Simple Flow Injection Analysis System for Simultaneous Determination of Phenolic Antioxidants with Multiple Pulse Amperometric Detection at a Boron-Doped Diamond Electrode

A method for simultaneous determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in food was developed that uses multiple pulse amperometry (MPA) with flow injection analysis (FIA). Determination of these phenolic antioxidants was carried out with a cathodically pretreated boron-doped diamond electrode and an aqueous ethanolic (30% ethanol, v/v) 10 mmol L-1 KNO3 solution (pH(cond) = 1.5) as supporting electrolyte. A dual-potential waveform, at E-det1 = 850 mV/200 ms and E-det2 = 1150 mV/200 ms versus Ag/AgCl (3.0 mol L-1 KCl), was employed. The use of E-det1 or E-det2 caused the oxidation of BHA or of BHA and BHT, respectively; hence, concentration subtraction could be used to determine both species. The respective analytical curves presented good linearity in the investigated concentration range (0.050-3.0 mu mol L-1 for BHA and 0.70-70 mu mol L-1 for BHT), and the detection limits were 0.030 mu mol L-1 for BHA and 0.40 mu mol L-1 for BHT. The proposed method, which is simple, quick, and presents good precision and accuracy, was successfully applied in the simultaneous determination of BHA and BHT in commercial mayonnaise samples, with results similar to those obtained by HPLC, at a 95% confidence level.