title: Performance of metal-organic framework MIL-101 after surfactant modification in the extraction of endocrine disrupting chemicals from environmental water samples.
abstract: The research presented in this paper explored the modification and application of a metal-organic framework, MIL-101, with nonionic surfactant-Triton X-114 in dispersive solid-phase extraction for the preconcentration of four endocrine disrupting chemicals (estrone, 17α-ethynylestradiol, estriol and diethylstilbestrol) from environmental water samples. Triton X-114 molecules could be adsorbed by the hydrophobic surface of the MIL-101 crystals, and thus improved the dispersibility of MIL-101 in aqueous solution by serving as a hydrophilic coating. Cloud point phase separation from Triton X-114 accelerated the separation of extracts from the aqueous matrix. The proposed method combines the favorable attributes of strong adsorption capacity resulting from the porous structure of MIL-101 and self-assembly of Triton X-114 molecules. Post-extraction derivatization using N-methyl-N-(trimethylsilyl)trifluoroacetamide was employed to facilitate the quantitative determination of the extracts by gas chromatography-mass spectrometry. The main factors affecting the preparation of modified MIL-101, and extraction of the analytes, such as the amount of surfactant, the ultrasonic and vortex durations, solution pH and desorption conditions, were investigated in detail. Under the optimized conditions, the present method yielded low limits of detection (0.006-0.023 ng/mL), good linearity from 0.09 to 45 ng/mL (coefficients of determination higher than 0.9980) and acceptable precision (relative standard deviations of 2.2-13%). The surface modified MIL-101 was demonstrated to be effective for the extraction of the selected estrogens from aqueous samples, giving rise to markedly improved extraction performance compared to the unmodified MIL-101.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Zhenzhen
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore; National University of Singapore Environmental Research Institute, T-Lab Building #02-01, 5A Engineering Drive 1, Singapore 117411, Singapore. Electronic address: chmleehk@nus.edu.sg.
authors.forename: Hian Kee
authors.initials: HK
authors.lastname: Lee
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D004054:Diethylstilbestrol / Q000032:analysis / Q000737:chemistry; D060766:Drinking Water / Q000032:analysis; D052244:Endocrine Disruptors / Q000032:analysis* / Q000737:chemistry; D004964:Estriol / Q000032:analysis / Q000737:chemistry; D004967:Estrogens / Q000032:analysis / Q000737:chemistry; D004970:Estrone / Q000032:analysis / Q000737:chemistry; D004997:Ethinyl Estradiol / Q000032:analysis / Q000737:chemistry; D000073396:Metal-Organic Frameworks; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000737:chemistry*; D045483:Rivers / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D056831:Coordination Complexes; D060766:Drinking Water; D052244:Endocrine Disruptors; D004967:Estrogens; C000589635:MIL-101; D000073396:Metal-Organic Frameworks; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; D004970:Estrone; D011092:Polyethylene Glycols; D004997:Ethinyl Estradiol; D004054:Diethylstilbestrol; D017830:Octoxynol; C010615:Nonidet P-40; D004964:Estriol
keywords: Dispersive solid-phase extraction; Endocrine disrupting chemicals; MIL-101; Surface modification; Triton X-114