A Simple and Rapid LC-MS/MS Method for Determination of Dexamethasone in Bovine Milk

This study provides insight into the development and validation of the simple, rapid and sensitive method of Liquid Chromatography-Tandem Mass Spectrometry for determining the residues of dexamethasone in bovine milk. The maximum residue limit for dexamethasone in bovine milk is 0.3 ng/ml⁻¹. Chromatographic separation was achieved on an Agilent Proshell 120 SB:C18 (2.7µm 100x3.0 mm) column. The bovine milk was extracted with ethyl acetate, and the evaporated elution was dissolved with hexane, water and methanol, and analyzed by the LC-MS/MS method. The mobile phase A was a solution of 5 Mm ammonium formate in water, while the mobile phase B was 0.1% formic acid in acetonitrile. The calibration graphics were prepared within the range of 0.15–0.6 ng/ml⁻¹, and a successful linearity was achieved (r ≥0.999). The limit of detection was 0.016 ng/ml⁻¹. The decision limit (CCα) and detection capability (CCβ) were 0.34 and 0.38 ng/ml⁻¹, respectively.