Latest Developments in Direct and Non-Direct LC-MS Methods Based on Liquid Electron Ionization (LEI).
Genny Grasselli1, Adriana Arigò1, Pierangela Palma1
1Department of Pure and Applied Sciences, University of Urbino Carlo Bo, Urbino, Italy.
Critical Reviews in Analytical Chemistry
|July 24, 2024
Summary
Liquid Electron Ionization (LEI) offers a robust alternative to atmospheric pressure ionization in mass spectrometry. This technique enhances molecular identification and quantification, overcoming limitations of current methods for diverse compounds.
Area of Science:
- Analytical Chemistry
- Mass Spectrometry
Background:
- Atmospheric pressure ionization (API) coupled with liquid chromatography-mass spectrometry (LC-MS) is widely used but faces limitations.
- Challenges include low spectral information, poor reproducibility, matrix effects, and difficulties with nonpolar analytes.
- These issues necessitate complex sample preparation or costly labeled standards.
Purpose of the Study:
- To review the development and applications of the Liquid Electron Ionization (LEI) interface for mass spectrometry.
- To highlight LEI's advantages over traditional API techniques.
- To present the latest advancements and future potential of LEI technology.
Main Methods:
- Development and application of the Liquid Electron Ionization (LEI) interface.
- Integration of LEI with various mass spectrometry detectors (single quadrupole, triple quadrupole, QToF) and ionization modes (EI, CI).
- Coupling LEI with different liquid chromatography modes (RPLC, NPLC) and advanced interfaces (MOI, MIMS, M-WATF).
Main Results:
- LEI demonstrates excellent robustness and reproducibility in mass spectral analysis.
- Successfully analyzed a wide range of compounds including pesticides, drugs, phenols, and PAHs.
- Validated versatility across different MS detectors, ionization modes, and chromatography techniques.
- Successful integration with microfluidic interfaces expanded its application scope.
- Recent development of Extractive-Liquid Sampling Electron Ionization-Mass Spectrometry (E-LEI-MS) enables real-time surface analysis.
Conclusions:
- LEI is a versatile and powerful interface for mass spectrometry, overcoming many limitations of API techniques.
- It offers improved sensitivity, identification power, and robustness for diverse analytical challenges.
- LEI and its derivatives like E-LEI-MS represent a significant advancement in analytical chemistry, enabling broader and more efficient molecular analysis.
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