高效液相色谱苯胺甲基键合硅胶固定相的保留机理研究

Studies on the Retention Mechanism of N-Methylaniline Bonded Silica for High Performance Liquid Chromatography

制备了 3种不同键合量的苯胺甲基键合硅胶固定相 ,分别在正、反相色谱条件下研究了它们对芳烃及其极性、酸性、碱性取代衍生物的保留和分离选择性 ,探讨了该固定相的色谱保留机理 ,并考察温度对溶质在具有不同键合量的固定相上保留的影响。结果表明 :苯胺甲基键合硅胶固定相对溶质的保留是疏水、π π、偶极 偶极和电荷转移等多种作用的结果 ,在反相色谱模式中 ,疏水作用对溶质的保留起主要作用。

Three N methylaniline bonded stationary phases containing different bonding amounts were prepared by modifying silica gel with N methylanilinetriethoxysilane Influences of the bonding amounts on the retentions and selectivity of polycyclic aromatic hydrocarbons(PAHs), polar , acid and basic substituted aromatic compounds were investigated in reversed and normal phase high performance liquid chromatography. In the reversed phase liquid chromatography, the plots of log k′ against the carbon atom numbers for alkylbenzenes are linear, and the retentions and relative retentions of the solutes(including alkylbenzenes, PAHs and nitrobenzenes) increased with the increase of the bonding amounts and water volume fractions in mobile phase. The results indicated that the hydrophobic interaction played a major role in the retention process. In the normal phase liquid chromatography, the retentions of PAHs increased and the retentions of nitrobenzenes decreased with the increase of bonding amounts. With the increase of bonding amounts, the retentions of acidic compounds increased and the retentions of basic solutes decreased considerably. It is indicated that the number of imino groups increased and the activity of residual silanols diminished with the increase of bonding amounts. The retentions of solutes on the stationary phases result from acid basic, dipole dipole, π π and charge transfer interactions in the normal phase chromatography.