Micellar electrokinetic chromatography with acid labile surfactant

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Established pseudostationary phases in micellar electrokinetic chromatography (MEKC) include sodium dodecyl sulphate (SDS) and polymeric micelles.
• Coupling MEKC with electrospray ionization mass spectrometry (ESI-MS) is challenging due to surfactant interference.

Purpose of the Study:

• To evaluate the performance of a novel acid-labile surfactant (ALS) as a pseudostationary phase in MEKC.
• To assess the compatibility of ALS and its degradation products with ESI-MS.

Main Methods:

• Comparative analysis of ALS against SDS, volatile surfactants, and polymeric micelles as pseudostationary phases.
• Determination of separation efficiency and electrophoretic mobility relative standard deviation (RSD).
• Correlation analysis of retention factors and selectivity for different solute types (non-hydrogen bonding, hydrogen bond donor, hydrogen bond acceptor).

Main Results:

• ALS achieved high separation efficiencies (100,000-145,000 theoretical plates) and low RSD (<3%).
• Retention factors with ALS strongly correlated with SDS (R²=0.79 overall, R²=0.992 for non-hydrogen bonding analytes).
• ALS exhibited different selectivity compared to SDS for hydrogen bonding solutes.
• ALS degraded in acidic solution to less surface-active compounds compatible with ESI-MS, with a half-life of 48 min at pH 4.

Conclusions:

• ALS is a viable pseudostationary phase for high-efficiency MEKC separations.
• The acid-labile nature of ALS facilitates direct coupling with ESI-MS by degrading into compatible species.
• ALS shows potential for developing robust and sensitive hyphenated MEKC-ESI-MS methods.