If you have a trap filled with 5A molecular sieve immersed in liquid nitrogen, you will freeze out O2. This is standard for purifying O2 away from other goodies. If it is whole air, I would recommend at least three traps, one to dry (dry ice ethanol), one to remove CO2 etc (liquid nitrogen without molecular sieve), and then the one to grab O2 (liquid nitrogen, 5A mol sieve). N2 will pass through these. Argon, however, remains with O2. 

andy



 Andrew Schauer
ISOLAB
Department of Earth and Space Sciences
University of Washington
Seattle, WA 98195


206.543.6327
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----- Original Message ----
From: Olha Furman <[log in to unmask]>
To: [log in to unmask]
Sent: Friday, January 30, 2009 11:13:38 AM
Subject: [ISOGEOCHEM] extracting oxygen from air

Dear All,

Could anybody tell what will be the easiest way to extract oxygen from air 
using the vacuum line and without conversion to CO/CO2, so it can be 
analyzed further on a dual-inlet mass spectrometer?

Thank you,

Olga