Electroanalytical investigation and voltammetric quantification of daidzein at a non-modified boron-doped diamond electrode in the existence of cationic surfactant

Abstract A unmodifed and pretreated boron-doped diamond (BDD) electrode was used as a sensitive electrochemical sensor for the determination of daidzein (DZ) using square-wave voltammetry (SWV). Cyclic voltammetric studies showed the irreversible behavior and well-defined two oxidation peaks at +0.98 (PA1) and +1.35 V (PA2) of DZ, respectively, in H2SO4 solution. It was shown to have a diffusion-controlled electrode reaction with two electrons. pH and cationic surfactant (cetyltrimethylammonium bromide, CTAB) medium was observed to play a significant role in DZ oxidation. Quantitative analyzes of DZ were evaluated on the basis of its both oxidation peaks (PA1 and PA2). With optimized experimental and instrumental parameters, the current response of DZ was proportionally linear in the concentration range from 0.1 to 5.0 μg mL−1 (3.93 × 10−7-1.97 × 10−5 mol L−1), with a detection limit of 0.017 μg mL−1 (6.69 × 10−8 mol L−1) and 0.029 μg mL−1 (1.14 × 10−7 mol L−1), respectively in 0.1 mol L−1 H2SO4 solution containing 5 × 10−5 mol L−1 CTAB (after 30 s accumulation at open-circuit condition). Finally, this sensor was successfully administered for the determination of DZ in commercial tablet forms.