title: Ion-pair extraction and ion-pair adsorption thin-layer chromatography for rapid identification of ionic food dyes.
abstract: An easy, rapid and accurate method for routine analysis of seventeen commonly used ionic food dyes by means of ion-pair extraction and ion-pair adsorption thin-layer chromatography on silica gel plates has been developed. Cetyltrimethylammonium bromide was selected as the counter ion for both isolation and separation. Its concentration in the sample before extraction with methylene chloride should be around 0.0125 M. A pH value of 2.5 for the extraction gives an acceptable recovery of most of the dyes. The thin-layer plates were impregnated with the counter ion which was also present in the eluent. Sharp spot application yields a very good separation, enabling satisfactory identification of the dyes.
mesh_terms: D002855:Chromatography, Thin Layer / Q000379:methods; D005504:Food Analysis; D005505:Food Coloring Agents / Q000032:analysis* / Q000592:standards
chemical_list: D005505:Food Coloring Agents