Kinetic-spectrophotometric determination of rhodium based on its catalytic effect on the butylrhodamine B-potassium periodate reaction

A kinetic method for the spectrophotometric determination of trace rhodium based on its catalytic effect on the oxidation of buthlrhodamine B by potassium periodate is reported. The conditions of kinetics has been studied in detail. The linear relation between the log(A(0)/A) and the concentration of Rh(III) was found in the range of o to 180 mu g/L and the detection limit was 2.84 x 10(-10) g/L. The reaction was the first-order on for rhodium or butylrhodamine B and the apparent activation engrgy of catalytic reaction was found to be 64.04 kJ/mol. The method has been used to determine trace rhodium in some catalyst samples with the recovery of 96.8% similar to 104.7% and relative standard deviations of 1.8% similar to 3.5%.