The chromatographic separations were carried out on a reversed
phase LiChrospher RP-18 column (250 x 4 mm ID, particle size
5 mm, Merck, Darmstadt, Germany) in association with a LiChrospher
100 RP-18, 5 mm guard column, both maintained at 24 C. The
fluorescence detector was set at 270/305 nm (lEx/lEm), and UVeVis
detector at 224 nm.