Calcium Isotopic Reference

 δ(⁴⁴Ca/⁴⁰Ca) Values of Carbon Isotopic Reference Materials

† Exact value defining the delta scale.  However, for some studies, δ(⁴⁴Ca/⁴⁰Ca) measurements may be more appropriate.

Comment

Although n(⁴⁴Ca)/n(⁴⁰Ca) calcium isotope-amount ratios commonly are measured to determine δ(⁴⁴Ca/⁴⁰Ca) values (δ⁴⁴Ca), 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}