LAUSR

Progesterone is the predominant gestagen in most mammals studied so far. It plays a substantial role in the regulation of the female reproductive cycle and in providing support for pregnancy maintenance. Despite its known functions, gaps in knowledge are present regarding its reduced metabolites that potentially exert biological activity. Therefore, a new UHPLC-HRMS method based on a Q Exactive™ mass spectrometer was developed to detect and quantify simultaneously progesterone, its hormone precursor pregnenolone and 10 reduced progestogens (20α-DHP, 20β-DHP, 3α,5α-THP, 3α,5β-THP, 3β,5α-THP, 3β,5β-THP, 3α-DHP, 3β-DHP, 5α-DHP and 5β-DHP) in plasma and serum samples. Purification was achieved by an optimized solid phase extraction (SPE) and the analysis was conducted in positive electrospray ionization (ESI) mode with the application of multiplexed selected ion monitoring (msx-t-SIM). The method validation included the study of sensitivity, selectivity, curve fitting, carry-over, accuracy, precision, recovery and matrix effects. Despite the poor ionization properties of underivatized steroids, a high sensitivity in the range of pg/mL was achieved.