Chiral electrochemical sensing for tyrosine enantiomers on glassy carbon electrode modified with cysteic acid

A chiral electrochemical sensor has been prepared via cysteic acid modified glassy carbon (CyA-GC) electrode to discriminate tyrosine (Tyr) enantiomers. Sweep cycles of CyA-GC in modification process and pH of solution were investigated to obtain optimum experimental conditions. Electrochemical impedance spectroscopy was employed to characterize the electrical conductivity of the modified electrode. For the first time, different oxidation peak potentials (Ep) of l- and d-Tyr were observed in the differential pulse voltammograms obtained in the solution containing l- or d-Tyr. Further study showed that only one peak appeared in mixture solution containing l- and d-Tyr and Ep of that peak shifted positively and linearly with an increasing percentage of l-isomer of Tyr racemic mixture.

► Simple preparation of chiral surface on GC electrode by oxidation of cysteine
► Large difference between oxidation peak potentials of l-tyrosine (Tyr) and d-Tyr
► The only peak in l/d-Tyr mixture shifting linearly with increasing ratio of l-Tyr
► Indication of the ratio of l/d-Tyr enantiomers in racemic mixture based on Ep