大黄素键合硅胶高效液相色谱柱的制备和应用

采用中间体法,先将大黄素配体与γ-(2,3)-环氧丙氧]丙基三甲氧基硅烷(KH-560)偶联剂反应制备含配体的硅氧烷试剂,然后再与硅胶键合,最终制得大黄素键合硅胶液相色谱固定相(以下简称ESP)。通过红外光谱、元素分析和热重分析表征固定相的结构。以萘作为溶质探针,甲醇-水(60∶40,v/v)为流动相,流速为0.8 mL/min,测得ESP柱的柱效。采用传统的反相C18和苯基柱作参比,将ESP应用于系列中性、碱性和酸性芳香族化合物以及实际样品风油精的分离分析,并探讨相关的色谱分离机理。结果表明,配体大黄素被成功地键合到球形硅胶表面,测得配体键合量为0.23 mmol/g,ESP柱理论塔板数约为19874 N/m。ESP的偶联剂链和蒽醌环提供了疏水性的结构基础,大黄素配体还能为溶质提供π-π或p-π、电荷转移、氢键、偶极-偶极等作用点。多位点的协同作用使得ESP柱具有独特和优秀的色谱分离选择性,并且无需调节pH值,采用简单而廉价的甲醇-水流动相就能实现胺类、酚类等极性样品的基线分离,实验条件简单、方便。

Preparation and application of an emodin-bonded silica gel chromatographic column for high performance liquid chromatography

An emodin-bonded silica gel stationary phase (ESP) for high performance liquid chromatography has been synthesized by the intermediate method. The preparation process was as follows:γ-glycidoxypropyltrimethoxy silane (KH-560) firstly reacted with emodin ligand; then the intermediate was chemically immobilized to the surface of silica gel. Characterization of ESP was carried out with Fourier transform infrared spectroscopy (FTIR), elemental analysis and thermogravimetric analysis. Naphthalene was used as a probe to determine the column efficiency with methanol-water (60:40, v/v) as binary mobile phase at a flow rate of 0.8 mL/min. In order to elucidate the related separation mechanism, ESP was used to separate a series of neutral, basic and acidic aromatic compounds, as well as a sample of wind medicated oil. The conventional C₁₈ column and phenyl column were also tested under the same chromatographic conditions for comparison. The results showed that the emodin ligand was successfully bonded to the surface of spherical silica gel with a 0.23 mmol/g of bonded amount, and the theoretical plate number of ESP column was about 19874 N/m. The coupling reagent chains and anthraquinone rings in ESP offered a structural basis for hydrophobic interaction. Meanwhile, the emodin ligands provided π-π or p-π, charge transfer, hydrogen bonding, dipole-dipole action sites for different analytes. The synergistic reaction of various action sites endowed ESP column special and excellent chromatographic separation selectivity. And a baseline separation of polar compounds such as amines and phenols on ESP was easily achieved by using common and cheap methanol-water mobile phases without buffer salts. The experimental conditions were simple and convenient.