Capillary Electrochromatography Based On Polymer Coating For Separation Of Antibiotics And Alkaloids

Alkaloids and antibiotics drugs indeed have therapeutically effects on human beings,but when there is a low or high amount in human bodies,it will induce side effects.Thus,the analysis of these two drugs in body fluids has a great significance.These two kinds of drugs,have their own similar structures,or are neutral,which have difficulty in capillary zone electrophoresis analysis.Micellar electrokinetic capillary chromatography(MEKC),which adds with surfactants in running buffer,is widely used by researchers for the analysis of alkaloids and antibiotics for it makes up the deficiency of capillary zone electrophoresis.However,the addition of substantial surfactants in running buffer may interfere the stability of the separation system.Also,when CE combined with mass spectrum(MS),the surfactants in running buffer will induce the contamination of the ion source and the suppression of the analyses signal,which greatly limit the application of CE-MS method in the analysis of unknown drugs.In order to solve these problems and improve the separation selectivity,ionic liquids were used as the running buffer additives and polymers were used to modify the inner surface of the capillaries to construct new open-tubular capillary electochromatography(OT-CEC)systems,which are used to avoid the surfactants in running buffer.Major work was laying on the following three parts:(1)Based on the principle of the electromoostic flow could be controlled by ionic liquids,ionic liquids was used as the running buffer additives in the separation and analysis of ?-lactam antibiotics.The results display that the resolution of three analytes was improved for the ionic liquids in running buffer decreased the electroosmotic flow.Moreover,the influence of substituent groups and anions of ionic liquids on separation efficiency was discussed briefly.(2)Based on the principle of the electromoostic flow could be decreased by homopolymer poly styrene coating,a new OT-CEC system with polystyrene coating was constructed for the separation and analysis of methylxanthine alkaloids.The homopolymer was synthesized through the reversible addition fragmentation chain transfer reaction,and the new OT-CEC system was constructed by immobilizing the polymer on the capillary through physical absorption.The results exhibit that homopolymer based coating capillary decreased the electroosmotic flow which induced a good separation of methylxanthine alkaloids.What's more,the stability of the coating capillary prepared by physical absorption was investigated.(3)Based on the hydrogen bond / hydrophobic interaction of the new multi-functional block co-polymer poly(maleic anhydride-styrene-N-isopropylacrylamide)coating and the analytes,the multi-functional block co-polymer based coating was used to construct a new OT-CEC system for the separation and analysis of ?-lactam antibiotics.This new block co-polymer was also synthesized through the reversible addition fragmentation chain transfer reaction,and was coated on the capillary inner wall through covalently bonding.The new OT-CEC system with good stability and repeatability validation was successfully used in the analysis of ?-lactam antibiotics in human serum.The separation mechanism based on hydrogen bond and hydrophobic interaction between tri-block polymer coating and analytes was preliminary discussed.What's more,the thermo-responsive property of the block co-polymer on separation efficiency was investigated in detail.This paper focus on the low efficiency of capillary zone electrophoresis and the limitation of CE-MS due to the surfactants in MEKC,based on the development of new materials,a new CE system with ionic liquids as additives was constructed and two kinds of polymers based coating based OT-CEC system were developed to improve the separation efficiency of methylxanthine alkaloids and ?-lactam antibiotics,which could avoid the surfactants in running buffer.The results display that the new CE system with ionic liquids as additives improved the separation efficiency of antibiotics and the polymer based OT-CEC systems realized the baseline separations of antibiotics and alkaloids,which had a great potential for the separation and analysis of unknown drugs in CE-MS.