Extraction of cytochrome c by a functionalized ionic liquid containing a crown ether

Kubota, Fukiko*; Koyanagi, Yusuke*; Nakashima, Kazunori*; Shimojo, Kojiro   ; Kamiya, Noriho*; Goto, Masahiro*

We carried out the extraction of a protein cytochrome c (Cyt-c) with an ionic liquid with an attached crown ether moiety in the imidazolium cation. The functional ionic liquid, [18C6mim][PF], was dissolved in two different ionic liquids as diluents, one having a hydroxyethyl group, [COHmim][TfN], and the other an ethyl group, [Cmim][TfN], respectively. The transfer of Cyt-c from the aqueous phase to the ionic liquid phase took place with [18C6mim][PF] in the [COHmim][TfN] system. Although the extraction ability was lower than that of dicyclohexano-18-crown-6 (DCH18C6), the functionalized ionic liquid system gave a better stripping performance than the ordinary crown ether system. The extraction efficiency was not influenced by operating temperature when the concentration of [18C6mim] was high whereas it was greatly affected by temperature at low [18C6mim] concentration.