The isotope abundances and the atomic weight of cadmium by a metrological approach

Gravimetric synthetic mixtures of seven enriched, purified cadmium isotope materials were used to determine the correction factors for mass fractionation (MC-TIMS) and mass discrimination (MC-ICP-MS). The isotope abundance ratios determined for various natural cadmium materials represents the isotope composition for natural cadmium materials. Correction of the isotope abundance ratios observed yielded isotope abundances of 106Cd 0.012450(8), 108Cd 0.008884(4), 110Cd 0.124846(16), 111Cd 0.127955(14), 112Cd 0.241110(38), 113Cd 0.122254(22), 114Cd 0.287439(60) and 116Cd 0.075183(32). The newly determined atomic weight of natural cadmium based on SI-traceable evaluation of the isotope abundance ratios is 112.41384(18). The cadmium material designated in the paper as Cd-2211 can be used as an isotope reference material with a δ(114Cd/110Cd)-value of 0‰. The results obtained show that the uncertainties for the isotope abundances and the atomic weight given as IUPAC values for cadmium are overestimated.