Accurate and precise determination of Li isotopic compositions by multi-collector sector ICP-MS

A new method is presented for the preparation of geological materials (wate r and rock) and their accurate analysis, by multiple collector magnetic sec tor ICP-MS, for the isotopic composition of Lithium. Based on multiple dupl icate and replicate measurements over an 8-month period, the precision of t his technique is conservatively estimated to be +/-1.1 parts per thousand ( 2 sigma population), which is similar to the precision of other methods in current use: The delta(7)Li (Li-7/Li-6 relative to the L-SVEC standard) det ermined for Pacific seawater is +31.8. The delta(7)Li of the basalt standar ds JB-2 and SRM-688 are +5.1 and + 2.8, respectively. The new technique has additional advantages over other methods in small sample size(similar to 4 0 ng Li), rapid analysis (similar to 2 samples/h) and relative insensitivit y to trace element contamination of analyte solutions. (C) 1999 Elsevier Sc ience B.V. All rights reserved.