维生素C在多壁碳纳米管/壳聚糖复合膜修饰玻碳电极上的电化学行为及测定

Electrochemical Behaviour and Determination of Vitamin C Based on Multiwalled Carbon Nanotubes/Chitosan Composite Film Modified Glassy Carbon Electrode

研究了维生素C在多壁碳纳米管/壳聚糖复合膜修饰玻碳电极上的电化学行为及测定。实验结果表明,在0.2 mol/L PBS（pH6.0）缓冲溶液中,修饰电极对抗坏血酸的氧化具有明显的催化和增敏效应,其氧化峰电位由＋0.5 V负移至＋0.1 V（vs.AgCl/Ag）。对修饰剂碳纳米管的用量、支持电解质、富集电位和富集时间等进行了优化。采用半微分伏安法进行定量测定,其线性范围为4.0×10^-6~2.0×10^-3mol/L,r=-0.998 3,检出限为1.0μmol/L。对抗坏血酸在修饰电极上的电化学行为进行了探讨,其电极反应为具有吸附特性和不可逆的电极过程,测得参加反应的质子数为2,电极反应的电子转移系数为0.59。测定了维生素C药片中抗坏血酸的含量,回收率在93%~105%。

Electrochemical behaviour and determination of vitamin C（Vc） based on multiwalled carbon nanotubes（MWCNTs）/chitosan（CS） composite film modified glassy carbon electrode were studied.The results showed that in 0.2 mol/L PBS（pH 6.0） buffer solution,the GC/CS＋MWCNTs exhibited a remarkable electrocatalysis and enhancement effect on oxidation of the Vc.The oxidation peak potential of Vc shifted negatively from ＋0.5 V at bare GC to ＋0.1 V at GC/CS＋MWCNTs.Some experimental conditions were optimized.The linear range between the peak current and the concentration of Vc was 4.0×10^-6-2.0×10^-3 mol/L（r=0.998 3） with a detection limit of 1.0 μmol/L by using semidifferential voltammetry.The electrochemical behaviors of the Vc were studied,and the electrode process was irreversible with adsorptive characteristics.Electron transfer coefficient（α=0.59） and proton numbers（X=2） have been determined.This method has been used to determine the content of the Vc in medical tablets.The recovery was determined to be 93%-105% by means of standard addition method.