Determination of polychlorinated biphenyls in biota samples using simultaneous pressurized liquid extraction and purification.
In order to reduce time and cost of analysis, a new pressurised liquid extraction method that automatically and rapidly achieves quantitative and selective (i.e., lipid-free) extraction of polychlorinated biphenyls (PCBs) in biota tissues was optimized. It consists of on-line clean-up by inclusion of sorbents in the extraction cell. The freeze-dried sample is dispersed with Florisil and loaded in the extraction cell containing an extra amount of Florisil. The extraction is performed under mild conditions using 55 ml of a dichloromethane-pentane (15:85) mixture, a temperature of 40 degrees C, a static extraction time of 10 min and two extraction cycles. The Florisil retains coextracted lipids from the matrix, and the extract, after pre-concentration, is clean enough for direct injection into GC-MS and GC-electron-capture detection (ECD). Quantitative recoveries (from 90 to 106%) are obtained for both native and spiked PCB congeners in samples with a high lipidic content (up to 42% dry mass, in spoonbill eggs). The reproducibility of replicate extractions was better than 11% relative standard deviation. Method detection limits were in the ranges of 0.001-0.004 and 0.002-0.07 ng g(-1) dry mass for GC-ECD and GC-MS-MS, respectively. The method was validated using the standard reference material SRM 2974 (a mussel tissue) from the US National Institute of Standards and Technology, compared to Soxhlet and matrix solid-phase dispersion extraction methods, and used to evaluate the contamination by PCBs in bivalves from South of Spain.
Gómez-Ariza
J L
JL
Departamento de Químicas y Ciencias de los Materiales, Escuela Politecnica Superior La Rábida, Universidad de Huelva, Spain.
Bujalance
M
M
Giráldez
I
I
Velasco
A
A
Morales
E
E
D000818:Animals; D049872:Bivalvia; D004785:Environmental Pollutants / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D011312:Pressure; D012015:Reference Standards; D015203:Reproducibility of Results
D004785:Environmental Pollutants; D011078:Polychlorinated Biphenyls