| A variety of complex organic pollutants are entering the environment and food.Most of these pollutants have the characteristics of long half-life,long-distance migration,food web aggregation and high toxicity.Organic pollutants are highly toxic and can cause varying degrees of harm to the human body through accumulation in the food chain or direct skin contact.Therefore,the monitoring and control of organic pollutants in water and food has always been the focus of research in the field of food safety.Due to their low concentration in complex samples and the complexity of the matrix,it is difficult to be detected directly by modern technology.Therefore,the pretreatment of water and food complex matrix and the enrichment analysis of trace OPs are particularly important.In this study,three types of magnetic nanomaterials based on covalent organic framework materials:magnetic covalent organic framework and metal organic framework composite material(Fe3O4@TAPB-COF@ZIF-8),magnetic covalent organic framework material(Fe3O4@Si O2@COF-V and Fe3O4@Si O2@COF-TAPB-BPDA)were developed and applied as magnetic solid phase extraction adsorbents for determination of bisphenols,polybrominated diphenyl ethers and organophosphorus in water and food samples.At the same time,we explored the adsorption mechanism of different functional magnetic nanomaterials for different organic pollutants.The main results of this paper are as follows:1.A novel porous composite(Fe3O4@TAPB-COF@ZIF-8)consisting of metal–organic and covalent organic frameworks was developed and applied to the magnetic solid-phase extraction(MSPE)of bisphenols in functional beverages.The prepared materials were characterized through scanning electron microscopy,Fourier transform infrared spectroscopy,X-ray diffraction,vibrating sample magnetometer.Meanwhile,the extraction parameters such as the extraction time,solution p H,amounts of adsorbent,and ionic strength were investigated.By optimizing the MSPE,a convenient and sensitive analytical method was established.The method achieved low detection limits(0.04-0.05ng·m L-1),wide linear range(0.25-1000ng·m L-1),good repeatability(1.20-4.30%),good reproducibility(1.34-4.03%),and satisfactory recoveries of four functional beverages(66.2-116.6%).The new composite material has been successfully applied to the sensitive analysis of trace bisphenol compounds in plastic-packaged functional beverages.2.Novel core shell structured magnetic covalent organic frameworks(Fe3O4@Si O2@COF-V)was synthesized at room temperature and applied in water and milk samples for the enrichment of trace polybrominated diphenyl ethers(PBDEs)through magnetic solid-phase extraction.The prepared materials were characterized through transmission electron microscopy,Fourier transform infrared spectroscopy,X-ray diffraction,vibrating sample magnetometer and X-ray photoelectron spectroscopy.During adsorption,the parameters affecting extraction and desorption efficiency were further optimized.Combined gas chromatography and mass spectrometry(GC-NCI/MS)revealed that high enrichment factors(275–292),low limits of detection 0.12-0.38ng·L-1),wide linear ranges(0.5-1000ng·L-1),and good reproducibility(intra-day 1.40-4.31%and inter-day 5.14-9.12%)were obtained under optimal conditions.The method successfully detected PBDEs in different water samples.This method has been successfully applied to the analysis and detection of PBDEs in water and milk samples.3.The room-temperature preparation and application of novel magnetic core-shell covalent organic framework made from(1,3,5-Tris(4-aminophenyl)benzene(TAPB)and4,4-Biphenyldicarboxaldehyde(BPDA)(Fe3O4@Si O2@COF-TAPB-BPDA)as sorbent for the selective capture of five kinds of organophosphorus pesticides(OPPs)were reported.Transmission electron microscopy,Fourier transform infrared spectroscopy,X-ray diffraction,vibrating sample magnetometry and X-ray photoelectron spectroscopy were performed to reveal the structure and properties of the sorbent.Then,gas chromatography–mass spectrometry(GC-MS)technique was employed to identify and quantify the OPPs.Under optimized experimental parameter conditions,low limits of detection(0.007-0.05?g·L-1)with good reproducibility(1.45-6.14%),wide linearities(1.45-6.14%,R?0.9935),and satisfactory recoveries(87.3-110.4%)were obtained.These results demonstrate that the prepared Fe3O4@Si O2@COF-TAPB-BPDA coupled with the GC-MS/MS hold unique advantages for the trace analysis of OPPs in foodstuffs. |
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