Catalytic wave of cobalt and its analytical application in rapid determination of trace cobalt in complex zinc electrolyte solution

A polarographic catalytic wave of cobalt in the substrate solution (pH=8.5) of diacetyldioxime-potassium pyrophosphate-ammonium chloride was studied and a new method for rapid determination of trace cobalt in complex zinc electrolyte solution was developed. The results show that there is a very sensitive catalytic wave of cobalt at -1.23 V. At least three hundred thousand fold Zn²⁺ does not affect the determination of cobalt. The method is easy to operate and rapid, and when the signal-to-noise rate equals 2, the detection limit is 6 × 10⁻⁹ mol·L⁻¹. A good linear relationship exists between the concentration of cobalt within 0.001–3.0 μg·mL⁻¹ and the peak current. The method has successfully been used in the determination of trace cobalt in complex solution of the workshop for electrolyzing zinc. Foundation item: The Science and Research Foundation of Education Commission of Hunan Province(No. 98C118) Biography of the first author: ZHANG Ming-hao, associate professor, born in 1956, majoring in analytical chemistry.