Synthesis Of Scholl-coupling Mesoporous Polymer And Its Application In Online Extraction Of Growth Regulators From Food

The determination of external contaminants and functional components is of great significance to food safety analysis.Sample pretreatment,as the key of the food analysis,directly affects the accuracy and reliability of the analytical method.Compared with the offline pretreatment method,online solid-phase extraction(online SPE)has the characteristics of automation,lower solvent consumption,shorter fewer errors,and high precision.Adsorbent,as the key of online SPE,plays a role in the accuracy,precision and reliability of the analytical method.The functional porous polymers can be constructed via Scholl coupling reaction,which possesses the advantages of low cost,stable structure and easy preparation.Scholl coupling polymers(SMP)have been widely used in gas storage,heterogeneous catalysis,and semiconductor industries.Aiming at the functionalization of SMP were developed using post-synthetic modification methods,such acetamido hydrolysis and Schiff base condensation,which broke through the difficulties restricting the preparation of functional SMP materials.Two SMP materials with different pore structures and functional groups were synthesized.The two SMP were used to efficiently enrich plant growth regulators(PGRs)in bean sprouts and brassinosteroids(BRs)in fifteen plant-derived foodstuffs,respectively.The relationship between the adsorption efficiency and functional groups was also investigated.These results can provide the experimental method and theoretical basis for assembling functional SMP with specific application.The research contents of this thesis include three parts.1?The research progress of SMP was introduced.The common detection techniques and sample preparation methods were reviewed.Moreover,the research background,purpose,contents and innovations of the study were summarized.2?Acetylamino-Scholl-coupling mesoporous polymer(SMP-1)was synthesized at the micron scale,using acetanilide as the monomer.Amino-modified Scholl-coupling mesoporous polymer(SMP-2)was synthesized by acid-catalyzed deacetylation of SMP-1.The structure and morphology of SMP materials were characterized using characterization methods,including scanning transmission electron microscopy spectra,fourier-transform infrared spectra,N₂ adsorption-desorption experiment,X-ray photoelectron spectroscopic,solid-state ¹³C NMR spectra and elemental analysis.Typical PGRs,such as 1-naphthaleneacetic acid,1-naphthaleneacetic acid,2,4-dichlorophenoxyacetic acid,4-chlorophenoxyacetic acid,thidiazuron,indole-3-acetic acid and indole-3-butyric acid,were chosen to evaluate the adsorptive property of SMP.SMP-2 exhibited superior extraction capability for PGRs,compared with SMP-1,C₁₈and SAX.The SMP-2 was then packed in SPE cartridge.The operational parameters of the SPE cartridge were optimized,including loading solvent,p H of loading solution,eluting solvent,and flow rates of loading and elution.Under the optimized conditions,SMP-2-online SPE coupled with HPLC(SMP-2-online SPE-HPLC)was established.The method exhibited good linearity(R²?0.9915),low limits of detection(2.34-20.2ng kg^-1),limit of quantification(7.81-67.3 ng kg^-1)and good precision(RSD,1.3-7.3%).Compared with previously-reported methods,the proposed method can reduce the limit of detection by more than 17 times.In the spiked recovery experiment,the recovery was between 86.0%and 109.1%,and the RSD?9.8%,which indicated that the matrix interferents show minor effects on the SMP-2-online SPE-HPLC.Finally,the method was successfully used for determination of PGRs in bean sprouts.3?Based on the reversible covalent reaction between boric acid and cis-hydroxyl containing BRs,boronic acid-functionalized Scholl-coupling microporous polymer(SMP-4)was synthesized via Scholl-coupling and Schiff-base reaction using the low-cost aniline as the monomer.The structure and morphology of SMP materials were characterized using characterization methods,including scanning transmission electron microscopy spectra,fourier-transform infrared spectra,N₂ adsorption-desorption experiment,and X-ray photoelectron spectroscopic.Typical BRs,such as BL,2,4-epi BL and 28-homo BL,were chosen to evaluate the adsorptive property of SMP-4.The adsorption of three BRs on SMP-4 increased quickly and achieved equilibrium within5 min.The maximum adsorption capacities of SMP-4 were higher than 72.4 mg g^-1.The isotherms models,adsorption kinetics and density functional theory calculations were used to fit the adsorption process.The results indicated that the boronate affinity and electrostatic interaction endowed SMP-4 the fast adsorption kinetics and high adsorption capacities.The operational parameters of the SPE cartridge were optimized using the three-factor-three-level Box-Behnken design.Under the optimized conditions,SMP-4-online SPE coupled with HPLC-MS/MS(SMP-4-online SPE-HPLC-MS/MS)was established and used for the determination of BRs.The method exhibited good linearity(R²?0.9970),low limits of detection(0.010-0.070 pg m L^-1),limit of quantification(0.035-0.210 pg m L^-1)and good precision(RSD,3.1-8.7%).Compared with previously-reported methods,the prepared method possessed significant sensitivity and accuracy.The content level of BRs in frequently consumed plant-derived foodstuffs was obtained,which displayed that the types and contents of BRs are highly foodstuff-species-related.Moreover,in the spiked recovery experiment,the recovery was between 90.3%and 109.3%,and the RSD?9.7%,which indicated that the matrix interferents show minor effects on the SMP-4-online SPE-HPLC-MS/MS.The results confirmed that the prepared method is efficient and simple,which can be applied to the sensitive determination of BRs from plant-derived foodstuffs.