Determination of trace elements in geological sample materials using ICP-MS

Abstract

The SCIEX Perkin-Elmer ICP mass spectrometer, which was installed in 1984 in the Department of Earth Sciences, has now been integrated into the department's elemental analysis facilities. ICP-MS is a routine analytical tool for many applications, determining trace elements in approximately 5000 samples per year. In rock matrices, it has been found especially suited to determining the heavier elements, from and including Rb to U. The major elements in rock samples along with the light trace elements Sc through Ga are determined using XRF or AAS. The trace elements Sc, Rb, Sr, Y, Zr, Nb, and Ba are determined by both XRF and ICP-MS thus serving as a quality control. Three ICP-MS packages are routinely available for elemental determinations including: 1. 33 trace elements: (Li, Be, Sc, Rb, Sr, Y, Zr, Nb, Mo, Cs, Ba, the lanthanides (La through Lu), Hf, Ta, W, Tl, Pb, Bi, Th, and U; in whole rock and mineral separate samples following an HF-HNO3 acid dissolution. 2. rare-earths and Th in rocks with a sodium peroxide sinter procedure, and 3. precious metals (Ru, Rh, Pd, Re, Os, Ir, Pt, and Au) following a NiS and Te precipitation collection. Procedures for determining elements in fresh waters have been developed for application to geological programs. The water analysis includes several of the light elements in addition to a selection of heavier elements which are quantifiable in fresh surface and well waters. The long term precision and accuracy of the method will be demonstrated.