Abstract: A new method for the extraction and purification of Ginkgo biloba flavonoids in an aqueous two-phase system (ATPS) formed from hydrophilic ionic liquid ［C₈ mim］［N(CN)₂］(1-octyl-3-methylimidalium dicyanamide) and phase-forming salt (NH₄)₂SO₄ was studied in this study.The effects of concentration of salt, temperature of system,pH value,amount of electrolyte of NaCl on extraction efficiency were investigated.The parameters influencing the recovery efficiency of (NH₄)₂SO₄ were investigated.(NH₄)₂SO₄ can be recovered from salt solution with higher recovery efficiency.When the ATPS contained 18.52% ［C₈ mim］［N(CN)₂］and 25.93% (NH₄)₂SO₄,and 1.5 mmol NaCl was added at 298.15 K with pH being not adjusted,the extraction efficiency was 96.73%.IL/salt ATPS had higher extraction efficiency and lower viscosity than other ATPSs.When adding 2 volumes of methanol, (NH₄)₂SO₄ can be recovered 90.54%.ATPS based on ［C₈ mim］［N(CN)₂］/(NH₄)₂SO₄ was a good method on extraction and purification of Ginkgo biloba flavonoids.

Key words: ionic liquid;aqueous two-phase system;(NH₄)₂SO₄, Ginkgo biloba flavonoids