On-line removal of mass interferences in palladium determination by ICP-MS using modified capillaries coupled to micro-flow nebulizers

This paper describes a novel approach developed for on-line removal of interferences within modified capillaries coupled to micro-flow nebulizers, for palladium determination by inductively coupled plasma mass spectrometry (ICP-MS). A strong cation exchanger [2-(4-chlorosulfophenyl)ethyltrichlorosilane)] was covalently bound to the silica capillary that was coupled to a microconcentric nebulizer (MCN) or to a direct injection nebulizer (DIN). The modified surface of the capillary was able to selectively retain copper and yttrium from aqueous samples at pH 7.5 during the sample introduction step, while Pd was not retained and Pd-105 could be determined in the absence of interferent elements. The capillary was easily regenerated by flushing with 100 muL of 10(-2) mol L-1 HCl. Since calibrations showed no significant difference between the absence and presence of interfering elements, the palladium detection limits of 8.8 and 5.8 ng L-1 for MCN and DIN, respectively, were not influenced by adding up to a 300-fold excess of interferents. The developed method constitutes, for the first time, a simple way to determine ultratrace amounts of palladium in samples containing the above-mentioned interferents by using ICP-MS. The method was successfully applied to determine palladium in different environmental samples such as road dust and car exhaust fumes.