SIA of trace gases by CF-IRMS

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, 12mLAvoid “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 HgCl2Please 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

Chromatography

Data Review

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.