高效液相色谱槲皮素键合硅胶固定相分离极性化合物

摘要

槲皮素是一种植物体中含量丰富、价格较便宜的黄酮类化合物,本研究以γ-[(2,3)-环氧丙氧]丙基三甲氧基硅烷(KH-560)为偶联剂,将其化学键合到硅胶上,得到一种含天然配体的槲皮素键合硅胶固定相(QUSP).采用红外光谱、热重分析、元素分析及固体核磁对其结构进行表征,测得硅胶表面槲皮素的键合量为0.139 mmol/g.采用不同结构的溶质作探针,在评价固定相反相液相色谱疏水作用性能的基础上,侧重研究新固定相对极性芳香族化合物的分离能力,探讨了新固定相的色谱分离机理.研究表明,仅采用甲醇或乙腈-水简单流动相,无需用缓冲液精确控制pH值,QUSP就能分别实现吡啶类、芳胺类、苯酚类、苯甲酸类和黄酮类等极性化合物的快速基线分离.QUSP键合的槲皮素除含疏水性的C6-C3-C6骨架外,黄酮环还能为溶质提供氢键、偶极、π-π、电荷转移等多种作用位点,各种协同作用有利于提高色谱分离选择性,尤其对极性的可离子化的酸性和碱性化合物.%Quercetin is one of the abundant and cheap flavonoids in herbs.In this paper,quercetin was first chemically bonded to silica gel.A natural ligand quercetin-bonded silica gel stationary phase (QUSP) was obtained by using γ-[(2,3 )-glycidyloxypropyl trimethoxysilane ( KH-560 ) as a coupling agent.Its chemical structure was characterized by infrared spectrometry,thermogravimetric analysis,elemental analysis and C solid-state nuclear magnetic resonance ( NMR).The amount of bonded quercetin was determined to be about 1.39 mmol/g.The reversed-phase property of QUSP based on hydrophobic interaction was first evaluated on high-performance liquid chromatography.The separation abilities of new stationary phase for different polar aromatic compounds were systematically studied by using basic and acidic solutes with different structures as probes.Some retention mechanism in the above separations was also discussed.The results showed that the novel quercetin-boned stationary phase exhibited high separation selectivity for polar compounds,including pyridines,aromatic amines,phenols,benzoic acids,and flavonoids.The baseline separations of the above species were easily achieved by using only simple methanol or acetonitrile water as the mobile phases without fine adjustment of pH in isocratic mode.This is because besides the hydrophobic C6-C3-C6 skeleton,the quercetin ligand QUSP can also provide various active sites for polar solutes,such as hydrogen bonding,dipole-dipole,π-π and charge transfer interactions,in which the synergic interactions could improve separation selectivity,especially for the ionized acidic and basic compounds.