Tetracyclines and Their Epimers in Animal Tissues by High-performance Liquid Chromatography

An analytical method for the simultaneous determination of tetracycline (TC), oxtetracycline (OTC), chlortetracycline (CTC) with their 4-epimers, and doxycycline (DC) in animal tissues has been developed and validated. The extraction of the analytes from biological matrice was carried out with a 0.02 M oxalic acid (pH=4.0). The samples were cleaned up by using a solid phase extraction procedure with polymeric cartridges. Chromatographic separation was achieved on a C 18 analytical column using a mobile phase consisting of acetonitrile, methanol and 0.02 M oxalic acid in gradient mode. Detection was carried out by UV detector at λ = 355 nm. The method has been validated according to the Commission Decision 2002/657/EC. The recoveries of the analytes from the spiked samples were 50%-80%. The decision limits (CCα) were from 110 to 125 μg/kg and the detection capabilities (CCβ) were from 120 to 155 μg/kg, depending on the analytes. The prepared method was successfully verified in the National Residue