Research And Application Of On-Line Double Focusing Method Of Capillary Electrophoresis

Currently,the harm for social caused by drug residues and drug abuse is more and more obvious,so the detection of trace drug residue composition has also received significant attention.In the process of drug detection,the traditional detection method have some problems including low concentration of the tested substance,complicated matrix and large amount of interferons and so on.Therefore,in order to quantify the quantitative analysis of ultra-trace components,it is urgent to establish a method with efficient,simple,fast and sensitive.Capillary electrophoresis is one of the most active methods in the separation of disciplines which has the characteristics of simple operation,high efficiency,high speed,simple sample pretreatment and small sample requirement.The inner diameter of capillary is small and the detection window optical path is short which resulted in small sensitivity,this become the maximum limit for the detection of trace material in complex matrix.We can improve the sensitivity by modifying the instrument,such as the replacement of different detectors,but the price is expensive and the potential for further development is small.So,the current solution to the problem of sensitivity mainly depend on the online enrichment technology.Online enrichment enhances the sensitivity of sample by compressed the sample zone to increase the sample concentration within the capillary through changing the conditions of the system.For each online enrichment technology has a certain scope of application and prerequisites,in order to obtain the lower limit of detection,in consideration of the physical and chemical properties of the analyte and the complexity of the matrix,workers usually combined several online enrichment technology.Therefore,the development of on-line enrichment technology of capillary electrophoresis has become the emphasis for researchers.Based on our previous work,the application of capillary on-line enrichment technology in drug residues has been studied in this paper.The mainly innovative work is as follows:1.The separation and enrichment system of sulfamethoxazole and trimethoprim was established by combining micelle to solvent stacking with field amplified sample stacking.Trimethoprim and sulfamethoxazole are hydrophobic that they can form micelles with sodium dodecyl sulfonate which is added to the sample matrix.An organic solvent is introduced after the introduction of the sample solution,the micelles are easily depolymerized for inducing by the organic solvent.The system have completed the micelle to solvent stacking.Taking advantage of the charge of sulfamethoxazole and trimethoprim in acid solution to complete the field amplified sample stacking in the border between organic solvent solution with low conductivity and buffer solution with high conductivity.The new method for the detection of trimethoprim and sulfamethoxazole in biological samples was established,and apply it to six kinds of animal origined food(milk,milk powder,goat milk,honey and eggs).2.The on-line double focusing system with the aid of P-cyclodextrin was established in the capillary electrophoresis,the two-step enrichment which field amplified sample stacking as first step and micelle to solvent stacking as second step was realized,the feasibility of the method have been verified by the molecule of atenolol and metoprolol.Adding a small amount of β-CD into the sample matrix to reduce the surface tension of micelles namely reduce its critical micelle concentration,which is beneficial for the disaggregation of micelles.This method is simple,rapid,feasibility and has been applied to the residual detection of atenolol and metoprolol of human urine.