Analysis of Geological Materials for Bismuth, Antimony, Selnium and Tellurium by Continuous Flow Hydride Generation Inductively Coupled Plasma Mass Spectrometry

Abstract

A new method to determine Bi, Sb, Se and Te, at concentrations as low as their natural concentration ranges in geological samples, has been developed based on continuous flow hydride generation inductively coupled plasma mass spectrometry. Samples are dissolved by digestion in either aqua regia or HF–HClO 4 –HNO 3 –HCl acid mixtures and analytes separated from potential interferences ( e.g. , Cu, Ni and Co) by coprecipitation with La(OH) 3 . Addition of a small amount of KI and ascorbic acid, to a concentration of 0.005% in the final analysis medium of 4 m HCl, negates the most serious mutual interference of As V on Te. Analysis is carried out in two batches, the first for Se alone, and the second for the other three elements in the presence of KI. The method was applied to 18 stream sediment and rock standard reference materials from the People's Republic of China (GSD and GSR series). Precision is typically in the range 3–8% relative standard deviation, the higher values usually being associated with concentrations in the very low µg kg -1 range. Detection limits were achieved of 1 µg kg -1 for Bi and Te, and 6 µg kg -1 for Sb and Se. Bismuth was completely extracted from all samples by both digestions but some matrices required the more comprehensive decomposition of HF–HClO 4 –HNO 3 –HCl for full recovery of Te, Se and, to a lesser degree, Sb.