离子色谱-直接电导检测法测定离子液体的阴离子p-甲苯磺酸根

Determination of Ionic Liquid Anion of p-Toluenesulfonate by Ion Chromatography with Direct Conductivity Detection

建立了离子液体阴离子p-甲苯磺酸根的离子色谱-直接电导检测分析方法。采用Shim-pack IC-A3季铵型阴离子交换色谱柱,考察了流动相种类和色谱柱温度对分离测定p-甲苯磺酸根的影响。确定最佳色谱条件为:以1.2 mmol/L柠檬酸-15%乙腈混合水溶液(pH 5.0)为流动相,流速1.0 mL/min,柱温45℃。在此条件下,p-甲苯磺酸根与常见无机阴离子(氟离子、氯离子、溴离子和硝酸根)可以获得很好的分离。该方法测定p-甲苯磺酸根的线性范围为4～100 mg/L,检出限(S/N=3)为1.22 mg/L,保留时间和峰面积的相对标准偏差(n=5)分别为0.42%和1.8%。将方法用于离子液体中p-甲苯磺酸根的测定,加标回收率为99.6%。

A method was developed for the determination of ionic liquid anion of p-toluenesulfonate by ion chromatography with direct （non-suppressed） conductivity detection.Chromatographic separation was performed on a Shim-pack IC-A3 anion exchange column.The influences of mobile phase types and column temperature on retention time of p-toluenesulfonate were investigated.The optimal chromatographic conditions for the determination of p-toluenesulfonate were using 1.2 mmol/L citric acid-15% acetonitrile（pH 5.0） as mobile phase with a column temperature of 45 ℃ and a flow rate of 1.0 mL/min.Under the optimal conditions,a good separation of p-toluenesulfonate with common inorganic anions（e.g.fluoride,chloride,bromide and nitrate） was obtained.The calibration curve for p-toluenesulfonate was linear in the range of 4.0-100.0 mg/L with a detection limit（S/N=3） of 1.22 mg/L.The relative standard deviations（n=5） for retention time and peak area of p-toluenesulfonate were 0.42% and 1.8%,respectively.The method was successfully applied in the determination of p-toluenesulfonate in ionic liquids with spiked recoveries of 99.6%.This method is simple,accurate,reliable and practical,and could meet the requirements for quantitative analysis of p-toluenesulfonate in ionic liquids.