Gschwend%20thesis.pdf

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sample. Sample water was forced into the stripper reservoir by connecting
a 2 -liter round bottom flask containing the sample to the sidearm piece
for sample introduction and pressurizing this flask with helium. Midway
through sample transfer, the stopcock was closed 1 the pressure was released,
the joint in the transfer line was parted ~ and an internal standard (20 ng
each l-chloro~hexane~ -decane~ -dodecane in 2 ~1 acetone) was injected into
the water in the transfer line. Connections were rapidly remade and the
stripper filling was completed. This transfer took about LO minutes during
which time a 1700 ml sample initially at l50C was heated to 200C at the
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stripper bottom and 40 C at the top. Immediately upon bubbling, temperatures
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equilibrated, and at the end of a 5 minute strip, the water was at 50 C.
Once the sample was introduced~ purging with helium was begun. High-
purity charcoal-filtered helium was used for stripping at iSO ml/min.
After 5 minutes of stripping, the gas flow was stopped, and the trap was
replaced by the glass plug. The trap was returned to the small vial and
stored in a freezer. The seawater was then forced out the sample inlet
tube by continued bubbling with helium into the plugged stripper; once the
stripper was empty, the helium flow was continued for an additional 5
to 10 minutes to flush the stripper and leave it full of helium for the ¡,
next sample.
Gas chromatography and combined gas chromatography-mass spectrometry
The volatile organic compounds were detected and identified using
glass capillary gas chromatography (GC) and combined gas chromatography-
mass spectrometry (GC-MS). GC was performed with an HP5700 chromatograph
equipped with a flame ionization detector and subambient attachment (C02),
An O.125" injector was used and filled halfway with 0.125" o~d. glass
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