Selective extraction and isolation of vitamin B12 using homogeneous liquid-liquid extraction with perfluoro surfactant

Cyanocobalamin (vitamin 1312) was selectively extracted from a biological sample by the homogeneous liquid-liquid extraction based on a pH-dependent phase separation with perfluorooctanoate ion (PFOA(-)). When the experimental conditions were [PFOA(-)](T) = 2.86 x 10(-3) mol L-1, [HCl](T) = 0.66 mol L-1, and [Acetone]T = 2.86 vol%, 8.46 x 10(-7) mol L-1 (1.14 ppm) of vitamin B-12 was selectively extracted at 95.2% (sample solution; 35 mL --> a liquid sedimented phase; 30 muL). This liquid sedimented phase consisted of large amounts of HPFOA. When microliter levels of THF and water were added to this sedimented phase, vitamin B-12 is completely and rapidly back-extracted from the sedimented phase to the water phase. Vitamin B-12 was then extracted into the water phase at 96.2% and all HPFOA remained in the sedimented phase. The rest of the sedimented phase after the back-extraction was dried and completely recovered as a powder of HPFOA. Consequently, this method was able to recycle HPFOA as a separation medium. Vitamin B-12 in a water phase was also crystallized by the addition of excess THE Moreover, this method was applied to the extraction from rare oysters. As a result, a few micrograms of vitamin B-12 were recovered.