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 (IC 50 ) 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 (IC 50 ) 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.

Simple DPPH.‐Based Electrochemical Assay for the Evaluation of the Antioxidant Capacity: a Thorough Comparison with Spectrophotometric Assays and Evaluation with Real‐World Samples

“…Such approaches were used for evaluating the antioxidant capacity of pure antioxidant solutions (e.g. 6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐carboxylic acid, Trolox) and of real samples such as Thai indigenous vegetables 11, plant and berry extracts 12, beverages such as tea, wine, soft drinks, and fruit juices 7, 13, and drugs in both raw materials and pharmaceutical formulations 14. Few works focused on automating the assays, for example by developing microtiter plate‐based robotic electrochemical antioxidant assay 15 or by including the electrochemical detection in a FIA system 11.…”