Determination of Finasteride in Human Plasma by HPLC-MS

The study developed a high-performance liquid chromatography and electrospray ionization mass spectrometry (HPLC-ESI-MS) method to determine finasteride levels in human plasma. The method used a mobile phase of ammonium acetate/water and methanol, with plasma samples extracted using ethyl acetate and separated by a C_18 column. The results showed a linear standard curve for finasteride concentration ranging from 0.491 to 98.2 μg·L^-1, with a high correlation coefficient (r=0.9999). The method demonstrated a relative recovery of 90%-110%, with intra-day and inter-day relative standard deviations (RSD) under 5%. The quantitation limit was 0.49 μg·L^-1, and the extraction recovery exceeded 90%. The study concluded that this method was stable and reliable for determining finasteride in human plasma and suitable for pharmacokinetic studies.