Pee Dee Belemnite

Pee Dee Belemnite also Peedee Belemnite (abbreviated PDB ) is a common standard for the measurement of δ ¹³ C . It comes from a marine fossil from the Cretaceous Period, a specimen of the belemnite species Belemnitella americana , from the Peedee Formation in South Carolina (USA). The ¹³ C / ¹² C ratio of this fossil consisting of calcium carbonate (CaCO ₃ ) is higher than in most natural substances due to its unusually high ¹³ C content, which means that the δ ¹³ C values measured in other samples are mostly negative.

It is ${\displaystyle ^{13}\mathrm {C} /^{12}\mathrm {C} _{\mathrm {PDB} }=R_{\mathrm {PDB} }=0{,}011\,237\,2}$

However, this fossil was soon used up, which is why the IAEA in Vienna published an artificial standard. This has a slightly smaller isotope ratio compared to the PDB. To clearly differentiate it from the original standard, it is referenced as VPDB - the V stands for Vienna , the English name of Vienna.

It is ${\displaystyle ^{13}\mathrm {C} /^{12}\mathrm {C} _{\mathrm {VPDB} }=R_{\mathrm {VPDB} }=0{,}011\,180\,2}$

For ¹³ C / ¹² C values ​​of any sample, standardization is carried out as follows:

${\displaystyle \delta ^{13}\mathrm {C} _{\text{Probe}}=\left({\frac {^{13}\mathrm {C} /^{12}\mathrm {C} _{\text{Probe}}}{^{13}\mathrm {C} /^{12}\mathrm {C} _{\mathrm {VPDB} }}}-1\right)}$

The result is given in per mille (for example −40 ‰ for the result −0.040).

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General

• Overview of Stable Isotope Research. Subpage of the old website of the Stable Isotope / Soil Biology Laboratory (SISBL) of the Institute for Ecology at the University of Georgia in Athens, GA (English)

Individual evidence

1. ^ QL Zhang, TL Chang, WJ Li .: A Calibrated Measurement of the Atomic-weight of Carbon. Chinese Science Bulletin. Vol. 35, No. 4, 1990, pp. 290-296.