Determination of tilmicosin in bovine milk by liquid chromatography with ultraviolet detection.
A method is described for determining tilmicosin in bovine milk by liquid chromatography with ultraviolet (UV) detection. Samples are defatted by centrifugation. The lower skim layer is cleaned on a C18 solid-phase extraction cartridge. The extract is concentrated and analyzed with a reversed-phase phenyl column with UV detection at 280 nm. The method was validated with control milk fortified at 50, 100, and 200 ng/mL. Average recoveries (and intralaboratory coefficients of variation) were 97% (9%), 98% (5%), and 101% (3%), respectively. The limit of quantitation is approximately 20 ng/mL, and the limit of detection is approximately 13 ng/mL. The method was tested on milk from a cow dosed with tilmicosin.
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U.S. Food and Drug Administration, Center for Veterinary Medicine, Office of Science, Beltsville, MD 20705, USA.
D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002417:Cattle; D002853:Chromatography, Liquid; D005260:Female; D018942:Macrolides; D008892:Milk / Q000737:chemistry*; D015645:Tylosin / Q000031:analogs & derivatives* / Q000032:analysis; D014466:Ultraviolet Rays
D000900:Anti-Bacterial Agents; D018942:Macrolides; C052319:tilmicosin; D015645:Tylosin