title: Simultaneous derivatization and extraction of primary short-chain aliphatic amines using an ultrasonic-mixed water-ionic liquid two-phase system for liquid chromatography.
abstract: Here, we report on a procedure in which ultrasonic waves were used to mix a water-ionic liquid two-phase system to simultaneously derivatize amines with dansyl chloride and extract, and the resulting dansyl amines into an ionic liquid (IL) at room temperature within 15 min. The ILs used were room-temperature ionic liquids (RTILs), such as 1-alkyl-3-methylimidazolium hexafluorophosphate ([C(n)MIM][PF(6)], n = 4, 6, 8), which are insoluble in water, and can extract more than 88% of the total dansyl amines (Dns-amines) present in aqueous solution. The Dns-amines formed were separated by chromatography in 20 µL of RTIL in a mobile-phase gradient of acetonitrile-water flowing through an Agilent Zorbax SB-C18 column. The eluents were analyzed at 333 nm using a UV detector. The optimal analytical conditions were achieved by using the following: RTILs with a 4-carbon alkyl chain; a 7-mL water sample and 1 mL each of 5 mM dansyl chloride in acetone and 20 mM sodium tetraborate buffer for use with a fixed volume (1 mL) of IL; buffer pH of 10.4; duration of 15 min; and an acetonitrile-water ratio of 50:50 from zero time to 3 min, 80:20 from 4 to 10 min, and 50:50 from 11 to 16 min. In comparison to the single-phase hot-water (70°C) derivatization process reported earlier, the simultaneous process developed here showed a higher derivatization efficiency at the tested concentration. The linear range of analysis (0.14-7.14 mg/L) was determined, and the correlation coefficient (R) ranged from 0.9878 to 0.9980. Furthermore, the estimated percentage of recovery from amine-spiked river-water samples ranged from 76 to 108%. The method presented here is simple and fast, and does not involve the use of volatile organic extractants.
authors.affiliation: Analysis and Testing Center, Ningbo Institute of Technology, Zhejiang University, 1st Qianhu Nan Road, Ningbo, Zhejiang 315100, P. R. China. jhl@nit.zju.edu.cn
authors.forename: Hailiang
authors.initials: H
authors.lastname: Jiang
authors.forename: Liyan
authors.initials: L
authors.lastname: Ying
authors.forename: Yueli
authors.initials: Y
authors.lastname: Hao
authors.forename: Saichun
authors.initials: S
authors.lastname: Zhou
authors.forename: Haoyu
authors.initials: H
authors.lastname: Shen
authors.forename: Ying
authors.initials: Y
authors.lastname: Tang
authors.forename: Yazhen
authors.initials: Y
authors.lastname: Bao
mesh_terms: D000588:Amines / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D052578:Ionic Liquids / Q000138:chemical synthesis / Q000737:chemistry*; D014465:Ultrasonics; D014867:Water / Q000737:chemistry*
chemical_list: D000588:Amines; D052578:Ionic Liquids; D014867:Water