Residues of nitrofuran antibiotic parent compounds and metabolites in eyes of broiler chickens
Résumé
Nitrofuran antibiotic residues in food continue to be of international concern. The finding of sources of semicarbazide (SEM), other than through the misuse of nitrofurazone, present a challenge to the use of SEM as a definitive marker residue for this drug. Detection of intact (parent) nitrofurazone would avoid confusion over the source of SEM residues. Broiler chickens were fed sub-therapeutic nitrofuran-containing diets and tissues analysed for parent compounds and metabolites by LC-MS/MS. Depletion half-lives in muscle were longer for tissue-bound metabolite residues, 3.4 d (AOZ, AMOZ) to 4.5 d (SEM), than total metabolite residues, 2.0 d (AOZ) to 3.2 d (SEM). Metabolite concentrations were higher in eyes than muscle. Metabolite half-lives in eyes ranged from 8.5 d (AHD) to 20.3 d (SEM). Nitrofuran parent compounds were also detected in eyes.. Furaltadone was detected in single eyes after 21 d withdrawal of a 6 mg kg-1 furaltadone diet. When 50 eyes from broilers containing metabolites in muscle close to the 1 µg kg-1 MRPL were pooled into single samples, 1.2 ng furazolidone and 31.1 ng of furaltadone were detected, but nitrofurazone was not detected due to the long depletion half-life of SEM in muscle. Further studies are required to improve LC-MS/MS nitrofurazone sensitivity and refine the sample size necessary to use nitrofurazone detection in pooled eyes as a complement to SEM detection in muscle.
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