Visualizing agents for short-chain fatty acids in TLC

Abstract

Fatty acids from ethanoic to octanoic have been chromatographed on silica gel with n -hexane-acetone, 4 + 1 ( v/v ), and acetone-water-chloroform-ethanol-aqueous ammonia, 30 + 1 + 3 + 5 + 1 ( v/v ), as mobile phases. New visualizing agents and selected visualizing agents described in the scientific literature have been used for detection. The results obtained for the free fatty acids and their ammonium salts by use of the individual visualizing agents depend on method of application — spraying or dipping. Dipping of chromatographic plates into solutions of the visualizing agents leads to chromatographic spots of the fatty acids with better contrast than the spots obtained by direct spraying of the plates. In general better visualization was achieved with ammonium salts of the fatty acids than with the free acids. Of the agents described in the scientific literature free fatty acids from ethanoic to octanoic can be detected only by use of bromocresol green, bromophenol blue, potassium permanganate, and met...