Determination of Finasteride by Single-Sweeping Oscillopolarography

In a mixed base solution of 0.01 mol·L-1 HCl and 2.5×10-5mol·L-1 dodecyl-trimethyl ammonium chloride in aqueous ethanol solution (H2O+C2H5OH=21+4),a sensitive reduction wave was given by finasteride with its peak potential at -1.27 V (vs.SCE) by single sweeping oscillopolarography.Linear relationship between the 2nd derivative of peak current (I″p) of the reduction wave and the concentration of finasteride was obtained in the range of 1.0-10.0 mg of finasteride per L of solution (r=0.999 6),with a detection limit of 0.2 mg·L-1.The RSD′s found when tested at the concentration level of 2.0 mg·L-1 was 1.3% (n=11).The proposed method has been applied to the analysis of finasteride tablet samples,giving recoveries in the range of 99.7%-105.2%.