Molecular-Imprinted Electrochemical Sensor for Recognization of Enantiomorphs of D-Tyrosine and L-Tyrosine

Polypyrrole membrane,which was spiked with template molecules of L-phenyl lactic acid,was polymerized electrochemically on to the surface of pasty carbon electrode by cyclic voltammetry,and then the electrode was peroxidized in 0.1 mol·L-1 NaOH solution.The modified pasty carbon electrode obtained as mentioned above was used as the working electrode,platinum wire was used as counter electrode and saturated calomel electrode as reference electrode,and 1 mmol·L-1 D-tyrosine solution was enriched on the modified electrode from the solution at pH 2.0 for 20 min,and stripped from the electrode in 0.1 mol·L-1 KCl solution at the same pH value.The I-E curve was recorded by cyclic voltammetry.Residual D-tyrosine remained on the surface of the electrode was removed by peroxidization in 0.1 mol·L-1 NaOH solution.L-tyrosine was then tested by the same method.Stripping potentials of the enantiomorphs of tyrosine at the modified electrode were moved negatively by 200 mV as compared with the bare pasty carbon electrode.Under the optimum condition,the ratio of values of stripping peak current of L-tyrosine to D-tyrosine was found to be 2.18.