High-pressure ion source combined with an in-axis ion trap mass spectrometer. 1. Instrumentation and applications

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Chemical Ionization

Background:

• Traditional mass spectrometry methods face challenges in efficiently producing and analyzing negative ions.
• Developing sensitive techniques for trace contaminant detection is crucial for environmental and safety monitoring.

Purpose of the Study:

• To develop and validate a new instrumental coupling combining a dual EI/CI ion source with a quadrupole ion trap mass spectrometer.
• To efficiently produce and utilize specific reactant negative ions for the analysis of volatile organic compounds.

Main Methods:

• Utilized a dual EI/CI ion source coupled with a quadrupole ion trap mass spectrometer.
• Employed negative ion chemical ionization (NICI) with specific reactant ions (O2*-, CH3O-, Cl-) for targeted ion/molecule interactions.
• Analyzed volatile compounds using gas chromatography (GC) hyphenated with the mass spectrometer.

Main Results:

• Successfully produced and utilized specific reactant negative ions for trace analysis.
• Demonstrated the capability for sensitive detection of phosphorus-containing pesticides (malathion, parathions) and nitro-containing explosives (2,4,6-trinitrotoluene).
• Showcased the formation of deprotonated molecules ([M-H]-), diagnostic ions ([M-R]-), and molecular species (M*-) based on reaction pathways.

Conclusions:

• The novel instrumental coupling offers a promising approach for efficient negative ion generation and analysis.
• This technique provides high sensitivity for trace-level detection of diverse contaminants.
• The study highlights the potential of this method for environmental monitoring and security applications.