Liquid chromatography and electrochemical detection of organic peroxides by reduction at an iron phthalocyanine chemically modified electrode

Chemically modified carbon paste electrodes containing incorporated iron phthalocyanine (FePC) exhibited an electrocatalytic response for the 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 compounds. Because this potential was 100 mV more positive than that required for oxygen reduction at this electrode, amperometric detection of peroxides by this approach was possible in flow injection and high‐performance liquid chromatography without deoxygenating the sample or mobile phase solutions. In flow injection, the detection limit using this approach was 5 picomole (pmol) for hydrogen peroxide and varied from less than 1 pmol to as high as several hundred pmol for other peroxides. Cyclic voltammetry (CV) and visible spectroscopy experiments were consistent with a two‐step electrocatalytic mechanism involving the Fe(III)PC/Fe(II)PC couple.