Determination of tilmicosin in swine feeds by liquid chromatography.
This method determines tilmicosin in feeds over a concentration range of 100 to 600 mg/kg. Tilmicosin is extracted from swine feeds by adding 200 mL of a swine feed extractant (20 + 80, acetonitrile-Millipore water, pH 2.5, with 25 mM dibutylammonium phosphate) to 20 g feed and placing on a shaker table for 1 h. This extractant is filtered and analyzed by liquid chromatography (LC). A gradient LC method is used to separate tilmicosin from the feed matrix in 30 min of run time. The recovery of tilmicosin from fortified feeds ranged from 96.7 to 112%, with the coefficients of variation (CVs) ranging from 1.4 to 3.9%. The determination of tilmicosin in medicated feeds resulted in an average recovery of 92.7% of labeled claim for pelleted feeds at 200 mg/kg and 99.1% of labeled claim for mash feeds at 400 mg/kg. Determination of tilmicosin in medicated feeds resulted in CVs ranging from 2.6 to 3.8%. The method has shown no interference with 18 other drugs.
Readnour
R S
RS
Elanco Animal Health, A Division of Eli Lilly and Co., Greenfield, IN 46140, USA.
Helton-Groce
S L
SL
Dixon
S S
SS
D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002853:Chromatography, Liquid; D005506:Food Contamination; D016014:Linear Models; D018942:Macrolides; D011786:Quality Control; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D015645:Tylosin / Q000031:analogs & derivatives* / Q000032:analysis
D000900:Anti-Bacterial Agents; D018942:Macrolides; C052319:tilmicosin; D015645:Tylosin