| The analytical methods for the determination of anions by liquid chromatography with indirect ultraviolet detection using ionic liquids as mobile phase additives are studied in this paper.The purpose is to develop simple,fast and effective new methods to determine anions.The paper mainly includes the following three parts:Firstly,an analytical method for the simultaneous determination of trifluoromethanesulfonate and trifluoroacetate by liquid chromatography with indirect ultraviolet detection using pyridinium ionic liquids as mobile phase additives was developed.The effects of pyridinium ionic liquids,imidazolium ionic liquids and ion pair reagents as mobile phase additives on the separation and detection of the two anions were investigated.The effects of the concentrations of pyridinium ionic liquids,organic solvents on the determination were also investigated.The retention behaviors of the two anions were discussed.The separation of the anions was performed on the C18 reserved-phase column using methanol/0.3 mmol/L N-hexylpyridine bromide?10/90,v/v?as mobile phase,with column temperature of 30?,flow rate of 1.0mL/min and detection wavelength of 250 nm.Under these conditions,two anions can be completely separated in 12 min.The limits of detection were 0.09 mg/L and 0.18mg/L,respectively.The method was applied in the determination of trifluoromethanesulfonate and trifluoroacetate in ionic liquid samples,and the spiked recoveries were 96.0%?101.0%.This method is simple,rapid and has practicability.Secondly,an analytical method for the simultaneous determination of thiocyanate and iodide by liquid chromatography with indirect ultraviolet detection using imidazolium ionic liquids as mobile phase additives was developed.The effects of imidazolium ionic liquids,pyridinium ionic liquids and ion pair reagents as mobile phase additives on the separation and detection of the two anions were investigated.The effects of concentrations of imidazolium ionic liquids,organic solvents on the determination were also investigated.The retention behaviors of the two anions were discussed.The separation of the anions was performed on the C18 reserved-phase column using acetonitrile/0.3 mmol/L 1-amyl-3-methyl-imidazolium tetrafluoroborate?10/90,v/v?as mobile phase,with column temperature of 35?,flow rate of 1.0mL/min and detection wavelength of 210 nm.Under these conditions,the two anions can be completely separated in 6 min.The limits of detection were 0.05 mg/L.The method was applied in the determination of thiocyanate and iodide in ionic liquid samples and iodide drugs,and the spiked recoveries were 97.0%?101.0%.This method is simple and reliable and this study can provide a reference method for the determination of thiocyanate and iodide in actual samples.Finally,an analytical method for the simultaneous determination of fluoride,chloride,nitrite and nitrate by liquid chromatography with indirect ultraviolet detection using imidazolium ionic liquids as mobile phase additives was developed.The effects of reversed-phase C18 column and monolithic column on the separation and detection of the four anions were compared.The effects of chromatographic columns,ionic liquid types and concentrations,organic solvents on the determination were investigated.The mechanism of ionic liquids in the analysis of anions was clarified.The chromatographic conditions were optimized and the retention behaviors of the four anions were discussed.The separation of the anions was performed on the C18 reserved-phase column using acetonitrile/0.5 mmol/L 1-octyl-3-methyl-imidazolium tetrafluoroborate?8/92,v/v?as mobile phase,with column temperature of 35?,flow rate of 1.0 mL/min and detection wavelength of 210 nm.Under these conditions,four anions can be completely separated in 20 min.The limits of detection were less than 0.50 mg/L.The method was applied in the determination of anions in beverages and tap water,and the spiked recoveries were96.0%?102.7%.This method is simple and reliable and this study can provide a reference method for the determination of fluoride,chloride,nitrite and nitrate in actual samples. |
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