44 

 1/4" glass filled teflon ferrule. The tube had an inner diameter slightly larger than 



the bead diameter (approximately 1/8"). 



Once the sample was placed in the apparatus contained in the GC oven, 

 evacuation is conducted by opening the toggle to vacuum. After 2-3 s of evacuation, 

 the toggle was closed and the second toggle, supplying helium, is opened. The 

 helium pressure was set to 8 psig via the regulator normally used to control injection 

 port pressure on the Varian 3400 GC. Data acquisition was started at this point via 

 instrument automated control through an ICL program. 



The GC column was a 1.0 to 1.5 m .x 0.10 to 0.25 mm i.d. deactivated FSOT 

 column. The heating parameters consisted of a GC oven ramp and a transfer line 

 ramp. The GC oven ramp consisted of a 0.5 to 1.0 min hold at 25 to 30"C followed 

 by a 10-15°C/min ramp up to a final temperature of 190-210°C and a final hold of 

 2.0 to 5.0 min. The transfer line was initially set to 50°C and ramped immediately 

 at 207niin up to 200-2 10°C and held at that temperature for the duration of the 

 experiment. 



The NCI experiments were conducted with 1650 mtorr methane as the 

 electron moderating gas. The scan times were 0.5 to 3.0 s; scanning over Q3 (i.e. 

 Q3MS) was employed with a mass range of m/z 10-650. The electron multiplier was 

 set at -900 V, the conversion dynode at +5kV, and the filament emission current set 

 at 200 ij,A with 100 eV electron energy. The ion source temperature was set at 

 150°C and the manifold set at 70°C. Prior to analysis, the mass spectrometer was 



