LC–Tandem-MS Validation for the Quantitative Analysis of Levonorgestrel in Human Plasma

Abstract

In this study, a rapid, sensitive and reproducible liquid chromatography–tandem mass spectrometry method for the determination of levonorgestrel in human plasma, was developed and validated. With a structural analogue norethindrone as the internal standard, levonorgestrel was extracted from plasma using ethyl acetate. The organic layer was evaporated to dryness and the residue was reconstituted in mobile phase. An aliquot of 20 μL was chromatographically analyzed on a Phenomenex Luna C18 column with water and acetonitrile as the mobile phase. Selected reaction monitoring was specific for mass detection employing positive electrospray ionization. The calibration standards were linear over the concentration range 0.625–40 ng mL−1. The intra- and inter-day precision over the entire concentration range were less than 8.16%. The method was found to be suitable for application to a pharmacokinetic study after oral administration of 1.5 mg levonorgestrel tablet to 20 healthy female volunteers.