The present invention pertains to a method for isolating extracellular nucleic acids from a sample, wherein said sample is optionally stabilized, by binding the extracellular nucleic acids to a solid phase which carries anion exchange groups, comprising the following steps:
a. binding the extracellular nucleic acids to the solid phase in a binding mixture having a first pH which allows binding the extracellular nucleic acids to the anion exchange groups of the solid phase; wherein the sample makes up at least 85% of the volume of the binding mixture;
b. separating the solid phase with the bound extracellular nucleic acids;
c. optionally washing the extracellular nucleic acids;
d. optionally eluting extracellular nucleic acids from the solid phase.
The method has the advantage that large sample volumes can be processed and that extracellular nucleic acids can be isolated rapidly with a high yield. The method is particularly suitable for automatable processes.