A new separation procedure for Cu prior to stable isotope analysis by MC-ICP-MS

Abstract

A novel ion exchange chromatography was developed for the separation of Cu from biological samples prior to stable isotope analyses. In contrast to previous methods, the new technique makes use of the different distribution coefficients of Cu(I) and Cu(II) to anion exchange resin and this helps to significantly improve the purity of the Cu separates obtained from biological samples, whilst maintaining crucial quantitative yields. Careful method validation confirmed that the procedure yields sufficiently pure Cu fractions after a single pass through the anion exchange columns, with a recovery of 100 ± 2%. Subsequent isotopic analyses of the Cu by multi-collector inductively coupled plasma mass spectrometry, using admixed Ni for mass bias correction, produced accurate Cu stable isotope data with a reproducibility of ±0.04‰ for pure standard solutions and of ±0.15‰ for samples of biological origin.