ИСТИНА

Polystyrene-divinylbenzene (PS-DVB) copolymers are the best substrates for obtaining anion exchangers for suppressed ion chromatography (IC) due to their high chemical and mechanical stability, but non-ionic interactions taking place between polarizable anions and aromatic rings of PS-DVB can be a reason of serious peak tailing and asymmetry, as well as poor efficiency for such anions. This problem can be solved by shielding polymer surface with functionalized polyamine attached to the substrate surface via hydrophiliclinkers thus creating pellicular structure. Polyethyleneimine (PEI) is one of aminopolymers, which can potentially be used for obtaining pellicular anion exchangers, since it contains primary, secondary and tertiary amino groups, which can be quaternized with different hydrophilic reagents after the attachment to the substrate. This is a very convenient way to control ion exchange capacity, the structure of functional ion-exchange layer and, as a result, selectivity of the stationary phase. Attachment of polyamine allows one to avoid multistep synthesis of anion exchangers, which is usually required for creating the most popular branched or hyperbranched functional layer structure. In the present work new anion exchangers obtained via covalent attachment of PEI to the PS-DVB surface with hydrophilic linkers followed by the quaternization with different hydrophilic reagents are presented. The synthesis included preliminary covering odf PS-DVB substrate with the secondary aminogroups, which served as the anchors for the attachment of the functional layer. Diepoxy compounds were used as a hydrophilic linker for the covalent attachment of PEI, which was further alkylated with reagents of various hydrophilicity, namely, glycydol and 1,4-butanediol diglycidyl ether. Obtained anion exchangers were packed into 100 x 4 mm i.d. columns. Stationary phase modified with glycydol provides the separation of 11 anions including 7 standard anions (fluoride, chloride, nitrite, bromide, nitrate, phosphate and sulphate), formiate, chlorite, iodide and thiocyanate in 26 minutes using gradient elution with hydroxide solutions. Moreover, such anion exchanger enables efficient and selective separation of highly polarizable anions including thiosulphate, chlorate, bromate, iodide, and perchlorate in 20 minutes. Anion exchanger having the layer of PEI quaternized with 1,4-butanediol diglycidyl ether provides the separation of the anions of weakly retained organic acids (acetate, formate), which also can be separated from fluoride and chloride. The obtained anion exchangers can be successfully used for solving wide variety of analytical tasks, including the analysis of water, air and soil extracts.