Voltammetric Determination of Methadone at Stacked Cysteic Acid Film and Gold Nanoparticles Composite Modified Glassy Carbon Electrode

In this paper, a sensitive and convenient electrochemical sensor based on stacked cysteic acid film and gold nanoparticles (AuNPs) composite modified glassy carbon electrode (GCE) was developed for the determination of Methadone (MET). Electrochemical investigation of the modified electrode is achieved using cyclic voltammetry (CV), differential pulse voltammograms (DPV) and field emission scanning electron microscopy. The effective surface areas of AuNPs/cysteic acid/GCE increased for about 4-fold larger than that of the unmodified GCE. The kinetic parameters of the electron transfer coefficient (α) and number of electrons involved in the rate determining step (nα) for the oxidation of MET were determined utilizing CV. The designed modified electrode was revealed linear responses in the ranges of 0.024 to 4.45 μM and 4.45 to 12.67 μM with a limit of detection (LOD) of 0.014 μM (S/N=3). Excellent recovery results were obtained for determination of MET in spiked human blood plasma and urine samples at the modified electrode.