A well-defined block copolymer serving as surfactants in separation of 1,4-dihydropyridines by open-tubular capillary eletrochromatography

A novel series of diblock copolymers, poly(butyl methacrylate)n-block-poly(glycidyl methacrylate)m [P(BMA)n-b-P(GMA)m], were synthesized by atom transfer radical polymerization and developed as covalent coating of capillaries. The excellent performance of this coating in separation of three 1,4-dihydropyridines (DHPs) derivatives (amlodipine, nicardipine, nitrendipine) was achieved when the diblock copolymers self-assembled into micelles, which was confirmed by transmission electron microscopy, dynamic light scattering, and atom force microscopy. Meanwhile, the effects of block ratio n/m, pH value, buffer concentration, and organic solvents on the separation of 1,4-DHPs were investigated in detail. Then, the relationship between the morphologies of copolymers and the separation resolutions of 1,4-DHPs was discussed. Furthermore, the proposed method exhibited good run-to-run and column-to-column precision with relative standard deviations of electroosmotic flow less than 3.0%. It was also validated with linearity of three 1,4-DHPs in the range of 0.011.80 mM (r2 = 99.7%), efficient recovery (94103%), and good repeatability (= 3.8%). In addition, three 1,4-DHPs were successfully separated in the spiked human serum sample, which indicated the potential utility of this method in biological sample analysis.