Gschwend%20thesis.pdf

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tubing into round bottom flasks. Finally, on the Peru cruise J the seawater
was passed through polypropylene tubing, precornbusted glass fiber filters,
and a stainless steel filter holder before entering the glass flasks. No
indication of contamination by these transfers was found. It seems that
the limited contact with open ocean air during transfers does not add
volatile organic compounds at the ng/kg level. This was also found by
Schwarzenbach et al. (1978) for samples transferred at coastal sampling
sites.
Tenax Methodology
The first method chosen to investigate open ocean volatiles sought
to provide rapid and routine semiquantitative analysis of this fraction.
Based on the literature, methods utilizing Tena~ as a solid adsorbent of
volatiles purged from aqueous samples by dynamic headspace stripping
seemed most suitable. The following is a description of the details of
this methodology as it was applied to the analysis of seawater samples.
Tenax traps :'¡ ~,
The Tenax traps were made from 0.125" o.d; x 1. 5" long Pyrex glass
tubing. One end was firepolished until the opening constricted to
less
than i ro. A glass wool plug was inserted and packed into this constricted
end.
2
Then 6 mg 60/80 mesh Tenax beads (approximately O. i m surface area)
followed by a second plug of silanized glass wool were added . Individual
traps were stored in Teflon-lined screw-cap vials which were previously
washed with soap and water and baked dry. The traps were cleaned just
before use by heating to 2500C under helium flow (2 ml/min) for i hour.
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