Procedure
Separately inject equal volumes (about 20 µL) of the
Standard preparation and the
Test preparation into the chromatograph, record the chromatograms, and measure the responses for the peaks. Calculate, in turn, the percentages of 1-[2,4-dichloro-
-[(3-thenyl)-oxy]phenethyl]imidazole hydrochloride (tioconazole related compound A), 1-[2,4-dichloro-
-[(2,5-dichloro-3-thenyl)-oxy]phenethyl]imidazole hydrochloride (tioconazole related compound B), and 1-[2,4-dichloro-
-[(5-bromo-2-chloro-3-thenyl)-oxy]phenethyl]imidazole hydrochloride (tioconazole related compound C) in the portion of Tioconazole taken by the same formula:
100(WI / WU)(rU / rS),
in which
WI is the weight, in mg, of the respective USP Reference Standard taken to prepare the
Standard preparation,
WU is the weight, in mg, of Tioconazole taken to prepare the
Test preparation, and
rU and
rS are the peak responses at corresponding retention times, obtained from the
Test preparation and the
Standard preparation, respectively. The limit of each related compound is 1.0%.