L-半胱氨酸在玻碳汞膜电极上的直接和间接测定

研究了玻碳汞膜电极上L-半胱氨酸(L-Cys)的直接和间接测定方法,并建立了间接和直接测定的最佳条件.在pH=4.56的缓冲溶液中L-Cys于-0.44 V处有一灵敏的不可逆的循环扫描还原峰,其峰电流与L-Cys的浓度在1×10-6～1×10-4 mol/L内呈良好线性关系(r=0.998 9).另外,根据L-Cys在适当的pH条件下与铜离子的络合作用,通过阳极溶出伏安法测定Cu2+来间接测定L-Cys的含量,本法L-Cys浓度在2×10-7～3×10-6 mol/L内呈良好线性关系(r=0.999 2).2种方法可成功地用于合成样品中L-Cys的测定.

Direct and Indirect Determination of L-Cysteine at Glassy Carbon Mercury Film Electrode

The direct and indirect determination of L_Cysteine on glassy carbon mercury film electrode has been studied, and the optimized conditions for the determination of L_Cysteine has been founded. In the buffer solution of pH=4.56,a sensitive reductive peek of L_Cysteine was observed at-0.44 V on the mercury film electrode. Linear relationship was obtained between the peek current (I_P) and the concentration of L_Cysteine in the range from 1×10~(-6) to 1×10~(-4) mol/L. Further more, based on the complex formation between copper ion and L Cysteine, the amount of L Cysteine can be indirectly determined by measuring the amount of Cu~(2+) in the solution with anodic stripping voltammetry. The linear range was 2×10~(-7)～3×10~(-6)mol/L. The methods have been successfully applied to the determination of L Cysteine in synthetic sample.