Application of the PASSIL technique for the passive sampling of exemplary polar contaminants (pharmaceuticals and phenolic derivatives) from water

Ionic liquids (ILs) are one of the very promising media for the passive sampling of organic contaminants in water. These compounds offer a wide range of interactions with various analytes and give possibilities to control analyte properties by altering their structures, but most of all, possess a high polarity independent of the water solubility. Recently, some ILs were successfully applied as the receiving phase in the passive sampling of polyaromatic hydrocarbons, and this approach was acronymized to PASSIL. In this paper, we aimed to verify the applicability of the PASSIL technique for the selective extraction and enrichment of polar and semi-polar compounds from aqueous environments. The test kit of analytes comprised selected pharmaceuticals and phenol-type compounds, while the applied ILs were alkylimidazolium- and alkylphosphonium entities with a variety of anions. The 14-day-long experiments were performed in static and semi-static no-renewal systems. The kinetics of the uptake process, the analyte extraction efficiency and the sampling rates for all analytes were determined. One of the tested ionic liquids [P666-14][N(CN)2] presented very promising properties both as a stable medium between polyethersulfone (PES) membranes as well as a highly effective extraction phase. The uptake kinetics of the analytes and the determined sampling rates confirm the better and faster efficiency of PASSIL extraction when compared to commercially available passive samplers. Additionally, some selectivity was observed during analyte extraction, which results from the specific interaction between the IL and analytes, but not from the lipophilicity or ionization state of the analytes. These very promising findings make the PASSIL approach a very promising and competitive analytical tool for the extraction of environmental contaminants over a wide polarity range.

Phosphonium-based ionic liquids in electrokinetic capillary chromatography for the separation of neutral analytes

In this work we elucidated the applicability of phosphonium-based ionic liquids (ILs) as pseudostationary phase in electrokinetic capillary chromatography (EKC) with UV-detection. The phosphonium ILs studied contain bromide, chlorine, or tosylate ions, as counter ions, and alkyl side chains of variable length on the phosphorous atom. The effects of the type and concentration of the IL, pH, ionic strength, and type of background electrolyte solution on the electroosmotic flow (EOF) and on the effective electrophoretic mobilities of some neutral model analytes were investigated and large variations in the migration times were observed. Especially the IL employed remarkably affected the strength and direction of the EOF Successful separations were obtained for neutral aromatic singly substituted analytes, namely benzene, toluene, phenol, and nitrobenzene. The results demonstrated the potential of capillary electromigration methods for rapid interaction studies between ILs and analytes, which is useful for the development of novel materials for sample preparation and separation purposes or for novel catalyst and chemical processing studies.