Benzenesulfonic acid, 4-2-2,5-dimethoxy-4-2-(sulfooxy)ethylsulfonylphenylazo-1,3-dioxobutylamino-5-methoxy-2-methyl-, sodium salt

4-[[2-[[2,5-dimethoxy-4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1,3-dioxobutyl]amino]-5-methoxy-2-methylbenzenesulphonic acid, sodium salt

4-[[2-[[2,5-Dimethoxy-4-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]azo]-1,3-dioxobutyl]amino]-5-methoxy-2-methylbenzenesulfonic acid/sodium,(1:x) salt