Application Of ZIF-8 In SERS Detection Of Bisphenol A,Sibutramine And Fenfluramine

Surface-Enhanced Raman（SERS）technology has the advantages of high sensitivity,fast analysis speed,and simple operation.It has great potential in large-scale detection of food contaminants and prohibited additives.Problems such as poor substrate stability.Zeolitic imidazolate framework（ZIF-8）is a typical metal-organic framework（MOFs）with strong adsorption capacity,which can effectively enrich harmful substances in food.The combination of MOF and SERS can realize rapid and accurate screening of food harmful substances in.Bisphenol A is an endocrine disruptor.In the past,people paid more attention to its migration in food packaging.Nowadays,due to environmental pollution,bisphenol A is also commonly found in fish.How to deal with rapid detection bisphenol A residues in fish meat is a problem worth exploring.Therefore,this study took bisphenol A as the target,and optimized the pretreatment method of SERS technology and ZIF-8 to prepare a new type of reinforced substrate,and established a rapid detection method for bisphenol A.It was extended to the screening of prohibited additives,and a simultaneous detection method of sibutramine and fenfluramine was established.The main contents include:（1）In this study,ZIF-8 materials were prepared at room temperature,and their morphology,molecular structure and elemental composition were analyzed by several characterization techniques,and the characterization results demonstrated the synthesis of well-shaped ZIF-8materials.The most suitable experimental conditions were 30 min adsorption time,25℃adsorption temperature,p H 7,and 20 mg of material used,and the maximum adsorption rate was about 96%and the maximum adsorption capacity was about 60.96 mg/g.ZIF-8 materials was used for the enrichment of BPA in food samples,and the corresponding SERS assay was established.The effects of solvent,p H and mixing ratio on the SERS effect were investigated.The SERS detection of BPA was achieved under the optimal conditions of methanol-water 1:1 as the solvent,p H 3,and the ratio of liquid to be measured to gold soluble gel was 1:3;under the optimal conditions,the Raman peak at 1172 cm^-1 with good enhancement effect was used as the quantitative characteristic peak,and the limit of detection was 1 mg/L,and the standard curve range was 1～50 mg/L with R²=0.9846;the standard addition experiment was carried out with fish meat as the actual sample,the recoveries were 76.35%～85.57%,and the RSD values were 2.43%～11.81%,which proved that the combination of ZIF-8 and SERS could realize the rapid detection of BPA in fish meat..（2）Different sizes of Au@ZIF-8 composites with intact core-shell structure were further prepared,the different sizes composites all showed good SERS activity.The enhancement effect of the material was inversely proportional to the thickness of the shell layer,and the best Raman enhancement was achieved when the cladding thickness of ZIF-8 was 3 nm.The spectra were collected at 12 random points,and the SERS intensities of the five characteristic peaks were relatively stable with a mean RSD of 6.01%,and the material reproducibility was good.The SERS signal intensity was basically unchanged within 30 days,and the stability of the material was guaranteed.The material was used as an enhanced substrate to establish the SERS detection method for BPA.The rapid detection of BPA was achieved at the optimal conditions of 1:3 ratio of the solution to be tested to the substrate and 3 min mixing time.The Raman peak at 1172cm^-1 was used as the quantitative characteristic peak,and the minimum detection concentration of BPA was as low as 0.1 mg/L.The linear relationship between SERS peak intensity and concentration was good in the concentration range of 0.1～10 mg/L with R² of 0.9241.The recoveries were 99.68%～102.35%with the RSD values of 3.28%～7.58%for the actual samples spiked.7.58%,similar to the detection results of high performance liquid chromatography.The above results indicated that the detection of BPA with Au@ZIF-8 composite as the Raman-enhanced substrate could further reduce the detection limit of the SERS method.The detection limit of this method also meets the limit standard of bisphenol A residues in food in EU2004/19/EC regulation.（3）In order to broaden the application of Au@ZIF-8 material,banned additives were selected according to the adsorption characteristics and enhancement mechanism,and a SERS method was established to simultaneously detect banned additives in weight loss health care products.According to market surveillance and sampling,the two commonly used banned additives in weight loss health care products are sibutramine and fenfluramine.The Raman enhancement effect of Au@ZIF-8 material on sibutramine and fenfluramine was discussed.,a simultaneous detection method of two prohibited additives was established under the optimal conditions of the ratio of the liquid to be tested and the substrate of 1:2 and the mixing time of2 min.Taking weight-loss health products as actual samples,the simultaneous detection of two prohibited additives can be realized.At the spiking level of 25 mg/kg,the characteristic peaks of the two are clearly visible,and the recovery rate is 96.49%～100.26%,which can be Meet the needs of rapid screening of prohibited additives in health products.