Position specific 15N isotope analysis at natural abundance by 1H NMR
Abstract
Stable isotope analysis of nitrogen (N) at natural abundance provides key insights into biochemical processes. However, position-specific isotope analysis (PSIA) of 15 N remains technically challenging due to the low sensitivity of conventional approaches. The approach we present here relies on resolving the 1 H– 15 N doublets embedded within dominant 1 H– 14 N triplets and quantifying them via spectral deconvolution under rigorously optimized quantitative NMR conditions. Using ammonium chloride as a model, we established the experimental and processing parameters required for precision (≤ 2‰) and trueness (< 3‰), validated against isotope ratio monitoring Mass Spectrometry (irm-MS). The method was successfully extended to structurally more complex compounds (aniline, indole, urea, and N-acetylated tryptophan methyl ester), achieving accurate position-specific δ 15 N determinations. Importantly, we demonstrate the feasibility of applying this strategy to a human urine sample, enabling direct δ 15 N measurement of endogenous urea in a complex biological matrix at natural abundance. This non-destructive method requires minimal sample amounts and offers a robust complement to irm-MS, expanding the analytical toolbox for nitrogen isotope research in environmental, biochemical, and biomedical contexts.
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BibTeX
@article{couton2026position,
title = {{Position specific 15N isotope analysis at natural abundance by 1H NMR}},
author = {Maylis Couton and Margot Sanchez and Valérie Fargeas and Illa Tea},
journal = {Analytica Chimica Acta},
year = {2026},
month = oct,
doi = {10.1016/j.aca.2026.346112},
url = {https://hal.science/hal-05796092v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Position specific 15N isotope analysis at natural abundance by 1H NMR
AU - Maylis Couton
AU - Margot Sanchez
AU - Valérie Fargeas
AU - Illa Tea
PY - 2026
DA - 2026/10/12
JO - Analytica Chimica Acta
DO - 10.1016/j.aca.2026.346112
UR - https://hal.science/hal-05796092v1
AB - Stable isotope analysis of nitrogen (N) at natural abundance provides key insights into biochemical processes. However, position-specific isotope analysis (PSIA) of 15 N remains technically challenging due to the low sensitivity of conventional approaches. The approach we present here relies on resolving the 1 H– 15 N doublets embedded within dominant 1 H– 14 N triplets and quantifying them via spectral deconvolution under rigorously optimized quantitative NMR conditions. Using ammonium chloride as a model, we established the experimental and processing parameters required for precision (≤ 2‰) and trueness (< 3‰), validated against isotope ratio monitoring Mass Spectrometry (irm-MS). The method was successfully extended to structurally more complex compounds (aniline, indole, urea, and N-acetylated tryptophan methyl ester), achieving accurate position-specific δ 15 N determinations. Importantly, we demonstrate the feasibility of applying this strategy to a human urine sample, enabling direct δ 15 N measurement of endogenous urea in a complex biological matrix at natural abundance. This non-destructive method requires minimal sample amounts and offers a robust complement to irm-MS, expanding the analytical toolbox for nitrogen isotope research in environmental, biochemical, and biomedical contexts.
SN - 0003-2670
ER -