Liquid chromatography-based nucleic acid separation is widely used for oligonucleotide purification and analysis. Reversed-phase chromatography is based on the principle of separation using differences in hydrophobicity and uses a support of silica gel C18. Anion-exchange chromatography is based on the principle of separation using the polyanionic nature of nucleic acids and uses a support of an anion-exchange resin (rigid polymer, etc.) that is positively charged to capture anions.