The use of internal standard method for derivative-spectrophotometric determination of chlorpromazine hydrochloride

The use of 1,10-phenantroline as internal standard (IS) is proposed for spe ctrophotometric determination of chlorpromazine hydrochloride in pharmaceut ical formulations. The spectra of both compounds: analyte and internal stan dard are partially overlapped, so the Savitzky-Golay alghoritm was used to obtain separated signals of analyte and IS. The best parameters to generate the second-derivative spectra were: Delta lambda = 10 nm (5 experimental p oints) and second polynomial degree. For quantification of chlorpromazine i n pharmaceuticals, the zero-crossing technique was used. The values of the second-derivative peaks were measured for chlorpromazine at 256 nn and at 2 36 nm for IS. Analytical characteristic for proposed method was evaluated ( r(2) = 0.9990, detection limit=3.97 ng/ml). The obtained analytical results were in good agreement with results obtained using the UV-spectrophotometr ic Blazek method.