Synthesis Of Novel Schiff-base Covalent Organic Polymers And Their Applications In The Pretreatment Of Samples With Complex Matrix

With the rapid development of life sciences,the detection of micro and trace substances in complex samples is increasing,such as biomarkers in animal tissues,cancer biomarkers in blood samples,and phytohormones in plant tissues.Sample preparation plays a vital role in the detection of these substances.Among many sample preparations,solid phase extraction?SPE?has attracted much attention due to its low solvent consumption,good purification,enrichment effects,simple and quickness.The adsorbent is the core of SPE device.Covalent organic polymers?COPs?are a kind of porous polymer materials emerging in recent years.They have many advantages such as light weight,large specific surface area,high porosity,adjustable pore size,and good hydrothermal stability.Schiff-base COPs,which are synthesized based on Schiff-base reactions,have easily available monomers and mild ly preparation conditions.They have great potential for the application in sample pretreatments,and are favored by researchers.The full thesis is consist of four chapters:Chapter one,this part summerized the concept and classification of sample preparation methods,and focuses on the preparation and application of covalent organic polymer materials.Chapter two,based on the Schiff-base reaction principle,TpDMB-COP was synthesized under the refluxing conditions.1,3,5-triformylphloroglucinol?Tp?and 3,3'-dimethylbenzidine?DMB?were used as the reaction monomers,p-toluenesulfonic acid?PTSA?as the catalyst,and N,N-dimethylformamide?DMF?as the reaction solvent.After characterization,the results showed that TpDMB-COP had a loose and porous nanoskeleton structure with a specific surface area as high as 1157 m² g^-1.TpDMB-COP was used as SPE adsorbent,which was combined with micellar electrokinetic capillary chromatography?MEKC?for the enrichment and separation of four endogenous phytohormones,including abscisic acid?ABA?,indobutyric acid?IBA?,naphthaleneacetic acid?NAA?and gibberellin?GA3?.The enrichment factor of this method was 200 times.The limit of detection?LOD?and limit of quantitation?LOQ?were 0.04⁰.25 ng/mL and 0.13⁰.83 ng/mL,respectively.The method is simple,accurate and reproducible,and can achieve the good enrichment and separation of endogenous phytohormones in tomatoes.Chapter three,another excellent Schiff base covalent organic polymer,TpTMB-COP was used as the adsorbent of pipette-tip solid phase extraction?PT-SPE?for the extraction of cell free DNA?cfDNA?in normal human serum.Qualitative analysis of the extracted cfDNA was carried out by three methods:?1?in non-gel capillary electophoresis?NGCE?,the molecular weight range of the extracted DNA segments was proved to be consistent with cfDNA;?2?the nucleosides obtained through enzymolysis from extracted DNA segments,were determined to be various deoxynucleotides constituting DNA by high performance liquid chromatography-mass spectrometry.?3?compared with commercially available cfDNA extraction kits,the qualitative results were identical.Finally,NGCE was used to quantitatively detect the extracted cfDNA.The LOD and LOQ were 0.04 pg/?L and 0.10pg/?L,respectively.In this study,the extraction of cfDNA from normal human serum could be completed in 30 minutes,and then analyzed by NGCE.The established method was simple,fast,reproducible,accurate and low cost.Chapter four,conclusions and prospects were made.