ИСТИНА

For creating highly efficient and selective anion exchangers for ion chromatography (IC) on the basis of hydrophobic polysterene-divinylbenzene (PS-DVB) copolymers, simultaneous hydrophilization of the anion exchanger’s surface and spatial moving of ion exchange sites away from it is required, which can be realized by creating hyperbranched hydrophilic functional layers. Di- and mono-epoxides are widely used for obtaining hyperbranched polyelectrolyte anion exchangers or hydrophilization of the functional groups (FG). In the present work covalent attachment of hydrophilic branched anion exchange layer to the PS-DVB surface is presented. Two diepoxides – 1,4-butanediol diglycidyl ether (1,4-BDDGE) and resorcinol diglycidyl ether (RDGE) – were used for the alkylation of the preliminary obtained aminated PS-DVB and served as hydrophilic linkers for the covalent attachment to the matrix of the FG of various hydrophilicity, namely, trimethylammonium (TMA), dimethylethanolammonium (DMEA), methyldiethanolammonium (MDEA), triethanolammonium (TEA) groups. As an alternative approach for the creation of branched layer, alkylation of secondary aminogroup with glycidiltrimethylammonium chloride (GTMA) was also proposed, which allowed the insertion of both hydrophilic linker and trimethylammonium FG in one step. Anion exchanger obtained with using GTMA, demonstrates the highest efficiency (up to 59000 theoretical plates per meter for nitrate) among all the adsorbents, but inferior selectivity as compared with anion exchangers modified with diglycidyl ethers. It is shown that the increase of FG hydrophilicity results in the growth of efficiency and the selectivity decrease. Anion exchanger modified with 1,4-BDDGE and MDEA possesses the best chromatographic properties and allows the separation of 7 anions in the gradient IC mode in less than 6 minutes using potassium hydroxide as an eluent.