Analysis of hydrogen peroxide and an organic hydroperoxide via the electrocatalytic Fenton reaction

A new concept for the electrochemical detection of hydrogen peroxide, and organic hydroperoxides is presented. One advantage of the significance of this technique is that it does not require chemical modification of the electrode or addition of enzymes. Direct electro-reduction of the peroxides was not observed on the carbon disk electrode as it is a kinetically slow process. Redox cycling of the iron complex is apparent as FeIIEDTA rapidly reduces the O–O bond of the peroxides (Fenton Reaction) upon its production by the kinetically facile electro-reduction of FeIIIEDTA. This provides an enhanced and steady-state reductive current as observed by cyclic voltammetry. These features are indicative of the electrocatalytic (EC′) mechanism. A calibration curve was constructed based on the chronoamperometric response at 32 s and a detection limit for H2O2 and t-butyl hydroperoxide was calculated to be 0.4 μM and 20 µM, respectively. This difference is attributable to the rate in which the iron(II) complex reduces the O–O bond, H2O2 (2.3 × 105 M− 1 s− 1) being faster than for the organic peroxide (5.1 × 104 M− 1 s− 1). The FeIIEDTA complex was observed to be unreactive toward dialkyl peroxides. This method may find use in the detection of peroxide-based explosives or in enzymatic assays as it is rapid, simple, inexpensive and should prove to be robust.