Electrochemical behavior of a glassy carbon electrode modified with poly (hydroxynaphthol blue) and its application for simultaneous determination of diclofenac and acetaminophen.

2-[(2,6 dichlorophenyl) amino] benzene acetic monosodium salt commonly known as diclofenac sodium (DCF) (Scheme 1A), is a compound with anti-inflammatory and analgesic properties. It widely used for the treatment of inflammatory disorders and painful conditions [1]. Acetaminophen (AC) (Paracetamol or N-acetyl-4-aminophenol), is a popular antipyretic and analgesic agent (Scheme 1B). It is one of the most used medicines as an alternative to aspirin (acetylsalicylic acid) [2]. The combination of acetaminophen and diclofenac sodium is used as analgesic and anti-inmmatory drug [3]. A sensitive and selective electrochemical method was developed for simultaneous determination of diclofenac and acetaminophen based on a poly (hydroxynaphthol blue)/ multi wall carbon nanotubes film modified glassy carbon electrode. The electrochemical behaviors of DCF and AC at the modified electrode were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results showed that this new electrochemical sensor exhibited excellent electrocatalytic activity towards the oxidation of the two analytes. The anodic peaks of the two species were well defined with lowered oxidation potential and enhanced oxidation peak currents, so the modified electrode was used for simultaneous voltammetric measurement of DCF and AC by differential pulse voltammetry. Under the optimum conditions, the detection limits were 0.310 µmol L−1 for DCF, 0.196 µmol L−1 for AC, respectively. The proposed method has been successfully applied to simultaneous determination of DCF and AC in some real samples.