The absolute isotopic composition and atomic weight of ytterbium using multi-collector inductively coupled plasma mass spectrometry and development of an SI-traceable ytterbium isotopic certified reference material

Abstract

We have determined the absolute isotopic composition of ytterbium in six varieties of (terrestrial source) materials based on calibrated mass spectrometry using multi-collector inductively coupled plasma mass spectrometry. Instrumental mass bias was corrected by measuring a series of mixture solutions, which were gravimetrically prepared with three high purity and isotopically enriched isotopes ¹⁷¹Yb, ¹⁷²Yb and ¹⁷⁴Yb. The isotopic compositions of three enriched isotope materials were accurately measured by means of total evaporation thermal ionization mass spectrometry. Six natural-like ytterbium materials including NIM GBW04623 and NIST SRM3166a, yielded the absolute isotopic composition (in at%) of ¹⁶⁸Yb 0.12648(22), ¹⁷⁰Yb 3.0280(19), ¹⁷¹Yb 14.239(5), ¹⁷²Yb 21.789(5), ¹⁷³Yb 16.119(3), ¹⁷⁴Yb 31.881(8), and ¹⁷⁶Yb 12.817(12). The new atomic weight of ytterbium was calculated to be 173.0417(5) (k = 2) based on these data. In addition, an ytterbium isotopic certified reference material in nitric acid solution (GBW04623) was developed by using a metrological approach, which would be proposed as the delta zero reference for ytterbium.