Determination of sulfonated azo dyes in river water samples by capillary zone electrophoresis

A method based on capillary zone electrophoresis coupled with photodiode-ar ray detection has been developed to determine several sulfonated dyes, incl uding a sulfonated dye (acid yellow 1), and the sulfonated azo dyes acid or ange 7, acid orange 12, acid orange 52, acid red 26, acid red 27 and acid r ed 88. A CElect-FS75 CE column is used. The electrophoresis buffer contains a 1:5 dilution of 10 mM phosphoric acid and tetrabutylammonium hydroxide b uffer (pH 11.5), and 25 mM of triethylamine, the final pH being 11.55. The detection limits for the seven dyes ranged from 0.1 to 4.53 mu g/ml. Spiked river water samples (100 ml), containing different concentration levels (0 .025-0.150 mu g/ml) of the dyes were analyzed after acidification (pH 3) an d pre-concentration in disposable SPE Oasis HLB, 1 ml cartridges. (C) 2000 Elsevier Science B.V. All rights reserved.