Ma Qiao, Chen Ming, Yin Hong-Rui, Shi Zhi-Guo, Feng Yu-Qi
Department of Chemistry, Wuhan University, Wuhan 430072, China.
J Chromatogr A. 2008 Nov 28;1212(1-2):61-7. doi: 10.1016/j.chroma.2008.10.007. Epub 2008 Oct 10.
Novel pH-responsive polymer-grafted silica was successfully synthesized through the radical "grafting from" polymerization on azo initiator-immobilized silica. The immobilization of azo initiator onto the silica surface was achieved by the reaction of surface amino groups with 4,4'-azobis(4-cyanovaleric acid chloride). The polymer-grafted silica was prepared by stirring suspension of the azo initiator-immobilized silica in anhydrous dioxane containing acrylic acid (AAc) and butyl acrylate (BA). The resulting polymer-grafted silica was demonstrated to be pH responsive to hydrophobic/hydrophilic property by reversed-phase liquid chromatography (RPLC) and hydrophilic interaction chromatography (HILIC). In RPLC mode, the retention of aromatic compounds decreased with the increase in the pH of mobile phase. However, the opposite result was obtained in HILIC mode; the retention of soybean isoflavones was stronger with the mobile phase at higher pH. Finally, the separations of sulfonamides and soybean isoflavones were carried out in RPLC mode and the separation of some nucleotides was achieved in HILIC mode.
通过在偶氮引发剂固定化的二氧化硅上进行自由基“接枝聚合”，成功合成了新型pH响应性聚合物接枝二氧化硅。通过表面氨基与4,4'-偶氮双（4-氰基戊酰氯）的反应，将偶氮引发剂固定在二氧化硅表面。聚合物接枝二氧化硅是通过将偶氮引发剂固定化的二氧化硅悬浮在含有丙烯酸（AAc）和丙烯酸丁酯（BA）的无水二氧六环中搅拌制备的。通过反相液相色谱（RPLC）和亲水相互作用色谱（HILIC）证明，所得聚合物接枝二氧化硅对疏水/亲水性质具有pH响应性。在RPLC模式下，芳香族化合物的保留率随流动相pH值的增加而降低。然而，在HILIC模式下得到了相反的结果；在较高pH值的流动相中，大豆异黄酮的保留更强。最后，在RPLC模式下进行了磺胺类药物和大豆异黄酮的分离，并在HILIC模式下实现了一些核苷酸的分离。
