume.