Central composite rotatable design in the development of a new method for optimization, voltammetric determination and electrochemical behavior of betaxolol in the presence of acetaminophen based on a gold nanoparticle modified electrode

Abstract

In the present study, the oxidation peak current of the betaxolol in a 0.20 M Britton–Robinson buffer solution was optimized by experimental design for its determination in the presence of acetaminophen. A central composite rotatable design was used to evaluate the effects of the variables by the differential pulse voltammetry method. These variables include scan rate, step potential, modulation amplitude, gold nanoparticles content and pH. Then, under the optimized conditions the dynamic range for betaxolol in the presence of acetaminophen was from 0.50 μM to 125.00 μM and the detection limit was found to be 46.00 nM. The characterization of the gold nanoparticle modified carbon paste electrode was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Other voltammetric methods such as double-potential step chronoamperometry and linear sweep voltammetry were also applied. Using these methods, the diffusion coefficient (D = 7.43 × 10⁻⁵ cm² s⁻¹) and the kinetic parameters such as the electron transfer coefficient (α = 0.60) and exchanging current density (j₀ = 4.6 × 10⁻⁴ μA cm⁻²) for BET were determined. The results indicated that the gold nanoparticle modified carbon paste electrode could be employed for the determination of betaxolol in real samples such as pharmaceutical formulations and plasma samples.