Determination of 5β-finasteride in Finasteride by HPLC
Objective:To establish a HPLC method for the determination of 5β-finasteride in finasteride.Method:The separation was achieved on Welch Xtimate C18(4.6×150 mm,3.5 μm)column using 8%tetrahydrofuran in water(mobile phase A)and 8%tetrahydrofuran in acetonitrile(mobile phase B)with gradient elution program.The flow rate was kept at 1.0 mL/min at 25℃,the detection wavelength was 210 nm.Results:In this method,the well separation of 5β-finasteride from finasteride,impurities(A,B,C and 17α-finasteride)and the other impurities produced from the forced degradation tests of finasteride which proved the method was specific.The results showed a good linear relationship(r≥0.990)between the concentrations of 5β-finasteride and finasteride in the ranges of 0.27～2.17 and 0.28～2.23 μg·mL-1,respectively.The recovery of 5β-finasteride was 108.2%.The injection precision and repeatability were good.The resolution solution and the sample solution were stable for 94 hours and 82 hours at room temperature.The resolutions between 5β-finasteride and finasteride were 4.10～4.80 under different chromatograph conditions with good durability.Conclusion:The method was established with good specificity,high accuracy,simple and durable which can be used for the quantitative analysis of 5β-finasteride in finasteride.
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