Abstract
Thin-layer chromatography will resolve impurities in commercial dyes, and will do so much faster than paper chromatography. Solvent systems consisting of (a) n-propanol: n-butanol: NH4OH (conc.): H2O—4:4:1:1; (b) n-propanol: NH4OH (conc.): H2O—8:1:1 on silica gel G plates; and (c) n-propanol: NH4OH (conc.): H2O-7:2:1 on Adsorbosil plates were found to be the most effective. Dyes studied were azure A, azure B, azure C, methylene blue, toluidine blue O, thionin, pyronin B, pyronin Y, methyl green, crystal violet amido black 10B and buffalo black (NBR).