A new voltammetric method for the simultaneous determination of the antioxidants TBHQ and BHA in biodiesel using multi-walled carbon nanotube screen-printed electrodes

An electroanalytical method for the simultaneous detection and quantification of tert-butylhydroquinone (TBHQ) and butyl hydroxyanisole (BHA) in biodiesel was developed using a voltammetric technique and screen-printed electrodes. The supporting electrolyte solution was composed of Britton–Robinson buffer (0.04 mol L−1) containing methanol (2.0%) and the cationic surfactant cetyltrimethylammonium bromide (CTAB). In the presence of CTAB, the peak current intensity and voltammetric resolution increased significantly for both studied antioxidants. Using the optimized conditions, the method presented a linear response in the concentration range of 5.0 × 10−7–1.0 × 10−5 mol L−1 for TBHQ (r = 0.999) and BHA (r = 0.999) with detection limits of 3.40 × 10−7 mol L−1 and 1.76 × 10−7 mol L−1, respectively. The proposed method was successfully applied for the quantification of TBHQ and BHA in biodiesel samples after a simple and rapid dilution with recoveries from 97.90% to 110.0% and 91.90% to 101.0%, respectively. The obtained results were satisfactory when compared with those obtained using high-performance liquid chromatography (HPLC). Additionally, the proposed method can be easily adapted for on-site analysis.