Identification of Dyes in Paper for Tobacco Products with Particular Consideration of Humic Acid/Identifizierung von Farbstoffen bei Papieren für Tabakerzeugnisse unter besonderer Berücksichtigung der Huminsäure

After a brief look at the food law situation, the particular problems of the presence of humic acid in paper are dealt with. Origin and significance as well as physical and chemical properties of humic acid are described. The principle of the method of analysis is that the dyes transferred from the paper to an aqueous solution are freed of humic acid by acidification and extracted from the centrifugate, using isoamyl alcohol. The concentrated aqueous eluate from the amyl alcohol is examined paper chromatographically. The Rf figures for the dyes after their said preparation are quoted and the analytical procedure explained by means of examples.