Еlеctrochemical characterization of phenytoin and its derivatives on bare gold electrode

• Phenytoin was examined at gold electrode by cyclic and square wave voltammetry.
• Gold electrode is highly sensitive to the phenytoin concentration from 0.5 to 50 μmol dm−3.
• Substituent effects on the electrochemical behavior of derivatives were examined.
• The reaction mechanism for the oxidation of phenytoin was proposed.

Phenytoin (5,5-diphenylhydantoin), one of the most frequently used anticonvulsant and antiarrhythmic drugs, was examined and determined at bare gold electrode in 0.05 M NaHCO3 using its anodic activity by cyclic voltammetry (CV) and square wave voltammetry (SWV). Gold electrode is highly sensitive to the phenytoin concentration (the investigated level of concentrations is usually found in human serum of patients treated with phenytoin), providing linear relationships for a set of lower concentrations (0.5, 0.6, 0.8, 1.0 μmol dm−3) and for a set of higher concentrations (10, 20, 30, 40, 50 μmol dm−3). The effects of the substituent on the phenyl rings on the electrochemical behavior of two derivatives, 5,5-di(4-chlorophenyl) hydantoin and 5,5-di(4-methylphenyl) hydantoin, were examined by CV. A computational study in correlation with the experimental voltammetric results enabled to propose the oxidation mechanisms: the investigated compounds undergo oxidation involving transfer of 1e– and 1 proton by irreversible, diffusion controlled process.

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