Spectrophotometric determination of flurazepam in pharmaceutical formulations

Abstract

Two spectrophotometric methods are proposed for the determination of flurazepam in pharmaceutical formulations. The first one, a very sensitive and fast direct spectrophotometric method is based on the measurement of the absorbance of aqueous flurazepam monohydrochloride solution (pH 6) at the wavelength of maximum absorption at 230 nm. The second one, a difference spectrophotometric method, is based on the measurement of the absorbance difference between equimolar solutions of flurazepam monoprotonated (pH 6) and diprotonated (pH 0) forms at 225 nm. Both methods were applied to the determination of flurazepam in capsules which contain flurazepam monohydrochloride. To extend the application range of both methods, we examined optimum conditions which enable the determination of flurazepam in formulations in form of flurazepam dihydrochloride.