Micellar electrokinetic chromatography-mass spectrometry

Area of Science:

• Analytical Chemistry
• Separation Science
• Mass Spectrometry

Background:

• Micellar electrokinetic chromatography (MEKC) coupled with mass spectrometry (MS) is valuable for analyte identification and structure confirmation.
• Direct coupling faces challenges due to nonvolatile MEKC surfactants affecting MS performance, causing sensitivity loss and ion source contamination.

Purpose of the Study:

• To review and evaluate various on-line coupling approaches for MEKC-MS.
• To identify methods that overcome the limitations of direct MEKC-MS coupling.

Main Methods:

• Review of different on-line MEKC-MS coupling techniques.
• Evaluation of strategies including high-molecular-mass surfactants, electrospray-chemical ionization (ES-CI) interfaces, voltage switching, buffer renewal, partial-filling micellar plugs, and anodically migrating micelles.

Main Results:

• The ES-CI interface shows promise for routine on-line MEKC-MS with nonvolatile salts and surfactants.
• High-molecular-mass surfactants reduce background ions and allow low surfactant concentrations.
• Partial-filling micellar plugs and anodically migrating micelles effectively prevent MEKC micelles from entering the ESI-MS system.

Conclusions:

• On-line MEKC-MS coupling can be achieved without instrument modification using partial-filling micellar plugs or anodically migrating micelles.
• The ES-CI interface is a promising solution for routine MEKC-MS operations.
• These advancements facilitate direct transfer of MEKC separations to ESI-MS.