Research And Application Of Surface-enhanced Raman Spectroscopy In Veterinary Drug Detection

The detection of veterinary drug residues in food has a significant and far-reaching impact on protecting the health of residents and promoting social stability and development.The establishment of a sensitive,stable and selective method for the detection of veterinary drugs is of great significance for food safety,especially for food safety of animal origin.In recent years,surface-enhanced Raman spectroscopy（SERS）technology with high sensitivity,good reproducibility,low cost and easy operation has been favored by many researchers.This paper mainly developed three SERS techniques for the detection of four veterinary drugs.The main contents of the study were as follows:A novel SERS assay for marbofloxacin was developed based onβ-cyclodextrin-modified silver nanoparticles（β-CD-AgNPs）.Theβ-CD-AgNPs substrate synthesized in laboratory was characterized by scanning electron microscope（SEM）and UV-vis.The binding effect of marbofloxacin andβ-CD-AgNPs was characterized by FT-IR and UV-vis spectra,and the binding mechanism was discussed.The optimum experimental conditions of SERS detection system for marbofloxacin were investigated.In 0.033 mol L^-1 HCl solution,marbofloxacin had a sensitive SERS signal at 806 cm^-1,and the enhancement factor（EF）was 2.11×10⁷.Under the best experimental conditions,there was a good linear relationship between the concentration of marbofloxacin and the intensity of SERS in the range of 3-30 nmol L^-1.The linear equation was I_SERS=1.078×10⁴ c+343673(c:nmol L^-1,R²=0.996).The detection limit（LOD）was 1.7 nmol L^-1（S/N=3）.Moreover,the influence of some interferences including Cu²⁺,K⁺,Zn²⁺,Ca²⁺,Na⁺,Mg²⁺,glucose and tiamulin on the determination were studied.The developed SERS method was used to detect the content of marbofloxacin in chicken and duck,the recovery was 101.3%–103.1%with RSD 4.07%–6.83%,n=5.Based on Au@AgNPs substrate,a new SERS method for detecting amprolium HCl was established.The synthesized Au@AgNPs substrates were characterized by TEM,UV-vis and nano-particle size analyzer.The interaction between the substrate and amprolium HCl were further studied by FT-IR and UV-vis.The optimum determination conditions were studied by single factor experiment and response surface analysis.The EF was 1.60×10⁷.Under the best experimental conditions,there was a good linear relationship between the concentration of amprolium HCl and the intensity of SERS in the range of 0.66-200 nmol L^-1,and the linear equation was I_SERS=2.882×10³ c+305185(c:nmol L^-1,R²=0.995).LOD was 0.48 nmol L^-1（S/N=3）.The influences of interfering substances were discussed in detail.The method was successfully used to detect amprolium HCl in the samples of chicken and duck,the recovery was 97.4%-103.5%with RSD 1.08%-3.39%,n=5.Based on the AgNPs modified by bovine serum albumin（Ag@BSA NPs）,a new SERS method for the determination of ampicillin sodium and ciprofloxacin lactate was established.The synthesized Ag@BSA NPs substrate was characterized by TEM and UV-vis.The binding of ampicillin sodium and ciprofloxacin lactate to the substrate was studied by FT-IR and UV-vis.The optimum experimental conditions were explored by single factor experiment and response surface method.The EF values of ampicillin sodium and ciprofloxacin lactate were 7.77×10⁶ and 3.87×10⁷respectively.Under the best experimental conditions,there was a good linear relationship between the concentration of ampicillin sodium and the intensity of SERS in the range of 6.67-1000 nmol L^-1,and the linear equation was I_SERS=139.49 c+10119.44(c:nmol L^-1,R²=0.995);there was a good linear relationship between the concentration of ciprofloxacin lactate and the intensity of SERS in the range of 6.67-300 nmol L^-1,and the linear equation was I_SERS=184.40 c+29226.23(c:nmol L^-1 R²=0.995).The LOD values of ampicillin sodium and ciprofloxacin lactate were 2.50 nmol L^-1 and 4.64 nmol L^-1（S/N=3）,respectively.The effects of several interfering substances on the experimental system were explored.The method was applied to the determination of ampicillin sodium and ciprofloxacin lactate in beef and mutton samples.The recoveries of two drugs were 96.73%-105.69%with RSD 5.31%-7.98%and 96.58%-104.10%with RSD 3.10%-8.40%,n=5,respectively.