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

The development and characteristics of a reagentless amperometric orga nic phase enzyme electrode (OPEE) employing covalently attached horser adish peroxidase and an electrochemically deposited ferrocene-modified polyaniline film on a glassy carbon electrode is reported, The covale nt attachment of ferrocene to an electrochemically deposited insoluble polymer film provided a mechanism of preventing the leaching of ferro cene into the predominantly organic solvents, required for constructio n of reagentless OPEE. Hydrodynamic voltammetry studies showed that th e response of the OPEE to hydrogen peroxides increased at higher catho dic potentials; however, interference due to molecular oxygen also inc reased. Interference of molecular oxygen was minimized when the OPEE w as 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 fro m 0% to 5% and then plateau with no further increase when the buffer c ontent was increased to 30%. The dynamic properties of this enzyme ele ctrode were exploited for the detection of micromolar concentrations o f 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 demon strated.