Dear Blair,

Regarding your studies of 13C in breath of birds and using gas
containers.

The containers you mention, in their evacuated form, have only been
designed for 13C breath tests in human subjects where the normal
concentration range of CO2 is 1 to 5%. The studies you describe are more
akin to trace gas studies (ppm range). You need to be aware that a
standard evacuated tube can contain about 1 ml of atmosphere which would
obviously be detrimental to your work. Where the tubes are to be used
for 'trace gases' we recommend that the containers are re-evacuated to a
lower pressure so that you can be sure that when you fill them that the
resulting contents are only from your study (we supply suitably
evacuated containers at special request). The tubes have an inner
silicon coating baked on them during the annealing process.

Our own experience with these containers is that you can store samples
for at least 3 months without fear of leakage (or fractionation). They
are also good for repeated use provided you use replacement septa/caps
which can be purchased separately. Beware, of some look-a-likes on the
market which have a more brittle black septa. I have received reports
that these septa are more prone to 'coring' and have a suspicious 'oily'
texture. They have a much higher residual gas content even when
re-evacuated.

Steve

Steve Brookes, PhD
Sales & Marketing Manager

PDZ Europa Ltd
Europa House
Electra Way
Crewe
CW1 6ZA
United Kingdom

+44 1270 589398
+44 1270 589412
www.europa-uk.com
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