title: Clenbuterol storage stability in the bovine urine and liver samples used for European official control in the azores islands (portugal).
abstract: Clenbuterol is a well-known growth promoter, illegally used in farm animals, especially in cattle. Samples collected for the screening of beta(2)-agonist residues in Portuguese Azores Islands must travel through all the nine islands until they reach Azores Central Laboratory. If any suspicious sample is detected, it must be further transported to the National Reference Laboratory in Lisbon for confirmation. As a consequence of these circumstances, samples are submitted to different transport and storage times, as well as different temperature conditions and in some cases successive freezing and thawing cycles. As clenbuterol is the most detected beta(2)-agonist growth promoter in the Portuguese Residue Monitoring Plan, studies were conducted on the stability of this compound in incurred samples (bovine liver and urine) at +4, -20 and -60 degrees C over time. Samples kept at -20 degrees C were also analyzed over time after successive freezing and thawing cycles. The analyses of clenbuterol over time were performed by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM). Clenbuterol in incurred urine and liver samples was significantly stable up to 20 weeks at -20 and -60 degrees C and after, at least, six consecutive freezings and thawings. At +4 degrees C, clenbuterol remained stable, at least until 12 weeks in urine and up to 20 weeks in liver.
authors.affiliation: Laboratorio Regional de Veterinaria, Direccao de Servicos de Veterinaria, Direccao Regional do Desenvolvimento Agrario, Vinha Brava, Angra do Heroismo, Acores, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Pinheiro
authors.forename: Bruno
authors.initials: B
authors.lastname: Jesuino
authors.forename: Jorge
authors.initials: J
authors.lastname: Barbosa
authors.forename: Humberto
authors.initials: H
authors.lastname: Ferreira
authors.forename: Fernando
authors.initials: F
authors.lastname: Ramos
authors.forename: José
authors.initials: J
authors.lastname: Matos
authors.forename: Maria Irene Noronha
authors.initials: MI
authors.lastname: da Silveira
mesh_terms: D000318:Adrenergic beta-Agonists; D000818:Animals; D002417:Cattle / Q000378:metabolism* / Q000652:urine; D002976:Clenbuterol / Q000032:analysis* / Q000737:chemistry / Q000652:urine; D004355:Drug Stability; D005615:Freezing; D008401:Gas Chromatography-Mass Spectrometry; D006133:Growth Substances; D006358:Hot Temperature; D008099:Liver / Q000737:chemistry*; D011174:Portugal; D012680:Sensitivity and Specificity
chemical_list: D000318:Adrenergic beta-Agonists; D006133:Growth Substances; D002976:Clenbuterol