Analysis Of Anions And Organic Acids By Liquid Chromatography

In this paper,hydrophilic interaction chromatography,reversed-phase chromatography and ion chromatography were used to study the analysis of common anions and organic acids.The purpose is to expand the methods for the analysis of anions and organic acids and provide more methods for the qualitative and quantitative analysis of anions and organic acids in real samples.The paper mainly includes the following four parts:Firstly,a method for the determination of iodide,iodate,nitrate and nitrite by hydrophilic interaction chromatography with ultraviolet detection using amino column has been developed in this paper.The effects of the kinds and concentrations of salts,organic solvents and other factors on the separation and detection of these four anions were studied,and the retention rule of anions was discussed.The separation and detection of these four anions were realized by using amino column and acetonitrile/sodium chloride as mobile phase.The detection limits for iodide,iodate,nitrate and nitrite were 1.7,16.9,1.9,and 2.9?mol/L,respectively.Linearity and reproducibility of the method were good.The method was applied to the determination of povidone-iodine drugs and drinking water boiled repeatedly in drinking fountains.The recovery of standard addition was 91%-105%,and the relative standard deviation of the recovery rate was less than 3.5%,which met the requirements of quantitative analysis.Secondly,a method for the simultaneous separation and detection of common anions containing fluorine BF₄?,PF₆?,CF₃COO?and CF₃SO₃?using imidazolium ionic liquids as mobile phase additives by reversed-phase chromatography and indirect ultraviolet detection was developed.The influences of positive phase chromatography,hydrophilic interaction chromatography and reversed-phase chromatography on the separation and detection of four kinds of fluorine-containing anions were studied.The influences of the types and concentrations of ionic liquid cations in mobile phase,the types and concentrations of organic solvents,the detection wavelength and temperature on the determination were also investigated.The optimum chromatographic conditions were selected.Under the chromatographic conditions,the limits of detection for BF₄?,PF₆?,CF₃COO?,CF₃SO₃?were 0.6,0.6,1.5,3.1?mol/L,separately.This method has been applied to the determination of ionic liquid samples synthesized in the laboratory.The recovery of standard addition was 95.0%-102.5%.The results meet the requirements of daily quantitative analysis.Thirdly,a method for the determination of four short chain fatty acids,formic acid,acetic acid,propionic acid and butyric acid,by reversed-phase chromatography using phosphoric acid as mobile phase was developed.The influence of chromatographic columns on the separation and detection of four kinds of short chain fatty acids was studied.The influence of chromatographic column,mobile phase type and concentration on the retention of fatty acids on the stationary phase was investigated.Acetonitrile/0.3mmol/L phosphoric acid aqueous solution?v/v=10/90?was used as the mobile phase,with the UV detection wavelength 210 nm,flow rate of 1.0 mL/min and column temperature of 40?,four short chain fatty acids were completely separated within 8min,and the detection limits were 0.07,0.06,0.12 and 0.25 mg/L respectively.This method was applied to the determination of fatty acids in drinking water and root exudates of maize.The recovery of standard addition was 95.5%-103.3%.This method provides a reference for the determination of short chain fatty acid in practical samples.Finally,the determination of citric acid,malic acid,succinic acid and acetic acid by ion exclusion chromatography was studied.The separation mechanism of ion exclusion chromatography in the analysis of four organic acids was described.1.0 mmol/L p-toluenesulfonic acid was mobile phase.Under these conditions,the detection limits of four organic acids were 0.02,0.02,0.12 and 0.23 mg/L,respectively.This method was applied to the determination of organic acids in the root exudates of maize.The recovery of standard addition was 95.5%-103.0%.This method provides a reference for the detection of biological samples.