Absolute measurements of neodymium isotopic abundances and atomic weight by MC-ICPMS

Gravimetric synthetic mixtures prepared from highly enriched isotopes of neodymium in the form of oxides of well-defined purity were used to calibrate a multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Measurements on natural neodymium samples yielded an absolute isotopic composition 27.147(20) at.% 142Nd, 12.182(21) at.% 143Nd, 23.803(14) at.% 144Nd, 8.297(6) at.% 145Nd, 17.190(13) at.% 146Nd, 5.755(8) at.% 148Nd, 5.626(10) at.% 150Nd, and the atomic weight of neodymium as 144.2409(17) both with an uncertainty given on the basis of 95% confidence limit. No isotopic fractionation was found in terrestrial neodymium materials. Thermal ionization mass spectrometry (TIMS) analyses were carried on the same samples measured by MC-ICPMS and the essentially identical results were obtained, both for the abundances and the atomic weights.