A method was developed for the determination of halide impurities including fluoride, chloride and bromide, in ionic liquids by ion chromatography coupled with direct conductivity detec-tion. The separation of analytes was performed on a Shim-pack IC-A3 anion-exchange column using potassium biphthalate as eluent. Influences of type, concentration and flow rate of eluent, and col-umn temperature on separation efficiency of halide ions were investigated. The optimized chromato-graphic conditions for determination of halide ions were using 1. 25 mmol/L potassium biphthalate as eluent with a flow rate of 1. 5 mL/min at 45 ℃. Under the optimal conditions, a good baseline separation of halide ions was achieved. Nitrate, tetrafluoroborate and sulfate did not interfere with the determination of halide ions. The detection limits ( S/N = 3 ) of halide ions by the method were in the range of 0. 02 - 0. 11 mg/L. The linear ranges of calibration curves between chromatographic peak area and concentration of analytes for fluoride, chloride and bromide were 0. 1 - 50, 0. 1 - 50 and 0. 5 - 100 mg/L, respectively. The relative standard deviations(RSDs) of chromatographic peak ar-eas for halide ions were less than 0. 7% (n = 5). The method was successfully applied to determine halide impurities in alkyl-imidazolium terafluoroborate ionic liquids. The spiked recoveries of halide ions ranged from 98% to 102% . The good linearity, repeatability and low detection limits of the method made it meet the requirements of quantitative analysis of halide impurities in ionic liquids.%研究了离子色谱-直接电导检测法分离测定离子液体中的卤素离子(F~-、Cl~-、Br~-)杂质.采用Shim-pack IC-A3阴离子交换色谱柱,考察了淋洗液种类及浓度、流速和色谱柱温度对分离测定的影响.最佳色谱条件为:以1.25 mmol/L邻苯二甲酸氢钾为淋洗液,流速1.5 mL/min,色谱柱温45 ℃.在此条件下可以基线分离卤素离子,且NO_3~-、BF_4~-、SO_4~(2-)不干扰测定.该法测定卤素离子的检出限(S/N=3)为0.02 ～0.11 mg/L,峰面积的相对标准偏差(n=5)不大于0.7%,F~-、Cl~- 和Br~- 的标准曲线的线性范围分别为0.1 ～50、0.1 ～50、0.5 ～100 mg/L.将方法用于烷基咪唑四氟硼酸盐离子液体中卤素离子杂质的测定,加标回收率为98% ～102%.
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