Focused ultrasound assisted extraction for the determination of PBDEs in vegetables and amended soil

Focused-ultrasound solid-liquid extraction was developed for the extraction of polybrominated diphenyl ethers in vegetables and amended soil. Firstly, solid-phase extraction clean-up using 2 g and 5 g of Florisil and 2-g silica cartridges were evaluated and elution profile was also optimised. Similar recoveries were obtained for most compounds while better recoveries were obtained for 5-g Florisil in the case of the heavier PBDEs. FUSLE extraction time (2 min) guaranteed quantitative extraction of the target analytes in the four studied matrices (69-130%). Method detection limit values were in the range of 1-5 ng g−1 for splitless injection in a gas chromatograph coupled to a mass spectrometer and no significant improvement was obtained for large volume injection. Relative standard deviation values were between 1% and 30%. Recoveries obtained using FUSLE were compared with those obtained with microwave assisted extraction and the developed method was also applied to a certify reference material of polybrominated diphenyl ethers and polychlorinared biphenyls in sediment. Similar values were obtained in the case of carrot and pepper matrices (77-130% for FUSLE and 77-112% for MAE). However, MAE provided extraction recoveries higher than 100% for most of the BDE congeners in lettuce and amended soil.