Rapid SERS Inspection And Quantitative Detection Of Typical Organic Pollutants

Surface-enhanced Raman spectroscopy（SERS）is widely used in the rapid detection of organic molecules due to its high sensitivity,convenience and efficiency.Considering the diverse properties of the targets,it is necessary to design simple and effective SERS substrates and corresponding application solutions for different target molecules.In this dissertation,several typical organic pollutants are taken as the research object,and the appropriate SERS substrates and analysis methods are designed for them respectively.The main research contents of this dissertation are as follows:（1）Aromatic amines are of great variety in species and Raman activity.For the prohibited aromatic amines in textile industry,a rapid SERS detection method was proposed by combining SERS substrate and mathematical cluster analysis.To detect the aromatic amines with weak Raman active,an array type SERS substrate based on self-assembly with good enhancement effect was constructed.In this method,target aromatic amines were extracted from textiles,and then gold nanoparticles were added to the organic extractant,which assembled into closely packed Au array at oil-water liquid interface in situ.Finally,fingerprint SERS signals of the target aromatic amines were detected on the generated Au array on the basis of strong chemical interaction between the aromatic amines and the Au surface.The proposed method provided good reproducibility with a relative standard deviation of 3.5%for ten parallel tests of benzidine.It was applied to analyze 70 textile products.To strengthen the spectroscopic data processing,a cluster analysis model was established to automatically identify the spectra.20 samples were used as test sets to validate this model.It was found that all the positive samples were successfully identified.（2）For the detection of paraquat with high Raman activity,a simple and effective Cu chip with low cost was designed to reduce the material cost of above Au-based SERS substrate.Cu was cheaper than Ag and Au,and its energy level matched well with the paraquat.However,Cu-based SERS substrates generally have weak SERS enhancement effects and poor stability.In the preparation process,Cu NPs were densely deposited onto fabric supports,and then Ag was introduction onto the Cu surface by a replacement reaction,a Cu-based SERS substrate with good SERS enhancement and oxidation resistance was finally obtained.The enhancement factor of Cu substrate was increased from 2.0×10⁶ to 7.6×10⁶ due to the plasma coupling between Cu and Ag.Owing to the hydrophobicity of SERS substrate and additional protection of Ag shell,the SERS intensity of the Cu-Ag chip still maintained 80%of the original intensity after a two-month storing.Then,the substrate was used to quantitatively detecte the paraquat with accurate results,the recovery was 93.1%.The limit of detection was 10^-9 mol/L,which met the detection requirements of paraquat.Besides that,this SERS method had the potential for the selective detection of paraquat residues in complex water samples（3）Tetrabromobisphenol A（TBBPA）,a brominated flame retardant,represents a class of organic pollutants that are difficult to effectively combine with SERS substrate.For the detection of them,an improved construction strategy of above Cu-based SERS substrate was proposed.The Ag chip with hydrophobic Cu support was prepared for the SERS detection of TBBPA by improving the interaction through the hydrophobicity and the Ag-Br bond.Combined with ultrasonic assisted extraction,the substrate was used for the quantitative determination of TBBPA and bromine content in electronic products.Results confirmed that the hydrophobicity of substrate and synergistic coupling between Cu and Ag played an important role in its SERS detection.The SERS detection limits of TBBPA and Br contents in electronic products were 2.0 mg/kg and 1.2 mg/kg respectively.Compared with other detection methods,the above SERS method was fast,convenient and of high sensitivity.According to its detection results,it could accurately distinguish whether the bromine content in electronic products is qualified.For the three kinds of objects with the characteristic of weak Raman activity,easy for SERS measurement and poor bongding ability with the substrate,the corresponding SERS substrates and sample pre-processing methods were designed respectively to achieve their SERS rapid screening and quantitative detection.This dissertation provided the research direction and application reference for subsequent studies.