修饰铋盘电极吸附伏安法测定痕量钴的研究

Fabrication of Dimethylglyoxime Modified Bismuth Disk Electrode for the Determination of Trace Cobalt by Adsorptive Voltammetry

研究了利用丁二酮肟修饰铋电极测定钴的吸附伏安分析方法.在0.4 mol/L NH3·H2O-NH4Cl缓冲溶液(pH=9.0)中,Co(Ⅱ)与铋盘电极表面修饰的丁二酮肟形成螯合物.并于-1.20 V附近产生一个灵敏的还原峰.富集时间分别为60s和280 s时,峰电流与钴的质量浓度在0.01～25μg/mL和0.002～2μg/mL范围内呈线性关系.该还原峰与采用汞电极时的峰形相似、电位相近、灵敏度相当.优化了实验条件,拟订了样品分析的步骤,利用该法测定了合金、维生素B12针剂样品中的微量钴.

Dimethylglyoxime modified bismuth disk electrodes are proved to be alternatives to the mercury electrodes used for adsorptive vohammetric measurements of trace cobalt. In the solution of 0.4 mol/L NH3 · H2O - NH4Cl（pH = 9） containing cobalt（Ⅱ）, a sensitive linear scanning vohametfic peak is obtained at - 1.20 V（ vs. Ag/AgCl） on dimethylglyoxime modified bismuth electrode, which is similar to that on the hanging mercury electrode in its peak-form, potential and sensitivity. Variables affecting the response have been assessed and optimized. Such optimization resulted in a favorable and highly stable reductive peak with good sensitivity. There were linear relationships between the derivative peak currents and Co （Ⅱ） concentrations in the range of 0.01 - 25 μg/mL by the accumulation of 60 s at - 0.70 V, and 0. 002 - 2 μg/mL for 280 s accumulation. The proposed method has been applied to the determination of cobalt （Ⅱ） in the alloy and vitamin B12 injection samples with satisfactory results.