多巴胺在聚亚甲基蓝/石墨烯修饰电极上的电化学行为研究

利用电聚合方法在石墨烯修饰的玻碳电极表面制备了聚亚甲基蓝/石墨烯修饰电极(PMB/GH/GCE)。采用循环伏安法(CV)和差分脉冲伏安法(DPV)研究了多巴胺(DA)和抗坏血酸(AA)在该修饰电极上的电化学行为。在pH 6.9的磷酸盐缓冲溶液中,DA和AA分别在0.208 V和-0.108 V处产生灵敏的氧化峰,与其在聚亚甲基蓝和石墨烯单层修饰电极上的电化学行为相比,两者的峰电流明显增加,峰电位差达316 mV。研究表明,电聚合方法使亚甲基蓝牢固地非共价修饰到石墨烯上,并产生协同增效作用,较好地提高了电极的灵敏度和分子识别性能,有利于在大量AA存在下实现对DA的选择性测定。在1.00×10-3mol/L AA的存在下,DA的差分脉冲伏安法峰电流与其浓度在1.00×10-7～5.00×10-3mol/L范围内呈良好的线性关系,检出限达1.00×10-8mol/L。将该方法用于盐酸多巴胺注射液的测定,结果满意。

Electrochemical Behavior of Dopamine at Poly(Methylene Blue)/Graphene Modified Glassy Carbon Electrode

A poly(methylene blue)/graphene modified glassy carbon electrode(PMB/GH/GCE) was fabricated by electropolymerizing methylene blue on the surface of glassy carbon electrode modified with graphene.The electrochemical behaviors of dopamine(DA) and ascorbic acid(AA) at the prepared electrodes were investigated using cyclic voltammetry(CV) and differential pulse votammetric(DPV) methods.In pH 6.9 phosphate buffer solution(PBS),the anodic peak potentials of DA and AA were 0.208 V and-0.108 V,respectively.In comparison with poly(methylene blue) modified glassy carbon electrode(PMB/GCE) and graphene modified glassy carbon electrode(GH/GCE),the composite modified electrode(PMB/GH/GCE) had superior electrocatalytic activity toward the oxidation of DA and AA,with a peak to peak separation up to 316 mV.Studies showed that MB was firmly non-covalent modification of graphene by electropolymerizing method,and created synergistic effect which could improved sensitivity and molecular recognition ability of the modified electrodes and enabled the sensitive and selective detection of DA in the presence of large number of AA.A DPV technique for measurement for DA over the range of 1.00×10-7-5.00×10-3 mol/L was developed in the presence of 1.00×10-3 mol/L AA,with detection limit of 1.00×10-8 mol/L.The modified electrode was applied in the determination of dopamine hydrochloride injection solution with satisfactory result.