一种可控离子比例的两性亲水色谱固定相的制备及性能研究

将不同比例的氨基和巯基的硅烷偶联剂键合到硅胶表面,再利用巯基与乙烯基膦酸之间的点击化学反应将膦酸基团引入到硅胶表面,制备了一种可调节正负离子比例的两性亲水色谱固定相。通过测定固定相中C、H、N、P元素的含量,证明了氨基与膦酸基团已成功键合到固定相的表面,同时通过N元素与P元素的质量分数确定固定相表面氨基与膦酸基团的比例。制备了3种不同电荷比例的氨基膦酸固定相,将其作为亲水模式下的固定相填料填装在150mm×4.6mm不锈钢色谱柱中。以一系列经典的极性小分子作为探针,研究了流动相中乙腈含量、缓冲盐pH值及缓冲盐浓度等因素对探针分子在3种色谱柱上的保留的影响,结果表明,分析物在固定相上是多重保留机理。最后通过比较核苷、水溶性维生素、碱性化合物、苯甲酸这几类标准物质在3种色谱柱上的保留行为来对比3种不同电荷比例的固定相的分离选择性与色谱性能。结果表明,对于不同的分析物,3种固定相表现出完全不同的分离选择性和色谱行为。可以根据分析物的特征选取不同电荷比例的固定相,表明此种固定相在极性化合物的分离上具有良好的应用前景。

Preparation and chromatographic evaluation of zwitterionic stationary phases with controllable ratios of positively and negatively charged groups

The present study focuses on the preparation and application of zwitterionic stationary phases with controllable ratios of positively charged amino groups and negatively charged phosphonic acid groups. Successful grafting was confirmed by elemental analysis and evaluation of pore structure characteristics. Additionally, the proportion of amino and phosphonic acid groups could be easily determined by the mass fractions of N and P. In this study, three types of amino phosphate-based zwitterionic surface-bonded stationary phases (APS) were prepared with different ratios of amino and phosphonic acid groups. The resulting APS silica materials were slurry-packed into stainless-steel columns (150 mm×4.6 mm). Various parameters such as column temperature, water content, pH, and ionic strength of the mobile phase were investigated to evaluate the chromatographic characteristics of the APS columns. A mixed-mode retention mechanism involving surface adsorption, partitioning, and electrostatic interactions was revealed. Finally, a set of test mixtures (nucleosides, water-soluble vitamins, benzoic acids, and basic compounds) were employed to evaluate the separation selectivity and retention characteristics of the three prepared APS stationary phases. The APS phases demonstrated entirely different selectivity and retention behavior for various polar analytes under the same conditions, thus demonstrating excellent application potential for the analysis of polar compounds in hydrophilic interaction chromatography (HILIC).