Analysis Of Sulfonamides In Drugs And Environmental Contaminants By Capillary Micellar Electrokinetic Chromatography Under Reversed Voltage

Capillary micellar electrokinetic chromatography is a separation mode of capillary electrophoresis by adding ionic micelles to a background electrolyte.This method is especially suitable for the separation of neutral substances and charged small molecules,and can achieve high-efficiency separation in a short time with a small amount of reagents.In this thesis,based on capillary micellar electrokinetic chromatography,analysis of three components in Sulfamethoxazole,Sulfadiazine and Trimethoprim Tablets and five sulfonamides in environmental water samples under reverse voltage.Due to the small residual amount of sulfonamides in environmental water samples and the complex sample matrix,the detection sensitivity needs to be improved,the simplest and most effective way is to combine the pre-column or on-column enrichment technology.This type of technology has many outstanding advantages,such as simple and convenient operation,low cost,and no need to modify commercial instruments.Therefore,the thesis prepared magnetic carboxylated multi-walled carbon nanotubes and applied them to the pre-column enrichment technology of magnetic solid phase extraction,and pre-enriched five sulfonamides in environmental water samples.The details of the study and the results are as follows:1.A method for simultaneous analysis of trimethoprim,sulfamethoxazole and sulfadiazine in Sulfamethoxazole,Sulfadiazine and Trimethoprim Tablets by reverse voltage-driven capillary micelle electrokinetic chromatography was established.The analytical conditions were optimized and the analytical performance of the method was investigated.The electrophoresis buffer solution was 60 mmol·L^-1SDS-45mmol·L^-1H₃PO₄-6%CH₃OH.Under the optimized conditions,the R~2were 0.9773,0.9900 and0.9913 for the three substances,the limit of detection were 7.88×10^-6mol·L^-1,9.27×10^-6mol·L^-1and 9.96×10^-6mol·L^-1,respectively,RSD was between 0.8%and 4.7%（n=5）,and the recovery rate of standard addition was between 96.7%and 99.2%.It shows that the method has good applicability,fast and simple,and can be used for the detection of major components in Sulfamethoxazole,Sulfadiazine and Trimethoprim Tablets.2.Preparation of magnetic carboxylated multi-walled carbon nanotubes for pre-column pre-enriched of sulfamethoxazole,sulfamethazine,sulfathiazole,sulfamethoxazole,and sulfadiazine combined with reverse voltage-driven capillary micelles analysis of five sulfonamides residues in environmental water samples by capillary micelle electrokinetic chromatography.The experimental conditions were optimized and the analytical performance of the method was investigated.The electrophoresis buffer solution was 60 mmol·L^-1SDS-35mmol·L^-1H₃PO₄-12%ACN.Under the optimized experimental conditions,the R~2of the five substances were 0.9942,0.9940,0.9850,0.9898 and 0.9947,respectively,and the limit of detection were 4.30×10^-7mol·L^-1,3.87×10^-7mol·L^-1,4.56×10^-7mol·L^-1,3.66×10^-7mol·L^-1and 4.70×10^-7mol·L^-1,RSD was between 0.8%and 4.5%（n=5）,the recovery rate of the standard addition was 96.7%-101.0%,and the enrichment fold was 13-30.The experimental results show that the method has good precision and selectivity,high enrichment ratio,and the magnetic material used is easy to separate from the solution and can be recycled and reused.The method established in this part has certain significance for the detection of low levels of sulfonamide drug residues in environmental water samples.