Research On Substrate Preparation And Heavy Metal Detection Based On SERS And Raman Technology

Food and water safety issues have been a hot topic of continuous concern at home and abroad.Strengthening the attention and research depth of food pollution issues is conducive to ensuring the health of the people and the long-term social stability.There are many types of food contaminants and great hazards.Among them,heavy metal residues present a wide range of pollution,strong enrichment,and great harm to the human body.Heavy metal detection is one of the important ways to prevent the circulation of the contaminated food market.However,the traditional detection methods have problems such as cumbersome pretreatment,long detection cycle,and high detection cost.Therefore,in order to further reduce the hidden dangers of food heavy metal pollution and improve the quality,there is an urgent need to develop a technology or method that can be used for on-site rapid and micro-trace detection of heavy metal residues.Surface-Enhanced Raman spectroscopy(SERS)technology is a fingerprint spectral detection method with ultra-high sensitivity.Its spectral data contains rich material feature information,with rapid detection,high sensitivity,low background interference,fast non-destructive detection and Many advantages such as miniaturization of equipment.In recent years,SERS technology has been reported in many fields of application,and has become one of the important means of micro-trace and rapid detection;and it also has the advantage of rapid detection in heavy metal detection,but it is currently based on SERS technology in heavy metal ion detection The problems of poor selectivity,high detection limit,and narrow detection range still need to be solved and optimized;among them,the SERS active substrate composed of noble metal nanoparticles and rough surfaces is responsible for the surface plasmon resonance phenomenon,which produces the Raman enhancement effect.Crucially,the preparation of active substrates has also become a key technology for the efficient application of SERS technology.Starting from the pollution of heavy metals in water,this paper focuses on the preparation,optimization,modification of sol-state active substrates and solid surface active substrates with array structures and their quantitative detection and application in heavy metal ion solutions.It is discussed in three parts.First,the sources and hazards of the four pollutants of arsenic,lead,cadmium,and mercury,which are the most serious pollutions and hazards among heavy metals,are introduced.The advantages and disadvantages of commonly used heavy metal detection techniques are outlined.The principle of Raman scattering and its enhancement mechanism,the application of SERS technology in food safety and heavy metal detection,as well as the types,preparation methods and application prospects of common surface-enhanced Raman active substrates.Secondly,we focused on the preparation and optimization of a modified sol-state active substrate,and investigated the SERS activity of the substrate and the quantitative detection ability of heavy metal ions.The preparation conditions were investigated in detail,and the molar ratio,time and p H of the reactants were optimized to improve the SERS activity of the gold sol.The particle size uniformity,morphology and optimization process of the prepared gold sol were characterized;the mercaptobenzoic acid was used as the internal standard and the probe molecule to modify the gold sol for the adsorption detection of heavy metal ions;the substrate was compared with arsenic and lead,Cadmium,mercury ion Raman spectrum signal differences to explore its selectivity and discrimination ability;concentration gradient Raman detection of heavy metal ions,to explore its quantitative analysis ability.It is concluded that under the conditions of MR=2,t=18min and p H=4,the prepared modified gold nanosol active substrate has the best SERS enhancement effect;the substrate has the lowest detection limit of heavy metal ions arsenic,lead,mercury It can reach 0.1mg/L(cadmium is 0.5mg/L),and the peak intensity-concentration in0.5-100mg/L has a good linear relationship,and has the ability of quantitative analysis;and the arsenic,cadmium,lead and mercury ions are in There is a difference in wave number near the characteristic peak,which has a certain ability to distinguish.The Pb2+ spiked recovery experiment was carried out on the actual water samples,and satisfactory test results were obtained.The preparation and modification process of the sol-state active substrate is simple and easy to operate,low cost,and good enhancement effect.It has good rapid quantitative detection ability for trace heavy metal ions and is worthy of further in-depth study.Finally,the preparation of a modified solid surface active substrate with high enhancement effect,stability and flexibility was further studied,and the detection ability of the substrate to heavy metal ions was investigated.The preparation of the base array structure substrate,the gold-coated substrate and the modification process were explored in detail.The PDMS substrate with periodic array structure was prepared by surface self-assembly and template transfer methods.The gold nanoparticles were deposited by chemical deposition Coated on the surface of the substrate structure,using mercapto isonicotinic acid as an internal standard and probe molecules to modify the surface of the substrate for the detection of heavy metal ions.The self-assembled array structure,substrate and substrate morphology were characterized,and the influence of spin coating speed and deposition time on the substrate array structure was investigated;and the enhancement effect of the substrate and the response ability to heavy metal ions were investigated.It is concluded that the prepared modified solid surface active substrate with array structure has a good enhancement effect,and the detection limit of the four heavy metal ions of arsenic,lead,cadmium and mercury is as low as 0.01mg/L,using the number of characteristic peaks The trend of the ratio between the peak intensity and the peak intensity ratio can be partially distinguished;the characteristic peak intensity and the logarithm of the concentration in the Raman spectrum of the substrate for the four heavy metal ions at a concentration gradient of 0.01-10 mg/L have a good quantitative relationship and have a certain quantitative analysis ability.The solid surface active substrate has low preparation cost,good stability,low detection limit and can realize large-scale production.Whether it is in the rapid detection of micro-trace pollutants or heavy metal detection,it has broad development prospects and value.In this paper,by preparing two modified active substrates for rapid quantitative detection of heavy metal ions,combined with the detection results of the two substrates,the four heavy metal ions of arsenic,lead,cadmium and mercury are distinguished and quantitatively detected.Good experimental results will help to establish a more complete method for the rapid and highly sensitive detection of heavy metal residues in food in the later work.