pH-induced difference spectrophotometric assay of acetazolamide, hydrochlorothiazide, and furosemide.

On the basis of pH-induced spectral changes for acetazolamide, hydrochlorothiazide, and furosemide, 3 different spectrophotometric methods are described. The methods were successfully applied to the assay of these drugs in different pharmaceutical formulations (tablets and ampoules). The accuracy of the analysis is increased by using the suggested methods as compared with conventional spectrophotometry.