system suitability.

A simple, specific, accurate and precise reverse phase high performance liquid chromatographic (RP-HPLC) method was developed with high sensitivity for determination of Valsartan and Hydrochlorothiazide drugs in combined dosage forms. The separation was achieved on Zorbax CN (25 cm x 4.6 mm, 5 µm) at flow rate of 1.8 ml/min with 70: 30 mixture of phosphate buffer: acetonitrile (pH 6) as the mobile phase. The quantification was achieved with PDA detector at 265 nm. The injection volume was 20 μl. The retention times of Valsartan and Hydrochlorothiazide were 6.04 min and 2.27 min, respectively. The method was validated for linearity, precision, specificity, robustness and recovery according to the ICH guidelines. The linearity of response for Valsartan and Hydrochlorothiazide were assessed by analysis of five independent levels of calibration curve in range of 20-100 µg/ml and 2-10 µg/ml respectively. The recovery data was between 98.77-99.73% and 98.75-100.56% for Valsartan and Hydrochlorothiazide respectively. The limit of detection and quantification for Valsartan were 0.98 and 2.97μg/ml respectively and for Hydrochlorothiazide were 0.18 and 0.57μg/ml, respectively. The method was found to be simple and highly sensitive and can be useful in the routine quality control of Valsartan and Hydrochlorothiazide in bulk manufacturing and pharmaceutical dosage forms.