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SIA of trace gases by CF- IRMS. Sample Types. CO 2 , N 2 O, N 2 , CH 4 ; other gases by arrangement Atmospheric, soil, breath, and dissolved gases Natural abundance to 99 atom% (>50 atom% by prior authorization only) Dual-tracer method (N 2 & N 2 O). Sample Preparation.
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Sample Types • CO2, N2O, N2, CH4; other gases by arrangement • Atmospheric, soil, breath, and dissolved gases • Natural abundance to 99 atom% (>50 atom% by prior authorization only) • Dual-tracer method (N2 & N2O)
Sample Preparation • Labco Exetainers, 12mL • Avoid “wide” exetainers (###W/W) • Other vials suitable by prior arrangement • Fill to ~ atmospheric pressure • Butyl or butyl/silicone septa are best • Overtightened septa can leak and clog autosampler needles Overtightening deforms septa
Sample Preparation • If samples require poisoning, use ~1mL 50% w/v ZnCl2; UCD SIF cannot accept samples containing HgCl2 • Please provide estimates of gas concentration and enrichment or provide test samples • For DIC, prepared samples do not require poisoning and should not be frozen
Evacuate and flush-fill sample vials • Do not buy “pre-evacuated” vials from Labco (hint: they are not empty). • If vials will not be filled with sample gas, flush fill your vials with helium to near atmospheric pressure.
Sample Organization and Shipping • If applicable, organize samples by increasing isotopic enrichment • Label vials clearly; avoid adding labels on top of labels • Protect glass from impact and label boxes as fragile
Paperwork • Complete an Analysis Order Form for each analysis type • Complete a sample list for each Analysis Order From • Email forms to sif@ucdavis.edu • Include printed copies with samples
SIA of trace gases by CF-IRMS • Three dedicated trace gas instruments • ThermoScientific and Sercon • Atmospheric concentrations to pure gases
Data Reduction and Corrections • Blank • Drift • Size • Scale expansion • Corrections follow those of Kaiser and Röckmann 2008 Kaiser, J. & T. Röckmann 2008. Rapid Commun. Mass Spectrom.