Preparation And Application Of Polydopamines-based Open Tubular Capillary Column For Capillary Electrochromatography Enantioseparation

Chiral is one of the essential attributes of nature,and the separation of chiral compounds has always been a hotspot and difficulty in the separation field.Recently,the application of polydopamine?PDA?in separation,especially in capillary electrophoresis,has attracted much attention of researchers.It attributed to the special properties of the PDA such as unique physical adhesion,hydrophilicity,stability and good biocompatibility and so on.To study the application of the novel materials similar in structure with PDA in capillary electrochromatography?CEC?enantioseparation,the following major innovative researches were carried out in this thesis on the basis of the previous works:1.A novel,rapid and in-situ modified strategy was developed to fabricate ?-CD/PDA composite material coated open tubular capillary column for OT-CEC for the first time at room temperature.The coated capillary was used to separae seven pairs of chiral analytes.2.A novel,rapid and in-situ modified strategy was developed to fabricate poly-?L-DOPA?coated capillary column by using CuSO₄/H₂O₂ as a trigger for OT-CEC enantioseparation at room temperature.3.A novel open tubular column was prepared by in-situ polymerization of L-DOPA and followed by L-His modification.The performence of the column was validated by the analysis of different model of chiral analytes.This dissertation consists of four chapters.Chapter 1: Recent advances and applications in open-tubular capillary electrochromatography?OT-CEC?for enantioseparations during the last decade were reviewed.Chapter 2: Inspired by the chiral recognition ability of ?-CD and the natural adhesive properties of the PDA under alkaline conditions,a rapid and in-situ modified strategy was developed to fabricate ?-CD/PDA composite material coated capillary column for enantiosepration in OT-CEC.The results of SEM,FT-IR,streaming potentials?SPs?and electroosmotic flow?EOF?indicated that ?-CD/PDA was successfully grafted on the inner wall of the capillary column.The effects of buffer pH and concentration,organic additives and polymerization conditions on enantioseparation were carefully explored.The results illustrated that the ?-CD/PDA coated capillary column obtained under the condition of 5 mg/mL DA,5mg/mL ?-CD and polymerization time of 1 h can realize the baseline separation of seven pairs of chiral analytes,including epinephrine,norepinephrine,isoprenaline,terbutaline,verapamil,tryptophane and carvedilol.Chapter 3: A novel and in-situ modified strategy was developed to rapidly fabricate poly-?L-DOPA?coated open tubular capillary column by using CuSO₄/H₂O₂ as a trigger for CEC enantioseparation of chiral compounds at room temperature.The feasibility of this method was explored in detail and the coated capillary columns were characterized by SEM,FT-IR,SPs and EOF.In addition,the effect of the polymerization time was examined.The performance of the poly-?L-DOPA?coated capillary was validated by the analysis of different model of chiral analytes,including chiral amine drugs,neurotransmitters and amino acid,and the good enantioseparation efficiencies were achieved.Additionally,the poly-?L-DOPA?coated capillary column could be successively used over 250 runs without observable change in the separation efficiency.Chapter 4: Based on the work in Chapter 3,after in-situ grafting poly-?L-DOPA?,the open tubular capillary column was prepared by the following L-Histidine?L-His?modification.The performance of the L-His/poly-?L-DOPA?cocated column was validated by the separation of chiral analytes.The results show that the coated column has an obvious enhancement of the enantioseparation efficiencies for tryptophan and carvedilol,which should be owed to the synergetic chiral separation capacity of L-His and L-DOPA.