From volcanic rock powder to Sr and Pb isotope ratios: A fit-for-purpose procedure for multi-collector ICP-mass spectrometric analysis

Geochemical research into volcanic rocks often involves isotopic analysis of whole rock powders. The method of Deniel and Pin (Anal. Chim. Acta, 2001, 426, 95-103) for simultaneous isolation of strontium and lead using extraction chromatography via Sr spec™ resin was therefore adapted into a straightforward procedure for Sr and Pb isotope ratio determination by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The main focus was to reduce their rather extensive and costly cleaning procedures for resin and columns without negatively affecting data quality. It was furthermore demonstrated that non-quantitative Sr and Pb recoveries do not compromise the quality of the isotope data obtained and that no Pb isotopic fractionation occurs on the Sr spec™ resin. The accuracy of the analyses was assessed by monitoring rock reference materials. GSJ basalt JB-2, commonly regarded as the most homogeneous Pb isotopic rock reference material, hereby produced one anomalous Pb isotopic composition out of eight analyses, suggesting that JB-2 might also be affected by nugget contamination.