Studies On The Simultaneous Determinations Of Candesartan Cilextil And Hydrochlorothiazide In Compound Tablets And Their Uncertainties

Compound tablets of Candesartan Cilexetil (CAN) plus Hydrochlorothiazide (HYD) have been used in clinic. The assay methods reported for CAN and HYD in compound preparation and human plasma mainly were First Derivative UV-Spectrophotometry and HPLC-DAD. However, these methods were complex or unusual in China. Therefore, it is necessary to establish an HPLC-UV method for simultaneous determinations of CAN and HYD in compound tablets.Uncertainty plays an important role in quantitative analysis. It can be used to evaluate reliability of quantitative analysis method and veracity of result. On the other hand, uncertainty can provide the information of resources for analytical error.OBJIEVTIVES1) To establish an HPLC-UV method for simultaneous determinations of CAN and HYD in compound tablets. 2) To establish a method for valuate uncertainties in the assay with HPLC-UV.METHODS1) HPLC-UV method for simultaneous determinations of CAN and HYD in compound tablets:A Phenomenex C18 column(250 mm×4.6 mm,5μm) was used with the mobile phase of acetonitrile-0.1 mol·L-1 sodium dihydrogen phosphate solution (added 0.1% triethylamine to 1L solution, adjusted to pH 5.0 with phosphoric acid) (65:35) at the detection wavelength of 262nm,the flow rate was 1.0 mL·min-1 and the column temperature was 35℃,injection volume is 5μL.2) An evaluative method for uncertainties of simultaneous determinations of CAN and HYD in compound tablets by HPLC-UV:The calculation formulas for the uncertainties of the assay were deduced.RESULTS1) HPLC-UV method for simultaneous determinations of CAN and HYD in compound tablets:The calibration curves of CAN and HYD were linear in the ranges of 1.6-32.0μg·mL-1 (r=0.9998) and 1.2-25.0μg·mL-1 (r=0.9999), respectively, the average recoveries (n=9) were 101.3% and 100.7%, respectively, the RSD (n=9) of precision are 1.5% and 1.7% respectively, the sample solutions were stable in 8h. 2) An evaluate method for uncertainties of simultaneous determinations of CAN and HYD in compound tablets by HPLC-UV:The determination Expanded Uncertainty of CAN and HYD are 2.08% and 1.88% respectively, the determination results of CAN and HYD are 98.7%±2.08%(k = 2) and 97.9%±1.88%(k = 2) respectively.