Tetrasodium;4-amino-6-[[4-[4-[(8-amino-1-oxido-7-sulfo-5-sulfonatonaphthalen-2-yl)diazenyl]-3-methylphenyl]-2-methylphenyl]diazenyl]-5-oxido-3-sulfonaphthalene-1-sulfonate
An azo dye used in blood volume and cardiac output measurement by the dye dilution method. It is very soluble, strongly bound to plasma albumin, and disappears very slowly.