Electroanalytical study of the antioxidant tert‐butylhydroquinone (TBHQ) in an oil‐in‐water emulsified medium

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Abstract
An electroanalytical study of the oxidation of tert‐butylhydroquinone (TBHQ) by differential pulse polarography (DPP) and square‐wave voltammetry (SWV) in an emulsified medium formed with ethyl acetate and Pluronic F‐68 is carried out. The optimization of the chemical variables of the emulsions by DPP allowed the choice of the following working conditions: pH 9.0, 0.04% Pluronic F‐68, 2.0 mL of ethyl acetate and 3 minutes as ultrasonic stirring time. The demonstrated reversibility of the electrode process at the mercury electrode makes it suitable for the application of SWV. The influence of the square‐wave (SW) characteristic parameters on the TBHQ net peak current at the hanging mercury drop electrode (HMDE) was tested. Calibration graphs were obtained within the ranges 1.0 × 10−5 to 1.0 × 10−4, 1.0 × 10−6 to 1.0 × 10−5, and 1.0 × 10−7 to 1.0 × 10−6 mol L−1. An improved sensitivity with respect to that obtained by DPP was produced. The limit of detection was found to be 6.2 × 10−8 mol L−1. Interferences from tert‐butylhydroxyanisole, tert‐butylhydroxytoluene, propylene glycol, citric acid, propyl gallate, and ascorbic acid were tested. The proposed method was applied with good results to the determination of TBHQ in spiked popcorn samples by direct emulsification of the ethyl acetate sample extract.