Abstract: A method for the manufacture of an agarose separation gel: The method is characterized in comprising the steps of: i) providing a solution of agar, and ii) one, two or more substeps (ii.A, ii.B, ii.C etc) which each comprises desulphating thereby transforming agar to agarose having a degree of substitution of sulphate groups that is at most 75% of the degree of substitution of sulphate groups in native agar, iii) gelling the dissolved agar prior to step (ii) and/or securing so that the desulphated agar is in gel form at least after one or more of the substeps of step (ii), and imperatively after step (ii). An agarose separation gel that exhibits a. a plurality of methoxy groups each of which are at the same position as in native agar and with a degree of substitution in the range of 1-100% of the degree of substitution of native agar, and b. sulphate groups with a degree of substitution which is <75% of the degree of substitution for sulphate groups in native agar.