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Dispersive liquid-liquid microextraction followed by gas chromatography-electron capture detection for determination of polychlorinated biphenyls in fish.

A new method of dispersive liquid-liquid microextraction (DLLME) combined with GC-electron capture detection (GC-ECD) was proposed for the extraction and determination of four polychlorinated biphenyls (PCBs) congeners in fish samples. Acetone was used as extraction solvent for the extraction of PCBs from fish samples. The target analytes in the acetone solvent were rapidly transferred to chlorobenzene, which was used as extraction solvent in DLLME procedures. Under the optimum conditions, linearity was obtained in the concentration range from 1.25 to 1250 microg/kg for PCB 52, and 0.25 to 250 microg/kg for PCB 101, 138 and 153. Coefficients of correlation (r2) ranged from 0.9993 to 0.9999. The repeatability was tested by spiking fish samples at 10 microg/kg PCBs, and RSD% (n = 8) varied between 2.2 and 8.4%. The LODs were between 0.12 and 0.35 microg/kg. The enrichment factors of PCBs were from 87 to 123. The relative recoveries of the four PCB congeners for the perch, pomfret and yellow-fin tuna at spiking levels of 10, 20 and 50 microg/kg were in the range of 81.20-100.6%, 85.00-102.7% and 87.80-108.4%, respectively. The results demonstrated that DLLME combined with GC-ECD was a simple, rapid, and efficient technique for the extraction and determination of PCBs in fish samples.