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Calcium Isotopic Reference

 δ44/40Ca Values of Calcium Isotopic Reference Materials

Description 

Material

Nominal Unit Size

δ44/40Ca SRM915a

Footnote

Ref

SRM 915a

calcium carbonate

20 g

0 ‰

21

† Exact value defining the delta scale.  However, for some studies, δ44/40Ca measurements may be more appropriate.

Comment

Although n(44Ca)/n(40Ca) calcium isotope-amount ratios commonly are measured to determine δ44/40Ca values, 40Ca may be a poor choice for the denominator in this ratio because it is a product of 40K radioactive decay; thus, the mole fraction of 40Ca will vary with the age and n(K)/n(Ca) ratio of a material.

References

21. Coplen, T. B., Böhlke, J.K., De Bièvre, P.,  Ding, T., Holden, N.E., Hopple, J. A., Krouse, H. R., Lamberty, A., Peiser, H. S., Revesz, K., Rieder, S. E., Rosman, K. J. R., Roth, E., Taylor, P. D. P., Vocke, Jr., R. D., and Xiao, Y. K., Isotope-abundance variations of selected elements, Pure Appl. Chem. 74, 1987-2002 (2002).  [full text  pdf 506 KB]  {SNIF.pdf}

 

 

 
2010 Commission on Isotopic Abundances and Atomic Weights | a commission of the International Union of Pure and Applied Chemistry