Electrochemical Determination of Bisphenol A by Single-Walled Carbon Nanotube Composite Glassy Carbon Electrode

ABSTRACT: A mesoporous composite of single-walled carbon nanotube-doped ionic liquid/sol–gel titania/Nafion has been used for the fabrication of a highly sensitive electrochemical sensor for bisphenol A. Four ionic liquids with varying hydrophobicity, 1-butyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, 1,3-dimethoxy-2-methylimidazolium, and 1-benzyl-3-methylimidazolium hexafluorophosphates, were incorporated into the composite films. Although the composite-modified electrode with 1-butyl-3-methylimidazolium hexafluorophosphate exhibited the largest voltammetric response, the incorporation of ionic liquids, regardless of the type, into the composite-modified electrodes increased the electron transfer ability of the composite due to the high conductivity of ionic liquids and accumulated bisphenol A on the electrode surface due to π–π interactions between aromatic rings of bisphenol A and imidazole groups of the ionic liquids. Therefore, the combination of ionic liquid and electrocatalytically active single-walled carbon nanotube in the composite film provided excellent analytical performance compared to other electrochemical sensors for bisphenol A. Under the optimized conditions, the electrochemical sensor provided a linear response to bisphenol A from 1.0 × 10⁻⁹ to 1.0 × 10⁻⁵ M with a detection limit of 5.0 × 10⁻¹⁰ M. The sensor was selective to the analyte and also exhibited good reproducibility, with a relative standard deviation of 3.5%.