Veterinary Drugs Residue Methods


Category Other Veterinary Drugs
Drug Class Name Macrolide
Method Title Confirmation of Tilmicosin by APCI-LC/MS3
Method Date 2002/03/15
Method Type Confirmatory, Quantitative
Scope and Application The method is suitable for the confirmation of Tilmicosin in liver, kideny 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 below 6.0. Partitioning is the 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) followed 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 also added prior to further centrifugation. The extract (an aliquot of which is used for HPLC-UV,Vis analysis) is then diluted 1 to 1 with 20,80 acetonitrile,water plus 0.05 percent TFA and pressed through a 0.2 micrometer acrodisc filter ready for analysis by positive mode APCI-LC,MS3. A Zorbax 2.1x50 mm SB-Aq analytical column is used.
Applicable Concentration Range The presence of trace levels of Tilmicosin residues may be confirmed in liver, kideny and beef/muscle tissue.
QC Requirements See attached SOP
Method Source USDA-FSIS
Method SOP PDF icon SOP