Ultrasound-assisted, hybrid ionic liquid, dispersive liquid-liquid microextraction for the determination of insecticides in fruit juices based on partition coefficients

An ultrasound-assisted, hybrid ionic liquid, dispersive liquid-liquid microextraction method coupled to high-performance liquid chromatography with a variable-wavelength detector was developed to detect ten insecticides, including diflubenzuron, triflumuron, hexaflumuron, flufenoxuron, lufenuron, diafenthiuron, transfluthrin, fenpropathrin, gamma-cyhalothrin and deltamethrin, in fruit juices. In this method, an appropriate extraction solvent was chosen based on the partition coefficient of the target compounds. A mixture of 1-octyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide was used as the extractant. The extraction efficiency was screened using Plackett-Burman design and optimized using central composite design. Under the optimal conditions, good linearity was obtained for all the analytes in the pure water model and the fruit juice samples. In pure water, the recoveries of the ten insecticides ranged from 85.7 to 108.9%, with relative standard deviations for one day ranging from 1.24 to 2.64%. The limits of detection were in the range of 0.19-0.69 mu g/L, and the enrichment factors were in the range of 123-160. The logarithm of the n-octanol/water partition coefficient in this experiment is a useful reference to select a suitable extraction solvent, and the proposed technique was applied for the analysis of ten insecticides in fruit juice with satisfactory results.