Purification and identification of several sulphonated azo dyes using reversed-phase preparative high-performance liquid chromatography

Reversed-phase preparative HPLC has been successfully used to isolate several sulphonated azo dyes (Acid Red 1, Acid Red 8, Acid Red 106, Acid Violet 5, Chromotrope 2R, Reactive Orange 16 and Cibacron Brilliant Red 3B-A) from their impurities. The separations were achieved using mobile phases of methanol and ammonium acetate. The major components of these azo dyes were collected and then identified by electrospray mass spectrometry using the characteristic ions [M-2Na](2-), [M-2Na+H](-) and [M-Na](-). The degree of purification, as measured by electrospray mass spectroscopy, was variable. (C) 1998 Elsevier Science B.V. All rights reserved.