Column Chromatography for the Separation and Identification of Synthetic Water-soluble Acid Dye Mixtures

Abstract

Seventeen synthetic water-soluble acid dyes were separated and identified by means of aminoethyl cellulose (A.E. cellulose) column chromatography.The procedure is following: A.E. cellulose-celite (2:1) mixtures were suspended in water and poured into a chromatographic glass tube (400×10mm) in height of about 300mm. After the column had been thoroughly washed with 1% acetic acid, the mixture of 17 dyes containing 0.1 mg of each dye was applied to the top of the column bed. Then, the dyes were developed 0.1 N ammonium chloride-0.1N ammonia buffer solutions (pH 6.8-7ml, pH 9.2-7ml and pH 10.2-10ml were used in this oder). The completion of the chromatography was required about three hours.Quantitative analysis of officially permitted synthetic food dyes was studied with sucrose, acetic acid and sodium chloride, or without same addition, and no effect of the addition of these substances on the analysis was recognized. However, only when 5% or more of sodium chloride was added, small changes in the adsorpive properties of some dyes on the column were shown.The behaviors of natural coloring matters which were watersoluble form were also studied with the A.E. cellulose column.