Microwave Digestion for the Determination of Platinum Group Elements, Silver and Gold in Chromite Ores by ICP-MS

Abstract

This paper describes an effective acid digestion procedure for

chromite samples utilising a laboratory microwave oven for the

determination of gold, silver and platinum group elements by

inductively coupled plasma mass spectrometer. The procedure was

evaluated by the analysis of some standard reference materials,

PTM-1, CHR-Pt+ and CHR-Bkg together with a few chromite ore

samples from the Sukinda Valley. The data obtained on Au, Ag, Ru,

Rh, Pd, Os, Ir and Pt in the standard reference materials showed

good agreement with the rreference values. Cesium was used as an

internal standard. The detection limits obtained for these elements

were in the range of 0.01 to 0.07 ng/g. The proposed microwave

digestion, in combination with ICP-MS method of estimation was

found to be particularly useful for rapid quantitative estimation of

precious elements in chromite ore samples. This method can in

general also be utilised for prospecting studies of precious metals

in all mafic and ultramafic rocks.