EXTRACTION OF TANNIN, GALLIC ACID AND PYROGALLOL FROM AQUEOUS MEDIA WITH WATER-SOLUBLE POLYMERS AND THEIR DETERMINATION IN CONCENTRATES BY THIN-LAYER CHROMATOGRAPHY

Abstract

For the first time water-soluble homo- and co-polymers based on N-vinylcaprolactam and N-vinylpyrrolidone were applied for the extraction of tannin, gallic acid and pyrogallol from the aqueous-salt solutions. The distribution coefficients and the degree of extraction of phenols were established. Extraction characteristics of phenols depend on their solubility, structure, and the number of functional groups in their molecules that can form hydrogen bonds and π-complexes with polymers. The large distribution coefficients of tannin are due to its high hydrophobicity. It was established that the copolymer of N-vinylpyrrolidone with N-vinylcaprolactam shows higher extraction efficiency than homopolymers. The efficiency of extraction of the studied phenols depends on the pH of aqueous solutions. The maximum degree of extraction of phenols was achieved at pH 3. Conditions of division and determination of phenols in the polymer-aqueous concentrate using the chromatography method in a thin layer were chosen. It has been established that the selective separation of the investigated phenols is achieved using a mobile phase of 1-butanol, acetic acid and chloroform in the ratio (vol.) 4 : 1 : 5. Eluent eliminates the blur spots.  Separation time of analytes is reduced from 60 to 20-30 min in comparison with known chromatographic systems. It was established that the nature of the polymer and its presence in the concentrate does not affect the chromatographic characteristics. The technique of determination of studied substances in aqueous media was developed.Keywords: polyphenols, tannin, gallic acid, pyrogallol, extraction, chromatography, water-soluble polymers, N-vinylpyrrolidone, N-vinylcaprolactam, copolymer(Russian)DOI: http://dx.doi.org/10.15826/analitika.2015.19.3.005 P.T. Sukhanov1, A.N. Il’yin1, E.V. Churilina1, G.V. Shatalov21Voronezh State University of Engineering Technologies, Voronezh, Russian Federation2Voronezh State University, Voronezh, Russian Federatio