title: Determination of levamisole in feeds by liquid chromatography coupled to electrospray mass spectrometry on an ion trap.
abstract: Test methods have to be developed by laboratories for official control to monitor possible misuse of veterinary drugs in animal productions, also through feeding stuff. A novel method for identification and quantification of levamisole in feeds by liquid chromatography coupled to electrospray mass spectrometry in an ion trap (LC/ESI-MS/MS) is herein described; after a single-step cleanup by liquid-liquid extraction from the feed and separation by reversed-phase liquid chromatography, levamisole was determined and unambiguously confirmed by tandem mass spectrometry, on the basis of two product ions. The method was in-house validated, according to the Regulation 882/2004/EC, evaluating trueness, repeatability, within-laboratory reproducibility, ruggedness, specificity, and the limit of quantification (LOQ). The method is reliable and specific for complete and complementary feeds for pigs, cattle, rabbits and poultry; very good mean recoveries (higher than 92 %) and precision (RSD values < 15.2%) were attained. The LOQ at 2.0 mg/kg was verified. Moreover, we describe how the method was developed to support Italian Police investigations regarding illegal treatments of pigs; in this case, since the drug(s) added to the feed were unknown, a preliminary untargeted analysis was performed by full scan mass spectrometry on an ion trap, from 50 up to 2000 m/z; the presence of levamisole was hypothesised, on the basis of the most abundant ion and its fragmentation pattern. Then, levamisole was unambiguously confirmed by the ion trap LC/ESI-MS/MS method.
authors.affiliation: Dept. of Chemistry, Istituto Zooprofilattico Sperimentale del Mezzogiorno, via Salute 2, Portici, NA 80055, Italy. pasquale.gallo@cert.izsmportici.it
authors.forename: Pasquale
authors.initials: P
authors.lastname: Gallo
authors.forename: Serena
authors.initials: S
authors.lastname: Fabbrocino
authors.forename: Luigi
authors.initials: L
authors.lastname: Serpe
mesh_terms: D000821:Animal Feed / Q000032:analysis* / Q000592:standards; D000822:Animal Husbandry / Q000331:legislation & jurisprudence; D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D007558:Italy; D007978:Levamisole / Q000032:analysis*; D059625:Liquid-Liquid Extraction; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods*; D013552:Swine; D019155:Veterinary Drugs / Q000032:analysis
chemical_list: D019155:Veterinary Drugs; D007978:Levamisole