A highly sensitive method for the quantification of fludrocortisone in human plasma using ultra‐high‐performance liquid chromatography tandem mass spectrometry and its pharmacokinetic application

A simple and high sensitive ultra‐high‐performance liquid chromatography tandem mass spectrometry method for the determination of fludrocortisone in human plasma was developed and validated as per guidelines. The analyte and internal standard (IS), fludrocortisone‐d₅, were extracted from human plasma via liquid–liquid extraction using tert‐butyl methyl ether. The chromatographic separation was achieved on a Chromolith RP_18e column using a mixture of acetonitrile and 2 mm ammonium formate (70:30, v/v) as the mobile phase at a flow rate of 0.7 mL/min. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring and positive ion mode. The precursors to product ion transitions monitored for fludrocortisone and IS were m/z 381.2 → 343.2 and 386.2 → 348.4, respectively. The assay was validated with linear range of 40–3000 pg/mL. The intra‐ and inter‐day precisions (relative standard deviation) were within 0.49–7.13 and 0.83–5.87%, respectively. The proposed method was successfully applied to pharmacokinetic studies in humans. Copyright © 2015 John Wiley & Sons, Ltd.