43 

 original stem and replacing it with a 1/2" diameter glass tube. This allowed the 



round bottom flask to be inserted into a Cajon fitting connected to a four-way 1/4" 



Swagelok cross via 1/4" tubing. The four-way Swagelok cross was attached to two 



toggle valves. One allowed for evacuation of air in the chamber prior to analysis; 



the other allowed for helium to be passed into the chamber, mixing with desorbed 



volatiles from the beads. The Whitey toggle valves were connected via a 1/4" to 1/8" 



reducer to the 1/8" Swagelok fitting. The vacuum line was connected to the TSQ70 



pumping system via a Swagelok fitting normally used to evacuate the calibration gas 



probe. TTie high purity helium was delivered to the apparatus by diverting the 



helium line out of the pressure regulator on the Varian 3400 GC and interfacing it 



with the toggle for helium introduction. The final port on the four-way cross 



consisted of reducing the 1/4" fitting to 1/16" and employing a 0.4 mm i.d. vespel 



ferrule (SIS, GVF16-004) for insertion of a 1.0 to 1.5 m x 0.10 to 0.25 i.d. deactivated 



fused silica open tubular (FSOT) column. One end of the column extended down 



into the round bottom flask, above the layer of beads. The other end of the column 



was interfaced to the ion source of the TSQ70 via the GC transfer line. 



The operation and sampling for the apparatus shown in figure 2-3 consisted 



of placing it in the Varian 3400 GC oven. The round bottom flask was removed 



from the Cajon fitting just prior to the transfer of glass beads into it. The flask was 



then re-inserted into the Cajon fitting. For some studies, the round bottom flask and 



Cajon fitting were replaced by a 3" x 1/4" o.d. glass tube swaged to the cross with a 



