Catalytic-voltammetric determination of the antioxidant tert-butylhydroxyanisole (BHA) at a nickel phthalocyanine modified carbon paste electrode

Abstract

The voltammetric behaviour of the antioxidant tert-butylhydroxyanisole (BHA), at a carbon paste electrode modified with the electron mediator nickel phthalocyanine, is described, and a method for the determination of this antioxidant, based on its oxidation on the modified electrode, is proposed. Cyclic voltammograms showed a well-defined oxidation peak for BHA slightly shifted towards less positive potentials with respect to that obtained at the plain carbon paste electrode. The peak current measured at the modified electrode is considerably higher than that obtained at the unmodified electrode. A modifier percentage of 2%, a methanol percentage of 2% and a 0.1 mol/HClO 4 medium were chosen as working conditions. The i p vs v 1 2 plot obtained by linear sweep voltammetry showed a linear relationship over the whole scan rate range studied (5–2000 mV/sec) which is typical of a diffusion-controlled current. Using differential pulse voltammetry at ΔE = 50 mV, linear calibration graphs were obtained in the concentration ranges 1.0–30.0, 0.10–1.0 and 0.02–0.10 mg/l BHA. The detection limit was 0.0036 mg/l (2.0 × 10 −8 mol/l). Interferences from other substances commonly present in commercial antioxidant mixtures were tested. The developed method was applied to the determination of BHA in spiked potato flakes.