Two-step stacking by sweeping and micelle to solvent stacking using a long-chain cationic ionic liquid surfactant.

Area of Science:

• Analytical Chemistry
• Separation Science
• Capillary Electrophoresis

Background:

• Capillary electrophoresis (CE) is a powerful separation technique.
• Enhancing sensitivity for anionic compounds in CE remains a challenge.
• Ionic liquids offer unique properties for CE applications.

Purpose of the Study:

• To develop a sensitive CE method for anionic compounds.
• To couple long-chain ionic liquid (LCIL)-based sweeping with micelle to solvent stacking (MSS).
• To utilize a novel cationic surfactant, N-Cetyl-N-methylpyrrolidinium bromide (C16MPYBr), and a polymeric ionic liquid for enhanced separation.

Main Methods:

• Capillary column conditioning with a polymeric ionic liquid for anodic electroosmotic flow (EOF).
• Preparation of a micellar solution (MS) zone using C16MPYBr.
• Integration of MSS by analyte sweeping into the micellar zone and subsequent migration to the micelle to solvent boundary (MSSB).
• Optimization of background solution (BGS) with methanol to reverse effective electrophoretic mobility.

Main Results:

• Achieved good linearity (0.9988–0.9999) for model analytes over a wide linear range.
• Obtained low limits of detection (LODs) from 0.025 to 0.25 mg/L.
• Demonstrated significant sensitivity enhancements: 34-60 times increase in peak area/height for specific analytes.
• Reported acceptable intraday and interday repeatabilities (2.12–7.29% RSD).
• Successfully applied the method to analyze spiked environmental water samples with satisfactory recoveries.

Conclusions:

• The coupled LCIL-sweeping and MSS technique in CE provides a highly sensitive method for anionic compound analysis.
• The use of C16MPYBr and a polymeric ionic liquid effectively enhances separation performance.
• The method is robust and applicable to real-world environmental water sample analysis.