Sensitive determination of platinum by the parallel catalytic hydrogen wave of Pt (IV) in the presence of persulfate

Abstract

A sensitive polarographic method for the determination of platinum is proposed, based on the so-called parallel catalytic hydrogen wave of the Pt (IV)–EDTA complex in the presence of persulfate. At mercury electrodes, the Pt (IV)–EDTA complex produces a catalytic hydrogen wave at −1.10 V (vs. SCE) in 1.0 mol l −1 HOAc+NaOAc (pH 4.4) buffer. When K 2S 2O 8 is present, the catalytic hydrogen wave is catalyzed further by S 2O 8 2− and its reduction intermediate sulfate radical anion SO 4 −, producing a kinetic wave, described as the parallel catalytic hydrogen wave. The second-order derivative peak current of the wave is rectilinear to the platinum concentration in the range 1.3×10 −10 to 7.7×10 −9 mol l −1 with a detection limit of 6.8×10 −11 mol l −1. The proposed method is free of interference from other metal ions except for Ru (IV), and is evaluated by the determination of platinum content in standard reference alloy materials and platinum catalysts.