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.