1H-Xantheno(2,1,9-def)isoquinoline-2(3H)-ethanesulfonic acid, 9-methoxy-1,3-dioxo- 59373-54-5 9-Methoxy-1,3-dioxo-1H-xantheno(2,1,9-def)isoquinoline-2(3H)-ethanesulphonate acid EINECS 261-721-6