Development And Application Of Capillary Electrochromatography Techniques For Separation And Detection Of Some Alkaline Compounds

Separation of alkaline compounds is difficult for reversed-phase chromatography.This is due to the irreversible adsorption between alkaline compounds and the silanol groups on the stationary phase,resulting in the prolong of migration time of analytes and the peak tailing,as well as the poor reproducibility.Biogenic amines is a kind of nitrogen-containing alkaline compounds,which widely exists in meat products and other fermented food at lower levels.When human intake accumulate to certain amount,a synergy will be generated to enhance toxicity,damage nerve systemand cardiovascular system,and even life threatening.So it is necessary to develop an analytical method to detect trace residues of biogenic amines.Capillary electrochromatography(CEC)has the characteristics of the high column efficiency,high selectivity,the ease use of the stationary phase with multiinteraction modes,and the ease combination with highly sensitive detection techniques.In this paper,novel capillary electrochromatography techniques suited for high efficient separation and detection of some basic compounds such as biogenic amines have been developed.To improve the separation and detection ability to alkaline compounds,a new type of ionic liquids functionalized polymer monolithic column with multiple interaction was prepared,and a hyphenated technique of CEC and laser induced fluorescence detection was applied for the residue analysis in food samples.Main points of this thesis are listed as following:1.An overview of the principle of capillary electrochromatography(CEC)and its related techniques was present in Chapter 1.The principle of laser induced fluorescence detection(LIF)technique,the types of capillary chromatographic column were introduced in detail.The application of click reactions and ionic liquids in the functionalization of polymer monolithic column was described.Finally,the topic and research content of this thesis were proposed.2.A high sensitive analytical method of biogenic amines in food was established by using the hyphenated technique of CEC and LIF(CEC-LIF).With 7-fluoro-4-nitrobenz-2-oxa-1,3-diazole(NBD-F)as efficient fluorescence reagent,a method for rapid derivatization of biogenic amine was proposed.Under the optimized separation conditions,five biogenic amines was separated within 15 min,with a wide linear range of 4 orders of magnitude,and the detection limits(S/N = 3)of 0.1-1.0 ng/mL were obtained.The proposed method is simple,cost effective,environmentally friendly.It has been used in the determination of biogenic amines in processed and fermented foods,and the results are in agreement with the HPLC method.It shows some advantages on the detection limit,selectivity and analysis speed.3.Based on a one-step thiol-ene click chemistry with radical polymerization technique,a novel poly(C18-co-EDMA-co-IL)monolithic column was synthesized with 1-octadecanethiol and 1-propylene-3-methylimidazolium tetrafluoroborate(IL)as the organic monomers,ethylene glycol dimethyl acrylate(EDMA)as crosslinker,and the ternary porogens and azodiisobutyronitrile as initiator.The composition of monomers,the proportion of porogen and crosslinker and the copolymerization conditions such as reaction temperature,were optimized.And the morphology,pore diameter and stability of the column,swelling and mechanical properties were characterized.The monolithic column exhibits a reversed-phase chromatographic characteristic,and multiple interaction modes and an adjustable electroosmotic flow.It can fulfill the requirement of fast separation of alkaline compounds and neutral compounds,intra-and inter-days RSD are less than 1.6%and 1.6%,respectively,and the column efficiency for alkyl benzene is higher than 87000 N/m.