2-[(1-ethyl-1,6-dihydro-2-hydroxy-4-methyl-6-oxo-3-pyridyl)azo]naphthalene-1-sulphonic acid

2-[[(1-Ethyl-1,6-dihydro-2-hydroxy-4-methyl-6-oxopyridin)-3-yl]azo]-1-naphthalenesulfonic acid