Employment of a novel magnetically multifunctional purifying material for determination of toxic highly chlorinated polychlorinated biphenyls at trace levels in soil samples

In this study, we developed a magnetically multifunctional purifying material for efficient removal of matrix interferences, especially certain organochlorine pesticide (DDT, DDE, and DDD), during the determination of toxic highly chlorinated polychlorinated biphenyls (PCBs) at trace levels in soil samples. The multifunctional adsorbent (CMCD-NH2-MNPs) was prepared by grafting carboxymethyl-β-cyclodextrin on the surface of amino-functionalized magnetite (Fe3O4) nanoparticles. CMCD-NH2-MNPs has stronger host-guest complexation with DDT, DDE, and DDD, but the same adsorbent shows weaker adsorption ability toward highly chlorinated PCBs (from tetra- to octa-chlorinated PCBs) owing to their steric hindrance effect. Based on this principle, a simple and rapid gas chromatography-mass spectrometry (GC-MS) method was developed for six indicator PCBs (PCB28, PCB52, PCB101, PCB138, PCB153, and PCB180) in soil. Comparative studies were conducted to determine the clean-up efficiency of the following three techniques: (i) Oasis-HLB, (ii) multi-layer silica column, and (iii) dSPE employing CMCD-NH2-MNPs. The results indicate that CMCD-NH2-MNPs as the purification material can easily and effectively remove DDT, DDE, and DDD in soil samples within a short duration of time. The recoveries for highly chlorinated PCBs were in the range of 85.4-102.2%, with RSDs varying between1.0 and 6.5%. The proposed method was verified as one of the most effective clean-up procedures for the analysis of highly chlorinated PCBs in real soil samples