High-Pressure Photon Ionization Source for TOFMS and Its Application for Online Breath Analysis

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Environmental Science

Background:

• Photon ionization mass spectrometry (PI-MS) is crucial for online trace substance detection in complex samples.
• Existing PI-MS methods face limitations in sensitivity and detection of compounds with higher ionization potentials.
• Analysis of exhaled breath requires sensitive and specific techniques for volatile organic compound (VOC) identification.

Purpose of the Study:

• To develop a novel high-pressure photoionization (HPPI) ion source for time-of-flight mass spectrometry (TOFMS).
• To improve detection sensitivity and analytical capabilities for complex gas mixtures, particularly exhaled breath.
• To enable accurate identification and quantification of VOCs in biological samples.

Main Methods:

• Development of a high-pressure photon ionization (HPPI) source utilizing a vacuum ultraviolet (VUV) Kr lamp.
• Integration of an RF-only quadrupole as an ion guide for high ion transmission efficiency.
• Implementation of in-source collision-induced dissociation (CID) for enhanced chemical identification.
• Operation under high humidity (100% relative humidity at 37 °C) to facilitate detection of compounds with higher ionization potentials.

Main Results:

• The HPPI-TOFMS system achieved significantly improved detection sensitivity, with limits of detection down to 0.015 ppbv for hydrocarbons.
• High ion transmission efficiency was maintained using the RF-only quadrupole ion guide.
• The system demonstrated effective online analysis of exhaled breath from healthy and smoker subjects.
• Several common VOCs in breath, including acetone, isoprene, and ethanol, were successfully identified and quantified.

Conclusions:

• The developed HPPI-TOFMS system offers enhanced sensitivity and analytical performance for complex gas analysis.
• The system is capable of online monitoring and characterization of volatile organic compounds in biological samples like exhaled breath.
• This technology holds promise for advanced diagnostics and research in respiratory diseases and metabolic disorders.