Determination of incompatible trace elements in mantle clinopyroxenes by LA-ICP-MS: A comparison of analytical performance with established techniques

Incompatible trace element abundances have been determined in mantle-derive d clinopyroxenes by laser ablation-inductively coupled plasma-mass spectrom etry (LA-ICP-MS) in a comparative study with established microanalytical an d bulk techniques. Individual clinopyroxene grains were sampled for the las er ablation study from sieved mineral separate fractions from which similar mineral grains had been previously extracted for microprobe (SIMS) and bul k (INAA and ID-TIMS) analysis. Mineral grains were ablated with variable de grees of surface spatial resolution (50-200 mu m) in order to maximise ICP- MS analyte count rates and to improve detection limits. A comparison of res ults from the different techniques reveals that for the most homogeneous sa mples LA-ICP-MS can achieve excellent levels of agreement with other techni ques (+/- 10%) and good precision for most of the studied elements (1-5% RS D). Variations in calculated concentrations by LA-ICP-MS confirm inter- and intra-mineral heterogeneity determined by SIMS, reflecting changes in samp le composition and texture. The long-term reproducibility of the technique is shown by the consistency of results for one sample analysed on thirteen occasions over a period of nine months.