Abstract: A base barrage focusing approach online-coupled to capillary electrophoresis(CE) was developed and used for the analysis trace aromatic amines. To realize online focusing, a plug of 200 mmol/L NaOH was introduced in front of a sample zone just before electrophoresis. This method is facile and can be conducted on any CE system. After some optimization of the base barrage length and concentration, the method could be applied to the assay of m-phenylenediamine, o-phenylenediamine and melamine, with limits of detection down to 0.10 μmol/L m-phenylenediamine, 0.05 μmol/L o-phenylenediamine and 0.05 μmol/L melamine respectively, producing about 100-fold increase of sensitivity compared with the common method. Linear relationship was found between the peak area and sample concentration over two grades of magnitude, with linear correlation coefficients better than 0.999. As a validation, the method has also been applied to the analysis of a commercial hair dye, with the recovery between 94% and 97%.

Key words: Base barrage focusing, Aromatic amines, Hair dye, Capillary electrophoresis