Precise determination of SmNd ratios,Sm and Nd isotopic abundances in standard solutions

The methods used for precise calibrations of $\text{Sm}\text{Nd}$ ratios and the average isotopic abundances obtained for normal Sm and Nd are given. A mixed Sm-Nd normal solution with a precisely known ${}^{147}\text{Sm}{}^{144}\text{Nd}$ ratio close to the nominal average chondritic value is described and the calibration discussed. Aliquots of this standard solution are available on request and may be useful for precise interlaboratory calibration of Sm and Nd.