RATIOS OF DERIVATIVE OPTIMA AS CRITERIA FOR THE APPLICATION OF DERIVATIVE SPECTROPHOTOMETRY IN PHARMACEUTICAL ANALYSIS

The ratios of derivative optima (maxima of positive and negative peaks ) of UV-absorption spectra are used to test for the presence of non-sp ecific matrix interference and to predict the validity of application of derivative spectrophotometry during analysis of pharmaceutical form ulations containing a single drug. The calculated ratios have been sho wn to be independent of the drug concentrations and some instrumental parameters such as ordinate maxima and minima, chart-speed and slit-wi dth. However, the calculated ratios have been shown to be affected by the scan speed of the monochromator. The use of derivative ratios in d etecting the validity of the assay results is presented for salbutamol sulphate tables, aspartame tablets and tetrahydrazoline hydrochloride drops as representative examples of single-component formulations. Th e results are reproducible with coefficients of variation less than 2% proving the efficiency of the derivative ratios for testing the valid ity and the possibility of application of derivative technique for ana lysis of drugs in their formulations.