Separation and determination of basic dyes formulated in hair care products by capillary electrophoresis

A capillary electrophoretic (CE) method for analyzing five basic dyes (Basic Red 76, Basic Brown 16, Basic Yellow 57, Basic Brown 17 and Basic Blue 99) sold under the trade name Arianor, which are commonly used in hair care products, has been established. A buffer of 100 mM acetic acid-ammonium acetate (50:50) containing 90% (v/v) methanol was employed in a fused-silica capillary of 40.0 cm × 50 μm I.D. with a bubble cell arrangement. Washing the capillary end immediately after injection was effective in preventing peak tailing of the basic dyes, which was due to their adsorption onto the outer wall of the capillary during the injection. Under these optimized conditions, acceptable results for reproducibility, limit of detection and quantitation, and linearity were obtained for the five authentic dyes tested. The recoveries of five authentic basic dyes spiked to three commercial hair care products also provided with acceptable results. This optimized CE method is useful for the analysis of mixed basic dyes in hair care products.