159 

 Experimental 



Analysis of Multiple Beads Without GC Separation 



Five beads handled 5 minutes by the author of this dissertation were placed 

 in a 1/4" glass tube (maximum 25 beads), which was inserted into the apparatus 

 described in Chapter 2 (figure 2-3). Helium, at 6-8 psig, was passed over the beads 

 and used as the carrier gas through a 1.0 m x 0.10 mm i.d. deactivated FSOT 

 column. The GC oven (holding the glass tube) was held initially at 28-30°C for 1.0 

 min, followed by a 12 min ramp at 15°C/min to 207-2 10°C, with a 5 min hold at the 

 final temperature. The transfer line was concurrently ramped from 50°C to 210- 

 215°C at 20°C/min once the run was started. 



Sample ionization was effected by positive ion CI or negative ion CI with 

 methane reagent gas at an indicated source pressure of 1687-1700 mtorr. The ion 

 source and manifold temperatures were set at 150°C and 70°C, respectively. The 

 electron energy was set at 100 e V with the filament emission current at 200 ^l A. The 

 parent ion was selected to be passed by Ql to the collision cell for fragmentation and 

 subsequent daughter spectrum analysis. The collision gas was argon at an indicated 

 pressure of 1.4-1.5 mtorr for positive ions and nitrogen at 1.97 mtorr for negative 

 ions; the collision energy was set at 15 eV for positive ions and 9 eV for negative 

 ions. The electron multiplier setting was -1200 V with the conversion dynode at -5 

 kV for positive ions and 4-5 kV for negative ions. Data were acquired with Q3 

 scanning at one s per scan for positive ions and 3 s per scan for negative ions. 



