电沉积咖啡酸玻碳修饰电极对抗坏血酸的催化氧化

在pH=7.0的磷酸缓冲溶液中采用电沉积技术将咖啡酸修饰于玻碳电极表面制备了一层稳定的薄膜,该修饰电极制备简单,稳定性良好.用循环伏安法研究了抗坏血酸在修饰电极上的电化学行为,其氧化峰电流与抗坏血酸的浓度和pH值有关,当pH值达到7.7时,抗坏血酸在修饰电极上的氧化峰电流最大,氧化峰电流与抗坏血酸浓度在4.0×10-5～2.0×10-2mol/L范围成良好的线性关系,检测限为1.0×10-5mol/L,方法简单、快速、准确,可应用于抗坏血酸药片的检测.

Electrocatalytic Oxidation of AA at GCE Modified by Electrodeposited Films of Caffeic Acid

A stable electroactive thin film of poly(caffeic acid) has been deposited on the surface of a glassy carbon electrode(GCE) by potentiostatic technique in a pH 7.0 phosphate buffer containing caffeic acid. The poly(caffeic acid)/glassy carbon electrode is easy to be prepared with good stability and reproducibility. The voltammetric behavior of ascorbic acid(AA) at the poly(caffeic acid) modified glassy carbon electrode was studied by cyclic voltammetry. It has been found that the catalytic current depends on the concentration and pH of ascorbic acid. At pH 7.7,the oxidation peak current of ascorbic acid on the modified electrode is the maximum. The oxidation peak current is proportional to the ascorbic acid concentration in the range of 4.0 × 10-5 to 2.0 × 10-2 mol/L and the detection limit for ascorbic acid is 1.0× 10-5 mol/L. The proposed method can be applied to the determination of ascorbic acid in practical tablet samples with simplicity, rapidness and accurate results.