DETERMINATION OF LIPID HYDROPEROXIDES BY ELECTROCHEMILUMINESCENCE

Electrochemiluminescence (ECL) was used for the detection of the lipid hydroperoxide methyl linoleate hydroperoxide (MLHP) at a glassy carbon electrode in acetonitrile (AN) neutral aqueous solution. The cyclic voltammograms of luminol and MLHP were measured to find the optimum applied potential. Luminol was oxidized at about 0.45 V with or without the presence of AN in the aqueous solution. MLHP was oxidized at a fairly positive potential (1.10 V). The oxidation products were determined to be conjugated triene, superoxide and proton by considering UV spectral changes. colorimetric reactions and reaction with the superoxide dismutase enzyme. In the ECL method, luminol was oxidized on the electrode to the excited intermediate (diazaquinone), which reacted with MLHP and emitted light. ECL spectra and decay times were studied. In a flow-injection system with pH 7.4 phosphate buffer-30% AN carrier solution, emitted light was detected at the oxidation potential of luminol. The detection limit was 0.3 nmol with a relative standard deviation of 1.3% (n = 5) at a signal-to-noise ratio of 1.5.