title: Determination of maduramicin in feedingstuffs and premixtures by liquid chromatography: development, validation, and interlaboratory study.
abstract: A reversed-phase liquid chromatography method for determination of maduramicin in feedingstuffs and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was methanol. Maduramicin was detected at 520 nm after postcolumn derivatization with vanillin. Recovery was >90%. The repeatability relative standard deviation (RSDr) in feeds (1-5 mg/kg) and premixtures (500 mg/kg) ranged between 2.7 and 7.7%; the within-laboratory reproducibility was between 3.7 and 8.5%. The limit of quantitation was 2 mg/kg. Other feed additives did not interfere in the assay. The method showed ruggedness against small changes in the extraction conditions, eluant composition, and conditions for postcolumn derivatization. The presence of water in the extraction solvent negatively affected the recovery. In the collaborative study, 5 feeds (4 positive at 2.5-9 mg/kg, 1 blank) and 1 premixture (450 mg/kg) were analyzed by 10 laboratories. The RSDr of the feedingstuffs varied between 3.29 and 8.53%. The HORRAT ranged between 1.10 and 1.98. Recoveries were >90%, except for one participant (80%). One laboratory detected small signals in the blank sample, corresponding to 0.7 and 0.8 mg/kg. For the premixture, the RSDr was 3.15% and the HORRAT was 1.80.
authors.affiliation: RIKILT-Institute of Food Safety, PO Box 230, 6700 AE, Wageningen, The Netherlands. jacob.dejong@wur.nl
authors.forename: Jacob
authors.initials: J
authors.lastname: de Jong
authors.forename: Bernd
authors.initials: B
authors.lastname: Stoisser
authors.forename: Karl
authors.initials: K
authors.lastname: Wagner
authors.forename: Marinka
authors.initials: M
authors.lastname: Tomassen
authors.forename: Jaap
authors.initials: J
authors.lastname: Driessen
authors.forename: Peter
authors.initials: P
authors.lastname: Hofmann
authors.forename: Hans-Artur
authors.initials: HA
authors.lastname: Putzka
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D002853:Chromatography, Liquid; D007783:Lactones / Q000032:analysis*; D012680:Sensitivity and Specificity
chemical_list: D007783:Lactones; C018091:maduramicin