the determination of cysteamine supplementation in commercial animal feeds was developed.Samples were extracted with a mixture of 0.5 % hydrochloric acid (HCl) – acetonitrile (ACN) (90:10,v/v), matrix interferences were removed with a C18 cartridge, and cysteamine was derivatized using5,5'-dithiobis-(2-nitrobenzoic) acid (DTNB) as Ellman's reagent targeting to the thiol group in themolecule. Quantification of cysteamine was performed on a C18 column with DAD at 323 nm. Thedeveloped method had a limit of detection (LOD) of 1.1 mg/l, good linearity of the calibration curve(R2 0.9998), high recoveries (>
92 %), and high reproducibility (RSD <
2.0%).