石墨烯修饰玻碳电极用于循环伏安法测定抗坏血酸

采用Hummers法制备了纳米石墨烯,并将该纳米材料分散在蒸馏水中得到悬浮液,取5μL的悬浮液滴涂在玻碳电极表面,制备石墨烯修饰电极。用循环伏安法研究了在pH 4.0磷酸盐电解质中,在-0.4～0.8V(vs.Ag/AgCl)电位范围内,抗坏血酸在修饰电极上的电化学行为。结果表明:抗坏血酸在修饰电极上在0.173V处可见明显的氧化峰,且氧化峰电流显著高于在裸玻碳电极上的氧化峰电流;并可有效排除肾上腺素、尿酸、多巴胺等物质的干扰。据此提出了用循环伏安法测定抗坏血酸的方法。抗坏血酸的线性范围为8.00×10-6～1.0×10-3 mol.L-1,检出限(3S/N)为1.0×10-7 mol.L-1。方法用于维生素C片的分析,回收率在96.3%～104.4%之间。

Use of Graphene Modified Glassy Carbon Electrode in Cyclic Voltammetric Determination of Ascorbic Acid

Nano-graphene was prepared by the method of Hummers,and graphene modified glassy carbon electrode(GCE) was prepared by addition of 5 μL of suspension of nano-graphene in distilled water dropwise onto surface of GCE.Electrochemical behavior of ascorbic acid(AA) at the modified electrode was studied by cyclic voltammetry in phosphate solution of pH 4.0 as supporting electrolyte in the potential range of-0.4-0.8 V(vs.Ag/AgCl).As shown by the experimental results,a significant oxidation peak was observed at 0.173 V,and the oxidation peak current was found to be higher than that obtained at bare GCE.The interferences of epinephrine,uric acid and dopamine were avoided completely.Based on these findings,a selective method for determination of AA by cyclic voltammetry was proposed.Linearity range between 8.00×10-6 and 1.0×10-3mol·L-1 was obtained,with detection limit(3S/N) of 1.0×10-7mol·L-1.The proposed method was used in the analysis of samples of Vitamin C tablets,and values of recovery found were in the range of 96.3%-104.4%.