Thin Layer Chromatographic Separation and Spectrodensitometric Determination of Higher and Lower Sulfonated Subsidiary Dyes in FD&C Yellow No. 6

A thin layer chromatographic method is presented by which higher and lower sulfonated subsidiary dyes are simultaneously separated from FD&C Yellow No. 6. After separation, the colors are quantitated directly, using a spectrodensitometer. Recoveries of 1, 2, and 5% of added 1-(4-sulfophenylazo)-2-naphthol-3,6-disulfonic acid ranged from 92 to 111%. Recoveries of 1, 2, and 5% of added l-(4-sulfophenylazo)-2-naphthol ranged from 90 to 110%.