Abstract
An apparatus for the thermal desorption of solvent vapors collected by adsorption on activated charcoal is described. The analytes are desorbed in a stream of an inert carrier gas and are accumulated in a reservoir, from which a fraction of the gaseous sample can be drawn for gas chromatographic analysis; the entire desorption cycle is controlled automatically by an electronic unit. The analysis can be repeated several times, and standards can be added to the sample in the reservoir through an injection port for identification and/or quantitation of desorbed compounds. Thirty-four solvents were tested individually and in mixtures; the desorption yields (generally higher than 90%) and the reproducibility of the yields (generally better than 2%) are quite satisfactory when compared with the corresponding data for the NIOSH standard (carbon disulfide) desorption technique, and are largely independent from the mixture composition, from the relative humidity of sampled air and from the concentration in the range usually observed in industrial hygiene practice.