Patent ID: 7432054

Claim:
A method for separating and purifying nucleic acids having a length of 2 kb or shorter and nucleic acids having a length of 10 kb or longer from a nucleic acid sample solution comprising said nucleic acids, which comprises the following steps performed in the following order: adsorbing a nucleic acid mixture comprising nucleic acids having lengths of 2 kb or shorter and comprising nucleic acids having lengths of 10 kb or longer to a first solid phase, wherein the first solid phase comprises a porous film of surface-saponified triacetylcellulose having a surface saponification rate of 50% and a pore size between 0.1 μm and 0.2 μm; collecting nucleic acids which do not adsorb to the first solid phase to obtain a first flow through fraction; washing the first solid phase using a nucleic acid-washing buffer; desorbing the nucleic acids adsorbed to the first solid phase by using a liquid capable of desorbing the nucleic acids adsorbed to the solid phase, thereby obtaining purified and separated nucleic acids having a length of 10 kb or longer; adsorbing the first flow through fraction to a second solid phase, wherein the second solid phase comprise a porous film of surface-saponified triacetylcellulose having a surface saponification rate of 100% and a pore size of between 2.5 μm and 10 μm; collecting nucleic acids which do not adsorb to the second solid phase to obtain a second flow through fraction; adsorbing the second flow through fraction to a third solid phase, wherein the third solid phase comprises porous film of surface-saponified triacetylcellulose having a surface saponification rate of 100% and a pore size of between 0.2 μm and 0.4 μm; washing the third solid phase using a nucleic acid-washing buffer; and desorbing the nucleic acids absorbed to the third solid phase by using a liquid capable of desorbing the nucleic acid adsorbed to the third solid phase, thereby obtaining purified and separated nucleic acids having a length of 2 kb or shorter.