Solid-phase spectrophotometry use for the determination of trace amounts of Rh(III)

A simple and sensitive solid-phase spectrophotometric method was developed for the determination of rhodium(III) trace amounts. The proposed procedure is based on the reaction product of disodium-1-nitroso-2-hydroxynaphthalene-3,6-disulfonate( Nitroso R salt) previously loaded on Dowex 1 x 1 anion exchanger. To find the best analytical conditions for the determination, the experimental variables (wavelength, pH, amount of resin, sample solution volume) were optimized. Under the selected conditions, rhodium(III) can be accurately determined in the range of 0.5-2 mu g/ml with an RSD of 1.18% and a degree of sensitivity, expressed by the molar absorptivity, of 3.0356x10(4) l/mol cm. The results obtained on synthetic solutions clearly indicate the feasibility of the proposed method for real sample analysis.