HPLC determination of colistin and aminoglycoside antibiotics in feeds by post-column derivatization and fluorescence detection

Reversed-phase, HPLC methods employing postcolumn derivatization and fluore scence detection were developed for the determination of the peptide colist in and four aminoglycoside antibiotics in feeds. Extraction of the analytes was by sonication and shaking with dilute hydrochloric acid. Post-column d erivatization was performed using orthophtaldialdehyde-2-mercaptoethanol ch emistry. Assay of colistin was by using an acetonitrile-aqueous sodium sulp hate-triethylammonium phosphate (pH 2.8) eluent. Aminoglycoside antibiotics :amikacin, kanamycin, gentamycin and neomycin were analyzed using a tetrahy drofuran-aqueous sodium sulphate-sodium pentanesulphonate-acetic acid mobil e phase. The method was also applied to some pharmaceutical preparations. P reliminary results showed that the method can be adapted for the assay of t he above antibiotics in meat and animal serum for residue and pharmacokinet ic studies.