磷钨酸改性蒙脱土修饰电极对多巴胺与尿酸的测定

摘要

制作了磷钨酸改性蒙脱土修饰电极(PTA-MMT/GCE),研究了该电极对多巴胺(DA)和尿酸(UA)的电化学响应特性.结果表明:在pH 6.5的PBS缓冲溶液中,DA在该电极上出现1对氧化还原峰,是受扩散控制的可逆电化学过程;UA在该修饰电极上0.328 V处出现一明显的氧化峰,电极过程为受扩散控制完全不可逆的过程.计算了DA和UA在该修饰电极上的反应电子数n和扩散系数.通过对比改性前后修饰电极的交流阻抗图,研究了电极表面的特性.用循环伏安法讨论了缓冲溶液、pH值、修饰剂用量、扫描速率及温度对测定的影响.在pH 6.5的PBS溶液中,DA和UA的氧化峰得到了较好地分离,且DA、UA的峰电流强度与浓度分别在2.0～110.0和20.0 ～350.0 μmol·L-1范围内呈良好的线性关系.运用该电极对盐酸多巴胺注射液以及人尿进行检测,效果良好,样品回收率分别为94%～102%、93% ～97%.%A novel phosphotungstic acid(PTA) clay-modified glassy carbon electrode(PTA-MMT/GCE) was prepared and successfully used to determine dopamine(DA) and uric acid(UA).The characterization of electrochemical response of DA and UA on PTA-MMT/GCE was investigated.The results indicated that in pH 6.5 PBS buffer,a pair of redox peaks of DA was observed on the modified electrode and the DA was controlled by diffusion and reversible process.An obvious oxidation peak of UA appeared at 0.328 V on the modified electrode.The electrode process of UA was inreversible and controlled by diffusion too.Reaction electronic numbers and diffusion coefficients of DA and UA were calculated with the method.The properties of electrode surface were studied by comparing the Nyquist plots of PTA-MMT/GCE and NaMM/GCE.The effects of buffer solution,pH,modifier dosage,scan rate and temperature were discussed by cyclic voltammetry.Under the optimal conditions,the oxidation peak of DA and UA was completely separated.The peak current intensities were linear over the dopamine hydrochloride injection and UA in uric sample with satisfactory results.The spiked recoveries of the two samples were 94%-102% and 93%-97%,respectively.