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

This paper describes a novel approach developed for on-line removal of inte rferences within modified capillaries coupled to micro-flow nebulizers, for palladium determination by inductively coupled plasma mass spectrometry (I CP-MS). A strong cation exchanger [2-(4-chlorosulfophenyl)ethyltrichlorosil ane)] was covalently bound to the silica capillary that was coupled to a mi croconcentric nebulizer (MCN) or to a direct injection nebulizer (DIN). The modified surface of the capillary was able to selectively retain copper an d yttrium from aqueous samples at pH 7.5 during the sample introduction ste p, while Pd was not retained and Pd-105 could be determined in the absence of interferent elements. The capillary was easily regenerated by flushing w ith 100 muL of 10(-2) mol L-1 HCl. Since calibrations showed no significant difference between the absence and presence of interfering elements, the p alladium detection limits of 8.8 and 5.8 ng L-1 for MCN and DIN, respective ly, 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 deter mine ultratrace amounts of palladium in samples containing the above-mentio ned interferents by using ICP-MS. The method was successfully applied to de termine palladium in different environmental samples such as road dust and car exhaust fumes.