Optimization and Validation of Europium-Sensitized Fluorescence Method for Determination of Tetracycline Antibiotics in Water from Fish Farms

Sensitized europium fluorescence was used for simple, fast and efficient determination of tetracycline residues in water from fish farms. Tetracycline antibiotics: oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) were extracted from water samples using polymeric hydrophilic–lipophilic balanced cartridges. After evaporation and pre-concentration, tetracyclines form a complex with europium and citric acid as coligand at pH 8.5. The complex formed has a wide absorption spectrum at 388 nm and a narrow emission maximum at 619 nm resulting from the 5D0 - 7F2 transition within the europium ion. The complex is stable with intensive fluorescence and linear in the concentration range of 5-2500 µg/L for tetracycline and oxytetracycline and 5-1000 µg/L for chlortetracycline. The detection limit was 0.68 µg/L for OTC, 1.29 µg/L for TC and 0.65 µg/L for CTC, respectively.The proposed method is very sensitive and particularly applicable to samples where low concentrations of tetracycline antibiotics are expected.