Method for desalting an aqueous liquid containing a charged substance comprising the steps of:(i) contacting liquid (I) with an ion-exchanger (1) under conditions permitting binding between ion-exchanger and substance, said ion-exchanger comprising a base matrix carrying an ion-exchange ligand (Ligand 1) with the opposite charge compared to the substance, (ii) desorbing said substance from said ion-exchanger by the use of a liquid (liquid (II)). Wherein: (A) ion-exchanger (1) is an ion-exchanger::(a) that can bind the substance in an aqueous reference liquid at an ionic strength corresponding to 0.1 M NaCl, preferably 0.25 M NaCl; and (b) permits a breakthrough capacity at the pH provided by liquid (I) which is more than 2 mg/ml of gel, at a breakthrough of 10% and linear flow velocity of 300 cm/h;and(B) in step (ii) the pH of liquid (II) is adjusted to a pH value where the charge difference between the substance, the ligand and/or the ion-exchanger is lowered.