Study And Application Of Rare Earth Europium Fluorescence Rapid Detection System For Malachite Green In Aquatic Products

Malachite green(MG),a synthetic triphenyimethane compound,is an effective aquaculture fungicide.As a drug for the treatment of fungal and protozoan infections,MG has the effect of deinsectization and sterilazation and prolongation of fish survival time.It was previously widely used in the aquaculfure industry.High residue and high toxicity of MG may cause teratological,carcinogenic and mutagenic effects.Consumption of aquatic products containing MG residue will damage human liver,kidney and other organs and cause cell carcinogenesis,gene mutation,skin,gastrointestinal irritation and permanent damage to the organism.At present,MG detection mainly uses chromatography and its combination,electrochemical method and immuno method,etc.Although these detection methods have high sensitivity and good selectivity,they all need to rely on large instruments for analysis,and the sample pretreatment is complicated,the operation is tedious,and the instruments are expensive.These disadvantage limit its use in actual sample testing.Therefore,it is still of great significance to find a fast and efficient MG detection method.in this paper,a fluorescent probe was prepared by combining rare earth complexes to realize the rapid detection of MG.The research content is divided into the tolloing three parts:In the first part,a rare earth complex Eu(Maa)₃Phen was prepared under mild conditions with methacrylic acid and o-phenanthroline as ligands.The complex has a fluorescence emission peak at 618 nm,with a large Stokes shift,a narrow emission peak and a half-peak width of only 15 nm.Because the emission peak of the complex matches the absorption peak of MG,the fluorescence of the complex can be quenched by MG,the fluorescence of the complex can be quenched by MG through fluorescence resonance energy transfer(FRET).the fluorescence life of the complex before and after the addition of 5?mol/L MG was 572?s and 450.9?s.The quantum yields of the complex before and after interacting with MG was 9.49%and 5.21%.The FRET efficiency is 0.21 and the X-Ray diffraction(XRD)pattern indicates that the complex has good crystal properties.Fluorescence intensity and fluorescence quenching efficiency were taken as indicators to optimize the fluorescence test conditions of the complex for MG.Under the optimized conditions,the response time of the complex to the MG was only 5 min,and compared with sulfanilamide,chloramphenicol and other banned fishery drugs,the degree of quenching of the complex to MG was the largest,indicating that the complex had a good selectivity to MG.The linear range was 0.5-20?mol/L,and the detection limit was 117.3 nmol/L(3?/S,n=9).The compound was used to detect MG residue in aquaculture water,and the standard recover was between 96.10%and 98.76%,indicating that the prepared rare earth complex fluorescent probe could be used for rapid detection of MG in aquaculture water.Rare earth complex is an excellent fluorescent substance,and there are few studies on its application in the field of food analysis.In this paper Eu complex was used for the fluorescence detection of MG for the first time and FRET effect was used to detect MG.The preparation process of the complex was simple and the detection process was simple and rapid,providing a new idea for the rapid detection of MG.The second part,molecular imprinted polymers(MIPs)are easy to prepare and have good chemical properties,which have attracted much attention in the field of food analysis Si O₂is widely used in chemical analysis because its surface is rich in silica-hydroxyl function groups and easy to be functionlized.This paper use the precipitation polymerization,leuco malachite green(LMG)as templates,methacrylic acid(AM)as functional monomer,ethylene glycol dimethacrylate(EGDMA)as crosslinking agent,the modified silica(Si O₂)for nuclear,rare earth fluorescent complex Eu(Maa)₃Phen as fluorescent light source,the molar ratio between LMG and AM and EGDMA is 1:4:10,rare earth complex of 15 mg,60 m L of acetonitrile,under the condition of MG molecular imprinted polymer was prepared,Complex of emission peak matching with the maximum absorption wavelength of MG,they can occur FRET effect.The adsorption,fluorescence and selectivity were studied.The results showed that under optimal conditions,the linear range of the polymer to the MG was 0-20?mol/L,and there was a good linear relationship between the concentration of MG and F₀/F.The linear equation was F₀/F=1.008C+0.344(0.1-1?mol/L,R²=0.991);F₀/F=0.587C+0.570(1-20?mol/L,R²=0.999),and the detection limit was 0.037?mol/L(3?/S,n=9),it was used as a fluorescent probe to detect MG in fish meat,and the recovery rate was within the range of 95.6%to 102.5%.The results showed that the prepared fluorescent probe could be used to detect MG residue in fish meat quickly and accurately.In this paper,a surface molecular imprinted polymer fluorescent probe with core-shell structure was prepared using the fluorescent microsphere Si O₂@Eu(Maa)₃Phen as the core.The core-shell configuration is conducive to mass transfer,which further improves the detection sensitivity of the fluorescent probe to MG.In the third part,a fluorescence analysis test paper based on rare earth complex was developed for the rapid visual detection of MG in the field,and an MG fluorescence analysis test paper by adsorbed rare earth complex solution on the test paper material.The rare earth complex Eu(Maa)₃Phen ethanol solution was used as the fluorescent substance,and the qualitative filter paper,PTFE,acetate fiber film and microporous filter film were used as the test paper for optimization.After optimization,the microporous filter film was selected as the test paper material,the concentration of the complex was 0.04 mg/L,the immersion time of the strip in the fluorescent solution was 15 min.Visually observe the color of the strip under ultraviolet lamp irradiation.When absence of MG in the sample,the strip emits red fluorescence.When MG is present in the sample,the red fluorescence emitted by the rare earth complex is gradually quenched,and the higher the concentration of MG in the sample,the weaker the fluorescence of the test paper.Dipsticks sensor because of its strong operability,don't need a professional and large equipment,required less sample weight,convenient to carry,can greatly shorten the testing time,is currently the focus of the research direction,this paper creatively and rare earth complex as fluorescent substances adsorbed on the strip,through the macroscopic observation,the color change of the strip of MG in the visual semi-quantitative detection,this method is low cost,simple operation,don't need a large instrument,for MG on-site rapid screening test provides a new way of thinking.