A normal phase high performance chromatographic method with evaporative light scattering detector(ELSD) and diode array detector(DAD), using n hexane/methanol/ethyl acetate(volume ratio 6∶3∶2 ) as the mobile phase, was established for the direct determination of active constituents gastrodin(GA) in the ethanol extracts of Gastrodia elata Blume . An silica gel column Zorbax RX SIL\[4 6 mm (\{i.d.\})×25 cm, 5 μm\] was employed. Regression equations revealed the linear relationships( r =0 998 and 0 999) between the peak areas of GA measured by ELSD and DAD and its concentration. The recoveries of GA measured by ELSD and DAD are 104 22% and 97 65%, respectively. The contents of GA measured by ELSD and DAD are 13 9 mg/g(2 79% RSD) and 12 1 mg/g(2 99% RSD) respectively in Gastrodia elata Blume . The detection limits of ELSD and DAD( S/N =3) are 3 mg/L and 1 mg/L respectively. This method is simple, selective and sensitive.
