Mesoporous silica-based electrochemical sensor for simultaneous determination of honokiol and magnolol

Abstract

A kind of mesoporous SiO₂ was synthesized using cationic surfactant as the structure-directing template. After that, the resulting mesoporous SiO₂ was used to modify the carbon paste electrode (CPE). The electrochemical behaviors of honokiol and magnolol were examined. In pH 6.5 phosphate buffer, two well-shaped oxidation peaks at 0.31 and 0.44 V were observed at the mesoporous SiO₂-modified CPE. Compared with the unmodified CPE, the mesoporous SiO₂-modified CPE remarkably enhances the oxidation peak currents of honokiol and magnolol. This suggests that mesoporous SiO₂ exhibits considerable surface enhancement effects to honokiol and magnolol. After optimizing the parameters such as pH value, amount of mesoporous SiO₂, and accumulation time, a sensitive and simple electrochemical method was proposed for the simultaneous determination of honokiol and magnolol. As to honokiol, the calibration curve is from 2.0 to 100.0 µg L⁻¹, and the limit of detection is 0.5 µg L⁻¹ (1.8 × 10⁻⁹ mol L⁻¹). For magnolol, the linear range is from 20.0 to 200.0 µg L⁻¹, and the limit of detection is 10.0 µg L⁻¹ (3.8 × 10⁻⁸ mol L⁻¹). Finally, the newly proposed method was successfully employed to determine honokiol and magnolol in Chinese traditional medicines.