Simultaneous determination of pseudoephedrine sulfate, dexbrompheniramine maleate and loratadine in pharmaceutical preparations using derivative spectrophotometry and ratio spectra derivative spectrophotometry

Two new spectrophotometric methods are described for the simultaneous analy sis of pseudoephedrine sulfate-dexbrompheniramine maleate (DBP) and pseudoe phedrine sulfate-loratadine combinations. In the first, derivative spectrop hotometry, dA/d lambda values were read at zero;crossing points.:In the sec ond, ratio spectra derivative spectrophotometry, analytical signals were me asured at the wavelengths corresponding to either maxima or minima for thes e drugs in the first derivative spectra of their ratio spectra. The procedu res do not require any separation step. Mean recoveries were found to be > 99% in the methods for these compounds in their synthetic mixtures. All the spectrophotometric methods proposed were compared with each other and HPLC which was also developed by us and applied to the pharmaceutical preparati ons selected. (C) 2000 Elsevier Science B.V. All rights reserved.