Preparation Of Carboxylated β-Cyclodextrin Chiral Stationary Phases And Its Application In Capillary Electrochromatography-Mass Spectrometry

At present,nearly 62%of drugs used in clinical treatment are chiral drugs.The toxic and side effects of enantiomers of chiral drugs have a potential threat to human health.Therefore,it is of great significance to design and prepare novel chiral stationary phase to apply separation and analysis of chiral drugs.Carboxylatedβ-cyclodextrin can form hydrogen bonds,electrostatics,and inclusions with chiral drugs and are widely used in chiral stationary phases.In this paper,the monolithic columns of 6-（N-ethylaminomaleic acid）-amino-β-CD（UPA-β-CD）were prepared with UPA-β-CD and poly glycidyl methacrylate（GMA）as functional monomers and ethylene glycol dimethacrylate（EDMA）as crosslinking agent by in-situ polymerization.The preparation conditions of the monolithic columns were investigated,and the optimal preparation conditions were obtained:the solution dosage of UPA-β-CD in dimethyl sulfoxide（DMSO）was 0.0025 g,the reaction temperature was 45℃,and the reaction time was 11 h.Infrared（IR）,scanning electron microscopy（SEM）and thermogravimetry（TG）were used to characterize the stationary phase and the monolithic column.The prepared monolithic columns had a complex network structure and good thermal stability.At the same time,the column efficiency,reproducibility and chiral separation capacity of the monolithic columns were studied.The results showed that the average column efficiency of five monolithic columns was 66397/m,and the relative standard deviation（RSD）was 3.74%.RSD of the column efficiency of one column was 1.43%（n=5）,and D/L-lysine and D/L-serine all reached baseline separation.The prepared monolithic column was applied to the separation analysis of chiral drugs.Under the optimal CEC separation conditions,the enantiomer of bromopheniramine achieved baseline separation with a resolution of 1.73.Under the optimal CEC separation conditions and MS detection conditions of pH 5,the separation voltage 18 kV,the separation temperature 20℃,and the rate of sheath flow liquid(V_methanol:V_water=1:1)0.5 mL/min,the two enantiomers of chlophenamin and oxybutynin hydrochloride all reached baseline separation with resolutions of 1.84 and 2.21,respectively.The two enantiomers of chlophenamin and oxybutynin hydrochloride were quanlitatively confirmed by MS and their ionization pathways were analyzed.It can be seen that the carboxylated UPA-β-CD has better chiral resolution performance and can be applied in the field of chiral separation.