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}
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