PORTABLE CRYOGENIC COLLECTION OF ATMOSPHERIC NITROUS-OXIDE AND CARBON-MONOXIDE FOR HIGH-PRECISION ISOTOPIC ANALYSIS

ih portable cryogenic collection system has been constructed for the i solation of atmospheric nitrous oxide (N2O) and carbon monoxide (CO). Ambient air enters the system at a rate of 10 L/min, and N2O condenses in a specially designed stainless steel ultrahigh-efficiency collecti on (UHEC) trap. The CO is next oxidized to CO2 and removed by a second UHEC trap. In conjunction with drying agents, the UHEC traps remove g reater than 99.9989% of atmospheric carbon dioxide (CO2) that would ot herwise interfere with CO-derived CO2 analysis. The oxygen in the N2O and CO-derived CO2 samples is subsequently separated for high-precisio n mass spectroscopic analysis. This system is unique in that it provid es for in situ collection and permits simultaneous measurement of the O-18/O-16 and O-17/O-16 ratios in N2O and CO. Results are presented fo r a series of trials run to determine the ultimate collection efficien cy of the UHEC cryogenic traps.