The present invention pertains to a process for the chromatographic separation of nucleic acid mixtures into their double-stranded and single-stranded nucleic acid fractions by simultaneously absorbing said nucleic acids as a whole to a mineral support, followed by separation into double-stranded and single-stranded nucleic acids by fractional elution, or by selectively absorbing double-stranded or single-stranded nucleic acid of a liquid sample to a mineral support, as well as solutions and a kit for performing the process according to the invention.