Low-density magnetofluid dispersive liquid-liquid microextraction for the fast determination of organochlorine pesticides in water samples by GC-ECD.

A new micro-extraction technique named low-density magnetofluid dispersive liquid-liquid microextraction (LMF-DMMLE) has been developed, which permits a wider range of solvents and can be combined with various detection methods. Comparing with the existing low density solvents micro-extraction methods, no special devices and complicated operations were required during the whole extraction process. Dispersion of the low-density magnetofluid into the aqueous sample is achieved by using vortex mixing, so disperser solvent was unnecessary. The extraction solvent was collected conveniently with an external magnetic field placed outside the extraction container after dispersing. Then, the magnetic nanoparticles were easily removed by adding precipitation reagent under the magnetic field. In order to evaluate the validity of this method, ten organochlorine pesticides (OCPs) were chosen as the analytes. Parameters influencing the extraction efficiency such as extraction solvents, volume of extraction solvents, extraction time, and ionic strength were investigated and optimized. Under the optimized conditions, this method showed high extraction efficiency with low limits of detection of 1.8-8.4 ng L(-1), good linearity in the range of 0.05-10.00 μg L(-1) and the precisions were in the range of 1.3-9.6% (RSD, n=5). Finally, this method was successfully applied in the determination of OCPs in real water samples.