Third derivative spectrophotometric determination of rhodium using 2-(2-thiazolylazo)-5-dimethylaminobenzoic acid as analytical reagent in the presence of triton X-100

A third derivative spectrophotometric method has been proposed for the trac e determination of rhodium (III) using 2-(2-thiazolylazo)-5-dimethylaminobe nzoic acid (TAMB) as the complexing agent and triton X-100 as surfactant. R hodium(III) forms a coloured complex with (TAMB) - triton X-100 in the pH r ange 5.2 - 6.8. Linearity is maintained in the concentration range 0.030 - 0.4 mu g mL(-1) of rhodium with correlation coefficient of 0.9998. The sens itivity of the method as determined from the slope of the calibration plot is 1.26 (d(3)A/d lambda(3))/(mu g mL(-1)). Nine replicate determinations of 5.0 mu g of Rh(III) in 25 mL of the final aqueous solution give a mean sig nal height of 0.250 (peak to peak distance between lambda(1) = 680.4 nm and lambda(2) = 663.5 nm) with a relative standard deviation of 0.92%. The eff ect of various parameters on the determination of rhodium has been studied in detail to optimize the conditions for its determination in various synth etic samples. The method has been found to be simple, sensitive selective, rapid and economical.