Liquid chromatographic determination of moxidectin residues in cattle tissues and confirmation in cattle fat by liquid chromatography/mass spectrometry.
Moxidectin, a potent new endo- and ectoparasitic agent, is determined in cattle tissues by liquid chromatography (LC) with fluorescence detection. Moxidectin residues in cattle fat are confirmed with thermospray LC/mass spectrometry (MS). Moxidectin is extracted from the tissue with acetonitrile; the extract is partitioned with hexane, concentrated, and reacted with acetic anhydride, 1-methylimidazole, and dimethylformamide to produce a fluorescent product. The validated sensitivity of the LC/fluorescence method was 10 ppb, with a limit of detection typically between 1 and 2 ppb. Average recoveries from cattle fat, muscle, liver, and kidney were 99, 95, 89, and 92%, respectively. LC/MS confirmatory method determined the underivatized parent compound following the acetonitrile-hexane partitioning step, with an average recovery of 108% at the 250 ppb level in cattle fat.
Khunachak
A
A
American Cyanamid Company, Agricultural Research Division, Princeton, NJ 08543-0400.
Dacunha
A R
AR
Stout
S J
SJ
D000273:Adipose Tissue / Q000737:chemistry*; D000818:Animals; D000871:Anthelmintics / Q000032:analysis*; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002417:Cattle; D002853:Chromatography, Liquid / Q000379:methods; D005453:Fluorescence; D007668:Kidney / Q000737:chemistry*; D008099:Liver / Q000737:chemistry*; D018942:Macrolides; D013058:Mass Spectrometry; D009132:Muscles / Q000737:chemistry*
D000871:Anthelmintics; D000900:Anti-Bacterial Agents; D018942:Macrolides; C027837:moxidectin