Analysis of phenolic components in Croatian red wines by thin-layer chromatography

Abstract

A thin-layer chromatographic (TLC) method has been used for determination of phenolic compounds in two samples of wine commercially available in Croatia. Sample preparation was by liquid-liquid extraction with diethyl ether at pH 2.0. Extracts and standard solutions were applied to 20 cm × 20 cm silica gel 60 F 254 TLC plates. After treatment of the developed plates with ammonia vapor, phenolic compounds were detected on chromatograms by their colors or by fluorescence in UV light at λ = 244 nm and at λ = 366 nm before and after spraying with 1% ethanolic AlCl 3 . The efficiency of eleven mobile phases was tested by three mathematical techniques — calculation of the information content ( I ) derived from Shannon’s equation, determination of discriminating power ( DP ), and formation of clusters and dendrogram. It was shown that the best mobile phase for separation of phenolic compounds in the wine extracts was benzene-ethyl acetate-formic acid, 30 + 15 + 5 ( v / v ). Six phenolic compounds were identified in the tested samples.