Derivative-ratio spectrophotometric method for the determination of ternary mixture of aspirin, paracetamol and salicylic acid.

A derivative spectrophotometric method was developed for the assay of a ternary mixture of aspirin (ASP), paracetamol (PAR) and salicylic acid (SAL). The method is based on the use of the first and second derivatives of the ratio spectra and measurement at zero-crossing wavelengths. The ratio spectra were obtained by dividing the absorption spectrum of the mixture by that of one of the components. The concentration of the other components are then determined from their respective calibration curves treated similarly. The described method was applied for the determination of these combinations in synthetic mixtures and dosage forms. The results obtained were accurate and precise.

New spectrofluorometric application for the determination of ternary mixtures of drugs.

A new spectrofluorometric method was developed for the determination of a ternary mixture of dexamethasone, dexchlorpheniramine maleate, and fluphenazine hydrochloride in dosage forms where the literature did not reveal any method for analysis of this mixture. The method was based on the use of the first and second derivatives of the ratio of the emission spectra with a zero-crossing technique. The ratio spectra were obtained by dividing the emission spectrum of the mixture by that of one of the components. The concentrations of the other components were then determined from their respective calibration graphs treated similarly. The method can resolve the spectral overlapping of the three components and was applied successfully for the determination of these drugs in synthetic mixtures and in commercial dosage forms.