scholarly journals Univariate Statistical Analysis as a Guide to 1H-NMR Spectra Signal Assignment by Visual Inspection

Metabolites ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 15 ◽  
Author(s):  
Chenglin Zhu ◽  
Beatrice Vitali ◽  
Gilbert Donders ◽  
Carola Parolin ◽  
Yan Li ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
1H Nmr ◽  
Nmr Spectra ◽  
Visual Inspection ◽  
Signal To Noise Ratio ◽  
1H Nmr Spectra ◽  
Proton Nuclear Magnetic Resonance ◽  
Signal Assignment ◽  
Hands On ◽  
Interested User

In Proton Nuclear Magnetic Resonance (1H-NMR) spectroscopy, the signals assignment procedure is normally conducted by visual inspection of the spectra, by taking advantage of the innate predisposition of human eye for pattern recognition. In the case of untargeted metabolomics investigations on food and body fluids, the complexity of the spectra may lead the user to overlook signals, independently from their biological relevance. Here, we describe a four steps procedure that is designed to guide signals assignment task by visual inspection. The procedure can be employed whenever an experimental plan allows for the application of a univariate statistical analysis on a point-by-point basis, which is commonly the case. By comparing, as a proof of concept, 1H-NMR spectra of vaginal fluids of healthy and bacterial vaginosis (BV) affected women, we show that the procedure is also readily usable by non-experts in three particularly challenging cases: overlapping multiplets, poorly aligned signals, and signals with very poor signal-to-noise ratio. The paper is accompanied by the necessary codes and examples written in R computational language to allow the interested user gaining a hands-on impression of the procedure’s strengths and weaknesses.

scholarly journals Large-Scale Evaluation of Major Soluble Macromolecular Components of Fish Muscle from a Conventional 1H-NMR Spectral Database

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1966 ◽  
Author(s):  
Feifei Wei ◽  
Minoru Fukuchi ◽  
Kengo Ito ◽  
Kenji Sakata ◽  
Taiga Asakura ◽  
...  
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Large Scale ◽  
Fish Muscle ◽  
1H Nmr Spectra ◽  
Proton Nuclear Magnetic Resonance ◽  
Training Dataset ◽  
Small Scale ◽  
Additional Measurement ◽  
Molecular Components

Conventional proton nuclear magnetic resonance (1H-NMR) has been widely used for identification and quantification of small molecular components in food. However, identification of major soluble macromolecular components from conventional 1H-NMR spectra is difficult. This is because the baseline appearance is masked by the dense and high-intensity signals from small molecular components present in the sample mixtures. In this study, we introduced an integrated analytical strategy based on the combination of additional measurement using a diffusion filter, covariation peak separation, and matrix decomposition in a small-scale training dataset. This strategy is aimed to extract signal profiles of soluble macromolecular components from conventional 1H-NMR spectral data in a large-scale dataset without the requirement of re-measurement. We applied this method to the conventional 1H-NMR spectra of water-soluble fish muscle extracts and investigated the distribution characteristics of fish diversity and muscle soluble macromolecular components, such as lipids and collagens. We identified a cluster of fish species with low content of lipids and high content of collagens in muscle, which showed great potential for the development of functional foods. Because this mechanical data processing method requires additional measurement of only a small-scale training dataset without special sample pretreatment, it should be immediately applicable to extract macromolecular signals from accumulated conventional 1H-NMR databases of other complex gelatinous mixtures in foods.

scholarly journals 1H-NMR metabolic profiling of wines from three cultivans, three soil types and two contrasting vintages

OENO One ◽  
2007 ◽  
Vol 41 (2) ◽  
pp. 103
Author(s):  
Giuliano Elias Pereira ◽  
Jean-Pierre Gaudillère ◽  
Cornelis Van Leeuwen ◽  
Ghislaine Hilbert ◽  
Mickaël Maucourt ◽  
...  
Keyword(s):  
1H Nmr ◽  
Metabolic Profiling ◽  
Nmr Spectra ◽  
Partial Least Square ◽  
1H Nmr Spectra ◽  
Proton Nuclear Magnetic Resonance ◽  
Soil Types ◽  
Quality Traits ◽  
Grape Quality ◽  
Nmr Signals

