用核磁共振波谱法研究反相液相色谱流动相强度

Study on the strength of mobile phase in reversed phase liquid chromatography by NMR

用NMR考察了甲醇、乙腈、四氢呋喃、丙酮、1,4-二氧六环与水混合溶液的化学位移,提出了计算反相液相色谱流动相强度的计算公式:f= V×niδi .式中f 为流动相强度,为流动相中有机改性剂的体积百分数,V为有机改性剂的摩尔分子体积,ni 为有机改性剂中与碳原子相连的等价质子数,δi 为有机改性剂中与碳原子相连的氢原子的化学位移.由上式得到的流动相强度值,用于不同体系之间流动相的等强度交换,获得满意结果.对279 组数据的考察结果表明,f 对logk的线形回归相关系数的平均值优于对logk的回归结果.

The strength of binary methanol/water,acetonitrile/water,tetrahydrofuran/water,acetone/water and 1,4 dioxan/water mobile phases chiefly used in reversed phase liquid chromatography is measured by NMR based on the following equation: f=V×n iδ i .where f is the strength of the mobile phase,  is the volume fraction of the organic modifer in the moble phase; n i and δ i are the number and chemical shift value of the hydrogen atoms attached to the carbon atom in the organic modifier molecule,respectively; V is the molar volume of the organic modifiers.The relationships between the mobile phase strength and the composition can be described as follows:MeOH/H 2O,log f =0.31+0.92log  ( r=0.999 2,S= 0.012 3) ;MeCN/H 2O,log f =0.39+0.89log  (r=0.999 1,S=0.017 0) ;THF/H 2O,log f =0.47+0.96log  (r=0.999 5,S=0.012 3); Aectone/H 2O,log f =0.51+ 0.85 log  ( r=0.997 6,S=0.020 1) ;Dioxan/H 2O,log f =0.41+0.97log  (r= 0.999 9, S=0.003 5) .Plots of log k vs.mobile phase strength value f are generally found to be better descripters of the retention than commonly used plots of log k vs.volume fraction of the organic modifier in the mobile phase.