49 

 is no heater for the manifold. Prior to analysis, the instrument was tuned with 



PFTBA. 



Results and Discussion 

 Thermal Desorption from a Single Bead 



The initial crucial phase of the work in this dissertation was demonstrating the 

 ability of mass spectrometry to detect emanations found on the skin. This problem 

 was approached by employing the knowledge gained from olfactometer experiments 

 that glass which has been handled retains attraction to mosquitoes. Shown in figure 

 2-4 is the total ion current versus time trace for a single handled glass bead. This 

 trace is typically called a reconstructed ion chromatogram (RIC), even though no 

 chromatography is being performed. This figure represents one of the experiments 

 from this beginning series where the single glass bead was introduced into the mass 

 spectrometer ion source via the direct insertion (solids probe). It is evident from the 

 shape of the RIC that separation from distillation off of the probe is minimal and 

 more sophisticated analyses would be required to discern the components hidden 

 below these peaks. This figure clearly illustrates the drawback to this probe method, 

 i.e. that temporal resolution, although satisfactory for simple samples, is not capable 

 of providing efficient resolution from so complex a sample as skin emanations. 



Matters are further complicated when searching for trace components. One 

 such example, for cholesterol (cholest-5-en-3-ol), is presented in figure 2-5. 

 Displayed in this figure are the mass chromatograms for m/z 386, the characteristic 