<p style="text-align: justify;"><strong>Aims</strong>: Differences in wine flavour proceed primarily from grape quality. Environmental factors (climate, soil), cultivars and training systems modify many grape and wine quality traits. Metabolic profiling based on proton nuclear magnetic resonance (1H-NMR) spectra has been proved to be useful to study multifactorial effects of the vine environment on intricate grape quality traits. The capacity of this method to discriminate the environmental effects on wine has to be demonstrated.</p><p style="text-align: justify;"><strong>Methods and results</strong>: : 1H-NMR spectra were made from wines produced with grapes harvested at maturity of three cultivars (Cabernet-Sauvignon, Cabernet franc and Merlot) and three soil types (gravely, sandy and clayey) during two vintages (2002 and 2003). Data were analysed by multivariate statistical methods. Principal component analysis applied on the NMR spectra data were not always able to separate satisfactorily wines from the 3 soil types. Conversely, partial least square analysis separated clearly the 3 soil types independently of the vintage and cultivar.</p><p style="text-align: justify;"><strong>Conclusion</strong>: By comparing the NMR signals that contribute to the two first axes of the PCA and PLS analyses, a significant soil effect on NMR signals in wines is reported. However, the effect of the vintage on wine composition was greater then the effect of the soil type.</p><p style="text-align: justify;"><strong>Significance and impact of study</strong>: After validation on a larger number of wine samples this chemical profiling will be a useful new method to the qualify wines in relation to climate, soil, and cultivar effects which contribute to the terroir.</p>

scholarly journals SYNTHESIS AND OPTICAL PROPERTIES OF CAMPHOR-SABSTITUTED TETRAPYRAZINOPORPHYRAZINES

2017 ◽  
Vol 60 (4) ◽  
pp. 60 ◽  
Author(s):  
Grigoriy V. Kuvshinov ◽  
Tatyana M. Ziyadova ◽  
Sofya A. Kuvshinova ◽  
Oscar I. Koifman
Keyword(s):  
Optical Properties ◽  
Sulfuric Acid ◽  
1H Nmr ◽  
Nmr Spectra ◽  
1H Nmr Spectra ◽  
Proton Nuclear Magnetic Resonance ◽  
Blue Color ◽  
Acid Solutions ◽  
Chemical Structures ◽  
Sulfuric Acid Solutions

The synthesis of the complexes of Cu, Ni, Co, Pd, Sn, Hg of 1',7',7'-trimethylbicyclo[2.2.1]heptano-[2',3'-b]-2,3-pyrazinoporphyrazine for new materials for variety of potential applications is described. Metallic complexes were synthesized by the template cyclotetramerization of dicarbonitrile with metal chlorides at temperature 140-150 ºС for 20 min. Ammonium molybdate tetrahydrate was used as a catalyst. The products were purificated by chromatography on silica gel (eluent -chloroform). Complexes of Pd, Sn and Hg were synthesized for the first time. The metallocomplexes of camphor-substituted tetrapyrazinoporphyrazine are crystalline substances of dark blue color, not fusible up to 300 ° C, which have good solubility in chloroform, toluene, ethanol, acetone, DMF, acetic and trifluoroacetic acids. The chemical structures of the complexes of Cu, Ni, Co, Pd, Sn, Hg of 1',7',7'-trimethylbicyclo[2.2.1]heptano-[2’,3’-b]-2,3-pyrazinoporphyrazine obtained in this study were characterized by proton nuclear magnetic resonance and mass spectrometry. The absence of impurity signals in the 1H NMR spectra indicates a high degree of purity of the compounds obtained. For copper, nickel and cobalt complexes, a good correlation was found between the experimental and literature data on the chemical shifts of protons in 1H NMR spectra. Optical properties of the synthesized complexes were studied. The electronic absorption spectra of the complexes in their chloroform, DMF, acetic acid and sulfuric acid solutions were obtained. In organic solvents the typical B band (Soret band, around 400 nm) and Q band (in 600-700 nm region) of phthalocyanines were identified in this study. Complexes of Pd, Sn and Hg in their sulfuric acid solutions are non-stable. The influence of the chemical structure of metalic complexes and solvents on the optical properties was studied. Emission properties of the synthesized complexes of Pd and Hg in their chloroform and DMF solutions were analyzed. Hg-porphyrazine has very intensive fluorescence. The solution has blue color and red fluorescence at common condition.Forcitation:Kuvshinov G.V., Ziyadova T.M., Kuvshinova S.A., Koifman O.I. Synthesis and optical properties of camphor-sabstituted tetrapyrazinoporphyrazines. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 4. P. 60-67.

1H-NMR spectra of high-boiling adamantylaromatic compounds

1978 ◽  
Vol 43 (1) ◽  
pp. 250-256
Author(s):  
Jaroslava Podehradská ◽  
Milan Hájek ◽  
Slavoj Hála
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
1H Nmr Spectra

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

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