227 

 analyzed. The time delay between rubbing and analysis of the beads in this mode 



was approximately 2 hr. 



The cryo-focusing parameters were identical to those described previously in 

 the experimental section of this chapter. The GC oven ramp, however, was 

 conducted at a lower rate than previously used in studies. This was done to provide 

 additional resolution for co-eluting peaks found in previous studies with ramp 

 programs employing a steeper ramp. The GC oven ramp consisted of an initial 1.0 

 min hold at 40°C, a 27 min ramp at 6°C/min up to 200°C, and then a hold at 200°C 

 for 12 min. The transfer line was concurrently ramped from 50°C up to 210°C at 

 107min for 16 min, and held for 24 min at 210°C. GC Separation was effected by 

 a 25 m X 0.20 mm i.d. HP5 FSOT column (df=0.33 tim). 



The mass spectrometer operation in EI and PPINCI modes is similar to that 

 described previously in this chapter. Methane reagent gas at 1680 to 1700 mtorr 

 (indicated) pressure was employed for PPINICI analyses. The third quadrupole was 

 scanned at 0.5 s per scan for EI and PPINICI analyses. The conversion dynode was 

 set at +5 kV for positive ion CI and EI, and -5 kV for negative ion CI. The electron 

 multiplier was set to -1000 V for EI experiments and -1100 V for CI experiments. 

 Prior to the analysis of blanks, the instrument was tuned with PFTBA. 

 Olfactometer 



Bio-assays of a glass petri dish handled by Mr. Ken Posey of the USDA were 

 conducted approximately one hour after sample collection for GC/MS analysis. 

 These experiments were conducted at the USDA laboratories and involved analysis 



