Simultaneous spectrophotometric determination of cobalt and nickel by H-point standard addition method (HPSAM) is described. The method was based on different colour reactions of 3-hydroxy-3-phenyl-1-(4-trifluoromethyl phenyl)triazene (HPTPT) with cobalt and nickel in aqueous medium at pH 7.5-9.0 in the presence of surfactant triton x-100 at two wavelength 410 and 445 nm. Experimental conditions such as colour development, reagent concentration, pH of the medium were optimized. The developed method has also been successfully applied to spectrophotometric determination of Co2+ and Ni2+ in synthetic samples with RSD of 0.55 and 0.10%, respectively.
Hydroxytriazenes, Simultaneous Spectrophotometry, Cobalt, Nickel