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Determination of Calcitriol and 5,6-Trans-Calcitriol in Soft Capsules by RP-HPLC

OBJECTIVE To establish a new method for determination of the main active ingredient and its isomer in commercially available calcitriol capsules by reverse phase-high performance liquid chromatography-diode array detector( RP-HPLC-DAD).METHODS The chromatographic separation was performed on a Symmetry C18column( 4. 6 mm × 250 mm,5 μm) with gradient elution of water-acetonitrile-methanol. The mass spectrometer was equipped with diode array detector. Using Chem Station chromatography workstation,the main ingredient and its isomer in commercially available calcitriol capsules were analyzed. RESULTS The linear ranges of calcitriol and its isomer were 0. 171 4- 1. 36 and 0. 161 3- 1. 28 μg·m L- 1,the detection limits were 39. 75 and 40. 90ng·m L- 1and the limits of quantification were 141. 6 and 136. 4 ng·m L- 1,respectively. The specificity of the method was good,the RSD values of the precision and stability tests were less than 1. 2%,and the recoveries were greater than 98%. The average contents of calcitriol capsules from three manufacturers were 72. 71%,80. 35%,and 78. 18%,respectively. CONCLUSION The method is simple,rapid,accurate,and easy to be popularized,which is suitable for the determination of calcitriol and trans-calcitriol in calcitriol capsules.