title: Ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction for the separation and determination of estrogens in water samples by high-performance liquid chromatography with fluorescence detection.
abstract: An ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction method was proposed for the extraction and concentration of 17-α-estradiol, 17-β-estradiol-benzoate, and quinestrol in environmental water samples by high-performance liquid chromatography with fluorescence detection. 1-Hexyl-3-methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion-pairing and salting-out agent NH4 PF6 was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1-hexyl-3-methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid-liquid microextraction was widened.
authors.affiliation: Department of Clinical Laboratory, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.forename: Chuanliu
authors.initials: C
authors.lastname: Wang
authors.forename: Qiaohong
authors.initials: Q
authors.lastname: Yue
authors.forename: Tiecheng
authors.initials: T
authors.lastname: Zhou
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.forename: Hanqi
authors.initials: H
authors.lastname: Zhang
authors.forename: Xiaoke
authors.initials: X
authors.lastname: Hao
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D004967:Estrogens / Q000032:analysis* / Q000302:isolation & purification*; D052578:Ionic Liquids / Q000737:chemistry; D059627:Liquid Phase Microextraction / Q000295:instrumentation / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000302:isolation & purification*
chemical_list: D004967:Estrogens; D052578:Ionic Liquids; D014874:Water Pollutants, Chemical
keywords: Dispersive liquid-liquid microextraction; Estrogens; Fluorescence detection; High-performance liquid chromatography; Ionic liquid foam floatation