Net-like mesoporous carbon nanocomposites for magnetic solid-phase extraction of sulfonamides prior to their quantitation by UPLC-HRMS.

A net-like mesoporous carbon nanocomposite (MCN) was hydrothermally prepared by using filter paper as the raw material. The MCN contains magnetic nanoparticles of type Fe3O4 which result from the addition of Fe(NO3)3·9H2O during synthesis. The MCN was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman spectra, Brunauer-Emmett-Teller methods and vibrating sample magnetometry. The MCN is shown to be a viable material for magnetic solid-phase extraction of trace sulfonamides (SAs) including sulfadiazine, sulfapyridine, sulfamerazine, sulfamethazine, sulfamethizole, sulfamethoxypridazine, sulfachloropyridazine and sulfadimethoxine. Following desorption with acetone containing 0.5% ammonia, the SAs were quantified by UPLC with high-resolution mass spectrometric detection. With sulfamethazine as an example, the adsorption equilibrium configurations and the major interaction mechanism between SAs and the MCN were calculated by using density functional theory. Under the optimal conditions, the calibration plots are linear in the 0.05-10 ng·mL-1 SA concentration ranges. The limits of detection are between 7.2 and 13.6 ng·L-1. The recoveries from spiked samples ranged from 79 to 107%, with relative standard deviations of <9.9%. Graphical abstractSchematic representation of nanocomposite preparation, adsorption mechanism of sulfonamide and magnetic solid-phase extraction (MSPE) for sulfadiazine (SDZ), sulfapyridine (SPD), sulfamerazine (SMR), sulfamethazine (SMZ), sulfamethizole (SMT), sulfamethoxypridazine (SMP), sulfachloropyridazine (SCP) and sulfadimethoxine (SDMX). Quantification was accomplished by UPLC with high-resolution mass spectrometric detection.