Determination of Finasteride in Human Serum by LC-MS/MS

The study developed and validated a method using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) to determine finasteride levels in human serum. Beclomethasone served as the internal standard, and methyl tert-butyl ether (MTBE) was used for liquid-liquid extraction. The method demonstrated a limit of quantitation of 0.1 ng/mL and excellent linearity in the 0.1-20.0 ng/mL range with an R² of 0.9997. Intra-day precision and accuracy ranged from 6.3-10.6% and 97.3-103.6%, while inter-day precision and accuracy were 0.8-5.2% and 99.8-102.5%, respectively. The recovery rate of the sample extract was between 80-83%.