Compositions, methods, and kits for isolating nucleic acids

A method for binding nucleic acids to a matrix comprising:

• contacting cell-free fetal DNA or circulating tumor DNA from a biological sample with a matrix comprising siliceous materials, silica gel, glass, glass fiber, zeolite, kaolin, gelatinous silica, or a combination thereof, in the presence of a binding buffer comprising 4 M to 6 M of guanidine chloride, 10% to 20% of acetonitrile and less than 2% alcohol,
• thereby binding 50% of the cell-free fetal DNA or circulating tumor DNA having a size of 72 bp to the matrix.

A kit for isolating nucleic acids from a biological sample, comprising:

• a binding buffer comprising 5 M to 8 M of guanidine chloride, 15% to 35% of acetonitrile, less than 2% alcohol and is free of both a nucleic acid sample and isopropanol;
• and
• a matrix for binding nucleic acids comprising siliceous materials, silica gel, glass, glass fiber, zeolite, kaolin, gelatinous silica, or a combination thereof.