D-Glucitol, 1-deoxy-1-[[[2-[7-[5-[[(1-deoxy-D-glucitol-1-yl)amino]carbonyl]-1,3-dihydr o-3,3-dimethyl-1-(4-sulfobutyl)-2H-indol-2-ylidene]-1,3,5-heptatrienyl]-3, 3-dimethyl-1-(4-sulfobutyl)-3H-indolium-5-yl]carbonyl]amino]-, inner salt, monosodium salt