Determination of irbesartan in the presence of hydrochlorothiazide by derivative spectrophotometry.

A first-derivative spectrophotometric method for the determination of irbesartan (IRB) alone and in the presence of hydrochlorothiazide (HCT) is described. Measurements are made at the zero-crossing wavelength at 263.0 nm for IRB. The calibration graph was linear over the range 1.0-12.0 mg l(-1) of IRB, detection limit was 0.15 mg l(-1). HCT, in the presence of IRB was determined by direct spectrophotometric method at 317 nm. The calibration graph was linear over the range 2.0-50.0 mg l(-1) of HCT, detection limit was 0.25 mg l(-1). The proposed methods were successfully applied to the determinations of IRB and HCT in combined tablets.