Interactions of basic compounds with ionic liquids used as oils in microemulsion liquid chromatography

Area of Science:

• Analytical Chemistry
• Separation Science
• Green Chemistry

Background:

• Reversed-phase liquid chromatography (RPLC) often requires organic solvents.
• Aqueous microemulsions (MEs) reduce organic solvent use but typically employ volatile, toxic oils.
• Microemulsion liquid chromatography (MELC) offers a greener alternative by replacing oils with ionic liquids (ILs).

Purpose of the Study:

• To develop and investigate a MELC method for analyzing basic compounds, specifically β-adrenoceptor antagonists.
• To explore the formation of MEs using sodium dodecyl sulphate (SDS) and various ionic liquids.
• To elucidate the interactions between cationic analytes, SDS anions, and IL components.

Main Methods:

• Formation and characterization of microemulsions containing SDS and methylimidazolium-based ionic liquids (with varying cations and anions) and 1-butanol as a co-surfactant.
• Analysis of cationic basic compounds using the developed MELC system.
• Comparative studies with classical MELC (using octane), micellar liquid chromatography (MLC), and RPLC.

Main Results:

• Successful formation of microemulsions with SDS and selected ionic liquids.
• Demonstration of MELC applicability for analyzing cationic β-adrenoceptor antagonists.
• Insights into the complex interactions governing the separation in SDS/IL-based MEs.

Conclusions:

• Ionic liquids can effectively replace volatile oils in MELC for analyzing basic compounds.
• The developed MELC system offers a promising, environmentally friendly approach to chromatography.
• Understanding analyte-surfactant-IL interactions is crucial for optimizing MELC performance.