Determination of neomycin B residue in bovine edible tissues and milk by ion-pair liquid chromatography-tandem mass spectrometry

Abstract An analytical method based on ion-pair liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed to accurately determine neomycin B in bovine edible tissues (muscle, kidney, liver, fat) and milk. The pre-treatment procedure, including protein precipitation and solid phase extraction, was investigated to extract the analytes of interest better and remove matrix interferences. After sample pre-treatment, the 1% heptafluorobutyric acid 20 μL was added to the final extract. Then, the chromatography and mass spectrometry conditions were optimized, and the established method was validated. Good linearity ( r > 0.999) was obtained at five matrices. The limit of detection, and the limit of quantitation were 10 and 20 μg kg −1 , respectively. Trueness and repeatability at 0.5× maximum residue limit (MRL), MRL, and 2× MRL ranged from 96.67 to 109.54% and 3.36 to 9.01%, respectively. Adding the ion-pair agent to the extracts, rather than the mobile phase, ensures that neomycin B is efficiently retained on the reverse-phase column without contaminating the ion source. This simple and sensitive LC-MS/MS method is suitable for regularly monitoring neomycin residue in bovine edible tissues and milk.