Preparation of Silica‐Based Chitosan Chiral Stationary Phases by Two Synthetic Approaches and Evaluation of Their Enantioseparation Performance by HPLC

Chitosan derivatives play an important role in chiral separation due to their excellent chiral recognition properties. However, the preparation of chitosan derivatives with good chiral separation performance and resistance to organic solvents still needs to be explored. Here, we prepared the chitosan (4-chlorophenylaminoformate) derivatives as the corresponding chiral stationary phases CSP-1 and CSP-2 through coating and bonding methods and compared them with CSP-3 prepared by changing the position of the chlorine substitution on the phenyl group. This revealed the interaction between the chitosan-type chiral selectors (CSs) and the chiral analytes during the chiral separation process. The enantioseparation capability of the CSPs was evaluated using high-performance liquid chromatography (HPLC). The CSPs demonstrated good enantioseparation performance for most of the tested chiral analytes, and the enantioselective separation of flucloxacillin was comparable with that of commercial Chiralcel OD-H and Chiralpak AD-H. We gained a deeper understanding of the chiral recognition mechanism by modifying the mobile phase composition and the position of chlorine substituents in the phenyl group. Furthermore, the CSP-2 overcomes the dissolution and high expansion problems of traditional coating-type CSP in unconventional eluents, and the separation performance achieved for some of the tested chiral compounds is even superior to that of CSP-1.