Microcomputer-aided titrimetric determination of bromine-containing active ingredients in some drug formulations

Abstract

Several microcomputer-aided titrimetric procedures were developed to determine active components with bromide or covalently bound bromine in their molecules in some pharmaceutical preparations of different formulations. Titrations were carried out either with a standard silver nitrate solution (indirect determination), employing catalytic spectrophotometric, potentiometric and controlled-current potentiometric methods to monitor the course of the titration, or with a standard solution of perchloric acid in acetic acid (direct determination) in catalytic thermometric titration. The indicator reaction used in catalytic spectrophotometric titrations was the peroxodisulfate - sulfanilic acid reaction in the presence of 2,2′-bipyridine as activator and acetate buffer (pH 4.35), whereas in catalytic thermometry it was the hydroquinone - acetic anhydride reaction. In the controlled-current potentiometric procedure, use was made of the peroxodisulfate decomposition reaction in the presence of 2,2′-bipyridine as the indicator. Amounts of 10-20 μmol of the investigated active ingredients per titration were determined with a relative standard deviation that, depending on the procedure and mode of sample preparation, was in the range 0-2.6%. The results are comparable to those obtained by official methods. The microcomputer-aided titrimetric procedures developed are relatively fast and economical and can be applied to the analysis of large numbers of pharmaceutical products.