Atmospheric pressure photoionization. II. Dual source ionization

Area of Science:

• Analytical Chemistry
• Mass Spectrometry

Background:

• Traditional single ionization sources limit the range of compounds detectable in complex mixtures.
• Simultaneous or rapid-switching dual ionization sources are needed to enhance analytical capabilities.

Purpose of the Study:

• To evaluate the performance of combined atmospheric pressure photoionization (APPI) with atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI).
• To explore the potential of dual ionizer configurations for simultaneous or rapid-switched analysis of diverse compounds.

Main Methods:

• Investigated three operational modes: single ionizer, simultaneous dual ionizer, and rapid switching between ionizers.
• Analyzed the impact of dual ionizer configurations on individual ionizer performance.
• Examined ion-molecule reactions and signal interactions between different ionization sources.

Main Results:

• Dual ionizer configurations showed minimal impact on individual source performance.
• Combined ionization did not consistently yield additive signal intensities; signal suppression was observed, particularly in ESI/APPI for proteins.
• Demonstrated preferential ionization of compounds by APPI, APCI, or ESI, explained by thermochemical arguments.
• Confirmed dual source operability in negative ion mode.

Conclusions:

• Combining APPI with APCI or ESI offers expanded analytical possibilities for a wider range of chemical compounds.
• Understanding ion-molecule interactions is crucial for optimizing dual ionization strategies.
• The developed dual ionizer system enhances analytical versatility, including negative ion analysis.