Ionization techniques in capillary electrophoresis-mass spectrometry: principles, design, and application

Area of Science:

• Analytical Chemistry
• Separation Science
• Mass Spectrometry

Background:

• Capillary electrophoresis-mass spectrometry (CE-MS) coupling, particularly with electrospray ionization (ESI), revolutionized analytical capabilities since its 1987 inception.
• While ESI remains dominant, ongoing research explores diverse soft ionization techniques to enhance CE-MS performance and applicability.

Purpose of the Study:

• To present a comprehensive review of the state-of-the-art in soft ionization techniques employed with CE-MS.
• To outline the fundamental challenges and principles of hyphenating CE and microchip electrophoresis with MS.

Main Methods:

• Detailed review of established and emerging soft ionization techniques for CE-MS.
• Discussion includes sonic spray ionization (SSI), thermospray ionization (TSI), atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), matrix-assisted laser desorption ionization (MALDI), and continuous-flow fast atom bombardment (CF-FAB).
• Description of experimental setups for CE-MS couplings and principles of each ionization method.

Main Results:

• Comprehensive overview of alternative soft ionization techniques for CE-MS.
• Analysis of the strengths and limitations of each technique in the context of CE-MS.
• Illustrative examples demonstrating the applicability of various CE-MS systems.

Conclusions:

• The evolution of CE-MS has been significantly advanced by the integration of various soft ionization techniques.
• Alternative ionization methods offer distinct advantages and address specific challenges, expanding the utility of CE-MS in diverse analytical applications.