DETECTION OF MONENSIN RESIDUES IN POULTRY LIVER USING AN ENZYME-IMMUNOASSAY

Monensin, a carboxylic acid ionophore, is commonly fed to poultry to c ontrol coccidiosis. A method for the detection and quantification of m onensin residues in liver has been developed, Samples (3 g) were extra cted with acetonitrile-water and applied to a competitive enzyme immun oassay using a polyclonal antiserum raised against a monensin-transfer rin conjugate, The limit of detection (mean + 3s) calculated from the analysis of 12 known negative samples was 2.91 ng g(-1). Intra- and in ter-assay RSD were determined as 8.5 and 10.6%, respectively, using a liver sample fortified with 20 ng g(-1) monensin, A pharmacokinetic st udy in which 70 six week old broilers were fed monensin at a rate of 1 20 mg kg(-1) in their feed for 14 d resulted in mean monensin liver re sidues of 102 ng g(-1). However these had fallen below the limit of de tection of the assay within the 3 d withdrawal period recommended by t he manufacturer.