Hard cap espresso extraction-stir bar preconcentration of polychlorinated biphenyls in soil and sediments

A Nespresso^© hard cap espresso machine has been employed for the quantitative extraction of polychlorinated biphenyls (PCBs) from sediments and soils. Sample extraction was performed from five grams of sample in less than 40 s, with 200 mL ethanol 40% (v/v) in water and PCBs were concentrated using stir bar sorptive extraction (SBSE) and determined by thermal desorption-gas chromatography-tandem mass spectrometry (TD-GC-MS-MS). Eleven PCB congeners (28, 52, 77, 80, 81, 101, 118, 138, 153,169, and 180) were determined in soils and sediments with limits of quantification in the 0.03-0.08 ng g^-1 range. Extraction efficiency was established by the analysis of soil samples spiked with the studied PCBs at concentrations from 0.1 to 10.0 ng g^-1, obtaining quantitative recoveries from 81 to 120% and an adequate precision with relative standard deviations lower than 20%. Certified reference materials and natural samples were analyzed by the proposed hard cap espresso extraction and results were compared with those provided by a reference procedure based on pressurized solvent extraction, obtaining statistically comparable results. Therefore, the use of a hard cap espresso machine in tandem with SBSE and TD-GC-MS-MS allowed a simple, sensitive and quantitative determination of PCBs.