Evaluating the Chemical Reactivity of Wildfire-Derived Dissolved Organic Molecules: Glutathione Binding through Kendrick Mass Defect Analysis

The emerging risks to organisms of pyrogenic-derived dissolved organic matter (PyDOM) from forest fires are of concern due to its toxic and mutagenic potential (e.g., pro-oxidative responses in fauna through the depletion of glutathione, a nitrogen- and sulfur-containing tripeptide found in cells). This study simulates this phenomenon in a laboratory setting by identifying bonding between reduced l-glutathione and organic molecules in leachates from environmentally weathered biomass samples (charred and uncharred) using Kendrick Mass Defect (KMD) analysis from formula lists obtained from negative-mode electrospray ionization-Fourier transform-ion cyclotron resonance-mass spectrometry ((−)ESI-FT-ICR-MS). These formula lists reveal a 10-fold increase in nitrogen- and sulfur-containing molecular formulas in the charred biomass samples compared with the unreacted charred biomass when subjected to reaction with glutathione. KMD analysis attributed the bonding of glutathione to the biomass leachates accounting for approximately 25% of the new nitrogen- and sulfur-containing molecular formulas as either addition-type or condensation/elimination-type reactions. KMD sheds light on a different fraction of chemically reactive wildfire-produced organic compounds that may be of interest for subsequent toxicological studies.