Room-temperature Fabrication Of Covalent Organic Frameworks For Solid-phase Microextraction And Gas Chromatography

Covalent organic frameworks?COFs?are a new class of multifunctional crystalline organic polymer constructed with organic monomers via robust covalent bonds.The unique properties such as large specific surface areas,adjustable pore diameter,good stability and convenient modification make COFs great potential in separation science.This dissertation starts with the design and room-temperature controlled preparation of a variety of novel COFs based on the analysis object,further constructs COF-based solid phase microextraction?SPEM?coating and chromatographic stationary phase for SPME of organic pollutants in food and the chiral separation by gas chromatography.The main research results are as follows:Three new COFs,TFPB-BD,TzDva and CTz Dva,were synthesized via a facile room temperature preparation strategy,which laid a good foundation for the preparation of COFs-based SPEM fiber and novel chrial chromatographic column.COF TFPB-BD was first prepared from 1,3,5-tris?4-formylphenyl?benzene?TFPB?and benzidine?BD?at room temperature,which is expected to be new SPME coating material for the trace determination of lipopholic organic pollutants.In addition,easily functionalized vinyl functional COF TzDva was constructed with the monomers 2,4,6-tris?4-aminophenyl?-1,3,5-triazine?Tz?and2,5-divinyl-1,4-Benzenedialdehyde?Dva?.The successful preparation of vinyl functional TzDva provides a precursor COF for the construction of specific functionalized COFs for pratical applications.To realize the chiral separation,chiral sulfur derivative?S?-N-?2-mercaptoethyl?-2-phenylpropanamide was further synthesized and bonded to the as-prepared vinyl functional TzDva to obtain chiral COF CTzDva via a simple and efficient"thiol-ene"click reaction.The good rigid planar structure of triazinyl is conducive to the formation of crystalline structure of COFs and the improvement of its stability.Moreover,triazinyl N atom is hydrogen bond donor,providing more bonding sites.Thus,the chiral COF CTzDva has the potential to be a new stationary phase for the chiral separation.A new method for in-situ room temperature preparation of TFPB-BD bonded fiber was developed for SPME of polychlorinated biphenyls?PCBs?in aquatic products.The surface of stainless steel wire was amino functionalized first to provide the reaction site of bonded COF coating.The aldehyde monomer TFPB of COF coating was then introduced with in-situ growth approach via schiff base reaction at room temperature.Then another amino monomer BD was added to build TFPB-BD bonded SPEM fiber.The extraction conditions of PCBs based on SPME fiber were systematically studied.The developed TFPB-BD bonded fibers were used to develop a new SPME methods for GC-MS/MS determination of trace PCBs in aquatic products.The developed method had higher enrichment factors?4471-7488?and lower detection limits(0.07 ng L^-1-0.35 ng L^-1).The precision of six replicate measurements of 100 ng L^-1 PCBs with a single SPME fiber and the inter-fiber reproducibility of three fibers prepared in parallel were in the range of 3.8%-8.8%and 5.3%-9.7%,respectively.The recovery ranged from 87.1%to 99.7%for 1.0?g kg^-11 PCBs spiked in aquatic products.This work provides a simple preparation method for COFs bonded SPME fiber,which can be extended to the efficient enrichment and determination of other aromatic toxic organic pollutants in environmental and food samples.A chrial COF CTzDva-based gas capillary column was fabricated via dynamic coating method for chiral separation.Mcreynolds constant revealed that CTzDva stationary phase was a medium polar stationary phase with strong ability to accept hydrogen protons.The as-prepared CTzDva-based gas capillary column not only showed good separation of benzene and cyclohexane,ester flavors,isomers,but also presented good prospect of chiral separation of racemates?such as citronellal and anisone?with better performance than the commercial chiral capillary columns?CP-Chirasil Dex CB and CycloSil-B?.In addition to the chiral microenvironment provided by the chiral groups,the interaction between the COF and the targets,such as hydrophobic effect,?-?interaction and spatial effect,also played an important role in the chiral separation.This work expands the application of COFs in the field of separation.