DETERMINATION OF ETHOXYQUIN IN FEEDS BY LIQUID-CHROMATOGRAPHY - COLLABORATIVE STUDY

Ethoxyquin is a chemical antioxidant used in feeds, ingredients, fats, and oils, A liquid chromatographic (LC) method for determination of e thoxyquin was developed. The method involves acetonitrile extraction o f the sample and isocratic C-18 reversed-phase chromatography with amm onium acetate buffer-acetonitrile as mobile phase and fluorescence det ection. A collaborative study of the determination of ethoxyquin in va rious meals and extruded pet foods was conducted by The rams Company R esearch Laboratory Eleven laboratories analyzed 16 samples (including 2 blind duplicates) consisting of 7 meat meals and 9 extruded pet food s. Sample means ranged from 0.25 to 289 ppm. Repeatability standard de viations ranged from 0.08 to 3.2 ppm, and repeatability relative stand ard deviations ranged from 4.5 to 32%. Reproducibility standard deviat ions ranged from 0.12 to 13 ppm, and reproducibility relative standard deviations ranged from 4.5 to 55%, The LC method for determination of ethoxyquin in feeds has been adopted first action by AOAC INTERNATION AL.