Hello,

I am interested in analysing 18O of O2 in breath samples. I'm presently
looking for a GC column to use with our multiflow which would adequately
seperate N2, O2 and CO2. Two columns from Alltech look like they would work,
the CTR1 and the Molecular Sieve 5A. The molecular sieve is considerably
less expensive. Does anyone have experience with either column? Or other
suggestions? Will these columns need to be reconditioned periodically in
order to deal with water accumulation?

Any help would be appreciated. Thanks in advance.

Matt