以离子液体为流动相的高效液相色谱-间接紫外检测法分析四甲基铵根离子

Analysis of Tetramethyl Ammonium Ion by High Performance Liquid Chromatography-Indirect Ultraviolet Detection Using Ionic Liquids as Mobile Phase

建立了四甲基铵根离子的反相高效液相色谱-间接紫外检测分析法。以ZORBAX ODS反相色谱柱为分离柱,采用间接紫外检测方法,考察了紫外检测波长和离子液体+有机溶剂(乙腈、甲醇)流动相对分离和测定四甲基铵根离子的影响。最佳色谱条件为:以80%1-乙基-3-甲基咪唑四氟硼酸盐水溶液(0.5mmol/L,乙酸调pH 3.5)+20%乙腈为流动相,检测波长210nm,柱温30℃,进样体积20μL,流速1.0mL/min。在此条件下,四甲基铵根离子的检出限为2.60mg/L(S/N=3),保留时间和峰面积的相对标准偏差(n=5)分别为0.04%和0.31%,其标准曲线在10～204mg/L范围内线性关系良好(r=0.9999)。将本方法应用于分析离子液体溴化四甲基铵中的四甲基铵根离子,其加标回收率为99.3%。

A method was developed for the determination of tetramethyl ammonium ion by reversed phase high performance liquid chromatography with indirect ultraviolet（UV） detection.Chromatographic separation was performed on a ZORBAX ODS reversed phase column using ionic liquids＋organic solvents（acetonitrile or methanol） as mobile phase.Chromatographic detection was carried out by indirect UV detection.The effects of the ultraviolet detection wavelength and mobile phases on the separation and determination of tetramethyl ammonium ion were investigated.The optimized chromatographic conditions for the determination of tetramethyl ammonium ion were as follows： 80% 1-ethyl-3-methyl-imidazolium tetrafluoroborate aqueous solution（0.5 mmol/L,pH 3.5 adjusted with acetic acid） ＋ 20% acetonitrile as mobile phase,detection wavelength 210 nm,column temperature 30 ℃,flow rate 1.0 mL/min.Under these conditions,the detection limit（S/N=3） of tetramethyl ammonium ion was 2.60 mg/L.The relative standard deviations（RSD） of the chromatographic retention time and peak areas for tetramethyl ammonium ion were 0.04% and 0.3%（n=5）,respectively.The calibration curve showed good linearity over the tested range from 10 to 204 mg/L for tetramethyl ammonium ion concentration with the correlation coefficients of 0.9999.The method has been applied to the determination of tetramethyl ammonium ion in ionic liquid tetramethyl ammonium bromide.The recovery of tetramethyl ammonium ion after spiking was 99.3%.