Determination of related substances for metolazone and valsartan in compound metolazone tablets by HPLC / 国际药学研究杂志

ABSTRACT

Objective To establish an HPLC method to determine the related substances of metolazone and valsartan in compound metolazone tablets. Methods An Agilent Eclipse SB-C18 column 4.6 mm × 250 mm, 5 μm was used with 0.01 mol/L KH2PO4 buffer pH=3.5-acetonitrile as the mobile phase with gradient elution at a flow rate of 1.0 ml/min. The column temperature was 30℃ and the detection wavelength was 237 nm. Injection volume was 20 μl. Results Metolazone, valsartan and related substance B of valsartan were separated completely. The calibration curves were linear within the range of 3-30 μg/ml for metolazone, 0.1-2.0 μg/ml for valsartan and 0.08-2.0 μg/ml for related substane B of valsartan. The average recoveries were 102.97%, 100.81% and 100.44%, respectively. The repeatability and intermediate precision met with requirements. The test solution was stable within 24 h. Conclusion The method is specific, sensitive, accurate and reliable, thereby can be used for the determination of metolazone and valsartan related substances in compound metolazone tablets.