study and electrochemical determination of tyrosine at graphene nanosheets composite film modified glassy carbon electrode

a graphene nanosheets (gns) film coated glassy carbon electrode (gce) was fabricated for sensitive determination of tyrosine (tyr). the gns-based sensor was characterized by scanning electron microscope and electrochemical impedance spectroscopy. the voltammetric techniques were employed to study electro-oxidation of tyr. the results revealed that the modified electrode showed an electrocatalytic activity toward the anodic oxidation of tyr by a marked enhancement in the current intensity and the shift in the oxidation potential to lower values (50 mv) in comparison with the bare gce. some kinetic parameters such as the electron transfer coefficient (α) were also determined for the tyr oxidation. the detection limit  for tyr was found to be 2.0×10-8 m (n=9), and the peak current increases linearly with the tyr concentration within the molar concentration ranges of 5.0 ×10-6 to 1.2 ×10-4 m. the modified electrode shows good sensitivity, selectivity and stability. the prepared electrode was applied for the determination of tyr in real sample.