Determination of palladium and platinum in fresh waters by inductively coupled plasma mass spectrometry and activated charcoal preconcentration

Abstract

A method was developed to analyse fresh waters for Pd and Pt by inductively coupled plasma mass spectrometry following preconcentration of the analytes by adsorption onto activated charcoal. Two modes of sample introduction were used: nebulization (NEB) and electrothermal vaporization (ETV). Using a 1 l sample volume and a preconcentration factor of 200, detection limits are in the range 0.3–0.8 ng l^–1 for both elements, with little difference between NEB or ETV introduction. Precision is typically 10% relative standard deviation at the 5 ng l^–1 level and 4–5% at 10-fold higher concentrations of Pd and Pt. Addition of 10 ml of concentrated HCl per litre of sample is necessary to maintain these elements in solution at their natural levels in waters, well below 50 ng l^–1, and even then stability beyond about 20 d is questionable. Application of the method to waters collected from various mineralized sites in Canada indicated that dispersion patterns can be identified, but maximum concentrations of soluble Pd and Pt are low and for the most part less than 5 ng l^–1. As the preconcentration procedure is also suitable for Au and Rh, this method can be extended to include their measurement.