Determination of polybrominated diphenyl ethers in aquatic animal tissue using cleanup by freezing-dispersive liquid-liquid microextraction combined with GC-MS.

A method for the determination of polybrominated diphenyl ethers (PBDEs) in aquatic animal tissue was developed, and it is based on cleanup by freezing-dispersive liquid-liquid microextraction (DLLME) for the pretreatment of samples with fat content. Aquatic animal tissue homogenate was extracted with acetone, and then frozen in a freezer at -80 degrees C. Fat in aquatic animal tissue was isolated from the analytes, i.e. PBDE congeners dissolved in acetone and fat formed floccules at low temperature. The supernatant was extracted using the DLLME technique. Under the optimum DLLME conditions, 0.75 mL supernatant with 33 microL chlorobenzene was added into 5.0 mL pure water, and subsequently cloudy solution was formed. After centrifuging, 1.0 microL lower phase was subjected to GC-MS analysis. Recovery test was performed at fortified concentrations of 5.0-2500 microg/kg. The detection results showed that the recoveries for each target analyte ranged from 75.3 to 127.8%. The repeatability of the proposed method by spiking aquatic animal samples at 10 microg/kg for PBDEs, expressed as RSD, n=5, varied between 4.3 and 10.3% (n=5). LOD of the proposed method for aquatic animal tissue samples were between 2.4 and 4.9 microg/kg for all the analytes.