Simultaneous determination of captopril, hydrochlorothiazide and their related compounds in a single pharmaceutical tablet using validated HPLC method

A new sensitive, rapid and simple HPLC-DAD method has been developed and validated for simultaneous determination of captopril (CAP), hydrochlorothiazide (HCTZ) and their related compounds, captopril disulfide (CAD), chlorothiazide (CTZ), and 4-amino-6-chloro-1,3 benzenedisulfonamide (BTDZ), in tablets. The chromatographic separation was performed using 5 μm particles packed into a 4.6 mm i.d. phenyl column 150 mm in length that was maintained at 40 ºC. A mobile phase consisted of a gradient of acetonitrile and phosphoric acid (0.067 %) eluted at 1.2 mL min-1 . The injection volume was 20 μL, and the detection wavelength was set at 220 nm. The validation procedures showed that the new method is selective and linear over a range of 0.5 to 400.0 μg/mL for CAP, 0.3 to 14.4 μg/mL for CAD, 0.05 to 100.0 μg/mL for HCTZ, 0.08 to 1.2 μg/mL for CTZ and 0.02 to 2.4 μg/mL for BTDZ. Recoveries in the range of 98.82 to 101.31 % and precision