Good's buffers as novel phase-forming components of ionic-liquid-based aqueous biphasic systems


Aiming at the development of self-buffering and benign extraction/separation processes, this work reports a novel class of aqueous biphasic systems (ABS) composed of ionic liquids (ILs) and organic biological buffers (Good's buffers, GBs). A large array of ILs and GBs was investigated, revealing than only the more hydrophobic and fluorinated ILs are able to form ABS. For these systems, the phase diagrams, tie-lines, tie-line lengths, and critical points were determined at 25 degrees C. The ABS were then evaluated as alternative liquid liquid extraction strategies for two amino acids (L-phenylalanine and L-tryptophan). The single-step extraction efficiencies for the GB-rich phase range between 22.4 and 100.0% (complete extraction). Contrarily to the most conventional IL-salt ABS, in most of the systems investigated, the amino acids preferentially migrate for the more biocompatible and hydrophilic GB-rich phase. Remarkably, in two of the studied ABS, L-phenylalanine completely partitions to the GB-rich phase while L-tryptophan shows a preferential affinity for the opposite phase. These results show that the extraction efficiencies of similar amino acids can be tailored by the design of the chemical structures of the phase-forming components, creating thus new possibilities for the use of IL-based ABS in biotechnological separations. (C) 2015 Elsevier B.V. All rights reserved.



subject category

Biotechnology & Applied Microbiology; Engineering


Luis, A; Dinis, TBV; Passos, H; Taha, M; Freire, MG

our authors


This work was developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM /50011/2013), financed by National funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement. The authors are also grateful for financial support from FCT - Fundacao para a Ciencia e a Tecnologia for the project PTDC/QUI-QUI/121520/2010 and post-doctoral and doctoral grants, SFRH/BPD/78441/2011 and SFRH/BD/85248/2012, from M. Taha and H. Passos, respectively. M. G. Freire acknowledges the European Research Council (ERC) for the Starting Grant ERC-2013-StG-337753.

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