Developing an electroanalytical procedure for the determination of caffeic acid phenethyl ester at a boron-doped diamond electrode by the use of cationic surfactant media

The aim of the present work is to describe voltammetric analysis of caffeic acid phenethyl ester (CAPE) by using a boron-doped diamond (BDD) electrode in the presence of the cationic surfactant. Using cyclic voltammetry, CAPE demonstrated a single well-defined, quasi-reversible, adsorption-controlled by oxidation and reduction peak at approximately +0.44 V & +0.22 V respectively, (vs. Ag/AgCl) in the Britton-Robinson buffer (BR, 0.04 mol L-1, pH 5.0). The obtained results showed that the oxidation peaks of CAPE are pH dependent (ranging from 2.0 to 6.0). The oxidation peak currents of CAPE were significantly increased by using cetyltrimethylammonium bromide (CTAB, cationic surfactant) in the selected supporting electrolyte. Under the optimum parameters of experiment, the linear relationship was found for CAPE determination in 0.04 mol L-1 BR buffer solution (pH 5.0) including 1 x 10(-4) mol L-1 CTAB at +0.41 V (vs. Ag/AgCl) (after 30 s accumulation at the open-circuit condition). The linear range was found with 0.01 to 1.0 mu g mL(-1) (3.5 x 10(-8)-3.5 x 10(-6) mol L-1) via the detection limit 0.0028 mu g mL(-1) (9.8 x 10(-9) mol L-1). The developed approach was used successfully to detect CAPE concentration in the model urine samples. To our knowledge, this is the first approach for electrochemically analyzing of CAPE.