Analysis Of Hydroxyl Functionalized Imidazolium Ionic Liquids By Liquid Chromatography

In this paper,the separation and detection of hydroxyl functionalized imidazolium ionic liquids were studied by liquid chromatography-ultraviolet detection.New methods for the analysis of hydroxyl functionalized imidazolium ionic liquids were developed.The methods have important practical value for the analysis and detection of ionic liquids in laboratory and industrial applications.The research contents mainly include the following three parts.Firstly,a reversed-phase ion-pair chromatography with ultraviolet detection method for the determination of 1-hydroxyethyl-3-methyl imidazolium cation([HOEtMIm]~+)and 1-hydroxypropyl-3-methyl imidazolium cation([HOPrMIm]~+)was developed.The method has been applied to the analysis of hydroxyl functionalized imidazolium ionic liquid cations in Songhua River water samples and the determination of hydrophobicity constants.[HOEtMIm]~+and[HOPrMIm]~+were completely separated in the reversed-phase ion-pair chromatography.The effects of ion-pair reagents and organic solvents on the separation and detection of hydroxyl functionalized imidazolium ionic liquid cations in reversed-phase ion-pair chromatography were investigated.Ordinary imidazolium ionic liquids do not interfere with the determination of hydroxyl functionalized imidazolium ionic liquids.The suitable ion-pair reagent was octanesulfonate.In the best chromatographic conditions,the baseline separation of[HOEtMIm]~+and[HOPrMIm]~+can be achieved within 20min.The detection limits were 0.36 and 0.50 mg/L,respectively.The relative standard deviation was not more than 0.8%.Recoveries of sample addition were between 97.3%and 100.5%.The experimental method is simple,reliable and practica.Secondly,an effective method for the separation and determination of[HOEtMIm]~+and[HOPrMIm]~+by hydrophilic interaction chromatography was developed.The effects of mobile phase composition and ultraviolet detection wavelength on the separation and determination of[HOEtMIm]~+and[HOPrMIm]~+were studied,and the retention rule was discussed.The mobile phase composition has a great influence on the retention and separation of[HOEtMIm]~+and[HOPrMIm]~+.The influence of acetonitrile content and salt concentration on retention behavior of the analytes has the characteristics of hydrophilic interaction chromatography.In the best chromatographic conditions,the baseline separation and detection of[HOEtMIm]~+and[HOPrMIm]~+can be achieved within 23 min.The detection limits were 0.18 and 0.25 mg/L,respectively,and the relative standard deviation was not more than 0.8%.The method has been applied to the determination of solubility of hydroxyl functionalized imidazolium ionic liquids in several aromatic reagents.It has high accuracy and precision,and meets the requirements of quantitative analysis.Finally,a method for the determination of hydroxyl functionalized imidazolium ionic liquid cations in environmental water by ion chromatography combined with solid phase extraction was developed.The effects of weak acid cation exchange column and mobile phase composition on the separation of[HOEtMIm]~+and[HOPrMIm]~+in ion chromatography were studied,and the retention rules were discussed.Under the optimum chromatographic conditions,[HOEtMIm]~+and[HOPrMIm]~+can be completely separated within 14 min,with detection limits of 0.13and 0.19 mg/L,respectively.The extraction efficiency of hydroxyl functionalized imidazolium ionic liquid cations in water by ion exchange solid phase extraction and reverse phase solid phase extraction in solid phase extraction was studied.The results show that the enrichment and purification of[HOEtMIm]~+and[HOPrMIm]~+can be better achieved by using strong acidic cation exchange solid phase extraction column,and the enrichment multiple is 40 times.The optimized solid phase extraction combined with ion chromatography was applied to the analysis of[HOEtMIm]~+and[HOPrMIm]~+in actual environmental water samples.The recovery of standard addition was between 82.5%and 96.0%.The detection limits in actual water samples were not more than 0.01 mg/L,and the relative standard deviations were less than 2.5%.The method is simple,accurate and reliable.It is suitable for the determination of hydroxyl functionalized imidazolium ionic liquid cations in environmental water.