Performance Of Enzyme Electrode Research Articles

Determination of phenolic compounds in wines with enzyme electrodes fabricated by immobilization of polyphenol oxidase in conducting copolymers

A copolymer of pyrrole with a new monomer (MBTA) containing an ester group derived from 3-thiophene acetic acid and (S)-(-)-2-methylbutanol was used as the matrix for immobilization of polyphenol oxidase. Enzyme electrodes were constructed by entrapment of enzyme in the conducting copolymer during the electrochemical polymerization of pyrrole. The performance of enzyme electrodes was optimized by examining the effects of pH and temperature on enzyme activity. The changes in the maximum reaction rate (V max) and Michaelis-Menten constant (K m) upon immobilization were investigated in addition to shelf-life and operational stability. By using these enzyme electrodes the total amount of phenolic compounds in red wines of Turkey was also analyzed.

Amperometric enzyme electrode for organic peroxides determination prepared from horseradish peroxidase immobilized in poly(vinylferrocenium) film

Organic peroxides, t-butyl hydroperoxide, 2-butanone peroxide, cumene hydroperoxide and t-butyl peracetate, were determined by an amperometric enzyme electrode. The enzyme electrode was prepared through electrostatic immobilization of horseradish peroxidase (HRP) in a polyvinylferrocenium (PVF) film. A PVF+ClO4− film was coated on a Pt foil at +0.70 V by electrooxidation of polyvinylferrocene in methylene chloride with 0.1 M tetrabutylammonium perchlorate (TBAP). The enzyme modified electrode PVF+HRP− was prepared by anion-exchange in a solution of HRP− in 0.05 M phosphate buffer at pH 8.5. FTIR spectroscopy was used to identify PVF, PVF+ClO4−, and PVF+HRP−. The immobilized amount of the enzyme in the film was determined by UV spectroscopy. The effects of the polymeric film thickness, bulk enzyme concentration used in the immobilization treatment and the temperature on the performance of enzyme electrode were investigated. The inhibitory effect of oxygen was also examined. Linearities, lower detection limits, active life times and sensitivities of the electrode were determined for each peroxide.