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Dear Koba,

We have used the Wheaton serum bottles to with gray septa for enriched N2O
samples.  However, there are several disadvantages to them:-

1) They are small, I think the biggest that you can get is 60mL.  Although I
do not do natural abundance N2O, my understanding is that the analysis
requires at least 100mL of air if the N2O is at atmospheric concentrations.
You should contact whoever will be doing your analysis and see if they can
evacuated or purge your sample from the container your choose to use.

2) Even the gray septa have a trace amount of N2O that can degas.  The
amount of N2O released seems to depend on the particular batch, and may be
simply the time that they have had to degas since they were manufactured.
You should check any batch you use for contamination.

3) For our work in the field we have evacuated the Wheaton vials simply with
a good rotary vacuum pump.  Since this will remove 99% of the atmosphere in
the vial it should be adequate for most purposes.

4) Vacutainers can contain up to 1.5 to 2 ppm N2O, so we have never used
them.  The N2O apparently comes from the septa.  Otto Heinemeyer and
Ernst-August Kaiser, (1996. "Automated Gas Injector System for Gas
Chromatography:Atmospheric Nitrous Oxide Analysis. Soil Sci. Soc. Am. J.
60:808-811), found that vacuum in freshly purchased vacutainers was not
sufficiently maintained, so they re evacuated them prior to use.  They still
got up to 5000 nL L-1 even after this pre treatment.  They therefore stored
the vacationer stoppers under vacuum for 24 hours which seemed to remove the
N2O contamination.

We have now got our analysis time for N2O concentration on the GC (not
isotope ratio analysis) down to 2 minutes per sample. I can send you details
if you are interested.

Hope this helps, Paul Brooks.


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Paul D. Brooks, Spectroscopist,
Dept. ESPM,
151 Hilgard Hall,
UC Berkeley, Ca. 94720-3110
USA.

email [log in to unmask]

phone: (510)642-3155
FAX:   (510)643-5098
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