ABSTRACT

An analytical technique for determining boron, zirconium, niobium, hafnium and tantalum contents in rock samples by inductively coupled plasma mass spectrometry (ICP-MS) is described. The rock samples (<30 mg) were decomposed with mannitol-added HF, and dissolved in a 0.015 M HF/0.12 M HNO₃ acid mixture for ICP-MS analysis. Boron, zirconium, niobium, hafnium and tantalum concentrations were measured by the internal calibration curve method using three internal standard elements, beryllium for boron, indium for zirconium and niobium, and rhenium for hafnium and tantalum. Seventeen rock reference samples from the Geological Survey of Japan and the U.S. Geological Survey were analyzed, and the determined concentrations showed good agreement with the reported values obtained by isotope dilution method, as well as with the recommended values. This technique is a simple method for the precise determination of boron, zirconium, niobium, hafnium and tantalum concentrations, and it has wide potential for geochemical application, particularly for the determination of boron.