Multiresidue Determination of Growth Promoters in Bovine Serum using QuEChERS and UHPLC-Q-ORBITRAP: Validation and In VivoStudy

A reliable method using a QuEChERS approach and liquid chromatography coupled to Q-Orbitrap mass spectrometry was optimized and validated for the quantification of 20 growth promoters in bovine serum. The recoveries ranged from 91.4–114.1%, relative standard deviations varied between 0.3–4.0%, and CCα values were between 0.023–0.350 μg L–1. The developed method was applied in an in vivostudy using steers, which were intramuscularly treated with commercial injections containing stanozolol. A rapid metabolization was observed, with a detection window ranging from 3 to 10 days. The stability of incurred stanozolol was confirmed after 240 days at −20 °C and also after 5 freeze–thaw cycles. To the best of our knowledge, this is the first work in which an in vivostudy was performed to support the monitoring of stanozolol in bovine serum. In addition, the use of Q-Orbitrap high-resolution mass spectrometry allows for retrospective analysis from a surveillance perspective.