4-(2-aminoethylamino)-7H-benz[de]benzimidazo[2,1-a]isoquinoline-7-one as ahighly sensitive fluorescent labeling reagent for carnitine

4-(2-Aminoethylamino)-7H-benz[de]benzimidazo[2,1-a]isoquinoline-7-one, synt hesized and identified by a HMBC study, can be used as a fluorescent labeli ng reagent for carnitine. The excitation and emission maxims in acetonitril e were observed at lambda 454 and 508 nm, respectively. This reagent smooth ly reacted with carnitine in the presence of 1-[3(dimethylamino)propyl]-3-e thylcarbodiimide hydrochloride to afford the corresponding amide under mild conditions. The detection limit (S/N > 3) of carnitine was ca. 12 fmol.