A simple, apid, and reliable method based on dispersive solid-phase extraction (d-SPE) and gas chromatography-mass\nspectrometry (GC-MS) was developed for quantitating polychlorinated biphenyls (PCBs) in vegetable samples. Parameters\naffecting both the extraction yields and cleanup efficiency, including the type and volume of extraction solvent, extraction time,\ntype and volume of cleanup sorbent, and cleanup time, were optimized. Matrix effects were evaluated, and matrix-matched\ncalibration was recommended. Under the optimized conditions, carboxylated multiwalled carbon nanotubes (MWCNTs-COOH),\nwhich exhibit excellent adsorption capabilities due to large surface area and unique structure, were employed as d-SPE sorbent to\nremove interfering substances, rather than the analytes, from vegetable samples. Satisfactory linear relationship was observed for\nall PCBs across a concentration range of 5-500 microg/kg with correlation coefficients no less than 0.9993. Four representative\nvegetables (cucumber, tomato, lettuce, and cabbage) were selected as matrices for method validation. Each matrix was spiked at\nconcentrations of 5, 10, and 100 microg/kg to evaluate recoveries, which ranged from 84.5% to 116.5% with relative standard deviations\n(n =6) between 0.6% and 17.6%. /e limits of detection and the limits of quantification ranged from 0.3 to 1.4 microg/kg and 0.8 to\n4.5 microg/kg, respectively. Twelve real vegetable samples were analyzed using the proposed method. /ree of the target PCBs were\ndetected in one lettuce sample with the total concentration of 17.9 microm/kg.
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