Capillary electrophoresis determination of two reactive dyes: monitoring of activation and hydrolysis in different alkali media.

HPLC often meets with difficulty in analyzing reactive dyes, their activation, and posterior hydrolysis. In this work, capillary electrophoresis methodology for two reactive dyes, C.I. Reactive Black 5 and C.I. Reactive Red 198, was studied. The methods developed permit the separation and detection of these reactive dyes and their major hydrolytic products. These methods can be used successfully for the optimization of these dye syntheses, purification process, formulation, and also to monitor effluents and dye-bath mixtures and extrapolation to similar compounds. Simple background electrolyte systems, such as 10 mM phosphate or 0.65% hydroxypropylmethylcellulose in 40 mM acetate, were used to follow the hydrolysis mechanism and process in the two different alkali media studied.