Combination of micro liquid liquid extraction and differential pulse voltammetry for determination of TBHQ in edible oil samples by pre-anodized glassy carbon electrode in the single drop mode

t-butyl hydroquinone (TBHQ) is a synthetic phenolic antioxidant which is used as a preservative in edible oil sample. Recently, carcinogenic effect of TBHQ has been reported in high dosage [1], therefore, determination and control of TBHQ is very important in food samples and many attempts have been performed [2]. In this research, a combination of micro liquid liquid extraction with differential pulse voltammetry has been introduced for extraction and determination of TBHQ in edible oil samples. The amount of 300 μL methanol was used for extraction step. Pre-anodized glassy carbon (PAGC) electrode was utilized as working electrode. Counter and reference electrodes were thin platinum and silver wires. A 100 μL solution of a mixed extraction solvent and aqueous buffer was put on the surface of the PAGC. Different effective parameters such as type and volume of solvent, pulse width and height, type and concentration of pre-anodizing solution were evaluated and optimized. The analytical performances of the method were studies under optimal conditions. Dynamic range of the method was achieved in the range of 10-200 μg/g and detection limit was3.7 μg/g based on S/N=3. Inter- and intra-day precision were in the range of4.2-6.9 %. Finally, proposed method was performed for determination of TBHQ in different brands of edible oils in the market and the results were compared by the results of the HPLC method. The amounts were between 140 to 400 μg/g and were not in the allowance level of Iranian standard. Relative recoveries were attained in the range of 95-105%.