Determination of valnemulin in swine and bovine tissues by ultra-high performance liquid chromatography–tandem mass spectrometry

• Residues of valnemulin in swine and bovine tissues were determined by UHPLC–MS/MS.
• LOD and LOQ for valnemulin were far below MRLs set by EU.
• Good recoveries and sample throughput were achieved after method optimization.

A sensitive and reliable method has been developed and validated for the determination of valnemulin in swine and bovine muscle, liver, and kidney using solid-phase extraction (SPE) and ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). The tissue samples were extracted with mixture solution of acetonitrile and 0.01 mol/L hydrochloric acid, defatted by n-hexane, and further cleaned up using SPE cartridges with polymeric sorbent. Gradient UHPLC separation was performed using an Acquity BEH C18 column with water and acetonitrile as the mobile phase. Multiple reaction monitoring mode of two precursor-product ion transitions for valnemulin was used. Mean recoveries from fortified samples ranged from 93.4 to 104.3% with 3.3–10.7% relative standard deviation. The limit of detection and quantification was 0.2 and 1 μg/kg for the analyte, respectively.