摘要：An ion exchange method is described for the separatory detection of a microquantity of coal-tar dyes in cosmetics which contain a large quantity of anionic surfactant. In this method, a sample (3-5g) is warmed on a water bath to remove volatile components and then dissolved in 20 ml of ethanol. The ethanol-soluble portion is passed through a column of 10 ml of DEAE-Sephadex A-25, and then the column is washed with 100 ml of 30% ethanol. The dyes are eluted with hydrochloric acid-30% ethanol mixture (1 : 9), at a flow rate of 0.4 ml/min, until they have completely been eluted. The effluent is evaporated on a water bath, the residue is dissolved in 1-2 ml of ethanol, and this ethanolic solution is submitted to thin-layer chromatography for the identification of each dye. This method was found to give a satisfactory result in the detection of a microquantity of coal-tar dyes in various cosmetics, shampoo, and kitchen-use liquid detergents containing a large amount of anionic surfactant.
