Conventional silica gel columns have advantages of high separation performance and well-known surface modification. Among them, the octadecyl silica (ODS) column is the most versatile column for reversed-phase high performance liquid chromatography (HPLC). However, its application is limited by the poor hydrolytic stability against alkaline mobile phases and the low separation performance for alkaline compounds. There is a demand for high performance separation of alkaline compounds, which are abundantly used as pharmaceuticals. Therefore, a new packing material with high stability against alkaline mobile phases is required. To develop a new alkaline stable packing material, this research focused on CaCO3 mesoporous microspheres. With the characteristics of alkaline stability, monodisperse spherical particles and 20 nm mesopores, they are suitable as a new packing material. For use in reversed-phase columns, the CaCO3 surface was modified with an alternating amphiphilic copolymer, poly(maleic acid-alt-1-octadecene) (PMAcO) consisting of regularly alternating hydrophobic alkyl chains and 2 carboxylate units, by utilizing the electrostatic adsorption to Ca sites on the particle surface. The electrostatic adsorption provides a thin and uniform coating, maintaining the porosity of the particles. In addition, this surface modification is highly durable, due to many adsorption sites of the polymer. The column packed with PMAcO-modified CaCO3 particles was evaluated. Mixed samples of 11 kinds of alkylbenzenes (C0-10) were completely separated by gradient elution and their elution order showed reversed-phase behavior. The column indicated high stability against alkaline mobile phases. In addition, we succeeded in separating two alkaline drugs spiked into pig whole blood with high recovery using an alkaline mobile phase. These results indicate a high potential for practical applicability.

Mesoporous CaCO3 -based alkaline stable reversed-phase HPLC packing material

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.