OBJECTIVETo develop a high performance liquid chromatographic method for the determination of DNJ in Morus alba leaves with fluorimetric detection after precolumn derivatization with 9-fluorenylmnethyl chlorformate (FMOC-Cl).

METHODDNJ in Morus alba leaves was extracted with 0.05 mol x L(-1) HCl, reacted with FMOC-Cl, and separated on a HiQSiL C18 column at 250 degrees C. Mobile phase consisted of acetonitrile-0.1% aqueous acetic acid (55:45) with a flow rate of 1.0 mL x min. The fluorescence detector was operated at lambdaEX = 254 nm, lambdaEM = 322 nm.

RESULTA satisfactory separation between DNJ and impurity was obtained. The calibration curve was linear over the concentration range from 0.567 microg x mL(-1) to 34 microg mL(-1), r = 0.9998. The average recovery was 97.2%. The contents of DNJ in M. alba collected in different seasons and grown in different environment were determined.

CONCLUSIONThe quantity of DNJ in leaves of M. alba is related to the environment factor, temperature and growing period. The method can be used for qualioy control of the medicinal material.