Fabrication Of Flexible Extraction Membrane With Surface-enhanced Raman Spectroscopy And Application In Analysis

With the development of social economy,environmental pollution has become a serious problem in human survival and development.The of variety of pollutants,the complexity of the sample matrix and the concentration the substances to be measured are often at trace levels,which require researchers to develop new portable,fast and reliable analytical methods.The appropriate sample preparation technique and analytical method are the key steps to ensure the accuracy and reliability of analysis data.The efficient sample pretreatment can be used to concentrate the trace components,eliminate the interference,thereby reducing the detection limit and increasing the sensitivity and selectivity.Solid phase extraction(SPE),as a sample preparatiom technology developed rapidly in recent years,has the characteristics of simple operation,low cost and low organic solvent.Surface enhanced Raman spectroscopy(SERS),a highly sensitive analytical technique,can provide fingerprint information of the molecules.The solid phase extraction-surface enhanced Raman spectroscopy(SPE-SERS),combining the advantages of both,achieves rapid pretreatment and in situ detection,and has been widely used in various analysis field.On the basis of SPE-SERS,the flexible extraction membrane with SERS activity can realize the enrichment extraction of the molecules on the complex surface in various ways,and conduct on-site qualitative and quantitative detection,which meets the development requirements of modern analytical technology.However,the sensitivity,stability and reusability of the substrate are still decisive factors in the actual application.In this paper,the flexible extraction membrane with SERS activity was developed,and the suitable extraction method can be used to achieve the rapid enrichment and in-situ detection of corresponding pollutants.The main contents of the paper are summarized as follows:1.We have synthesized silver nanoparticles with SERS activity on the surface of copper membrane by improved displacement reaction.The filtering-SERS detection of the large volume water samples has been achieved by using the porosity.The properties of the substrate were investigated by using p-Aminothiophenol as the probe molecule.The electron transfer caused by the Fermi energy level difference between copper and silver inhibits oxidation of the silver,and the extremely high heat conductivity of copper is beneficial to the heat dissipation of the substrate under intense laser,these two characteristics causes the substrate to show stability under the long time storage and s continuous laser irradiation.At the same time.The substrate has good uniformity,sensitivity and reproducibility.Using NaBH4 as the removal solution,there was no obvious change in the intensity and location of the characteristic Raman peaks after five cycles.Compared with the traditional drop method,the signal intensity of the filter method is 28 times as high as that of the drop method.By using this extraction technique,the qualitative and quantitative detection of phorate and malachite green were realized,and the detection of phorate in the actual water samples was further realized.2.We grow ZnO mesoporous nanosheets by seeding method on aluminum foil surface,and then sputter the gold nanoparticles on the surface of the ZnO,and further depositing a layer of silver nanoparticles by chemical reduction method to generate a flexible three-dimensional structure extraction membrane with SERS activity.The preparation conditions of the sputtering time and the volume of silver nitrate were optimized by using p-Aminothiophenol as the probe molecule,and the changes of the SERS intensity with the change of the substrate morphology were described.The substrate has good stability,uniformity and sensitivity.Using the flexibility of the substrate,the wiping extraction-SERS detection of the tomato and the apple surface were successfully carried out.The wiping extraction-SERS detection provides a quick and sensitive platform for the detection of the complex surface of fruits and vegetables.