Liquid chromatography-mass spectrometry methods for the determination of andarine and ostarine in rat serum after protein precipitation

Abstract

Quantitative determination of andarine and ostarine in rat serum was achieved using two selective liquid chromatography-mass spectrometry methods (LC-MS). After extracting the analytes and internal standards (ostarine and andarine) from the serum samples through a high throughput extraction method (protein precipitation), the samples were analysed by reverse phase liquid chromatography using as mobile phase a mixture of methanol and 10 mM ammonium formate solution (75:25, v/v). The analytes were detected following specific transitions in MS/MS mode of the QTOF mass spectrometer, after pre-ionization by a negative electrospray ionization source (ESI-). Both methods were validated for a concentration range between 50-10000 ng/mL according to the current official guidelines with regards to carry-over, selectivity, linearity, within-and between-run accuracy, precision and can be applied to accurately measure andarine and ostarine levels in rat serum samples in order to design a pharmacokinetic study or for doping control purposes.