Preparation of a Macrocyclic Polyamine-bonded Column for the Electrophoretic Separation of Inorganic and Organic Anions
A 24-membered macrocyclic polyamine based on the propylene-1,3-diamine unit that was able to form polyprotonated, highly charged species in the neutral pH region was selected to act as an anion complexone. It was synthesized and incorporated in a fused-silica capillary for the electrophoretic separation of inorganic and organic anions. This complexing agent can selectively modulate the mobility of anions by forming anion complexes with varying degrees of stability. Parameters which influence capillary electrophoretic separations such as applied voltage, choice of electrolyte anion, electrolyte pH and electrolyte concentration were investigated. A mixture of thiosulfate, chloride, sulfate, selenate, perchlorate, tungstate, carbonate and selenite could be separated in 5 mM sodium chromate at pH 10.0 within 13 min. A mixture of bromide, oxalate, malate, citrate, tartrate, maleate, succinate, acetate, lactate, butyrate, p-hydroxybenzoate, salicylate and octanesulfonate could be separated in 10 mM phthalate at pH 5.0 within 11 mins. Under the same conditions, even geometric isomers or mixtures of polycarboxylates and polyphosphates, such as ATP and ADP, could be well separated. The experimental results indicated that incorporating the chelating functional group in the inner wall of the capillary markedly enhances the selectivity of the system.