. 12C, 13C CM-CRDS PICARRO

δ¹³C is a proxy used in geochemistry, paleoclimatology and paleoceanography.
δ¹³C changes over time as a function of primary productivity, carbon burial and vegetation type.
It is the ratio of the two stable carbon isotopes, ¹³C / ¹²C, expressed in ‰.

where the reference is the unusually high ratio (¹³C / ¹²C) of a Cretaceous fossil belemnite shell from the Peedee Formation in South Carolina —> data versus Pee Dee Belemnite or VPDB

The CM-CRDS (Cavity Ring Down Spectroscopy) is an apparatus dedicated to measurements of the amounts of stable ¹²C and ¹³C isotopes in a solid sample.
It is possible to discredit the Total Carbon part from the Organic Carbon part by decarbonating the sample (developed in the lab).
The instrument returns the value of δ¹³C relative to the Pee Dee Belemnite standard. : δ¹³C VPDB

CM-CRDS PICARRO
Framework of use	Apparatus used within the framework of research projects at ISTerre and OSUG, or more rarely within the framework of external services.
Technical characteristics	Types of samples Solids, with specific preliminary preparation (contact us beforehand). Technical data Analysis time : approximately 10 minutes per sample. 33 samples per session, 10 standards ; 7 blanks. Concentration range : 0.5 to 1.5 mg pure C per sample. "Flash" combustion of the sample which converts all carbon to 12CO2(g) and 13CO2(g). The other combustion compounds are sorbed so that they are not injected into the reasoning cavity. Then detection of the ppmv content of each isotope by measuring the decay of the laser intensity in the cavity (absorbance). Types of analysis Carbon 12C and 13C. Isotopes on decarbonated samples (Laboratory developed method) to extract OM
Quality control	Certified standards
Responsible for the tool, Team to contact – Scientific leader Stephane Guedron->https://www.isterre.fr/annuaire/pages-web-du-personnel/stephane-guedron/] 04 76 63 59 28   – Technical manager Sylvain Campillo 04 76 63 51 31