Electroanalytical approach for determination of promethazine hydrochloride on gold nanoparticles-incorporated carbon paste electrode as a nanosensor

A carbon paste electrode modified with gold nanoparticles (Au-NPs/CPE) was used for the determination of promethazine (PMZ) in the presence of ascorbic acid (AA) and uric acid (UA) as the two main interferences in biological samples. Various methods, such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), double-potential chronoamperometry and chronocoulometry, linear sweep voltammetry (LSV) and hydrodynamic voltammetry, were used to investigate the electrocatalytic oxidation of PMZ at the surface of the modified electrode in 0.1 mol L-1 phosphate buffer solutions (pH = 6.0). The results showed that the oxidation peak current of promethazine at the surface of Au-NPs/CPE is 2.25 times larger than the bare electrode, and the peak potential at the Au-NPs/CPE is shifted 42 mV to more negative values. Using differential pulse voltammetry, the peak currents increase linearly with the PMZ concentration within the molar concentration ranges of 2.0-55.0, 55.0-165.0 and 165.0-225.0 mu mol L-1. The detection limit (signal to noise >3) for PMZ was found to be 64.8 nmol L-1. The diffusion coefficient, D/(cm(2) s(-1)), and kinetic parameters, such as the electron transfer coefficient (alpha), ionic exchanging current (i(o)) and catalytic rate constant (k/(cm(3) mol(-1) s(-1))), for promethazine were determined using electrochemical approaches. The modified electrode was applied to determine promethazine in real samples with satisfactory results.