Simultaneous square wave voltammetric determination of two anti-inflammatory drugs using a bare carbon paste electrode

Abstract

Background Diclofenac (DIC) is a nonsteroidal anti-inflammatory drug (NSAID) that is more potent than indomethacin. There is an extended-release form of this drug available for long-term treatment. Diflunisal (DIF) is a NSAID with less anticoagulant activity than aspirin. It is more potent than aspirin and is not converted to salicylic acid in vivo. Objectives A simple, direct, and sensitive method for the simultaneous determination of two types of NSAIDs, namely, diclofenac ‘DIC’ and diflunisal ‘DIF’ by square wave adsorptive anodic stripping voltammetry and applied at the same time in synthetic and pharmaceutical samples. Materials and methods In this method, both cited ingredients were oxidized by a bare carbon paste electrode (CPE) forming two well-separated peaks at the potential of 0.65 and 0.85 V, respectively, in 0.04 M universal buffer solution at pH 5 with 100 mV/s scan rate by square wave adsorptive anodic stripping voltammetry technique with an Autolab system of potentiostat/galvanostat. Results and conclusion The prepared sensor showed good linear regression curves over the concentration ranges of 1–6 and 5–25 μg/ml for DIC and DIF, respectively, while the detection limit ‘LOD’ and quantification limit ‘LOQ’ and were 0.204 and 0.68 μg/ml for DIC and 1.366 and 4.553 μg/ml for DIF, in turn. The cited sensor was applied with accurate and precise results for determining DIC and DIF at the same time in synthetic and pharmaceutical samples and gave close results in comparison with the official method, specifically by UV-high performance liquid chromatography.