Abstract: AIM: To establish a high performance liquid chromatography (HPLC) method to determine the concentration of valsartan in human plasma.METHODS: Using lrbesartan as internal standard, valsartan in plasma samples was determined by HPLC with liquid-liquid extraction, achieved by the column of Agilent ZORBAXSB-C18(150 mm ×4.6 mm, 5 μm) at room temperature.The mobile phase consisted of a mixture acetonitrile:water:phosphoric acid:triethylamine was the ratio of 40:60:1.0:1.5 (v/v), pumped at a flow rate of 1.0 ml·min^-1, the wavelengths of fluorimetric excitation and emission were set at 265 and 378 nm respectively.RESULTS: The drug-free plasma did not interfere with the determination of drugs and internal standard.There was good linear relationships (1/C 2 weighted) between peak area ratio of valsartan to internal standard and C (r =0.9996) within the range of 25-2 500 ng·ml^-1.The precision of within-day and between-day was good.The lower limit of quantification was 25 ng·ml^-1.The analytes reconstituted in the mobile phase were also stable at ambient conditions for at least 24 h.Furthermore, valsartan was stable for at least three freeze thaw cycles.CONCLUSION: The HPLC method can be used to determine the concentration of valsartan in human plasma.

Key words: valsartan, HPLC, fluorescence, plasma