Analytical procedure for the determination of doxycycline residues in animal tissues by liquid chromatography

A sensitive liquid chromatographic method for the determination of doxycycline in animal tissues has been prepared and validated. The extraction of the analyte from biological matrix was performed with the solution of oxalic acid and ethyl acetate. The samples were cleaned up by solid phase extraction (SPE) procedure using a carboxylic acid cartridge. Chromatographic separation was carried out on the C8 analytical column and the mobile phase consisting of acetonitryle-methanol-0.02 M oxalic acid (20:15:65, v/v/v), with the detection by UV detector at λ = 355 nm. This method has been successfully validated and used for the quantitative determination of doxycycline in animal tissues samples. Recoveries from spiked samples were from 65% to 90%. The decision limits (CCα) were 110 µg/kg and 610 µg/kg for muscles and kidneys, respectively.