A method for the purification of a nucleic acid, comprising the steps of: (a) adsorbing on a porous or non-porous mineral substrate selected from the group consisting of silica gel, glass fibers, quartz fibers, zeolites, and magnetically attractable particles coated with glass the nucleic acid sequence-independently from a composition containing (i) an aqueous buffer, (ii) salts in a concentration equal to or greater than 1 M, (iii) a water-miscible non-acidic organic compound comprising a functional group of Formula I, W ≡ Z whereby W is a carbon atom or a sulfur atom and Z is an oxygen atom or a nitrogen atom, whereby the functional group is selected from the group consisting of an oxo group, a sulfoxo group, a cyano group, and a carbonyl group of a carbamoyl function or an amide but not belonging to a carboxy function, and the water-miscible non-acidic organic compound is selected from the group consisting of acetylacetone, dimethylsulfoxide, diethylketone, methylethylketone, methylpropylketone, isobutylmethylketone, gamma-butyrolactone, gamma-valerolactone, propylene carbonate, and N-methyl-2-pyrrolidone, and whereby composition of step (a) contains 1 to 50 per cent volume by volume of the water-miscible non-acidic organic compound, and the water-miscible non-acidic organic compound is dissolved to form a homogeneous liquid phase, and (iv) the nucleic acid; (b) optionally washing with a washing solution the substrate with the adsorbed nucleic acid; followed by (c) contacting the substrate with the adsorbed nucleic acid with a solution containing salts in a lower concentration compared to the composition of step (a), thereby desorbing the nucleic acid from the substrate; and (d) separating the solution with the desorbed nucleic acid from the substrate, thereby purifying the nucleic acid; and optionally (e) precipitating the desorbed nucleic acid from the solution of step (d) and isolating the precipitated nucleic acid, thereby further purifying the nucleic acid. (a) adsorbing on a porous or non-porous mineral substrate selected from the group consisting of silica gel, glass fibers, quartz fibers, zeolites, and magnetically attractable particles coated with glass the nucleic acid sequence-independently from a composition containing (i) an aqueous buffer, (ii) salts in a concentration equal to or greater than 1 M, (iii) a water-miscible non-acidic organic compound comprising a functional group of Formula I, W ≡ Z whereby W is a carbon atom or a sulfur atom and Z is an oxygen atom or a nitrogen atom, whereby the functional group is selected from the group consisting of an oxo group, a sulfoxo group, a cyano group, and a carbonyl group of a carbamoyl function or an amide but not belonging to a carboxy function, and the water-miscible non-acidic organic compound is selected from the group consisting of acetylacetone, dimethylsulfoxide, diethylketone, methylethylketone, methylpropylketone, isobutylmethylketone, gamma-butyrolactone, gamma-valerolactone, propylene carbonate, and N-methyl-2-pyrrolidone, and whereby composition of step (a) contains 1 to 50 per cent volume by volume of the water-miscible non-acidic organic compound, and the water-miscible non-acidic organic compound is dissolved to form a homogeneous liquid phase, and (iv) the nucleic acid; (i) an aqueous buffer, (ii) salts in a concentration equal to or greater than 1 M, (iii) a water-miscible non-acidic organic compound comprising a functional group of Formula I, W ≡ Z whereby W is a carbon atom or a sulfur atom and Z is an oxygen atom or a nitrogen atom, whereby the functional group is selected from the group consisting of an oxo group, a sulfoxo group, a cyano group, and a carbonyl group of a carbamoyl function or an amide but not belonging to a carboxy function, and the water-miscible non-acidic organic compound is selected from the group consisting of acetylacetone, dimethylsulfoxide, diethylketone, methylethylketone, methylpropylketone, isobutylmethylketone, gamma-butyrolactone, gamma-valerolactone, propylene carbonate, and N-methyl-2-pyrrolidone, and whereby composition of step (a) contains 1 to 50 per cent volume by volume of the water-miscible non-acidic organic compound, and the water-miscible non-acidic organic compound is dissolved to form a homogeneous liquid phase, and (iv) the nucleic acid; (b) optionally washing with a washing solution the substrate with the adsorbed nucleic acid; followed by (c) contacting the substrate with the adsorbed nucleic acid with a solution containing salts in a lower concentration compared to the composition of step (a), thereby desorbing the nucleic acid from the substrate; and (d) separating the solution with the desorbed nucleic acid from the substrate, thereby purifying the nucleic acid; and optionally (e) precipitating the desorbed nucleic acid from the solution of step (d) and isolating the precipitated nucleic acid, thereby further purifying the nucleic acid.