4-(3-吡啶基)-2-巯基咪唑修饰金电极一阶微分线性扫描伏安法直接测定复方鱼腥草片中槲皮素

Direct Determination of Quercetin in Cordate Houttuynia Tablets by Differential Linear-scanning Voltammetry Using Gold Electrode Modified with 4-(3-Pyridyl)-2-Mercapto-Imidazole

利用分子自组装技术制备了4-（3-吡啶基）-2-巯基咪唑修饰金电极,用循环伏安法研究了抗坏血酸和槲皮素在该修饰电极上的电化学行为,发现该电极对两反应物均具有良好的催化作用。在抗坏血酸和槲皮素混合溶液中,采用一阶微分线性扫描伏安法进行检测,发现两物质氧化峰相差240 mV,建立抗坏血酸存在下槲皮素的直接测定方法。在抗坏血酸和槲皮素的共存溶液中,槲皮素峰电流的一阶微分与其浓度在2.0~200μmol.L-1范围内呈线性关系,方法的检出限（3S/N）为1.0μmol.L-1。方法的回收率在98.8%~102.0%之间。

Pretreated gold electrode was modified by self-assembling in 4-（3-pyridyl）-2-mercapto-imidazole（abbreviated as PMIZ） alcoholic solution.Electrochemical behaviors of ascorbic acid and quercetin at this modified electrode（or designated as PMIZ/AuE） were studied by cyclic voltammetry.It was found that the PMIZ/AuE showed catalytic effect towards both the reactions of ascorbic acid and quercetin at the electrode,and that in a solution containing both ascorbic and quercetin,a potential difference of 240 mV was observed between the oxidation peak potentials of these 2 compounds,when measured by 1st derivative linear scanning voltammetry.Based on these facts,a direct method for determination of quercetin in the presence of ascorbic acid was proposed.Linear relationship between values of 1st derivative of peak current（ip） and concentration of quercetin was found in the range of 2.0 to 200 μmol·L-1,with its detection limit（3S/N） of 1.0 μmol·L-1.Values of recovery found were in the range of 98.8% to 102.0%.