the invention relates to a novel sulphated cationic ion exchanger and to a method for preparation thereof . in addition it relates to a method of improving the capacity of an exchange matrix to receive sulphated groups . although the general attraction of sulphate groups to proteins is known we have found that sulphated ion exchangers selectively bind lipoproteins in blood serum or plasma under suitable conditions . we have also discovered that when hydroxyalkyl groups are introduced into the ion exchanger matrix its capacity for taking up sulphate groups is unexpectedly increased . a method of use of the ion exchanger is also described .