Solid-liquid extraction with low temperature purification coupled with gas chromatography and mass spectrometry for determination of polychlorinated biphenyls in sewage sludge

Abstract

Sewage sludge is the residue produced by the wastewater treatment plants, which can be used as soil conditioner in agriculture. However, the current legislation recommends monitoring chemical contaminants such as polychlorinated biphenyls (PCBs). In this study, solid-liquid extraction with low temperature purification (SLE-LTP) was optimized and validated for monitoring six PCBs. The analyses were performed by gas chromatography and mass spectrometry. Sulfur interference was removed by 1.5 g of copper metal. The extraction was carried out using 6.50 mL isopropanol, 1.50 mL ethyl acetate, 0.1 g NaCl, 0.8 mL water and 15 min into ultrasound. Extraction percentages were between 82 and 94% and relative standard deviation ≤ 16% for low concentrations. Detection and quantification limits were 3.3 and 10 μg kg-1, respectively. The method was applied to sludge samples collected monthly in the wastewater treatment plant and PCB 52 was detected in six samples.