Analysis of human skin emanations by gas chromatography/mass spectrometry.2. Identification of volatile compounds that are candidate attractants forthe yellow fever mosquito (Aedes aegypti)

Volatile compounds emanated from human skin were studied by gas chromatogra phy/mass spectrometry (GC/MS). The purpose of this study was to identify co mpounds that may be human-produced kairomones which are used for host locat ion by the mosquito, Aedes aegypti (L.). The procedure used to collect vola tiles was chosen because of prior knowledge that attractive substances can be transferred from skin to glass by handling. Laboratory bioassays have sh own that the residuum on the glass remains attractive to mosquitoes until t he compounds of importance evaporate. The sampling and analytical procedure s modeled the above-cited process as closely as possible except that the ev aporation of compounds from the glass surface was accomplished by thermal d esorption from glass beads in a heated GC injection port. This made possibl e the solventless injection of volatiles onto the column. The compounds wer e cryofocused on the head of the column with liquid nitrogen prior to GC se paration. A single stage of mass spectrometry on a triple quadrupole instru ment was used for mass analysis. A combination of electron ionization and p ulsed positive ion/negative ion chemical ionization modes on two different GC columns (one polar, one relatively nonpolar) was used to identify most o f the 346 compound peaks detected by this technique.