| Ciprofloxacin（CIP）and tetracycline（TC）are common antibiotics,which are widely used in the prevention and the treatment of infectious diseases in aquaculture because of their low cost and good antibacterial effect.However,these antimicrobial agents can accumulate in the environment and pose a threat to human health if they are not used properly,so it is very necessary to detect the residues of such drugs in aquatic products.Compared with the fluorescent probe which has one single emission wavelength,the ratio fluorescent probe has the advantages of strong anti-interference,high sensitivity and obvious fluorescence color change.Rare earth sensitized fluorescence is often used as the recognition element of the ratio fluorescence probe because of its advantages such as long excitation lifetime,narrow emission peak and large stokes shift.In this paper,based on the mechanism of rare earth sensitization fluorescence and europium element,ratio fluorescence sensors were prepared and used for the detection of ciprofloxacin and tetracycline antibiotics in aquatic products,which had good practical application and provided some reference basis for the application of rare earth sensitization fluorescence in food safety detection.The main contents of this paper are as follows:1.Based on europium ions and fluorescein isothiocyanate（FITC）,an Eu-FITC ratio fluorescence sensor was constructed and used for the quantitative determination of ciprofloxacin antibiotics.Under the excitation at 340 nm,the Eu-FITC ratio fluorescence sensor emitted a strong fluorescence peak of FITC at 505 nm,but didn’t show the characteristic fluorescence peak of europium ions at 615 nm.When CIP was added into the detection system,CIP formed a complex with europium ions and transferred energy to europium ions through antenna effect,thus emitting characteristic fluorescence of europium ions at 615 nm.The fluorescence intensity of Eu-FITC ratio fluorescence sensor at 615 nm increased with the increase of the concentration of ciprofloxacin,and the fluorescence intensity at 505 nm remained basically unchanged,which can be used as a reference.Under the optimal experimental conditions,when the concentration of CIP was in the range of 1.72×10-7-2.27×10-5mol/L,the fluorescence intensity ratio(I615/I505)of Eu-FITC ratio fluorescence sensor showed a good linear relationship with the concentration of CIP,and the detection limit was 5.24×10-8mol/L.Interference studies showed that the Eu-FITC ratio fluorescence sensor had strong selectivity to CIP.The recovery rate of CIP was 94.2%to 109.4%in the actual sample test and the relative standard deviation（RSD）was less than 3,the results showed that this sensor was successfully applied to the detection of CIP in fish.2.Eu-CDs ratio fluorescent probe was prepared by mixing europium ions and carbon dots（CDs）in a certain proportion for the detection of tetracycline antibiotics.Under the excitation at 340 nm,the Eu-CDs ratio fluorescence sensor emitted a characteristic fluorescence peak of CDs at 430 nm and a weak fluorescence peak of europium ions at 550nm.When TC was added into the detection system,TC formed a complex with europium ions and transferred energy to europium ions through antenna effect.Therefore,the fluorescence peak of the Eu-CDs ratio fluorescence sensor at 550 nm was significantly enhanced,while the fluorescence intensity at 430 nm remained basically unchanged.Under the optimum experimental conditions,the fluorescence intensity ratio(I550/I430)of the Eu-CDs ratio fluorescence sensor showed a good linear relationship with the concentration of TC when the concentration of TC ranged from 6.67×10-8to 1.33×10-5mol/L,and the detection limit was 3.24×10-8mol/L.The interference studies showed that the Eu-CDs ratio fluorescence sensor has strong selectivity for TC.The recovery rate of TC was 97.8%to121%in the actual sample test and the RSD was less than 3,the results showed that this sensor has been successfully applied to the detection of TC in fish. |
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