Quantification of Aged Veterinary Anticoccidials In Poultry Manure Using LC/MS-MS.

Veterinary antimicrobials are widely used in poultry feed at sub-therapeutic levels. These are mostly clinical antibiotics that have been found in agricultural watersheds, presumably from land application of manure. As a result, they are losing popularity and being replaced by anticoccidials such as polyether ionophores (e.g. monensin, salinomycin, and narasin). Poultry can excrete up to eighty percent of anticoccidials as the parent compound and similar concerns surround their persistence in the environment. Little attention has been directed to method development for quantitatively measuring polyether ionophores from complex matrices like poultry manure without using complicated sample clean up techniques. Also, most developed methods have been validated on only freshly spiked matrices. We have developed and validated a rapid and sensitive methanol extraction method for quantifying these commonly used ionophores from poultry litter that are aged analytes. Nigericin as a surrogate and ¹³C-erythromycin as an internal standard  have been used for precise quantification and recovery studies.  Results from these studies along with potential problems and solutions due to improper matrix-match during method development will be presented.