EFFECT OF THE NUMBER OF SULFO GROUPS ON THE ELECTROPHORETIC MOBILITY OF SULFONATED AZO DYES

Paper electrophoretic mobilities of azo dyes containing one to six sulpho groups were studied in alkaline (0.1 M NaOH) and acidic (30% acetic acid) media. The most significant contribution to the mobility is caused by the presence of the second and third sulpho groups in the original structure. The influence of the fifth and sixth sulpho groups is nearly negligible. The fact that isomers containing the same number of sulpho groups are separated indicates that further factors must be involved. The influence of the presence of the carboxy group and other structural factors was also studied.