36 

 Field studies 



Studies in the field are less precise in determining the actual percentage 



attracted to a sample. Sampling in the field also involves careful consideration in the 



design of traps, the release rates of samples, the location of samples, and the 



influence of parameters in the outdoors. Some of these parameters are wind speed, 



wind direction, humidity, and temperature. Additional concerns are manifested in 



the actual population of mosquitoes during the test, i.e. whether or not they are in 



close proximity to the test region such that odors could be detected. Trapped 



mosquitoes are separated and counted according to species. The information 



obtained from these experiments consists of a net capture rate relative to other 



species and/or a control. Estimating the total population of unattracted mosquitoes 



is not possible via field tests of this nature. 



Mass Spectrometric Methods of Sample Introduction 



The sampling for this dissertation was conducted numerous ways; a chart 

 representing this is portrayed in Figure 2-2. The sample in this diagram refers to 

 emanations or sweat found on human skin. These emanations were either deposited 

 on glass beads via handling the beads, washing the beads with solvent after handling 

 the beads, or directly dissolving perspiration into methanol. 



Methods of direct analysis of glass beads consisted of either using a single 

 bead fitted on the end of a solids probe stem or placing multiple beads in an 

 enclosed glass sample container or "vial". The term "vial" is used to describe any of 



