Application of high-performance liquid chromatography in the analysis of direct dyes in semipermanent hair colouring cosmetics

A method for the identification and the quantification of direct dyes in semipermanent hair colouring cosmetics by using a reversed phase high-performance liquid chromatography (HPLC) with gradient elution and diode array detector (DAD) detection is presented. A standard mixture of 18 commonly marketed dyestuffs (11 nitroderivatives, two anthraquinones and five Arianor dyes) was studied. The major problems in the analysis of the mixture of direct dyes is the different chemical structure and especially the wide range of polarities. However we succeeded in the complete separation of the standard dyes. A qualitative analysis of eight colouring commercial products selected from different shades and a quantitative analysis of three of them was carried out. Materials, methods and results are reported.