铋膜电极差分脉冲溶出伏安法同时测定食物中的锌和铜

目的]研究用铋膜电极代替汞膜电极同时测定食物中锌和铜元素含量的新方法。方法]以预镀铋膜的玻碳电极作为工作电极,饱和甘汞电极作为参比电极,铂电极作为辅助电极,采用差分脉冲溶出伏安法同时测定黄豆和板栗样品中锌和铜元素的含量。考察了镀铋液浓度、底液的种类和浓度、初始电位、电沉积电位、终止电位及电位增量等对试验结果的影响。结果]在1.0 mol/L硫氰化钾底液中,锌和铜均有灵敏的溶出峰,线性范围分别为0.20～12.00和0.10～6.00μg/ml,检出限分别为2.08、5.49μg/L,回收率为91.20%～104.50%。在所选择的电位范围内,铋膜稳定性较好,多次测定锌和铜的峰电流基本不变。结论]铋膜电极差分脉冲溶出伏安法简便快速、灵敏度高,适合于食物中锌和铜元素含量的同时分析。

Simultaneous Determination of Zinc and Copper in Foods by Differential Pulse Stripping Voltammetry Based on Bismuth-film Electrode

Objective]A method for the simultaneous determination of zinc and copper in foods by differential pulse stripping voltammetry based on bismuth-film electrode instead of mercury film electrode was studied.Method]The content of zinc and copper in soybean and Chinese chestnut was simultaneously determined by differential pulse stripping voltammetry using ex-situ plated glassy carbon electrode as the working electrode,saturated calomel electrode as the reference electrode and Pt as the auxiliary electrode.The effects of the concentration of the solution for plating bismuth,the kind and concentration of supporting electrolyte,initial potential,deposit potential,end potential and potential increment were discussed.Result]Sensitive stripping peak of Zn(Ⅱ) and Cu(Ⅱ) were observed in the solution of 1.0 mol/L KSCN.The peak current had good linear relationship with the concentration of zinc and copper at 0.20-12.00 μg/ml and 0.10-6.00 μg/ml respectively.The determination limit of zinc and copper were 2.08 and 5.49 μg/L respectively.The recovery rate was 91.20%-104.50%.The stability of bismuth film was good in the range of selected potential and peak currents of Zn and Cu were basically the same.Conclusion]The method of differential pulse stripping voltammetry on bismuth-film electrode is simple,quick,sensitive and suitable for the simultaneous determination of zinc and copper in foods.