abstract
Due to their unique properties, in recent years, ionic liquids (ILs) have been largely investigated in the field of analytical chemistry. Particularly during the last sixteen years, they have been successfully applied in the chromatographic and electrophoretic analysis of value-added compounds extracted from biomass. Considering the growing interest in the use of ILs in this field, this critical review provides a comprehensive overview on the improvements achieved using ILs as constituents of mobile or stationary phases in analytical techniques, namely in capillary electrophoresis and its different modes, in high performance liquid chromatography, and in gas chromatography, for the separation and analysis of natural compounds. The impact of the IL chemical structure and the influence of secondary parameters, such as the IL concentration, temperature, pH, voltage and analysis time (when applied), are also critically addressed regarding the achieved separation improvements. Major conclusions on the role of ILs in the separation mechanisms and the performance of these techniques in terms of efficiency, resolution and selectivity are provided. Based on a critical analysis of all published results, some target-oriented ILs are suggested. Finally, current drawbacks and future challenges in the field are highlighted. In particular, the design and use of more benign and effective ILs as well as the development of integrated (and thus more sustainable) extraction-separation processes using IL aqueous solutions are suggested within a green chemistry perspective.
keywords
CAPILLARY-ZONE-ELECTROPHORESIS; MOBILE-PHASE ADDITIVES; ULTRASOUND-ASSISTED EXTRACTION; HERBA ARTEMISIAE SCOPARIAE; GREEN ANALYTICAL-CHEMISTRY; 4 BIOACTIVE COMPOUNDS; STATIONARY PHASES; RP-HPLC; ELECTROKINETIC CHROMATOGRAPHY; ENVIRONMENTAL ASSESSMENT
subject category
Chemistry; Science & Technology - Other Topics
authors
Soares, B; Passos, H; Freire, CSR; Coutinho, JAP; Silvestre, AJD; Freire, MG
our authors
Groups
G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials
Projects
CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)
Igy Technology: A Purication Platform using Ionic-Liquid-Based Aqueous Biphasic Systems (IGYPURTECH)
acknowledgements
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and, when appropriate, co-financed by the FEDER under the PT2020 Partnership Agreement. The authors also acknowledge FCT for the doctoral grants SRH/BD/85248/2012 and SRH/BDE/103257/2014 of H. Passos and B. Soares, respectively. C. S. R. Freire acknowledges the FCT/MCTES (Portugal) for a contract under Investigador FCT 2012 contract number IF/01407/2012. M. G. Freire acknowledges the European Research Council under the European Union's Seventh Framework Programme (FP7/20072013)/ERC grant agreement no. 337753.