Open AccessDynamic Nuclear Polarization NMR as a new tool to investigate the nature of organic compounds occluded in plant silica particles
Author(s) -
Michel Armand,
Anne Alexandre,
Fabio Ziarelli,
Stéphane Viel,
Guaciara M. Santos
Publication year - 2017
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/s41598-017-03659-z
Subject(s) - organic molecules , natural abundance , carbon 13 nmr , chemistry , polarization (electrochemistry) , organic matter , molecule , two dimensional nuclear magnetic resonance spectroscopy , isotope , analytical chemistry (journal) , nuclear magnetic resonance , materials science , organic chemistry , mass spectrometry , physics , chromatography , stereochemistry , nuclear physics
The determination of the chemical nature of the organic matter associated with phytoliths remains a challenge. This difficulty mainly stems from amounts of organic carbon (C) that are often well below the detection limit of traditional spectroscopic tools. Conventional solid-state 13 C Nuclear Magnetic Resonance (NMR) is widely used to examine the nature and structure of organic molecules, but its inherent low sensitivity prohibits the observation of diluted samples. The recent advent of commercial microwave source in the terahertz range triggered a renewed interest in the Dynamic Nuclear Polarization (DNP) technique to improve the signal to noise ratio of solid-state NMR experiments. With this technique, the 13 C spectrum of a phytolith sample containing 0.1% w/w C was obtained overnight with sufficient quality to permit a semi-quantitative analysis of the organic matter, showing the presence of peptides and carbohydrates as predominant compounds. Considering the natural abundance of the 13 C isotope, this experiment demonstrates that DNP NMR is sufficiently sensitive to observe spin systems present in amounts as low as a few tens of ppm.