Electro-Polymerized Poly(L-Arginine) Film as An Efficient Electrode Modifier for Highly Sensitive Determination of Methadone in Real Samples

Developing simple yet efficient sensors for drug-abuse detection is highly required from both human health and medical aspects. In this work, a glassy carbon electrode modified by a thin layer of poly L-arginine (P-L-Arg/GCE) was fabricated by electropolymerization of L-arginine monomer using cyclic voltammetry (CV) and then it was used for determination of Methadone (MET). The surface characteristics of the P-L-Arg/GCE was examined by scanning electron microscopy and electrochemical impedance spectroscopy. To study the electrochemical responses of MET on P-L-Arg/GCE and bare GCE, cyclic and differential pulse voltammetric techniques were employed. For P-L-Arg/GCE, a considerable enhancement in electrooxidation signal of MET was observed compared to bare electrode. The influence of various determinant parameters on P-L-Arg/GCE performance was studied. At optimized conditions, using DPV technique, the electrooxidation peak current was linear to MET concentration in the ranges of 0.49-2.98 µM and 2.98-11.9 µM with a detection limit of 0.32 µM. The utility of P-L-Arg/GCE was successfully validated by analyzing MET in serum and urine samples, representing its potential application for real samples analysis.