Study On Ionic Liquids Used In The Analysis Of Amines By Liquid Chromatography

This paper uses ionic liquids as mobile phase additives and uses liquid chromatography-indirect ultraviolet detection to study the separation and detection methods of amines.The purpose is to develop a simple,fast and practical method for the analysis and detection of amines.The detection of similar substances provides new methods for separation and detection.The paper mainly includes the following three parts:Firstly,An analytical method for the separation of fatty amines by reversed-phase liquid chromatography using pyridine ionic liquid as a mobile phase additive was developed.The effects of pyridine ionic liquids and imidazole ionic liquids as mobile phase additives on the analysis of fatty amines were investigated.Factors such as the concentration of pyridine ionic liquids,the content of organic solvents,and the detection wavelength were discussed.The function of ionic liquids,the retention rule and the related mechanism were discussed.Pyridinium ionic liquids play the roles of ion pair reagent,background ultraviolet absorption reagent and shielding agent in separation and detection.A reversed-phase C18 column with acetonitrile/0.5 mmol/L N-ethylpyridinium aqueous solution(volume ratio 30/70)as mobile phase was used to separate methylamine,ethylamine,n-propylamine and n-butylamine in 16 min at column temperature of 25 ~oC,flow rate of 1.0 mL/min and ultraviolet detection wavelength of 210 nm.The limits of detection were 0.36,0.35,0.26 and 0.58 mg/L,respectively.The method has been applied to the determination of aliphatic amines in river water samples with recovery of 96.0%?100.0%.The method is simple and meets the requirement of quantitative analysis.Secondly,Hydrophilic interaction chromatography with pyridinium ionic liquids and ammonium formate as mobile phase additives was developed for the separation and ultraviolet detection of biogenic amines.The effects of pyridinium ionic liquids,imidazolium ionic liquids,ammonium formate,organic solvents,detection wavelength and other factors on the analysis of biogenic amines were investigated.The function of ionic liquids,retention rules and related mechanisms have been discussed.The hydrophilic interaction column is suitable for the separation of polar substance biogenic amines.The pyridinium ionic liquid and ammonium formate improved the separation and detection of biogenic amines.Tyramine,phenethylamine and tryptamine were completely separated and detected within 30 min using the hydrophilic interaction column and the mobile phase of acetonitrile/0.5 mmol/L N-ethylpyridinium-1.0 mmol/L ammonium formate mixed solution(volume ratio 25/75)at the column temperature of 30°C,the flow rate of 1.0 mL/min and the ultraviolet detection wavelength of 210 nm.The limits of detection were less than 1.0 mg/L.The linearity and reproducibility of the method are good.The method was applied to the determination of biogenic amine content in bread fermented beverage samples.The recoveries of standard addition were between 94.4%and 104.6%.This method is simple and easy to apply.Finally,A new analytical method for the determination of tetrabutylphosphorus and tetrabutylammonium using imidazolium ionic liquid as mobile phase additive in hydrophilic interaction chromatography with indirect ultraviolet detection was developed.The effects of imidazolium ionic liquid and pyridinium ionic liquid as mobile phase additives on the analysis of tetrabutylphosphorus and tetrabutylammonium were studied.The influences of concentration of imidazolium ionic liquid,organic solvent,detection wavelength and other factors were investigated.Tetrabutylphosphorus and tetrabutylammonium were completely separated and detected within 15 min by using a hydrophilic interaction chromatographic column and acetonitrile/1.0 mmol/L 1-ethyl 3-methylimidazolium tetrafluoroborate(volume ratio 60/40)as mobile phase at column temperature of 30℃,flow rate of 1.0 mL/min and ultraviolet detection wavelength of210 nm.The detection limit of the method was less than 1.2 mg/L,and the linearity and reproducibility were good.The method was applied to the analysis of tetrabutylammonium bromide ionic liquid samples and Songhua River water samples.The recovery was between 95.9%and 107.0%.This method is simple and easy to use.