Determination of catalpol in Radix rehmanniae by high performance liquid chromatography

Catalpol in radix rehmanniae was determination by high performance liquid chromatography. Catalpol was separated on a KYWG -C18 column (10um, 4. 6mm X 25cm), using water acetonitrile (99. 4: 0. 6) as mobile phase, and detection at 210nm. There was a good linearity ranging from 2 to 10ug of catalopl (r= 0. 9999, Y= 0. 0007158+0. 00004318X). The average recovery was 99. 00% and the coefficient of variation being 0. 5% (n= 6). Catalpol in 16 fresh radix rehmanniae and dry radix rehmanniae produced in Henan province was determined by this method.