A Supercritical Fluid Chromatography and Tandem Mass Spectrometry Method for the Simultaneous Quantification of Valsartan and Hydrochlorothiazide in Human Plasma

A simultaneous rapid, sensitive supercritical fluid chromatography and tandem mass spectrometry method for the separation and quantification of valsartan (VAL) and hydrochlorothiazide (HCT) is developed and validated. Separation was done in a Nucleosil (250 mm × 4.6 mm) 10 mm, Nucleosil-C₁₈ column with acetonitrile modified supercritical fluid carbon dioxide (15 mL min^–1) as mobile phase. The column temperature was 45°C and the outlet pressure was set at 17 MPa. The analytes were quantitated in negative ionization by multiple reaction monitoring (MRM) with a mass spectrometer, the mass ionizations m/z 434.2 – 350.2 and m/z 295.9 – 204.9 used to measure VAL and HCT respectively. The assay exhibited a linear dynamic range of 3.2 – 3200 ng/mL for VAL and 0.8 – 800 ng/ml for HCT. The method was validated and successfully used for simultaneous determination of drugs in tablets.