Font Size: a A A

Studies On Calixarene-Bonded Silica Gel Stationary Phases For High Performance Liquid Chromatography And Capillary Electrochromatography

Posted on:2005-06-16Degree:DoctorType:Dissertation
Country:ChinaCandidate:L S LiFull Text:PDF
GTID:1101360125955847Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
A great deal of studies has shown that calixarenes, the macrocyclic host molecules, possess special capacity of the molecular recognition for various species based on supramolecular interactions. Recently, their applications in the field of chromatography, including in gas chromatography (GC), high performance liquid chromatography (HPLC), capillary electrophoresis (CE), capillary electrochromatography (CEC) and so on, have attracted much attention. How to promote separation selectivity via the molecular recognition of calixarene ligands is an attracting subject in the overlapping area of modem chromatography with supramolecular chemistry, showing great promising prospect for the researches of separation theory and application. In this dissertation, the preparation, characterization, evaluation and retention mechanism of calixarene-bonded stationary phases for HPLC were studied systematically. Meanwhile, the new preparation method was also developed and used for the preparation of calixarene-bonded stationary phase for CEC. The preliminary evaluation of the stationary phase for CEC was carried out. The main contents studied are as follows:1.The progress of the study of calixarenes in HPLC, CE and CEC were reviewed in detail. The main subject focused en the preparation, chromatographic property, retention mechanism and application of calixarene-bonded stationary phases for HPLC. The application prospect of the calixarene-bonded for HPLC and related techniques in the future is discussed. Above all provide the basis and start point for further research of the subject.2. A new method for the preparation of calixarene-bonded stationary phases was developed, in which the calixarene-bonded were prepared via the breaking .epoxy group on solid surface of the bonded 3-glycidoxypropyl silica by using active phenolic sodium of calix[8]arene in the presence of phase-transfer catalyst. The method is moderate, universal,and to obtain the high bonded amounts.3. Several derivatives of calixarenes were synthesized. The new calixarene and derivative calixarene-bonded phases were prepared by using the new method established. Their structures were characterized by infared fourier transform spectroscopy, elemental analysis, thermal analysis and specific surface analysis.4. The HPLC properties of the new stationary phases were evaluated by using acidic, basicand neutral solutes as probes. The results indicate that the calixarene-bonded stationary phases exhibit excellent reversed-phase chromatographic properties, and the high selectivities for aromatic compounds and their positional isomers. This is because the calixarene ligands can provide various sites for analytes, such as hydrogen-bonding, hydrophobic, inclusion complex, n-n and electron transfer interactions and recognize them.5. In order to further study the retention mechanism, the influence of structures of ligands on chromatographic performance were investigated via del-butylation, fixing conformation and varying ring size. Some conclusions can be made as follows: The butyl groups at upper rim of calixarenes can enhance the hydrophobicity by extending the cavities and interaction with the substituents of aromatics; In order to fix the conformation, the introduction of ether-bridge can lead to lower hydrophobicity and different selectivities for some polar solutes as compared with the parent calixarene-bonded phase. The synergetic effect between the hydrophobic cavity and the crown ring of the calixcrown ligand can also be observed; In generally, the calix[8]arene-bonded exhibits superior chromatographic performance to calix[6]arene and calix[4]arene-bonded phases, which might be due to that large cavity of calix[8]arene has an advantage over calix[6]arene and calix[4]arene in the inclusion complex, hydrophobic interaction and n-n interaction.6. The new calixarene-bonded stationary phases were used for the separation of solute series, such as, nucleosides and bases, aromatic carboxylic acids and water-soluble vitamins. The various influence factors...
Keywords/Search Tags:high performance liquid chromatography, capillary electrochromatography, calixarene-bonded silica gel stationary phase, retention mechanism, chromatographic evaluation, chromatographic application
PDF Full Text Request
Related items