聚多巴胺/多壁碳纳米管/玻璃碳电极上多巴胺的电分析

Electroanalysis of Dopamine at Polydopamine/Multiwalled Carbon Nanotubes/Glassy Carbon Electrode

基于多巴胺(DA)在多壁碳纳米管(MWCNTs)修饰玻璃碳(GC)电极上的电聚合,制得聚多巴胺(PDA)/MWCNTs/GC电极,并对该修饰电极进行了电化学阻抗谱(EIS)和循环伏安法(CV)表征。在该修饰电极上,DA呈现良好的电化学行为。在pH=7.4磷酸缓冲溶液中其氧化电流显著高于在裸电极上的响应,且能有效地抑制2.0 mmol/L抗坏血酸(AA)或K4Fe(CN)6的直接电化学响应,表明MWCNTs可增敏信号,且阳离子选择透过性PDA膜可抑制阴离子的电化学干扰。采用CV实验检测DA,DA氧化的半微分伏安峰高(ipa-sd)与多巴胺浓度在0.08～1.76μmol/L范围内呈线性关系,在无抗坏血酸和有0.5 mmol/L抗坏血酸共存时的线性回归方程分别为ipa-sd(μA/s1/2)=0.107+0.405c(μmol/L)(r2=0.986)和ipa-sd(μA/s1/2)=0.628+0.649c(μmol/L)(r2=0.992),检测限均为8.0×10-8 mol/L(S/N=3)。该法用于盐酸多巴胺注射液中多巴胺的快速测定,结果满意。

On the basis of electropolymerization of dopamine（DA） at multiwalled carbon nanotubes（MWCNTs） modified glassy carbon（GC） electrodes,polydopamine（PDA）/MWCNTs/GC electrodes were prepared and characterized by electrochemical impedance spectroscopy（EIS） and cyclic voltammetry（CV）.The electrode exhibited well-defined electrochemical behavior of DA in pH=7.4 phosphate buffer,producing higher oxidation currents than those on a bare GC electrode,and the direct electrochemical responses of 2.0 mmol/L ascorbic acid（AA） or K4Fe（CN）6 were inhibited,demonstrating the nano-enhancement effect of MWCNTs and the anti-anion electroanalysis selectivity due to use of the PDA film with the selective cation-permeability nature.DA electroanalysis was conducted at the electrode using CV and semi-derivative methods.The semi-derivative voltammetric peak height for DA oxidation is linear with DA concentration in the range of 0.08～1.76 μmol/L,and the linear regression equation in a phosphate buffer solution without AA or with 0.5 mmol/L coexisting AA is ipa-sd（μA/s1/2）=0.107＋0.405c（μmol/L）（r2=0.986） or ipa-sd（μA/s1/2）=0.628＋0.649c（μmol/L）（r2=0.992）,both with detection limits of 8.0×10-8 mol/L（S/N=3）.This method was used for rapid determination of DA in a DA hydrochloride injection sample with satisfactory results.