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

Abstract

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.

Sensitive and rapid quantitation of dexamethasone in human plasma using liquid chromatography coupled with triple quadrupole mass spectrometer

“…The newly developed method perfectly covers the regulatory recommended lower limit of quantification concentration as well as accurately measuring the peak concentration (LLOQ: ∼2 ng/ml and ULOQ: ∼600 ng/ml) than any other published methods. 8–14 Although there are few methods like Mei Zhang et al, 8 who have developed the LC-MS/MS method with 0.5–500 µg/L linearity range, and an analogous internal standard or A. Laura Nijstad et al, 10 who have developed the LC-MS/MS method with 1–500 ng/ml linearity range, however, the newly developed method is superior to these methods for the simple reason of its superior extraction process (protein precipitation vs. liquid–liquid extraction). Protein precipitation is known to have an inherent matrix effect, that is normally not seen in liquid–liquid extraction.…”