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Study on Diphenylamine Oxidation by Ozone Using Atmospheric Pressure Chemical Ionization Mass Spectrometry
Eunji Chae1, Chae Eun Son1, Sung-Seen Choi1
1Department of Chemistry, Sejong University, Seoul, Republic of Korea.
Rapid Communications in Mass Spectrometry : RCM
|August 5, 2026
Summary
Diphenylamine (DPAH) derivatives are antioxidants that form radicals upon oxidation. This study used ozonation and mass spectrometry to analyze DPAH oxidation products, finding steric hindrance limits adduction to five oxygen atoms.
Area of Science:
- Chemical Analysis
- Oxidation Chemistry
- Mass Spectrometry
Background:
- Diphenylamine (DPAH) derivatives are crucial antioxidants.
- Their antioxidation mechanism involves radical intermediates, posing analytical challenges.
- Understanding DPAH oxidation is key to antioxidant stability and function.
Purpose of the Study:
- To investigate the rapid oxidation of DPAH using ozonation.
- To identify and characterize radical and neutral oxidation products of DPAH.
- To elucidate the factors influencing the extent of DPAH oxidation.
Main Methods:
- Rapid oxidation of DPAH via ozonation in acetone.
- Analysis of oxidation products using atmospheric pressure chemical ionization mass spectrometry (APCI-MS).
- Detection of species in both positive and negative ion modes using a single quadrupole mass spectrometer.
Main Results:
- Major oxidation products identified as (DPA• + nO) and (DPA• + nO - H).
- Product abundance increased up to two oxygen adductions, then decreased with further oxidation.
- Detected ions corresponded to protonated and deprotonated forms of oxidized DPAH.
Conclusions:
- No significant energy differences for consecutive oxygen adduction (n=1-6).
- Steric hindrance plays a critical role in limiting oxygen atom adduction to DPAH.
- A maximum of five oxygen atoms can be adducted to DPAH due to thermodynamic and steric factors.
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