PRECONCENTRATION AND MATRIX SEPARATION OF PRECIOUS METALS IN GEOLOGICAL AND RELATED MATERIALS USING METALFIX-CHELAMINE RESIN PRIOR TO INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

A method for determining Au, Pt, Pd, Ir and Rh in ores and silicates a nd Fe-formation rocks is described. Sample decomposition was carried o ut with aqua regia and HF, followed by fusion of any insoluble residue with Na2O2 in a glassy-carbon crucible. The precious metals were sepa rated, in 1.2 mol dm(-3) HCl media, from the matrix elements by ion-ex change, using a mini-column with tetraethylenepentamine (metalfix-chel amine) resin. The resin was destroyed with HNO3 and H2O2 in a high-pre ssure vessel assisted by microwave heating, and the precious elements were determined by flow-injection inductively coupled plasma mass spec trometry. The sample treatment, optimization of analytical variables a nd measurable concentration levels are discussed. The limits of quanti fication (10 sd(n-1)) calculated from a procedural blank sample soluti on were 4.0, 2.0, 1.5, 0.8 and 0.5 ng g(-1) for Au, Pt, Pd, Ir and Ph, respectively. The accuracy of the proposed method was tested by deter mining these elements in SARM 7 platinum-ore reference material. For a ll the analytes, the relative standard deviation of the combined disso lution, separation and determination methods was below 3.5% (n=6).