GEMOC ARC National Key Centre

Sharma, A.L., Alard, O., Elhlou, S., Pearson, N.J.
ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC), Department of Earth and Planetary Sciences, Macquarie University, Sydney, 2109, Australia.

Ultramafic rocks have very low levels of trace elements therefore making accurate quantification very difficult. In this study we have evaluated the advantages and disadvantages of two different digestion techniques: (1) HF+HNO3 and (2) HF+HClO4.

We will present data for 2 ultramafic rock standards (peridotites PCC-1, JP-1) and 3 mafic rock standards (basalts BCR-2, BIR-1, BHVO-2). Data were collected on an Agilent 4500 ICPMS Series 300 with a shield torch option. Our data suggest that for basic rocks, accurate trace element concentrations are obtained using either digestion method. However, for ultrabasic compositions, higher recovery is obtained for most elements using the HF/ HClO4 digestion technique. The different behaviour of the 2 compositions suggests a matrix effect on the recovery. Although higher recoveries are obtained with HF/ HClO4, the detection limits are also significantly increased due to the purity of the HClO4.  This must be considered along with safety issues in selecting the procedure best suited to the rock composition.

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