DES-mediated approaches toward green analytical chemistry

Abstract

Over the last few years, environment protection and human health and safety have gained considerable attention in the field of analytical chemistry. In this sense, green analytical chemistry (GAC) have emerged, bringing light for the alignment of process with sustainable developments [1]. Greening methodologies need a compromise between the analytical figures of merit (accuracy, robustness, precision, and sensitivity) and GAC principles and requirements.Analytical chemists have always been concerned over protecting the environment.In fact, the first descriptions of GAC methods appeared in 1987, in Paris during Euroanalysis VI [2]. Several years later, Professor Paul Anastas presented the principles of green chemistry [1]. The GAC principles were formally introduced by Gałuszka et al. in 2013 [3] as a general approach for analytical methods development (Figure 16.1).Taking this into account, analytical chemists are encouraged to change the way of designing methods and procedures. An analytical methodology can be considered as a series of consecutive steps that begin with the definition of ananalytical problem. Most of these steps, especially sample preparation, require the 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 utmost importance.Over the past two decades, ionic liquids (ILs), organic salts consisting entire lyof 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 eutectic solvents (DESs), representing a milestone for chemistry methodologies. DESs are mixtures where hydrogen bonding and van der Waals interactions are the main driving forces. These mixtures form a eutectic system with smart properties to be used in analytical processes. When the system is composed of naturally occurring molecules such as sugars, alcohols, amino acids, organic acids, and choline derivatives, they are called natural deep eutectic solvents (NADES) [6].Considering the afore mentioned, DES offer endless opportunities in analytical chemistry, changing the way for method development. Besides, they bring outstanding features considering that DESs are tailor made and switchable solventsthat could be created during a desired process. In this sense, DESs have been applied principally as extraction media. Also, they have been reported as mobile phase in liquid chromatography (LC) and electrochemical modifiers.Convinced to move from old practices to new roads at performing sustainable and efficient analytical methodologies, the driving motivation of this chapter is to present an overview of knowledge regarding principal applications of DES in the field of analytical chemistry. Extractions mediated by DES aligned with GAC.Opportunities involving the most popular separation techniques, as well as enhancement and 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 and challenges on how green solvents can contribute to the sustainability of analytical methodologies.