Free amines were analyzed according to the procedure of Flores
and Galston [41] with minor modifications [42]. Briefly, plant tissues
were homogenized in 5% (v/v) perchloric acid in ice-cooled
mortar. Homogenates were centrifuged, and amines in supernatant
were derivatized with benzoyl chloride for 45 min at 35 C. Amine
derivatives were extracted with ethyl acetate, which was then
evaporated to dryness at 40 C in a stream of air. Before high performance
of liquid chromatography (HPLC) analysis the residues
was dissolved in a mixture of acetonitrile–water (1:1).