Electro-enhanced solid-phase microextraction of bisphenol A from thermal papers using a three-dimensional graphene coated fiber.

Three-dimensional (3-D) graphene was synthesized by the assembly of graphene oxide with phenolic resin, followed by carbonization in argon. The as-synthesized 3-D graphene has excellent conductivity, good thermal stability, large specific surface area (1511 m² g) and pore volume (0.90 cm g). By immobilizing the 3-D graphene onto the stainless steel wire (SSW), we obtained a 3-D graphene coated fiber that was then used as a working electrode for electro-enhanced SPME, which shows a 3.2-fold improvement of extraction efficiency for bisphenol A (BPA) over that of traditional SPME. Coupled to gas chromatography, the method was developed to the determination of BPA with good linearity (R = 0.9935) in the range of 0.1-10 μg mL. The limit of detection was calculated to be 0.006 μg mL based on the signal-to-noise of 3. The proposed method was applied for the analysis of three kinds of thermal papers with BPA being detected in all samples (0.696-3.78 mg g). Recovery tests were performed to validate the reliability of the method, and the recoveries were found between 81.9% and 119% with relative standard deviations lower than 4.8%.