Magnetic solid phase extraction based on Fe3O4@SiO2@CTS nano adsorbent for the sensitive detection of trace polychlorinated biphenyls in environmental water samples

Abstract In this study, a magnetic composite material was developed by bonding the modified natural polysaccharide chitosan (CTS) with SiO2 on the surface of magnetic Fe3O4 nanoparticles to detect polychlorinated biphenyls (PCBs). The structural, porosity, and magnetic properties of Fe3O4@SiO2@CTS were characterized by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, nitrogen sorption, and vibrating sample magnetometry. Various experimental parameters affecting the extraction capacity were investigated, including extraction time, desorption time, desorption solvent, solution pH value, and salt ion concentration. Results showed that Fe3O4@SiO2@CTS exhibited excellent selectivity, easy separation by magnet, and reusability (at least 10 cycles). Under optimized experimental condition, this magnetic solid phase extraction material was applied to detect three PCBs with low limits of detection of 0.02–0.15 μg·L−1. The linear correlation coefficient was higher than 0.998, while the recoveries ranged between 90.34% and 106.99% with the relative standard deviation less than 11.31%. The practical application of Fe3O4@SiO2@CTS was verified through quantitative analysis of PCB residues in environmental water, supporting its promising role in simple, convenient, and low-cost detection of PCBs in real environmental samples.