DES-Mediated Approaches Toward Green Analytical Chemistry

FERNÁNDEZ, MARÍA DE LOS ANGELES; GOMEZ, FEDERICO J. V.; BOITEUX, JOANA; ESPINO, MAGDALENA; SILVA, MARÍA FERNANDA

Deep Eutectic Solvents: Synthesis, Properties, and Applications

Wiley ( VCH Verlag GmbH & Co. KGaA.)

Año: 2019; p. 321 - 334

Over the last few years, environment protection and human health and safetyhave gained considerable attention in the field of analytical chemistry. In thissense, green analytical chemistry (GAC) have emerged, bringing light for thealignment of process with sustainable developments [1]. Greening methodologiesneed a compromise between the analytical figures of merit (accuracy,robustness, precision, and sensitivity) and GAC principles andrequirements.Analytical chemists have always been concerned over protecting the environment.In fact, the first descriptions of GAC methods appeared in 1987, in Parisduring Euroanalysis VI [2]. Several years later, Professor Paul Anastas presentedthe principles of ?green chemistry? [1]. The GAC principles were formally introducedby Gałuszka et al. in 2013 [3] as a general approach for analytical methodsdevelopment (Figure 16.1).Taking this into account, analytical chemists are encouraged to change theway of designing methods and procedures. An analytical methodology can beconsidered as a series of consecutive steps that begin with the definition of ananalytical problem. Most of these steps, especially sample preparation, requirethe use of hazardous organic solvents, threatening the greenness of processes.Thus, the best solvent is sometimes no solvent. Even though the developmentof ?solvent‐free? schemes is gaining interest, in some cases their use is unavoidable.In this sense, the search for alternative solvents is of utmostimportance.Over the past two decades, ionic liquids (ILs), organic salts consisting entirelyof ions with melting points lower than 100 °C, have attracted the scientific community.Nevertheless, IL ?greenness? is often challenged due to their poor biodegradability,high cost, and high energy consumption during preparation.A spark of light emerged in 2004, when Abbott et al. [5] introduced deep eutecticsolvents (DESs), representing a milestone for chemistry methodologies. DESsare mixtures where hydrogen bonding and van der Waals interactions are themain driving forces. These mixtures form a eutectic system with smart propertiesto be used in analytical processes. When the system is composed of naturallyoccurring molecules such as sugars, alcohols, amino acids, organic acids, andcholine derivatives, they are called natural deep eutectic solvents (NADES) [6].Considering the aforementioned, DES offer endless opportunities in analyticalchemistry, changing the way for method development. Besides, they bring outstandingfeatures considering that DESs are ?tailor? made and switchable solventsthat could be created during a desired process. In this sense, DESs havebeen applied principally as extraction media. Also, they have been reported asmobile phase in liquid chromatography (LC) and electrochemical modifiers.Convinced to move from old practices to new roads at performing sustainableand efficient analytical methodologies, the driving motivation of this chapter is topresent an overview of knowledge regarding principal applications of DES in thefield of analytical chemistry. Extractions mediated by DES aligned with GAC.Opportunities involving the most popular separation techniques, as well as enhancementand compatibility with detection systems, are presented and discussed.methods (Figure 16.2), and DES have great potential as tools for analytical optimization.Furthermore, recent trends and future perspectives concern strategies andchallenges on how green solvents can contribute to the sustainability of analyticalmethodologies.