Synthesis of a novel restricted access chiral stationary phase based on atom transfer radical polymerization and click chemistry for the analysis of chiral drugs in biological matrices

A novel chiral restricted access material was synthesized via a combination of atom transfer radical polymerization (ATRP) and click chemistry. Poly(2-methyl-3-butyn-2-ol methacrylate) (pMBMA) was grafted onto porous silica gel by a surface-initiated ATRP in order to synthesize an inner layer for β-cyclodextrin (β-CD) immobilization. The azide-modified β-CD was bound to pMBMA by click chemistry. The results demonstrate that click chemistry provides an effective route for the immobilization of β-CD for chiral discrimination. A second ATRP reaction was then used to graft external poly(glycidyl methacrylate) (pGMA) layer onto the silica gel. The external hydrophilic layer was subsequently created by hydrolysis of the epoxy groups of the pGMA. This bi-layer grafted material exhibited both enantioseparation and protein exclusion. It can be used for the efficient separation of chiral compounds in biological samples with direct injection into an HPLC system.