LAUSR

The aim of the study was to examine the amounts of extractives in sapwood and heartwood of black locust recovered using three different conventional extraction techniques and three different solvent compositions. Heartwood contained larger amounts of total phenols, dihydrorobinetin and robinetin than sapwood, irrespective of the extraction technique and solvent used. Dihydrorobinetin and robinetin were the characteristic phenolic compounds of black locust wood, whereas the concentration of dihydrorobinetin was significantly higher. The highest concentrations of examined extractives were obtained by Soxhlet extraction. More than ninety percent of extractives were leached from wood in a Soxhlet apparatus in less than 2 hours. Maceration with stirring and ultrasonic extraction gave smaller yields of extractives. The amounts of total extractives, total phenols and robinetin leached with the three solvents were comparable. Extraction of heartwood with acetone yielded significantly larger amounts of dihydrorobinetin than extraction with methanol or ethanol. Four hours extraction of wood meal with aqueous acetone in a Soxhlet apparatus was found to be the optimal extraction procedure for the recovery of dihydrorobinetin.