Abstract:

Gas chromatography (GC)-high-resolution mass spectrometry (HRMS) with accelerated solvent extraction (ASE)-purification simultaneously coupled to the isotope internal standard method is proposed for the determination of 32 polychlorinated biphenyls (PCBs) in aquatic products. Synchronous purification was achieved by adding 2 g of anhydrous sodium sulfate, 1 g of Cleanert Florisil, and 50 g of neutral alumina as the adsorbent to the ASE system. The PCBs were extracted from aquatic product samples using a dichloromethane-n-hexane (1:1, v/v) mixture at 100 ℃ with two extraction cycles. The extracting solution was purified twice with 0.5 mL concentrated sulfuric acid. After concentration to a constant volume, the target compounds were detected by GC-HRMS and quantified by the isotope internal standard method. Under the optimized conditions, the relative standard deviations (RSDs) of the mean relative response factor (RRF) for the 32 PCBs in the range of 0.1-20 μg/L were less than 15%. The limits of quantification were 0.3-1.9 ng/kg. At three spiked levels (5, 20, and 50 ng/kg) in grass carp and sea bass, the recoveries of the 32 PCBs were between 71.9% and 119.0%, with the RSDs varying from 3.5% to 19.6%. This method effectively reduces the matrix interference and shows high sensitivity, good reproducibility, and stable recovery, thus proving useful for the detection of PCBs in aquatic products.

Key words: accelerated solvent extraction (ASE), gas chromatography-high resolution mass spectrometry (GC-HRMS), isotope internal standard, polychlorinated biphenyls (PCBs), aquatic products