sia of trace gases by cf-irms. sample types co 2, n 2 o, n 2, ch 4 ; other gases by arrangement...
Post on 15-Jan-2016
215 views
TRANSCRIPT
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 [email protected]
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.