Preparation And Application Of Solid Phase Extraction Adsorbent Based On Graphene Oxide And ZIF-8

Food safety has always been one of the hot issues in the scientific and technological circles and the public.Among them,dyes are used as fungicides in fish,posing a serious threat to human health.In addition,excessive levels of vitamins in foods can cause disease.However,these substances are often found in food in microscale and trace amounts.Therefore,it is of great research significance to establish a new pre-concentration method and filling materials to improve extraction efficiency and reduce detection costs.Graphene oxide(GO)and zeolite organometallic framework(ZIF-8)have a large specific surface area,good stability,can be easily modified and the absorption capacity is pretty good.They have broad application prospects in the field of adsorption and separation.Based on this,the main works of our study is as follows:(1)In order to improve the sensitivity and accuracy of the commonly used fungicide malachite green(MG)and crystal violet(CV)determination methods in seafood products,reduced the sample pretreatment time.Using ?-cyclodextrin ?-CD)and GO functionalized melamine sponge as a new type of solid phase extraction(SPE)adsorbent,pre-enrichment of MG and CV in seafood samples.Based on the synergistic effect of ?-CD and GO,the adsorption rate is significantly improved,the adsorption rate for MG was 81%,and the CV was 85%.Combined with high-performance liquid chromatography(HPLC)technology,a method for simple,rapid and accurate detection of MG and CV dyes in aquatic products was developed,and further research was conducted on the effects of experimental parameters on MG and CV preconcentration.The extraction process is improved,and this method is expected to be widely used in the pre-enrichment and detection of dyes in the environment.(2)The zeolite imidazolium salt skeleton 8(ZIF-8)/polymethyl methacrylate(PMMA)visual adsorption sensor was prepared by melt mixing method,and the corresponding color chart were established based on MG,CV&MG,and methylene blue(MB),respectively.It was used for visual inspection of the concentration of three cationic dyes.The visual adsorption sensor has low cost,high efficiency and high reproducibility.In addition,the method based on the adsorbent combined with ultraviolet spectrophotometry can also be applied to the determination of three cationic dyes in actual fish samples.The results show that using ZIF-8/PMMA as a visual sensor has great potential for the analysis of three cationic dyes in environmental and complex matrix samples.(3)A new composite nanomaterial ZIF-8/MWCNTs was prepared,based on ZIF-8 and multi-walled carbon nanotubes(MWCNTs).As a new type of dispersed solid phase extraction adsorbent,it was combined with HPLC for rich separation and detection of adenine and folic acid in vegetables.The material has good thermal stability,strong adsorption capacity,simple and fast sample preparation process,and small sample volume.The maximum adsorption capacities for adenine and folic acid are 6.86 mg/g and 12.67 mg/g,respectively,and the Freundlich model and quasi-second-order kinetic model can effectively describe the adsorption process of adenine and folic acid on ZIF-8/MWCNTs.After adding the standard of the sample,the recovery rate was 77.54-96.13%.The RSD of adenine was 0.72-4.5%,and the RSD of folic acid was 0.95-4.6%.The results show that this method can be successfully applied to the detection of adenine and folic acid in actual samples.