LIQUID-CHROMATOGRAPHY AND ELECTROCHEMICAL DETECTION OF ORGANIC PEROXIDES BY REDUCTION AT AN IRON PHTHALOCYANINE CHEMICALLY-MODIFIED ELECTRODE

Chemically modified carbon paste electrodes containing incorporated ir on phthalocyanine (FePC) exhibited an electrocatalytic response for th e reduction of organic peroxides. In pH 2 phosphate buffer, reduction at the FePC chemically modified electrode (CME) occurred at +0.1 to +0 .2 V (vs. Ag/AgCl) for all peroxides examined except for dialkyl compo unds. Because this potential was 100 mV more positive than that requir ed for oxygen reduction at this electrode, amperometric detection of p eroxides by this approach was possible in flow injection and high-perf ormance liquid chromatography without deoxygenating the sample or mobi le phase solutions. In flow injection, the detection limit using this approach was 5 picomole (pmol) for hydrogen peroxide and varied from l ess than 1 pmol to as high as several hundred pmol for other peroxides . Cyclic voltammetry (CV) and visible spectroscopy experiments were co nsistent with a two-step electrocatalytic mechanism involving the Fe(I II)PC/Fe(II)PC couple.