Preparation And Application Of Chiral Separation And Solid-phase Extraction Novel Materials Based On Nano-Silver And CD-MOF

Chiral separation has always been one of the research hotspots in analytical chemistry.As a multifunctional polymer,chiral separation materials play an important role in enantioselective separation and optical pure synthesis.In recent years,new chiral separation materials have emerged in an endless stream and been still on the rise.In order to further broaden the application of chiral separation materials,four novel chiral separation materials were prepared in this paper,which were applied in the chromatographic stationary phase and solid-phase extraction for a series of studies.The main achievements are as follows:(1)Material with core-shell structure based on a porous silica core and Ag nanoparticles(Ag NPs)as shell(SiO2@Ag)was prepared.Cellulose derivatives as chiral selector were coated on the surfaces of SiO2@Ag particles by means of coating and intermolecular polycondensation as chiral stationary phases(CSPs),respectively.Fifteen racemates were used to evaluate their chiral recognition ability.The results implied that the CSPs based on SiO2@Ag particles obtained stronger interaction with the analytes leading to better enantioseparation due to the existence of Ag NPs on the surfaces of silica gel,compared with cellulose derivatives modified silica column.In addition,the new CSPs showed special selectivity for ketone enantiomers,and Ag NPs played a synergistic effect with cellulose derivatives on enantioseparation.(2)A new L-cysteine modified silver-functionalized silica-based chiral separation material(SiO2@Ag-L-cysteine)was synthesized.It was used for the separation and adsorption of D,L-threonine.Then,a solid-phase extraction method based on SiO2@Ag-L-cysteine was developed and successfully used for bisphenol A determination.The results showed that the L-cysteine-silver at silica as an adsorbent exhibited good enrichment capability for bisphenol A,and the maximum adsorption saturation was 20.93 mg·g-1.Moreover,a short adsorption equilibrium time was obtained due to the presence of silver nanoparticles on the surface of the silica.The extraction efficiencies were then optimized by varying the eluents and pH.Under the optimized conditions,good linearity for bisphenol A was obtained in the range from 0.4 ?M to 4.0 ?M(R2>0.99)with a low limit of detection(1.15 ng·mL-1).The spiked recoveries from tap water and milk samples were satisfactory(85%to 102%),which indicated that the method was suitable for the analysis of bisphenol A in complex samples.(3)A facile approach was used to prepare a cyclodextrin metal-organic framework(CD-MOF)based on y-cyclodextrins(y-CDs)and alkali metal cations.This material was used as CSP,and flavanones,pachlorol,R,S-equol,2-phenylcycloalkanone,benzoin and ketoconazole were separated on CD-MOF CSP.Among them,the separation factor of flavanone reached 37.83.Moreover,CD-MOF was also used as solid-phase extraction(SPE)material,exhibits high selectivity and sorptive capacity toward sulfonamides(SAs).Therefore,five SAs including sulfathiazloe(STZ),sulfamethoxymidine(SMD),sulfamerazine(SMR),sulfadimethoxine(SDM)and sulfaquinoxaline(SQX)were selected as target analytes to validate the extraction performance of CD-MOF,and the adsorption mechanism was investigated.The results showed that the CD-MOF as adsorbent exhibited good enrichment capability for five SAs and obtained short adsorption equilibrium time(30 min).Under optimized conditions,the spiked recoveries into meat samples were satisfied(76%-102%)which indicated that the method was suitable for the effective extraction of SAs from complicated matrices.(4)A green,renewable composites was designed and fabricated,based on self-assembly of CD-MOF and graphene oxide(GO).Then,the self-assembled GO@CD-MOF was embedded in 0.45 ?m PTFE membrane to produce a dual-functional membrane which could carry out sample enrichment by capturing naringin molecules.The membrance filter was further improved by investigate the effects of the experimental parameters of amount of GO@CD-MOF,enrichment time and elution solvent.Further,the present method had been successfully applied to citrus sample and obtained satisfied recovery value(79,7-100.3%).Moreover,extraction naringin can be achieved for 2 min.The results demonstrate that the novel membrance filter based on GO@CD-MOF was a fast,simple and reliable operation and possesses great potentials in the determination of naringin from real samples by dual-functional of separation and enrichment.