Stable Isotope and Palæoclimate Analysis Laboratory - SPA Lab
 

Analytical Services - δ13C and δ18O of Gaseous CO2

The SPA lab uses a GasBench II attached to MAT-253 IRMS for the measurement of δ18O and δ13C ratios of CO2 in atmospheric air or breath.  The sample is introduced into a headspace vial and the GasBench automatically samples CO2 in the vial.  

During a run sequence, gas derived from the acid reactions (see Carbonate δ18O and δ13C Isotopes) three each of NBS-19 and LSVEC international standards are used to normalize isotope results using a two-point linear normalization technique.  Two NBS-19 limestone samples are run "as-a-sample" to monitor quality control and long term performance.  Normalized delta values are expressed relative to VPDB for δ13C and δ18O.

Gaseous CO2 Rates

Isotope Phase Quantity Measurement Precision Internal External
δ18O, δ13C Gas 20-50 µg ± 0.08 ‰ $6 $10

Sample Types: Air, breath, or gas with 400-8000 ppm CO2

Sample requirements: Air (or breath or gas) with 400-8000 ppm CO2 is usually and preferably submitted already in 12 ml labco vials with septate tops.  If air samples are submitted in other containers, then an additional charge of $2 is charged for flushing vials with helium and using a gastight syringe to transfer the sample.  The increased pressure in the vial from flushing with helium makes introducing the gas problematic.

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