Method of assay for the coccidiostat amprolium in a wide range of animal feedstuffs

Abstract

For a limited range of feedstuffs for broiler fowls, the current method of assay for amprolium gives accurate results but for other feedstuffs the results may be erroneous. For official testing, a method is needed by which all the amprolium can be isolated from other feed components. We have developed a method that is dependent on the cationic character of the active part of the amprolium molecule. After extraction with a mixture of methanol and water, the amprolium cation is combined with an anionic surfactant and the resulting complex is extracted with dichloromethane. From this solution, the amprolium cation is adsorbed on to aluminium oxide; the interfering feed components are eluted with a mixture of dichloromethane and methanol, and then the amprolium itself is eluted with pure methanol. After evaporation of the excess of methanol from the eluate, a colour reaction is carried out and a spectrophotometric reading taken.

Should a feed contain exceptionally large amounts of grassmeal or should bentonite be used as a pellet-improving agent, low results will be obtained by using the method described.