Extractive spectrophotometric determination of trimethoprim in pharmaceutical formulations

摘要

Two new, simple, sensitive, rapid and economical extractive spectrophotometric methods (A, B) have been developed for the determination of Trimethoprim in pharmaceutical bulk and tablet dosage forms. These methods are based on the formation of yellow colored chromogen by ion association reaction of Trimethoprim with Bromophenol Blue (BPB) and Bromo-cresol purple (BCP) exhibiting maximum absorbance at 422 and 418nm respectively against the corresponding reagent blank. Beer's law is obeyed in the concentration range of 4.0-24 ug/ml for method A and and 5.0-25 ug/ml for method B. The methods have been statistically evaluated and were found to be precise and accurate. The proposed methods have been successfully applied for the analysis of the bulk drug and its tablet dosage forms.