1-amino-9,10-dihydro-9,10-dioxo-4-[3-[[2-(phosphonooxy)ethyl]sulphonyl]anilino]anthracene-2-sulphonic acid, sodium salt

1-Amino-9,10-dihydro-9,10-dioxo-4-[[3-[[2-(phosphonooxy)ethyl]sulfonyl]phenyl]amino]-2-anthracenesulfonic acid/sodium,(1:x) salt