Selective determination of aromatic acids by new magnetic hydroxylated MWCNTs and MOFs based composite

A novel, efficient, and high-selectivity magnetic solid-phase extraction (MSPE) adsorbent based on Fe₃O₄ nanoparticles, hydroxylated multi-walled carbon nanotubes (MWCNTs-OH) and metal-organic frameworks (MOFs) was prepared and applied for trace aromatic acids determination in solid samples by applying a template-free in situ strategy. The morphology, configuration and magnetic behavior of the adsorbent were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, and vibrating sample magnetometer (VSM). The adsorbent can achieve the selective extraction of aromatic acids from the aromatic mixture in apple samples, which was mainly promoted by intermolecular hydrogen bonding and π-π electron-donor-acceptor (EDA) interaction. The potential application of the adsorbent was evaluated by MSPE of trace 1-naphthylacetic acid (NAA), cinnamic acid (CA) and terephthalic acid (TPA) from apple samples under the optimal conditions which were investigated. Satisfactory linearities were obtained in a range of 5-500ng/g and the recoveries of three aromatic acids at three spiked levels ranged from 91.2% to 98.0% with the relative standard deviations (RSD) of less than 5.5%. The limits of detection (LODs) for CA, TPA and NAA were 0.17, 0.61, and 0.86ng/g. The satisfactory results confirmed the great potential of the novel adsorbent for the selective extraction of aromatic acids from complex sample matrices.