Efficient magnetic sorbent for extracting bisphenol A from aqueous samples

Magnetic polymer sorbents were developed and evaluated for the extraction of bisphenol A (BPA) from aqueous solution using magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography with UV detection (HPLC-UV). Two sorbents were synthesized by modifying amine-terminated polydimethylsiloxane (PDMS) with 3-aminopropyltriethoxysilane (APTS): MPCNT, prepared with carboxyl-functionalized multi-walled carbon nanotubes (MWCNT-COOH), and MPTCl, synthesized without MWCNT-COOH and cross-linked with terephthaloyl chloride. Incorporation of MWCNT-COOH introduced additional π-π interactions, hydrogen bonding, and hydrophobic domains, which significantly enhanced BPA uptake. Various analytical techniques were employed to characterize the morphology, thermal properties, and particle stability of MPCNT, including X-ray photoelectron spectroscopy (XPS), zeta potential measurements, Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). To optimize the extraction performance, several extraction conditions were studied, including the amount of polymer content, the pH effect, the sample volume used for both adsorption and desorption, and the salting-out effect. The reproducibility of the MPCNT-based extraction method was found to be acceptable, with a relative standard deviation (RSD) of 7.85%. The method's linearity was tested, and the limits of detection (LOD) and quantification (LOQ) were determined to be 15.15 µg L^-1 and 50.00 µg L^-1, respectively, with a high coefficient of determination (r ² = 0.9992). The relative standard deviations obtained were consistently below 10% (n = 5).