The invention provides an improved method for the purification of nucleic acid molecules, which method comprises generating a cellular lysate containing the nucleic acid; contacting the lysate with an anion exchanger bound to a solid support matrix under conditions such that the anion exchanger binds the nucleic acid; followed by eluting the nucleic acid from the anion exchanger with an aqueous mobile phase comprising an elution solution; and desalting the eluted nucleic acid such that it is suitable for downstream applications. The improvement of the method includes providing the anion exchanger in a packed column, wherein the column is packed using a salt solution containing an antimicrobial agent. In addition, the salt solution has a salt concentration similar to that of the lysate, such that the column does not need equilibration prior to sample loading.