Imidazolium ionic liquid as the background ultraviolet absorption reagent for determination of morpholinium cations by high performance liquid chromatography-indirect ultraviolet detection

A novel analytical method was developed for determining morpholinium cations lacking ultraviolet absorption groups.This determination was carried out by high performance liquid chromatographyindirect ultraviolet（HPLC-1UV） detection using imidazolium ionic liquid as background absorption reagents,and imidazolium ionic liquid aq.soln.-organic solvent as mobile phase by a reversed-phase C18 column.The background ultraviolet absorption reagents,imidazolium ionic liquids and organic solvents were investigated.The imidazolium ionic liquid in the mobile phase is not only the background ultraviolet absorption reagent for IUV,but also an active component to improve the separation of morpholinium cations.It was found that morpholinium cations could be adequately determined when0.5 mmol/L 1-ethyl-3-methylimidazolium tetrafluoroborate aq.soln./methanol（80：20,v/v） was used as mobile phase with an IUV detection wavelength of 210 nm.In this study,the baseline separation of Nmethyl,ethylmorpholinium cations（MEMo） and N-methyl.propylmorpholinium cations（MPMo） was successfully achieved in 8.5 min.The detection limits（S/N = 3） for MEMo and MPMo were 0.15 and0.29 mg/L,respectively.This simple and practical method has been successfully applied to the determination of two morpholinium ionic liquids synthesized by the chemistry laboratory.

Separation and determination of pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection

A method for rapid and simultaneous determination of multiple pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection was developed.Chromatographic separations were performed on a cation exchange column using ethylenediamine-acetonitrile as the mobile phase.The effects of chromatographic column and the mobile phase,as well as the column temperature on the retention of the cations were investigated.The retention rules of the cations under different chromatographic conditions were formulated.The retention of the cations followed the carbon number rule.The method has been successfully applied to the determination of three ionic liquids synthesized by a chemical laboratory.

High-performance liquid chromatography utilization of ionic liquids as mobile phase additives for separation and determination of the isomers of amino benzoic acids

For the isomers of amino benzoic acid, including o-, m-, p-amino benzoic acid, the beneficial effects of using the ionic liquid, l-butyl-3-methylimidazolium tetrafluoroborate （[BMIm][BF4]）, as mobile phase additives on retention behavior and separation were investigated. Chromatographic separation of the o-, m-, p-amino benzoic acid was performed on a reversed-phase C18 column by ultraviolet detection at 245 nm. The effects of several chromatographic parameters, concentrations and pH values of [BMIm][BF4] solutions, methanol concentration and length of alkyl chain on different ionic liquids, on the separation and determination of the isomers were evaluated. The optimized chromatographic conditions were established using an aqueous 0.5 mmol/L [BMIm][BF4] solution （pH 3.0）/methanol （40：60, v/v） as mobile phase without need of gradient eiution, with separation of three amino benzoic acids achieved within four min. The calibration curve showed good linearity over the tested range of 2 mg/L to 120 mg/L for the three isomers with a correlation coefficients of 0.9999. The recoveries of the three amino benzoic acids of spiked components were between 99.8% and 100%. The method has been successfully applied to the determination of p-amino benzoic acid in the pharmaceutical, Bromine Mitag Procaine Injection.