Electrochemical determination of pterostilbene at a cathodically pretreated boron-doped diamond electrode using square-wave adsorptive anodic stripping voltammetry in cationic surfactant media

In the present paper, an electrochemical method was developed for the determination of pterostilbene (a phenolic phytoalexin) using adsorptive anodic stripping voltammetry at a cathodically pretreated boron doped diamond electrode. The oxidation of compound was irreversible and exhibited an adsorption controlled process which is of pH dependence. The sensitivity of the stripping voltammetric measurements was significantly improved in the presence of cationic surfactant, cetyltrimethylammonium bromide (CTAB). Using square-wave stripping mode, a highly linear analytical curve was obtained for pterostilbene determination in 0.1 M HNO3 solution containing 2 x 10(-4)M CTAB at +0.78V (vs. Ag/AgCl) (after 30 s accumulation at open-circuit condition). The process could be used in the range of 0.005-1.0 mu g mL(-1) (2.0 x 10(-8)-3.9 x 10(-6)M), with a detection limit of 0.0011 mu gmL(-1) (4.3 x 10(-9) M). The proposed method was successfully applied to measure the concentration of pterostilbene in the commercial dietary supplements, with results similar to those obtained using a HPLC method at 95% confidence level. As far as it could be verified, the proposed method is the first one based on the electrochemical investigation of pterostilbene. (C) 2016 Elsevier B.V. All rights reserved.