The azure dyes: their purification and physicochemical properties. II. Purification of azure B.
A method is described for the purification of the dye azure B in quantities sufficient for biological staining experiments on a larger scale. The method is based on the use of column chromatography. Two columns are employed. In column A with silica gel as adsorbent the azure B fraction is isolated from a suitable substrate ('technical' azure B gained by a modification of Bernthsen's synthesis of methylene blue, or polychrome methylene blue) using an acetate-formate mixture as eluent. In column B, on an Amberlite polymeric adsorbent (XAD-2) the acetate-formate anions are exchanged in chloride. Regeneration of both columns is possible: KMnO4, Na2S2O4 and water are run through column A; 5% NaOH, methanol and water through column B. Purification of azure B on economic terms is thus attained. The opinion is expressed that this method is also applicable to the purification of other cationic dyes.
D002712:Chlorides / Q000138:chemical synthesis; D002845:Chromatography; D002855:Chromatography, Thin Layer; D004396:Coloring Agents / Q000302:isolation & purification*; D004340:Drug Contamination; D008722:Methods; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet
D002712:Chlorides; D004396:Coloring Agents