Method and kit for purifying nucleic acids

A kit for isolating fetal nucleic acids from maternal nucleic acids in a plasma sample,

• comprising:
• a pipette tip comprising a self-supporting glass frit filter, wherein the glass frit filter specifically binds to nucleic acids, wherein the glass frit filter has a pore size of 2-220 microns and is not treated or coated with an agent that improves binding of nucleic acid to the glass frit filter,
• a first binding buffer formulated to be mixed with a first sample and provide a first binding mixture having about 17-25% v/v of an aliphatic alcohol and a chaotropic salt at a concentration of between about 0.5 M to about 4.0 M;
• and
• a second binding buffer formulated to mixed with a second sample and provide a second binding mixture having about 0-10% v/v of an aliphatic alcohol and a chaotropic salt at a concentration of between about 1 M to about 4.0 M.