Analysis of human skin emanations by gas chromatography mass spectrometry.1. Thermal desorption of attractants for the yellow fever mosquito (Aedes aegypti) from handled glass beads

Handled glass has the ability to collect and concentrate nonaqueous human s hin emanations while minimizing the collection of aqueous perspiration. Com pounds originating from the skin and collected on glass have previously bee n found to attract the Aedes aegypti species of mosquito. Therefore, glass beads were used as the medium to collect skin emanations from humans for su bsequent chemical analysis. This process consisted of a 5-15-min collection of sample on glass beads, followed by loading the beads into a gas chromat ograph (GC) injector insert for subsequent desorption of the collected comp ounds onto the GC column. After cryofocusing by liquid nitrogen at the head of the column, the thermally desorbed compounds were analyzed by GC/MS. Mi croscale purge and trap introduction was also used to provide complementary information. In this case, the beads are held in a round-bottom flask, pur ged with nitrogen, and heated as the concentrator collects the headspace ab ove the beads. The chromatograms produced by both of these sample introduct ion methods demonstrate good resolution of a complex sample. Cryofocusing v olatiles from handled glass allowed identification of lactic acid, aliphati c fatty acids, and other polar to nonpolar compounds of moderate volatility while purge and trap allowed detection of nonpolar to moderately polar com pounds of high volatility.