Veterinary Drugs Residue Methods


Category Other Veterinary Drugs
Drug Class Name Macrolide
Method Title Determination of Tilmicosin by HPLC/Ion Pairing
Method Date 2005/08/25
Method Type Screening, Quantitative
Scope and Application This method is useful for quantifying levels of Tilmicosin residues in liver, kidney, and beef/muscle tissue.
Method Summary Homogenized tissue in methanol is repeatedly extracted by centrifugation before adding a 10 percent solution of sodium chloride to the extract and the pH adjusted to below 6.0. Partitioning is then done by adding hexane to the aqueous extract before discarding the organic layer. The aqueous layer is adjusted to pH 9.0 plus or minus 0.4 prior to adding 2,1 chloroform,hexane (v,v) and the mixture shaken. This step is repeated before evaporating the combined organic layer to dryness. The residue is reconstituted in methanol and 0.05 M dibutyl ammonium phosphate added prior to further centrifugation. The extract is then pressed through a 0.22 micrometer acrodisc filter ready for analysis by HPLC,ion pairing with a UV,Vis detector. An Adsorbosphere Phenyl analytical column is used.
Applicable Concentration Range Tilmicosin may be determined in liver and kidney at ≥ 600 µg kg-1 concentration level, and muscle/beef at ≥300 µg kg-1.
QC Requirements See attached SOP
Method Source USDA-FSIS
Method SOP PDF icon SOP