A new type of three-phase separation phenomenon was found by the charge neutralization of perfluorooctanate ion {PFOA-, CF3(CF2)(6)-COO-} with amylammonium ion (R-N+H3). For example, a three-phase system was formed at pH=6.8 and [PFOA](T)/[amine](T)=0.5. The partition behaviors of solutes such as water-soluble porphyrin and compounds in vivo into each liquid phase were examined.