A new class of electropolymerized conducting film from the pyrimidine family for the simultaneous determination of ascorbic acid and dopamine

In this study, we report the electropolymerization of 4-amino-6-hydroxy-2-mercaptopyrimidine (AHMP) in 0.1 M H₂SO₄ on a glassy carbon electrode (GCE) and its application for simultaneous as well as the selective determination of ascorbic acid (AA) and dopamine (DA) at pH 4. The electropolymerized AHMP (p-AHMP) film was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The p-AHMP film showed a redox couple in 0.1 M H₂SO₄ and a p-AHMP film deposited by 10 cycles showed high sensitivity than that with 5, 15 and 20 deposited cycles. The surface coverage of the p-AHMP film was found to be 5.24 × 10⁻¹⁰ mol cm⁻², suggesting the formation of a nanostructured electroactive film on the GCE. Electrochemical impedance spectroscopy study revealed that the modified electrode underwent a facile electron transfer compared to the bare GCE. CV and differential pulse voltammetry (DPV) were employed to demonstrate the electrochemical behaviour of p-AHMP/GCE, which exhibited good electrocatalytic performance towards AA and DA without any electron mediator. The detection limit of AA and DA were found to be 1.20 and 0.28 μM, respectively (S/N = 3) by the DPV method. The modified electrode was successfully utilized to determine AA and DA in real samples such as dopamine injection and vitamin C tablets.