Determination of polybrominated diphenyl ethers in water and soil samples by cloud point extraction-ultrasound-assisted back-extraction-gas chromatography-mass spectrometry

A novel and efficient analytical methodology is proposed for extracting and preconcentrating polybrominated diphenyl ethers (PBDEs) from samples of environmental interest prior gas chromatography-mass spectrometry (GC-MS) analysis. It is based on the induction of micellar organized medium by using a non-ionic surfactant (Triton X-114) to extract the target PBDEs. To enable coupling the efficient extracting technique with GC analysis, ultrasound-assisted back-extraction (UABE) into an organic solvent was required. Several factors, including surfactant type and concentration, equilibration temperature and time, ionic strength, pH and buffers nature and concentration were studied and optimized over the extraction efficiency of the proposed technique. Under optimal experimental conditions, the target analytes were quantitatively extracted achieving an enrichment factor of 250 when 10mL aliquot of ultrapure water spiked with PBDE-standard mixture (10pg mL(-1) each PBDE) was extracted. Method detection limits (MDLs) calculated with aqueous PBDEs solutions as three times the signal-to-noise ratio (S/N), ranged from 1 to 2pg mL(-1) with RSDs values <= 8.5% (n=5). The coefficients of estimation of the calibration curves obtained following the proposed methodology were >= 0.9987 and linear range of all PBDEs was 4-150 pg mL(-1). The proposed methodology was validated by carrying out a recovery study by spiking the samples at two different concentration levels of PBDEs (10 and 50 pg mL(-1) for waters samples). Recoveries values in the range of 96-106% for water samples were obtained showing satisfactory robustness of the method for analyzing PBDEs in water samples. The proposed methodology was applied for the analysis of PBDEs: 2,2',4,4'-tetraBDE (BDE-47), 2,2',4,4,5-pentaBDE (BDE-99), 2,2',4,4,6-pentaBDE (BDE-100) and 2,2,4,4',5.5'-hexaBDE (BDE-153) in water samples, including drinking, lake, river water and soil samples. Significant quantities of PBDEs were not found in the analyzed samples. (C) 2009 Elsevier B.V. All rights reserved.