Applications Of Novel Materials In Capillary Electrophoresis

Capillary electrophoresis (CE) is a powerful analytical separation technique and has played a critical role in Human Genome Project. However, there still have been some limits in its applications. New materials are developing very rapidly in recent decades, their applications in CE can solve some problems, such as protein wall adsorption, EOF control, etc. They also bring new analytical methods in CE.The main work of this thesis is summarized as follows:1. Co-electroosmotic separation principle is usually used in CE to separate inorganic anions. Cationic coatings have been shown to be effective for CE of inorganic anions under the co-EOF mode. However, the strongly reversed EOF rapidly sweeps the analytes towards the detector and the detection window shrinks so that the resolution of the analytes is limited. We proposed a new coating that can not only reverse EOF but also modulate the magnitude of EOF. Gemini surfactants are a new series of surfactants that provide excellent properties, we demonstrate a novel semipermanent coating consisted of a Gemini surfactant18-10-18and a nonionic surfactant Tween20to separate inorganic anions. The hydrophobic chain of Tween20can interact hydrophobically with the bilayer formed by Gemini on the capillary wall, resulting in a reduced reversed EOF and improving the coating stability. Compared with previously reported Gemini coatings, highly efficient separation of inorganic anions is achieved (N=65040-169700) without any organic solvent additives, the detection limits reach20μM.2. Polyelectrolytes are polymeric compounds whose repeating units bear a functional group, capable of dissociation in aqueous solutions. They can easily form thin or thick films, often described as polyelectrolyte multilayers (PEMs) that are typically composed of alternating layers of oppositely charged polyelectrolyte chains held by electrostatic interaction. There is a high degree of interpenetration of the consecutively deposited polyelectrolyte layers. Such a coating can not only reverse the EOF, but also easily interact with ions from aqueous solution inside the capillary column and can thus be used as a stationary phase for their separation. Six inorganic anions were separated under capillary electrochromatography (CEC) mode. Compared with previously reported PDDA coating, this coating can effectively improve the resolution and efficiencies and is much more stable. 3. We also applied another new type of material-amino acid ionic liquid (AAILs) in CE. We presented for the first time the application of AAILs1-alkyl-3-methylimidazolium L-proline as chiral ligand coordinated with copper(Ⅱ) in chiral separation based on chiral ligand-exchange principle. We found that AAILs are good alternatives to conventional amino acid ligands. It is inferred that the alkylmethylimidazolium cations and L-Pro form ion-pairs on the capillary inner surface. The ternary copper complexes with L-Pro are consequently attached to the capillary surface, inducing an ion-exchange type of retention for the DL-enantiomers. This work reveals the tremendous application potential of this new type of task-specific ILs in CE.