Abstract: Described is a nucleic acid ligand, a mixture thereof, and the use thereof. The mixture contains two or more nucleic acid polymerase substrate analogs. The nucleic acid polymerase substrate analog is a single nucleic acid molecule or nucleic acid molecule analog which forms complementary pairing within a molecule, or a single or two nucleic acid molecules or nucleic acid molecule analogs which form complementary pairing between molecules; and a structure formed thereby has the characteristics of a nucleic acid polymerase substrate. The nucleic acid polymerase substrate analog is suitable for all polymerases and can be widely used in the field of nucleic acid amplification. The 3? end of the nucleic acid ligand has a modification which inhibits the extension thereof.

Abstract: Disclosed is a nucleic acid extraction method. By using a quaternary ammonium salt, nucleic acid molecules in a solution are adsorbed to adsorbing materials such as silicon beads, magnetic beads, diatomite or silica gel or precipitated, thereby improving efficiency of nucleic acid purification and recovery.