Cross-polarized magic-angle-spinning NMR (CPMAS-NMR) techniques are assumed to be only semi-quantitative in the assessment of carbon distribution in humic substances or natural organic matter, due to a number of interferences such as spinning side bands (SSB) in spectra, paramagnetic species in samples, and low or remote protonation of aromatic carbons. Fast rotor spin rates or direct polarizat...

Cross-Polarisation-magic-angle-spinning (CPMAS) with high-power proton decoupling [Schaefer, 1976] has been widely applied to obtain high resolution NMR spectra of dilute spin1/2 in solids. This method averages out all anisotropic NMR interactions which transform as second-rank tensors, such as chemical shift anisotropical interactions. However, the principal elements of chemical shift anisotro...

Cross-polarization (CP) magic angle spinning (MAS) 13C NMR spectroscopy has become a routine tool in pharmacy, employed to identify and characterize drugs in the solid phase. 13C CPMAS NMR spectra were recorded for solid hydrocortisone 21-hemisuccinate and suxamethonium chloride. White crystalline substances, such as these two drugs, can be easily distinguished; and solid-state 13NMR spectra of...

Direct excitation and {1H}13C-CPMAS NMR allowed detecting carbamate–ammonium ion pairs, carbamic acid bicarbonate species in amine-modified silica sorbents.

The temperature-dependent exchange rate and signal coalescence in the 13C CPMAS NMR spectrum of a crystalline molecular gyroscope are exposed by specifically deuterating the overlapping static carbons.

The transformation of organic matter during anaerobic digestion of mixtures of energetic crops, cow slurry, agro-industrial waste and organic fraction of municipal solid waste (OFMSW) was studied by analysing different samples at diverse points during the anaerobic digestion process in a full-scale plant. Both chemical (fiber analysis) and spectroscopic approaches ((13)C CPMAS NMR) indicated th...

Manure products fermented underground in cow horns and commonly used as field spray (preparation 500) in the biodynamic farming system, were characterized for molecular composition by solid-state nuclear magnetic resonance [(13) C cross-polarization magic-angle-spinning NMR ((13) C-CPMAS-NMR)] spectroscopy and offline tetramethylammonium hydroxide thermochemolysis gas chromatography-mass spectr...

In this article we describe the synthesis and dynamic behavior of two new molecular rotors with 1,4-diethynylphenylene rotators axially linked to two conformationally rigid steroidal norethisterone acetate or ethisterone frames. The resulting 1,4-bis(19-nor-17alpha-ethynyltestosterone-17beta-acetate)benzene (1) and 1,4-bis(17alpha-ethynyltestosterone)benzene (2) were fully characterized in solu...

This paper reports the (1)H, (13)C and (15)N NMR experimental study of five benzimidazoles in solution and in the solid state ((13)C and (15)N CPMAS NMR) as well as the theoretically calculated (GIAO/DFT) chemical shifts. We have assigned unambiguously the "tautomeric positions" (C3a/C7a, C4/C7 and C5/C6) of NH-benzimidazoles that, in some solvents and in the solid state, appear different (bloc...

Soil water repellency (SWR, i.e. reduced affinity for water owing to the presence of organic hydrophobic coatings on soil particles) has relevant hydrological implications because low rates of infiltration enhance water runoff, and untargeted diffusion of fertilizers and pesticides. Previous studies investigated the occurrence of SWR in ecosystems with different vegetation cover but did not cla...