1. SIA of trace gases by CF-IRMS

2. 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)

3. 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

4. Sample Preparation If samples require poisoning, use ~1mL 50% w/v ZnCl 2 ; UCD SIF cannot accept samples containing HgCl 2 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

5. 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.

6. 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

7. 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

8. SIA of trace gases by CF-IRMS Three dedicated trace gas instruments ThermoScientific and Sercon Atmospheric concentrations to pure gases

9. Chromatography

10. Data Review

11. 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.