ИСТИНА

Since the structure of stationary phase mainly determines its selectivity and efficiency, development and construction of novel types of functional layers remains one of the most important and interesting tasks of ion chromatography (IC). Covalently-bonded hyperbranched anion exchangers for IC are known to possess the highest selectivity and efficiency among all chemically derivatized resins. Traditionally, hyperbranched functional layers are formed using 1,4-butanediol diglycidyl ether and methylamine, but in our previous investigations the advantages of using glycine as a primary amine in the internal part of the functional layer were demonstrated, one of which was a significant selectivity improvement toward weakly retained organic acids. It made us expect alternative and improved selectivity when using other types of primary amines in hyperbranched layers. The purpose of the current work was to evaluate the influence of primary amine structure on column performance and the retention of weakly retained organic acids and inorganic anions. Hydrophilicity and charge of hyperbranched functional layer was varied by means of using different amino acids, amino sulfonic acids, and amino alcohols in either internal or external part of the layer. As a result, three different types of stationary phases were synthesized and compared for evaluating the selectivity shifts for anions of interest. The obtained stationary phases were studied in isocratic mode of reagent-free IC and retention mechanisms for weakly retained organic acids were established. The most selective anion exchangers provided the separation of up to 25 anions in gradient elution mode including standard inorganic anions, anions of mono-, di- and tri-valent organic acids, and oxyhalides. Revealed correlations between the structure of functional layers and chromatographic performance of stationary phases for IC allowed us to find the way of constructing anion exchangers with desired properties for solving particular analytical tasks.