Preconcentration and matrix separation of precious metals in geological and related materials using metalfix-chelamine resin prior to inductively coupled plasma mass spectrometry

Abstract

A method for determining Au, Pt, Pd, Ir and Rh in ores and silicates and Fe-formation rocks is described. Sample decomposition was carried out with aqua regia and HF, followed by fusion of any insoluble residue with Na22O2 in a glassycarbon crucible. The precious metals were separated, in 1.2 mol dm−3 HCl media, from the matrix elements by ion-exchange, using a mini-column with tetraethylenepentamine (metalfix-chelamine) resin. The resin was destroyed with HNO3 and H2O2 in a high-pressure vessel assisted by microwave heating, and the precious elements were determined by flow-injection inductively coupled plasma mass spectrometry. The sample treatment, optimization of analytical variables and measurable concentration levels are discussed. The limits of quantification (10 sdn − 1) calculated from a procedural blank sample solution were 4.0, 2.0, 1.5, 0.8 and 0.5 ng g−1 for Au, Pt, Pd, Ir and Rh, respectively. The accuracy of the proposed method was tested by determining these elements in SARM 7 platinum-ore reference material. For all the analytes, the relative standard deviation of the combined dissolution, separation and determination methods was below 3.5% (n = 6).