title: [Solvent demulsification-dispersive liquid-liquid microextraction based on solidification of floating organic drop coupled with gas chromatography-mass spectrometry for simultaneous determination of organochlorine pesticides in aqueous samples].
abstract: A novel method for simultaneous determination of eight organochlorine pesticides in solidification of floating organic drop coupled with gas chromatography-mass spectrometry (GC-MS) was established. A mixture of extractant (n-hexadecane) and dispersive agent (acetone) at the ratio of 1/5 (v/v) was injected into aqueous sample to form an emulsion and an extraction process was accomplished. The demulsifier (750 microL acetone) was then injected to break up the emulsion. The two phases were separated quickly without centrifugation. After being solidified in an ice-bath, the upper layer (n-hexadecane) was transferred into an Eppendorf tube and analyzed by GC-MS after melted at room temperature. Factors affecting extraction efficiency such as the type and volume of extractant, dispersive agent and demulsifier, also ionic strength and pH value of extraction system were studied. Under the optimized conditions, the working curve of the proposed method provided a good linearity in the range of 0.025-2.00 microg/L (r = 0.999 5-0.999 9). The detection limits of the organochlorine pesticides calculated by Hubaux-Vos method were 0.012-0.024 microg/L and the relative standard deviations (RSDs) ranged from 3.15% to 4.53%. The enrichment factors (EF) were 96-101. When the method was applied to the determination of farmland water, the average spiked recoveries were 96.77%-102.93% with the relative standard deviations of 2.68%-4.86%. The proposed method is sensitive and fast. It also has the advantage of little organic solvent consumption so that it is friendly to environment and suitable for batch analysis of organochlorine pesticides in aqueous samples. Meanwhile, it provides technical and methodological support for achieving the automation of sample pretreatment.
authors.affiliation: West China School of Public Health, Sichuan University, Key Laboratory of Food Safety Risk Assessment and Monitoring of Sichuan Province, Chengdu 610041, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: West China School of Public Health, Sichuan University, Key Laboratory of Food Safety Risk Assessment and Monitoring of Sichuan Province, Chengdu 610041, China.
authors.forename: Chenghua
authors.initials: C
authors.lastname: Zhu
authors.affiliation: West China School of Public Health, Sichuan University, Key Laboratory of Food Safety Risk Assessment and Monitoring of Sichuan Province, Chengdu 610041, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zou
authors.affiliation: West China School of Public Health, Sichuan University, Key Laboratory of Food Safety Risk Assessment and Monitoring of Sichuan Province, Chengdu 610041, China.
authors.forename: Lizhi
authors.initials: L
authors.lastname: Huang
authors.affiliation: West China School of Public Health, Sichuan University, Key Laboratory of Food Safety Risk Assessment and Monitoring of Sichuan Province, Chengdu 610041, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Yan
mesh_terms: D004655:Emulsions; D008401:Gas Chromatography-Mass Spectrometry; D006843:Hydrocarbons, Chlorinated / Q000032:analysis*; D059627:Liquid Phase Microextraction; D010573:Pesticide Residues / Q000032:analysis*; D012997:Solvents; D014867:Water; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D004655:Emulsions; D006843:Hydrocarbons, Chlorinated; D010573:Pesticide Residues; D012997:Solvents; D014874:Water Pollutants, Chemical; D014867:Water