New approach for measuring antioxidant activity via a graphite sensor

Abstract

An ion selective membrane sensor from dioctyl phthalate as a plasticizer in a polymeric matrix of polyvinyl chloride (PVC) and β-cyclodextrin as an ionophore was constructed and evaluated according to IUPAC recommendations. Linear Nernstian response of DPPH• within the concentration ranges of 10-6 to 10-2 mol L-1 was obtained with average recovery 99.87±0.617. Nernstian slope of 58.5 mV/decade with excellent selectivity over the pH range of 3-8 was observed. The suggested method was standardized using butylated hydroxyl anisole (BHA). The 50% radical scavenging activity (IC50) determined by the proposed sensor correlated well with that of the common spectrophotometric method based on scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH•). An algorithm implemented in Microsoft Visual Basic® 6.0 was used for calculating (IC50) values which are 7.38 μg/mL ± 0.35, 89.98 μg/ mL ± 0.45 and 1.45 mg/ mL ± 1.50 for BHA, Paracetamol and Dipyridamole, respectively. The proposed sensor represents a simple and reproducible tool for measuring DPPH• scavenging activity of Paracetamol and Dipyridamole in bulk powder, pharmaceutical formulations and simulated intestinal fluid (SIF) without sophisticated separation techniques.