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Mass Spectral Studies of N,N-Dialkylacetimidamides Using ESI-HRMS and MS/MS
S Babu Dadinaboyina1,2, Pranay Renukuntla1,2, Ramunaidu Addipilli1,2
1Centre for Mass Spectrometry, Department of Analytical and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, India.
Rapid Communications in Mass Spectrometry : RCM
|December 24, 2025
Summary
This study developed a rapid method for identifying N,N-dialkylacetimidamides, precursors to Novichok agents. The technique successfully identified these chemicals in Organisation for the Prohibition of Chemical Weapons (OPCW) proficiency tests.
Area of Science:
- Analytical Chemistry
- Forensic Chemistry
- Chemical Weapons Analysis
Background:
- Effective control of chemical warfare agents (CWAs) is crucial for global safety.
- Rapid identification of CWA precursors and degradation products is essential.
- N,N-dialkylacetimidamides (amidines) are key precursors/degradation products of Novichoks and are CWC-scheduled chemicals.
Purpose of the Study:
- To develop a swift and sensitive method for identifying N,N-dialkylacetimidamides (amidines).
- To characterize amidines and their isomers using advanced mass spectrometry.
- To validate the method using real-world samples from OPCW proficiency tests.
Main Methods:
- Synthesis and characterization of a series of amidines (1-10).
- High-resolution positive ion mode electrospray ionization tandem mass spectrometry (ESI-HRMS and MS/MS).
- Nuclear magnetic resonance (¹H NMR) spectroscopy for structural elucidation.
Main Results:
- Common fragment ions ([C₂H₄N]⁺, [MH-C₂H₃N]⁺, [MH-R₂NH₂]⁺) were observed in amidine product ion spectra.
- Isomeric amidines were differentiated using unique fragment ions and relative intensity variations at 20 eV collision energy.
- The method successfully identified specific amidines in OPCW proficiency test samples.
Conclusions:
- ESI-HRMS and MS/MS effectively differentiated synthesized amidines and their isomers.
- The developed tandem mass spectrometry method is suitable for trace-level identification of amidines.
- The method's efficacy was confirmed by successful application in OPCW official proficiency testing.
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