RUTHENIUM(III) DETERMINATION BY KINETIC-CATALYTIC METHOD USING THE NILE BLUE-ACIDIC CHLORITE REACTION

The mechanism of the Ru(III) catalysed oxidation of Nile blue (3-amino-7-diethylamino-8,9-benzo-2-phenoxazine chloride, NB+) by acidic chlorite were investigated by kinetic approach and using the stopped flow technique at 633 nm. The catalysed reaction had a first-order dependence on the concentrations of NB+, H+, ClO2- and catalyst. The pertinent mechanism, consistent with the experimental results is proposed. Based on the high sensitivity and selectivity of the reaction to the presence of Ru(III), using its catalytic efficiency on the oxidation of Nile blue (NB+) by acidic chlorite, a fixed-time kinetic method is reported for Ru(III) determination. Interference studies confirm that the proposed method allows determination of Ru(III) in presence of wide range of cations, including Pd(II), Rh(II), Fe(III) and Os(VIII). The lowest detection limit for Ru(III) ions is 0.2 nmoles L-1 (2.0 ng mL-1). KEY WORDS: Ru(III) determination, Photometric, Kinetic method, Nile blue, Chlorite Bull. Chem. Soc. Ethiop. 2007, 21(2), 171-178.