Ionic-liquid-based aqueous biphasic systems: enhanced one-step extraction/concentration techniques of water pollution tracers

Abstract

Pharmaceuticals are ubiquitous micropollutants due to their continuous consumption and consequent release via human excretions into aqueous systems. The low concentrations of these compounds in aqueous samples (from ng·L-1 to μg·L-1) results in the need of developing efficient pre-treatment/concentration techniques to accurately quantify and monitor these components in aqueous streams. As an alternative to the currently used concentration methods, mainly based on solid-phase extractions (SPE), liquid-liquid extraction based on aqueous biphasic systems (ABS) composed of ionic liquids (ILs) can be seen as more sustainable processes. In fact, ABS do not require the use of volatile and hazardous organic solvents (VOCs) typically employed in SPE and liquid-liquid extractions. Furthermore, the tunable properties of ILs are transferred to IL-based ABS, and high extraction efficiencies and selectivities have been reported for a wide range of compounds. In this work, we demonstrate the applicability of IL-based ABS for the concomitant extraction and concentration of several water pollution tracers, namely ethinylestradiol (EE2), caffeine, and carbamazepine, in which concentration factors up to 1000-fold have been gathered in a single-step. The increase in the concentration of pollution tracers from ng·L-1 to μg·L-1 allowed the use of high-performance liquid chromatography with fluorescence detection for their analysis/monitoring.