not-yet-known
      not-yet-known
    
    
      not-yet-known
      
      
        unknown
      
    
  
  
    Rationale: Stable isotope-labeled organic compounds, containing
D, 15N or 13C, have widespread
applications in chemistry, biology, environmental science, and
agriculture. However, the isotopic purity calculations for these labeled
organic compounds are usually complicated, especially in mixed
isotopes-labeled scenarios. Herein, the electrospray ionization-high
resolution mass spectrometry (ESI-HRMS) was applied to determinate the
isotopic purity for stable isotope-labeled organic compounds, containing
D, 15N or 13C. Methods: The
representative isotopolog ion with its specific molecular formula was
proposed to represent various labeled states. The isotopic purity was
calculated with the corrected intensities of representative isotopolog
ions by removing the natural isotopic contributions from preceding
peaks. A unified equation has been proposed for the calculation of
isotopic purity for various labeled situations including D,
15N or 13C. Results:
Several case studies were presented and our calculated isotopic purities
were all consistent with the isotopic purities provided in the
certificate. In-source CID method was applied for the labeled compound
(molecular weight＞400 u), when the maxim resolution setting was
insufficient to differentiate isobaric isotopolog ions.
Conclusion: Finally, a workflow with a Python calculation
program was summarized for determinations of the isotopic purity for
mono isotope-labeled or mixed isotopes-labeled organic compounds,
involving D, 15N or 13C, by using
ESI-HRMS to assigning the representative isotopolog ions with accurate
mass and excluding the isobar interference.