Objective: The self contrast and correction factor method was established to determine the content of the related substances in lisinopril and hydrochlorothiazide tablets. Method: Chromatography was carried out by reversed-phase technique to a Ultimate XB-C18 (4.6 mm×250 mm

5 μm) with a mobile phase composed of 0.05 mol·L-1 phosphate buffer (pH 7.3±0.1) -acetonitrile (85:15) pumped at a flow-rate of 1.0 mL·min-1. The detection was carried out at a wavelength of 210 nm and a column temperature of 30 ℃. The injection volume was 10 μL. The slope of linear equation was used to determine the correction factor of lisinopril related compound A and benzothiadiazine related compound A. Result: The relative retention times of lisinopril related compound A and benzothiadiazine related compound A were 1.88 and 0.69

respectively. The correction factors of lisinopril related compound A and benzothiadiazine related compound A were 1.16 and 0.87

respectively. The contentsof benzothiadiazine related compound A from three batches of samples were 0.671%

0.673% and 0.660%. Other impurities werent detected. Conclusion: The method was simple

efficient and accurate for analyzing the related substances in lisinopril and hydrochlorothiazide tablets.