FERROCENE-CONJUGATED POLYANILINE-MODIFIED ENZYME ELECTRODES FOR DETERMINATION OF PEROXIDES IN ORGANIC MEDIA

摘要

The development and characteristics of a reagentless amperometric organic phase enzyme electrode (OPEE) employing covalently attached horseradish peroxidase and an electrochemically deposited ferrocene-modified polyaniline film on a glassy carbon electrode is reported, The covalent attachment of ferrocene to an electrochemically deposited insoluble polymer film provided a mechanism of preventing the leaching of ferrocene into the predominantly organic solvents, required for construction of reagentless OPEE. Hydrodynamic voltammetry studies showed that the response of the OPEE to hydrogen peroxides increased at higher cathodic potentials; however, interference due to molecular oxygen also increased. Interference of molecular oxygen was minimized when the OPEE was operated at an applied potential of -50 mV (or less negative) vs Ag/AgCl. The cathodic response of the OPEE was found to increase steeply when the aqueous buffer content of the acetonitrile was increased from 0% to 5% and then plateau with no further increase when the buffer content was increased to 30%. The dynamic properties of this enzyme electrode were exploited for the detection of micromolar concentrations of different peroxides in now injection analysis where the sensitivity trend was lauroyl peroxide > hydrogen peroxide > 2-butanone peroxide > cumene hydroperoxide > tert-butyl hydroperoxide. Applicability of the enzyme electrode for measurement of peroxide in real sample was demonstrated.