Separation of aromatic sulphonic acid dye intermediates by high-performance liquid chromatography and capillary zone electrophoresis

• Published in: Journal of Chromatography A 1996-07, Vol.738 (2), p.201-213
• Main Authors: Jandera, Pavel, Fischer, Jan, Staněk, Václav, Kučerová, Martina, Zvoníček, Petr
• Format: Article
• Language: English
• Subjects: Mobile phase composition; Sulfonic acids Aromatic compounds
• ISSN: 0021-9673
• DOI: 10.1016/0021-9673(96)00082-9

The possibilities of separating various aromatic sulphonic acids used as intermediates in production of synthetic dyes by reversed-phase high-performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE) were studied. Isomeric naphthalene mono- to tetrasulphonic acids are best separated by HPLC with aqueous-methanolic mobile phases containing sodium sulphate. A high content of bonded hydrocarbon moieties is essential for successful separation. Components of technological samples of 4,4'-dinitrostilbene-2,2'-disulphonic acid can also be successfully separated using this technique, but the separation is very sensitive to the concentration of methanol in the mobile phase. Various aromatic aminosulphonic acids (letter acids) in technological samples can be separated by ion-pair reversed-phase chromatography with mobile phases containing tetrabutylammonium ions, but a better separation is possible using capillary zone electrophoresis with working electrolytes containing β-cyclodextrin. The opposite applies to the separation of naphthalenesulphonic acids and dinitrostilbenedisulphonic acid isomers, so that the HPLC and CZE are complementary to each other. Both HPLC and CZE techniques are suitable for the quantitative analysis of technical products containing aromatic sulphonic acids.