QuEChERS followed by dispersive liquid–liquid microextraction based on solidification of floating organic droplet method for organochlorine pesticides analysis in fish

A fast, sensitive and environmental-friendly method was developed to determine 13 organochlorine pesticides in fish tissue through gas chromatography with electron capture detection. Sample was extracted initially by acetonitrile and then concentrated through dispersive liquid–liquid microextraction based on solidification of floating organic droplet (DLLME–SFO). Dispersive solid phase extraction (d-SPE) was not a separate step but integrated to DLLME-SFO procedure. In order to separate the d-SPE sorbent , water and organic phase well, a modification to the glass centrifuge tube was made to achieving high centrifugal speed. The optimized method was validated with recoveries ranging from 88.1% to 121.2% (with relative standard deviations <15%) at three spiked levels for all of the pesticides. Good linearity was achieved at seven concentration levels from 6.25 to 625   μg   L −1 , which corresponded to 0.001–0.100   mg   kg −1 in the sample. The limits of quantification and the limits of detection for 13 OCPs ranged from 1.94×10 −3 to 4.93×10 −3   mg   kg −1 and 6.50×10 −4 to 1.58×10 −3   mg   kg −1 , respectively. The method was successfully applied to analyze real fish samples.