1.
High-resolution pure shift NMR spectroscopy offers better metabolite discrimination in food quality analysis.
Bo, Y, Feng, J, Xu, J, Huang, Y, Cai, H, Cui, X, Dong, J, Ding, S, Chen, Z
Food research international (Ottawa, Ont.). 2019;:108574
Abstract
PSYCHE homonuclear decoupling, a prominent pure shift NMR method, is successfully applied to adulteration discrimination of honey and geographical originality identification of tea. Effects of homonuclear couplings are efficiently suppressed, producing resolution-enhanced spectra. The pair wise honey and tea samples are well separated in OPLS-DA models with high predictability. Due to the well-resolved and accurate assignment of singlet resonances after decoupling, PSYCHE is advantageous in the identification of differential components and accurate quantification of compound concentrations presented by enhanced volcano and Beeswarm plots of honey samples, while the analysis of NOESY is easily interfered by overlapped resonances, which is further proved by the STOCSY analysis, displaying the spectral stability and reproducibility. Experimental results show that PSYCHE can improve the spectral resolution of natural complex products such as honey and tea and be combined with multivariate statistical analysis and serve as a supplementary technique to the standard methods, especially for samples systems composed by a few high-content compounds.
2.
Spectroscopic studies on the interactions between a bioactive diperoxovanadate complex and pyridine.
Yu, X, Cai, S, Chen, Z
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy. 2004;(1-2):391-6
Abstract
Interactions between a bioactive diperoxovanadate complex K3[OV(O2)2(C2O4)].H2O and pyridine in solution were studied by 2D NMR diffusion ordered spectroscopy (DOSY) as well as 1D 1H, 13C, 14N, and 51V NMR, variable temperature 1H NMR and spin-lattice relaxation time. Competitive coordination between C2O(4)(2-) and pyridine to [OV(O2)(2)](-) were observed in solution. A new species [OV(O2)2(Py)](-) was formed and its NMR data were reported for the first time. The experimental results indicated that both of the vanadium atom in species [OV(O2)2(C2O4)](3-) and [OV(O2)2(Py)](-) are six coordinated in solution. The conclusion was further supported by the results of ESI-MS. The newly-formed species is stable under the condition of near physiological pH value.