一种极性共聚合固定相的制备及其对碱性物质的色谱分离研究

Preparation of a Polar-Copolymerization Stationary Phase for Chromatographic Separation of Alkaline Analytes

疏水性长链烷基键合硅胶是常用的反相色谱固定相,其中的酸性硅羟基易导致碱性化合物严重拖尾甚至发生不可逆吸附,降低分离度与灵敏度。极性共聚合作为一种改良的极性封端方法,可以有效屏蔽酸性硅羟基。为探讨极性共聚合在碱性物质分离分析方面的优势,详细研究了反应条件对硅羟基掩蔽效果的影响。以硅胶为基质制备了一系列由疏水性C18和极性二醇基共同修饰的极性共聚合固定相,并进行表征及色谱评价。结果显示,相比于传统键合方法,极性共聚合法不仅可以有效抑制碱性物质的拖尾,还可提高烷基键合硅胶的硅烷键合率、改善长链烷基硅胶的疏水性塌陷;且对酸性硅羟基的屏蔽效果与硅胶润湿度、二醇基的键合量均呈正相关。

Hydrophobic long chain alkyl-bonded silica is the most commonly used stationary phase in Reversed-Phase Liquid Chromatography.However,the acidic silanol groups are apt to cause serious tailing even irreversible adsorption of alkaline analytes,thus reducing resolution and sensitivity.Polar-copolymerization,as the improvement of polar-endcapping,can shield the acidic silanol groups effectively.In order to explore the advantages of polar-copolymerization in the separation of alkaline analytes,and to study the factors of reaction conditions on the shielding effects of silanol groups in detail,herein,a series of polar-copolymerization stationary phases based on hydrophobic C18 and polar diol co-bonded silica were prepared,characterized and evaluated.The results show that polar-copolymerization can not only effectively inhibit the tailing of the alkaline analytes,but also increase the silane bonding rate of alkyl bonded silica and improve the hydrophobic collapse of long alkyl-bonded silica comparing with the conventional method.Moreover,the shielding effect on silanol groups was positively correlated with the wettability of silica and the amount of diol groups.