首先在非水介质中通过电化学氧化将L-酪氨酸以C-N键共价键合在玻碳电极表面,形成L-酪氨酸接枝单层膜.再在L-酪氨酸功能化的玻碳电极上对邻苯二胺进行电化学聚合,从而制备了聚邻苯二胺/L-酪氨酸复合膜修饰玻碳电极(聚-o-PD-Tyr/GCE).研究发现聚-o-PD-Tyr/GCE在pH 6.8的磷酸缓冲溶液(PBS)中对抗坏血酸的电化学氧化具有催化作用,其氧化电位为0.35 V,比在裸玻碳电极上(0.58 V)降低了0.23 V,峰电流也明显升高.抗坏血酸在修饰电极上响应电流与其浓度在2.5×10-4~1.5×10-3mol·L-1范围内呈线性关系,检出限(3s/k)为43.64 μmol·L-1.经修饰的电极保存在0.1 mol·L-1 PBS中,可至少稳定5d.对5×10-4mol·L-1抗坏血酸溶液连续测定10次,测得此电极的相对标准偏差为3.2%.

Glassy carbon electrode (GCE) modified with composite membrane of poly-o-phenylene diamine and L-tyrosine (poly-o-PD-Tyr/GCE) was prepared by electropolymerization of o-phenylene diamine onto the L-tyrosine functionalized GCE which was obtained by covalent bonding of L-tyrosine to the surface of GCE through C-N bond via electro-oxidation.It was found that in a PBS of pH 6.8,the modified electrode,poly-o-PD-Tyr/GCE,behaved to catalyze the electro-oxidation of ascorbic acid at the oxidation potential of 0.35 V,which is 0.23 V lower than that at the bare GCE.Linear relationship between values of oxidation peak current (Ip) and concentration of ascorbic acid was obtained in the range of 2.5×10-4-1.5×10-3mol·L-1.Detection limit (3s/k) of the electrode toward ascorbic acid was found to be 43.64 μmol·L-1.No significant change of current response was observed within 5d when the electrode was kept in 0.1 mol·L-1 PBS (pH 6.8).Value of RSD (n=10) of 3.2% was found when precision of measurements with the electrode was tested with ascorbic acid solution of 5×10-4mol·L-1.