Anion exchangers with negatively charged functionalities in hyperbranched ion-exchange layers for ion chromatography

•Novel PS-DVB-based anion exchangers with carboxyl functionalities in ion-exchange layers.•Use of glycine as a primary amine for the formation of hyperbranched functional layers.•Selectivity variations with changing the location and number of carboxyl groups in the layer.•Good selectivity toward weakly retained organic acids and oxyhalides.•Possibility of separating 22 anions on 25-cm column within 60 min in gradient mode.

Novel pellicular poly(styrene-divinylbenzene)-based (PS-DVB) anion exchangers with covalently-bonded hyperbranched functional ion-exchange layers containing negatively charged functionalities are obtained and examined. The hyperbranched coating is created on the surface of aminated PS-DVB substrate by repeating the modification cycles including alkylation with 1,4-butanediol diglycidyl ether (1,4-BDDGE), and amination of the terminal epoxide rings with methylamine (MA) or glycine (Gly). The influence of the position and the number of the layers with glycine, as well as of the total number of the layers of amine in the coating on the chromatographic properties of the obtained stationary phases is investigated. Chromatographic performance of the obtained stationary phases is evaluated using the model mixtures of inorganic and organic anions with hydroxide eluent. It is shown that the best selectivity toward weakly retained organic acids and oxyhalides is possessed by the anion exchanger obtained after 5 modification cycles, with glycine being used in the first one. Such anion exchanger packed in 25-cm long column is capable of separating 22 anions in 58 min including 7 standard anions, mono-, di- and trivalent organic acids, oxyhalides, and some other double- and triple-charged anions.