Simultaneous determination of chloride complexes of Pt(IV) and Pd(II) by capillary zone electrophoresis with direct UV absorbance detection

The chloride ion was found to be a suitable complexing agent for the separation and determination of a Pt(IV)/Pd(II) mixture with by capillary zone electrophoresis, using direct UV absorbance detection at 270 nm. The pH and chloride concentration had a significant effect on the determination for which a carrier solution containing 0.1 M HCl and 0.4 M NaCl was used. The optimum applied voltage was around -8 kV. The Joule heating effect was not observed, as the electric current and migration times were rather stable and reproducible. The method was validated with respect to its response linearity and reproducibility. The detection limits found were 0.9 and 1.4 mu g ml(-1) for Pt(IV) and Pd(II), respectively. By use of stacking conditions, the detection limits were improved by a factor of 13. It was demonstrated that at pH 2, two species of platinum were present, one probably having a negative charge, [PtCl5H2O](-). The method was applied to the determination of Pt in samples of catalytic converters. The same samples were analysed by flame atomic absorption spectrometry.