Work

Position specific 15N isotope analysis at natural abundance by 1H NMR

Year: 2026

Type: article

Abstract: 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.

Source: Analytica Chimica Acta

DOI: 10.1016/j.aca.2026.346112

Authors: Maylis Couton, Margot Sanchez, Valérie Fargeas, Illa Tea

Institutions: Centre National de la Recherche Scientifique, Chimie et Interdisciplinarité, Synthèse, Analyse, Modélisation, Nantes Université, Lyon 1 Université, Institut des Sciences Analytiques

Language: English

Topic: Advanced NMR Techniques and Applications

Subfield: Spectroscopy

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,270

Funder: Agence Nationale de la Recherche