Ionic liquids and deep eutetic solvents in the field of environmental monitoring

Abstract

A growing number of compounds resulting from human activities are continuously released into the environment. Many of these compounds may pose serious environmental threats, reinforcing the need of environmental monitoring to understand their impact on the environment and on human health and to create strategies to revert these risks. Although with serious impact, these pollutants are usually present in trace levels in environmental samples, turning their identification and accurate quantification a major challenge. To overcome this drawback, pretreatment techniques are usually employed, both to eliminate interferences and enrich the sample in the target pollutants. Within the significant developments achieved in this field, ionic liquids (ILs) and deep eutectic solvents (DESs) have shown to lead to relevant improvements in the enrichment factor and target pollutants recovery and in the limit of detection of the analytical technique when used as alternative solvents in pretreatment techniques of environmental matrices. These have been applied in the pretreatment of wastewaters, industrial effluents, human fluids, wine, milk, honey, fish, macroalgae, vegetables and soil. A wide number of pollutants, such as polyaromatic hydrocarbons (PAHs), active pharmaceutical ingredients (APIs), endocrine disruptors, pesticides, UV filters and heavy metals, are some of the most analyzed pollutants. In this work, we review and discuss the use of ILs and DESs as alternative solvents in pretreatment strategies in the field of environmental monitoring. We also highlight the most recent works on this area and provide new insights and directions to follow in this field.