Data-Based Chemical Class Regions for Van Krevelen Diagrams

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Organic Geochemistry

Background:

• Ultrahigh resolution mass spectrometry (UHR-MS) is crucial for natural organic matter (NOM) characterization.
• Data visualization of complex NOM using UHR-MS is challenging, often relying on Van Krevelen diagrams.
• Existing classifications for chemical classes on Van Krevelen diagrams lack standardization, leading to study variability.

Purpose of the Study:

• To establish standardized H/C and O/C elemental ratio ranges for key chemical classes on Van Krevelen diagrams.
• To provide consistent reference points for visualizing and comparing UHR-MS data of NOM.
• To improve the interpretation and discussion of NOM chemical formulas.

Main Methods:

• Utilized chemical formulas from public databases to determine H/C and O/C ranges.
• Developed specific H/C and O/C ranges for amino sugar, carbohydrate, lignin, lipid, peptide, and tannin classes.
• Compared newly defined regions with existing literature classifications.

Main Results:

• Established recommended H/C and O/C ranges for six chemical classes, presented in a table.
• Demonstrated good agreement with previous literature for amino sugar, carbohydrate, lignin, lipid, and peptide regions.
• Identified a distinct region for tannins at lower H/C and wider O/C values compared to prior studies.

Conclusions:

• The proposed standardized regions offer consistent reference points for UHR-MS based NOM characterization.
• Adoption of these regions will facilitate clearer data discussion and inter-study comparisons.
• This work addresses the need for standardized Van Krevelen diagram classifications in NOM research.