In the HAc-NaAc medium(pH = 4. 5), Co(II) and Pd(II) ions could react with 2-[2-(6-methylbenzothiazole)azo-]-5-[N-methyl-N-acetyl]benzoic acid (MCB) to form Co-MCB and Pd-MCB complexes, The experimental results showed that both Co-MCB and Pd-MCB had absorption peaks at 610.5 nm, and only Pd-MCB had an obvious absorption peak at 710 nm, therefore, the contents of Co and Pd can be determined simultaneously by measuring the absorbance of Pd at 710 nn and the total absorbance at 610.5 nm. The linear ranges were 0.2 similar to 4.0 mg/L (for Pd) and 0.4 similar to 2.25 mg/L (for Co). The relative standard deviations were less than 4%, and the recoveries were 91% similar to 108%. The method was rapid, simple, and it has been applied to determine the Pd and Co in the electroplating solution and electroplated layer.
