Gschwend%20thesis.pdf

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tubing to hold the short Tenax trap near the injection port opening and
to reduce the dead volume of the inj ec tion port. The column extended
into the injection port for the length of this glass insert. The other
end of the column extended into the detector just below the bottom of
the flame jet. The front of the. column was made into a small loop for
cryogenic trapping. Both ends of the column were deactivated with
PG20,000 (0.5% in CH2CI2).
Sargasso Sea samples were chroma tographed on an 0.3 ro o. d. x
20 m long SE30 glass capillary column purchased from J & W Scientific
(Sacramento, CA). This column was programmed at room temperature for
2 min and then 30-200oC at 4°C/min. The carrier was helium at I ml/min.
The western Equatorial Atlantic samples were analyzed using a
0.3 mm ~.d. x 20 m long UCON LB550 glass capillary column. This phase
was chosen to work in conjunction with the reduced temperatures made
possible
o 0
by the
0
subambient
I
attachment. The column was programed at
10 C to 120 C at 2 C min. Helium was again used as the carrier at
1 ml/min.
For analysis, the GC oven was cooled to its starting temperature,
and then the oven control was turned to "off". A liquid nitrogen (LN)
bath was placed around the cryogenic loop. Next, the septum cap was
removed~ the Tenax trap dropped into the injection port, and the cap
quickly reins taIled.
o
Desorption was then carried out at 250 C for
5 minutes with heliun flow carrying the volatiles into the cryogenic
loop at the front of the GC column. Finally, the LN was removed and
with the trap still in place, the temperature program was begun.
For GC/MS analysis ~ the UCON LB550 cOlumn was transferred to a Finnigan
. '. - _.' - - .
3200 quadrupole GCMS. Tenax traps were analyzed as with the GC. Electron
impact spectra were obtained with 70 eV ionization voltage. Chemical