Establishment Of New Fluorescent Detection Methods For Clenbuterol And Ractopamine In Food

Ractopamine(RAC)and clenbuterol(CLB)belong to β-agonists,which was used as growth promoters in livestock production to promote growth and increase the muscular mass.However,symptoms including muscle tremors,headache and heart palpitations can occur after eating the food containing RAC and CLB,which serious harm to human health.In this paper,novel fluorescence probes were synthesized using RAC and CLB as analyte,molecularly imprinted polymers as molecular recognition materials,upconversion nanoparticles as fluoresence conversion materials and fluorescence probe detection method was developed,which offered technical support to ensure meat food quality and safety.Yb(NO3)3,Y(NO3)3,Er(NO3)3,NaF and EDTA were used to synthesize upconverting fluorescent nanoparticles YF3:Yb3+,Er3+ using a facile hydrothermal approach.The morphology and crystal structures of YF3:Yb3+,Er3+ were characterized by scanning electron microscope and X-ray diffraction patterns.Spectrum analysis indicated that YF3:Yb3+,Er3+ nanoparticles can convert near-infrared or infrared light to ultraviolet or visible light.A novel RAC molecularly imprinted polymers fluorescent probe was successfully synthesized by non-covalent method using RAC as a template,methyl acrylic acid as functional monomer,ethylene glycol dimethacrylate as cross-linker,azobisisobutyronitrile as initiator,upconversion fluorescent nanoparticles as fluorescence lable.The obtained fluorescence probe was characterized by scanning electron microscope,X-ray diffraction patterns,energy-dispersive X-ray spectroscopy and thermogravimetric analysis.The binding experimental results showed that the obtained probe had high adsorption capacity,high specificity(QUCNF@MIP/QUCNF@NIP=1.85),fast adsorption kinetic(reaching balance within 10min at 20mg/L)and stable photochemical characteristics(fluorescence intensity can maintain for at least 1 h).Under the optimized experimental conditions,good linear calibration was obtained for RAC over the concentration range of 5.0～100.0μg/L with a detection limit of 0.26 μg/L(S/N=3).The proposed method was also applied to determine RAC in pork and potable water samples with recoveries ranging from 76.61～88.97%and relative standard deviation(RSD)ranging from 1.15～2.67%in all cases(n=3).Therefore,this method can be used in RAC analysis of practical samples.The derivative was synthesized by chemical reactions between CLB and methacryloyl chloride,which was characterized by nuclear magnetic resonance and mass spectrometry analysis,and the results showed that the CLB derivative was suitable for preparation CLB molecule imprinted polymers by covalent imprinting method.A novol CLB molecularly imprinted polymers fluorescence probe was successfully synthesized by covalent imprinting method utilizing CLB derivative as compound functional monomer,methyl acrylic acid as functional monomer,ethylene glycol dimethacrylate as cross-linker,azobisisobutyronitrile as initiator,upconversion fluorescent nanoparticles YF3:Yb3+,Er3+as fluorescence lable.The obtained fluorescence probe was characterized by scanning electron microscope,X-ray diffraction patterns and energy-dispersive X-ray spectroscopy.Binding experimental results showed that the obtained fluorescent probe had high adsorption capacity,high specificity(QMIPs@UVPs/QNIPs@UCPs=1.7),fast adsorption kinetic(20 min for reaching balance at 25 mg/L)and stable photochemical characteristics.Under the optimized experimental conditions,the linear range of the calibration curve was 5～100μg/L.The minimum detection limit was 0.12 μg/L(S/N=3).The proposed method was also applied to determine CLB in pork and potable water samples with recoveries ranging from 81.66-102.46%and RSD less than 5%(n=3).Therefore,this method can be used in RAC analysis of practical samples.