desorption of volatiles from handled glass beads placed in the injection port of a gas 

 chromatograph (GC) followed by cryo-focusing/GC analysis was determined to be 

 the best sampling method with respect to sensitivity and selectivity. 



Other than carbon dioxide, lactic acid is the only previously known chemical 

 attractant for the Aedes aegypti species of mosquito. The acid/base effects on 

 attraction to lactic acid, esters of lactic acid, and methyl isovalerate were studied. 

 The addition of acid enhanced attraction for all tested compounds, while the addition 

 of base decreased attraction. Perspiration was analyzed to determine the skin gland 

 origin of attractants. 



The major volatiles desorbed from handled glass beads have been identified 

 through the use of positive and negative ion chemical ionization in conjunction with 

 electron ionization. Mass spectrometric assays of two human subjects, differing 

 markedly in their attraction to mosquitoes, have been conducted to determine 

 differences in components present. Direct comparison of mass spectrometric assays 

 to bio-assays over a five day period has been carried out and is presented herein. 

 Additional identification of minor components present in skin emanations was 

 accomplished by purge and trap GC/mass spectrometry (GC/MS). The utility of 

 tandem mass spectrometry (MS/MS) as a tool for compound class screening is 

 presented in the context of this work. 



IX 



