A Miniaturized Linear Wire Ion Trap with Electron Ionization and Single Photon Ionization Sources

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Chemical Instrumentation

Background:

• Linear wire ion traps (LWITs) offer versatile platforms for mass spectrometry.
• Soft ionization techniques are crucial for analyzing sensitive organic compounds.
• Electron ionization (EI) can cause significant fragmentation, complicating analysis.

Purpose of the Study:

• To develop and evaluate a linear wire ion trap (LWIT) equipped with both electron ionization (EI) and single photon ionization (SPI) sources.
• To assess the performance of SPI using a vacuum ultraviolet (VUV) lamp for soft ionization of organic compounds.
• To compare the limit of detection (LOD) of SPI and EI for benzene analysis.

Main Methods:

• Construction of a linear wire ion trap (LWIT) incorporating EI and SPI capabilities.
• Utilizing a vacuum ultraviolet (VUV) lamp, driven by a pulsed amplifier and generator, for SPI.
• Introducing sample gas via a leak valve and optimizing system pressure for signal-to-noise ratio and resolving power.

Main Results:

• Single photon ionization (SPI) achieved a lower limit of detection (LOD) for benzene (80 ppbv) compared to electron ionization (EI) (137 ppbv).
• The system demonstrated the ability to distinguish different compound classes within a gasoline sample.
• System pressure was identified as a critical factor influencing signal-to-noise ratio and resolving power.

Conclusions:

• The developed LWIT with SPI is a promising tool for sensitive detection of organic compounds.
• SPI offers advantages over EI for certain analytes, providing softer ionization and improved LOD.
• Further optimization of system parameters can enhance the performance of LWIT-based mass spectrometry.