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Insight
from Carbon and Nitrogen Isotope Fractionation
of Sulfamethoxazole during Oxidative vs Reductive Transformation
Aoife Canavan (16049453)
Christopher Dirr (23146748)
Martin Elsner (1564447)
Biochemistry
Microbiology
Genetics
Chemical Sciences not elsewhere classified
Ecology
Inorganic Chemistry
study thus highlights
stable isotope fractionation
specific isotope analysis
resolution mass spectrometry
raising environmental concerns
product analysis would
nitrogen isotope fractionation
diverse environmental conditions
detecting ongoing transformation
caused normal carbon
n </ sub
c </ sub
oxidative transformation pathways
2 </ sub
transformation pathways
− 2
2 ‰,
transformation products
detect transformation
− 3
− 13
− 12
without buffer
oxidation products
frequently detected
explored information
easily identified
bond cleavage
aquatic systems
6 ‰
The antibiotic sulfamethoxazole
(SMX) is frequently detected in
aquatic systems, raising environmental concerns. Therefore, it is
necessary to investigate its transformation pathways under diverse
environmental conditions. Here, we explored information from stable
isotope fractionation during reductive transformation of SMX with
Fe(II)-amended goethite suspensions vs oxidative transformation with
MnO<sub>2</sub>. Transformation of SMX by surface-bound Fe(II) showed
significant carbon isotope fractionation (ε<sub>C</sub> = −3.6‰
± 0.1‰ and ε<sub>C</sub> = −2.9‰ ±
0.2‰, with and without buffer, respectively), pronounced nitrogen
isotope fractionation (ε<sub>N</sub> = −12.8‰
± 0.6‰ and ε<sub>N</sub> = −13.0‰
± 0.2‰, with and without buffer, respectively), and evidence
of transformation products that are consistent with initial reductive
N–O bond cleavage. In contrast, reaction with MnO<sub>2</sub> caused normal carbon but inverse nitrogen isotope fractionation
(ε<sub>C</sub> = −1.7‰ ± 0.1‰ and
ε<sub>C</sub> = −2.7‰ ± 0.2‰, with
and without buffer, respectively, ε<sub>N</sub> = +1.9‰
± 0.2‰ without buffer) indicative of an initial oxidative
electron transfer. Oxidation products were not easily identified by
high-resolution mass spectrometry, emphasizing the importance of compound-specific
isotope analysis (CSIA) as an alternative for detecting ongoing transformation.
Our study thus highlights the potential of CSIA to detect transformation
in settings where concentration and product analysis would be inconclusive
and to distinguish between reductive and oxidative transformation
pathways of SMX in the environment.
2026-10-01T00:00:00Z
Text
Journal contribution
10.1021/acs.est.6c07718.s001
https://figshare.com/articles/journal_contribution/Insight_from_Carbon_and_Nitrogen_Isotope_Fractionation_of_Sulfamethoxazole_during_Oxidative_vs_Reductive_Transformation/34047270
CC BY-NC 4.0