Determination of juglone (5-hydroxy 1,4-naphthoquinone) in Pterocarya fraxinifolia by RP-HPLC

A method for determination of juglone in leaves and hulls of Pterocarya fraxinifolia was developed, based on RP-HPLC. This compound was extracted from leaves and hulls by chloroform refluxing about 2 hours. The chloroform was evaporated under low pressure at 50 degrees C to produce a dry residue. The remained materials were dissolved in acetonitrile to be used for determination of this compound. Appropriate conditions for RP-HPLC were determined using standard of juglone. These conditions include, acetonitrile percentage in mobile phase, pH of mobile phase (phosphate buffer) and temperature Of column, which were 50%, 4 and 30 degrees C, respectively. Juglone concentration was determined using standard addition method The concentrations of juglone were 2.15, 2.74, 1.77, 1.12 and 0.34 g in 100 g of dry leaves in May, June, July, August and September 2001, respectively. The content of juglone in hulls was 0.44 g in 100 g of dry hulls in May.