氮掺杂碳纳米管修饰电极的电化学行为

制备了氮掺杂改性的碳纳米管, 并用循环伏安法(CV)测定了多巴胺(DA)和抗坏血酸(AA)在不同氮含量的碳纳米管修饰电极上的电化学行为. 结果表明, 氮掺杂碳纳米管修饰电极对AA和DA有不同的电催化行为, 其中高氮含量修饰电极对AA的催化作用强, 而低氮含量修饰电极对DA的催化作用强. 微分脉冲伏安法(DPV)的结果显示, DA的氧化峰电流与其浓度在5.0×10^－6～2.0×10^－4 mol/L范围内呈良好的线性关系, 检出限达1.64×10^－6 mol/L (S/N＝3); AA氧化峰电流与其浓度在3.0×10^－5～1.0×10^－2 mol/L范围内呈良好的线性关系, 检出限达3.26×10^－6 mol/L (S/N＝3). 该修饰电极在AA大量存在(AA浓度为DA浓度两万倍)时可选择性地实现多巴胺的测定而不造成干扰.

Electrochemical Behavior of Nitrogen-Doped Carbon Nanotube Modified Electrodes

The nitrogen-doped carbon nanotube (CN_x nanotube) modified glassy carbon elec-trodes were prepared for the study of electrochemical behavior of dopamine (DA) and ascorbic acid (AA). The effects of the content of nitrogen in the framework of CN_x nanotubes on the electrochemical behavior of DA and AA at the modified glassy carbon electrodes were investigated in acidic and neutral buffer solutions. The results of cyclic voltammetry indicated that the CN_x nanotube modified electrodes with a high content of nitrogen exhibited higher electrocatalytic activities for the AA, the modified electrodes with a low content of nitrogen, however, showed the favorable electrocatalytic activity for DA. Additionally, the modified electrodes showed a linear response to DA in the concentration range of 5.0×10^－6～2.0×10^－4 mol/L and AA in the concentration range of 3.0×10^－5～1.0×10^－2 mol/L. The detection limit (S/N＝3) is 1.64×10^－6 mol/L for DA and 3.26×10^－6 mol/L for AA, respectively. Such different catalytic behavior for DA and AA allowed the determination of DA in the presence of extremely excess AA (up to 20000 fold).