Pressurized liquid extraction of chlorinated polycyclic aromatic hydrocarbons from soil samples using aqueous solutions

A novel method was developed for the determination of chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) in soil. The method is based on pressurized liquid extraction (PLE) of the analytes using aqueous solutions, and combined with a further concentration step using solid-phase extraction (SPE) and followed by gas chromatography-mass spectrometry (GC-MS). The experimental parameters that influenced extraction efficiency were systematically evaluated. The optimal responses were observed by extracting 1 g of soil with the solution of water : acetone (75 : 25, v/v) at 150 degrees C for 5 min and circulated for three cycles. The obtained extracts were diluted and then concentrated by SPE. The recoveries ranged from 84.5 to 110.5% with standard deviations (RSDs) below 9.7%. The proposed method was successfully applied to the determination of Cl-PAHs in real soil samples. Most of the chlorinated polycyclic aromatic hydrocarbons were detected and 1-chloropyrene (1-ClPyr) was predominant in the studied soil samples. The toxic equivalency quotients (TEQs) of Cl-PAHs in the studied soil samples were calculated and were 5717 pg-TEQ per g for the soil from the chemical industrial complex, 3871 pg-TEQ per g for the soil from the e-waste recycling facility, 2061 pg-TEQ per g for the soil from the main traffic road and 11 pg-TEQ per g for the soil from the farmland. The high TEQs of Cl-PAHs means they are potential contributors of dioxin-like toxicity in urban soils.