Catalymetric determination of rhodium with photometric signal control

The catalytic oxidation of N-methyldiphenylamine-4-sulfonic acid (MDPASA) b y potassium periodate for the determination of 5.0 x 10(-3)-4.8 x 10(-2) mu g/mL of rhodium in complex materials was studied. The following optimal re action conditions were found: pH 2.5-3.5 (H2SO4); concentrations of reactan ts (MDPASA and KIO4) 8.0 x 10(-5) and 3.0 x 10(-3) M, respectively. The pot entialities of the proposed reaction were demonstrated in an analysis of ar tificial mixtures of various compositions and an industrial sample of a pla tinum concentrate. The relative error was no higher than 8%; rhodium can be determined in the presence of rare platinum-group metals.