离子液体修饰碳糊电极对黄芩苷的电催化作用及其分析应用

Electrocatalysis of Baicalin at Ionic Liquid Modified Carbon Paste Electrode and Its Analytical Application

用亲水性离子液体氯化1-戊基-3-甲基咪唑（[AMIM]Cl）作修饰剂构置了离子液体修饰碳糊电极（IL／CPE）。在pH=3．53Britton-Robinson（B．R）缓冲溶液中，用循环伏安法（CV）和方波伏安法（SWV）研究了黄芩苷在IL／CPE和裸碳糊电极（CPE）上的电化学行为，建立了测定尿样和血清样品中黄芩苷含量的新方法。在CPE上黄芩苷氧化、还原峰之间峰电位差（△Ep）为0．204V，在IL／CPE上其峰峰电位差减小为0．103V；黄芩苷在IL／CPE上的电流响应是其在CPE上的7．1倍。表明IL／CPE对黄芩苷的氧化还原反应有很好的电催化作用。计算了黄芩苷在此修饰电极上的电子转移系数和电子转移速率常数。在方波伏安曲线上，黄芩苷的氧化电流与其浓度在1．0×10^-8～2．0×10^-6mol／L范围内呈线性关系。检出限为3．0×10^-9mol／L（S／N=3）。连续6次测定浓度为4．0×10^-7mol／L黄芩苷溶液的RSD为1．3％。

An ionic liquid modified carbon paste electrode （IL/CPE） was fabricated with hydrophilic ionic liquid 1-amyl-3-methylimidazolium chloride （[ AMIM ] Cl ） as a modifier, The electrochemical behavior of baicalin at the modified electrode and bare carbon paste electrode （CPE） was investigated in a Britton- Robinson （ B-R ） buffer solution （ pH = 3.53 ） by cyclic voltamme.try （ CV ） and square wave voltammetry （SWV）, and a novel method ＇for the determination of baicalin in urine and serum samples was thus established. At CPE, the peak-to-peak potential separation（ △Ep ） of baicalin was 0. 204V, while at IL/CPE, the △Ep decreased to 0. 103 V. Furthermore, the current response of baicalin at IL/CPE was 7.1 times of that at CPE. These indicated the IL/CPE possessed an excellent electrocatalytic activity for the redox of baicalin. The electron transfer coefficient and standard rate constant of baicalin at IL/CPE were calculated. In the SWV curves, a linear dependence of oxidation current on baicalin concentration was obtained in the range of 1.0 × 10^-8 -2. 0 × 10^-6 mol/L（r =0. 999 8）, with a detection limit of 3.0 × 10^-9 mol/L（S/N =3 ）. The relative standard deviation of 4. 0 × 10^-7 mol/L baicalin was 1.3% for 6 consective measurements.