Preparation Of 2D Nanofilm Coated Capillary And Its Application In OT-CEC Enantioseparation

Nano-thin film refers to a thin film of nano-sized,which maybe single layer or multi-layer film of nanometers.Nano-thin film is divided into two types according to application: nano-functional film and nano-structured film.Because of its unique physical and chemical properties,such as large specific surface area,adjustable thickness,easy surface modification and high stability,film material has been widely concerned in separation science in recent years.Capillary electrochromatography(CEC)is a kind of chromatographic technique that combines the advantages of high efficiency of capillary electrophoresis(CE)and high resolution of high performance liquid chromatography(HPLC),which has been widely used in the separation of various analytes.The structure of nano-thin film suggestted that the possibility of improving the ability of CEC as stationary phase.Therefore,major researches of this academic dissertation were carried out on the preparation of nano-thin film coated capillary and its application in CEC enantioseparation on the basis of previous works.1.A two-dimensional lysozyme membrane coated capillary was prepared by super-molecular self-assembly under mild conditions,and the separation capacity of the coated column was evaluated by OT-CEC enantioseparation of two monoamine neurotransmitters and its analogues.2.The influence of preparation conditions on the chiral resolution of the supermolecular membrane coated column was investigated in details.The preparation conditions of the coated capillary were optimized by comparison of separation efficiency,reproducibility and stability.3.After modification of ZIF-90 by D-His,the prepared D-His-ZIF-90 coated capillary column was applied to OT-CEC enantioseparation of monoamine neurotransmitter,amine drug and amino acid.This dissertation consists of four chapters.Chapter 1: In this chapter,an overview of chiral compound and chiral separation was stated firstly.Secondly,a brief introduction about the basic concept of capillary electrochromatography(CEC),the development and the type of the column technology was given.Finally,the research progress and application of the biomimetic thin-film material were illustrated.Chapter 2: A rapid,simple and robust capillary column preparation process using a lysozyme phase transformation system under mild reaction condition was introduced.Separation of two monoamines neurotransmitters and its analogues was carried out by lysozyme supermolecule membrane coated capillary using OT-CEC.Under the optimum condition,resolution of the three pairs of enantiomers was from 1.27 to 1.84.The relative standard deviation(RSDs)of migration time for intra-day,inter-day and column-to-column were in the range of 0.7-1.5%,2.7-3.6% and 4.5-5.8%,respectively.The coating method proposed in this work overcame the disadvantages of heavy use of lysozyme as chiral additive in buffer and short lifetime of the existing coated capillary,meanwhile kept the enantioseparation capacity to a certain extent.In addition,the coated capillary column could be used over 100 runs without observable change in the separation efficiency and migration time,which demonstrated the good stability.Chapter 3: In this chapter,the preparation conditions of the starch-like protein molecular membrane coated capillary by non-reversible phase transition reaction were optimized.The experimental results show that the coating times,pH and concentration of the reactants did have a certain effect on the coating morphology and its enantioseparation capicity.The main cause for the difference was the effect of the exposure rate of the functional groups of lysozyme on the functional group number and the surface roughness of the film during the reaction between lysozyme and TCEP.The optimum preparation condition was that TCEP solution pH=5.0,the concentration of the lysozyme is 2 mg/ mL,and the number of coating layer is 1.The coated column prepared under this condition showed the high separation efficiency,good repeatibility and long-term stability.Chapter 4: D-His was used to carry out the chiral modification to ZIF-90,and the D-His-ZIF-90 coated capillary column was prepared.The coating column was used as a CEC separation channel to separate two monoamines neurotransmitters,a structural analogue and an amino acid.The resolution of the analyte under the optimum separation conditions was 0.93-1.11.The relative standard deviation(RSDs)of migration time for intra-day,inter-day and column-to-column were in the range of 0.2-0.6%,0.7-2.4% and 1.9-3.2%,respectively.