Lactose quantification in bovine milk by nuclear magnetic resonance without deuterated solvent (No-D qNMR)

2020 ◽  
Vol 12 (40) ◽  
pp. 4892-4898
Author(s):  
Danyelle Alves da Cunha ◽  
Thays Cardoso Valim ◽  
Paulo Roberto Filgueiras ◽  
Valdemar Lacerda Junior ◽  
Alvaro Cunha Neto

Validation of a method to quantify low lactose content in commercial lactose-free milk by 1H NMR analysis.

1984 ◽  
Vol 62 (2-3) ◽  
pp. 178-184 ◽  
Author(s):  
Eric C. Kelusky ◽  
Ian C. P. Smith

The binding of the local anesthetics tetracaine and procaine with multilamellar dispersions of egg phosphatidylcholine has been studied by 2H nuclear magnetic resonance (NMR). The 2H-NMR line shapes of specifically deuterated local anesthetics are found to be very dependent on the attainment of a true equilibrium. The equilibrium could be most properly reached by the use of repeated freeze–thaw–vortex cycles. The data for tetracaine are consistent with the three-site exchange model proposed earlier. Tetracaine is in slow exchange between a strongly bound site and a weakly bound site and in fast exchange between the weakly bound site and free in solution. The slow exchange rate is estimated, from temperature and dilution studies, to be approximately 1.5 × 103 s−1 at pH 5.5 and slightly faster at pH 9.5. Comparisons of the quadrupole splittings with those seen for our earlier work in egg phosphatidylethanolamine suggest that the location of the strongly bound site in phosphatidylcholine is dependent on the anesthetic charge. This is in contrast to egg phosphatidylethanolamine, where molecular shapes appear to be the determining factor for the location of the anesthetic. Procaine bound very weakly to the model membranes, to yield only a broad resonance and no quadrupole splitting. It appears that procaine, unlike tetracaine, is not bound by the ordered acyl chains.


2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Chuanjiang Li ◽  
Hui Wang ◽  
Manuel Juárez ◽  
Eric Dongliang Ruan

Maillard reaction is a nonenzymatic reaction between reducing sugars and free amino acid moieties, which is known as one of the most important modifications in food science. It is essential to characterize the structure of Amadori rearrangement products (ARPs) formed in the early stage of Maillard reaction. In the present study, the Nα-acetyl-lysine-glucose model had been successfully set up to produce ARP, Nα-acetyl-lysine-glucose. After HPLC purification, ARP had been identified by ESI-MS with intense [M+H]+ ion at 351 m/z and the purity of ARP was confirmed to be over 90% by the relative intensity of [M+H]+ ion. Further structural characterization of the ARP was accomplished by using nuclear magnetic resonance (NMR) spectroscopy, including 1D 1H NMR and 13C NMR, the distortionless enhancement by polarization transfer (DEPT-135) and 2D 1H-1H and 13C-1H correlation spectroscopy (COSY) and 2D nuclear overhauser enhancement spectroscopy (NOESY). The complexity of 1D 1H NMR and 13C NMR was observed due to the presence of isomers in glucose moiety of ARP. However, DEPT-135 and 2D NMR techniques provided more structural information to assign the 1H and 13C resonances of ARP. 2D NOESY had successfully confirmed the glycosylated site between 10-N in Nα-acetyl-lysine and 7′-C in glucose.


2005 ◽  
Vol 88 (1) ◽  
pp. 107-120 ◽  
Author(s):  
Gary Cartwright ◽  
Bobbie H McManus ◽  
Timothy P Leffler ◽  
Cindy R Moser

Abstract A peer-verified method is presented for the determination of percent moisture/solids and fat in dairy products by microwave drying and nuclear magnetic resonance (NMR) analysis. The method involves determining the moisture/solids content of dairy samples bymicrowave drying and using the dried sample to determine the fat content by NMR analysis. Both the submitting and peer laboratories analyzed various dairy products by using a CEM SMART system (moisture) and the SMART Trac (fat). The samples included milks, creams, ice cream mix, sour cream, yogurt, cream cheese, and mozzarella, Swiss, and cheddar cheeses. These samples represented a range of products that processors deal with in daily plant operations. The results were compared with moisture/solids and fat values derived from AOAC-approved methods.


1985 ◽  
Vol 5 (2) ◽  
pp. 267-274 ◽  
Author(s):  
Hiroyuki Kato ◽  
Kyuya Kogure ◽  
Hitoshi Ohtomo ◽  
Muneshige Tobita ◽  
Shigeru Matsui ◽  
...  

Evaluation of ischemic brain injury in experimental cerebral infarction in gerbils and rats was performed by means of both proton nuclear magnetic resonance imaging ([1H]NMR-CT) and various histochemical analyses. In vivo nuclear magnetic resonance (NMR) imaging was carried out employing saturation recovery, inversion recovery, and spin echo pulse sequences. Spatial resolution of the images was excellent. The ischemic lesions were detected with a remarkable contrast in inversion recovery and spin echo images within a few hours after insult. Those changes in NMR images consistently corresponded with the various retrospective histochemical observations, especially with methods related to brain edema (K+ staining) rather than structural (enzymatic) studies. Calculated T1 and T2 relaxation times indicated the evolution of the edema state in the brain in situ. They correlated excellently with the retrospective water content measurement. As a result, detailed characterization of the edema state induced by cerebral ischemia was possible in vivo using [1H]NMR imaging.


1997 ◽  
Vol 51 (5) ◽  
pp. 733-737 ◽  
Author(s):  
Markku Mesilaakso ◽  
Eeva-Liisa Tolppa ◽  
Paula Nousiainen

The 1H and 13C{1H} nuclear magnetic resonance (NMR) spectra of diphenylchloroarsine, diphenylcyanoarsine, and 10-chloro-5,10-dihydrophenarsazine were recorded from samples prepared in CDCl3, CD2Cl2, and (CD3)2CO. Spectra were analyzed, and detailed 1H NMR spectral parameters were determined by iterative analysis. Simulation of spectra and their use as reference spectra for identification of the compounds under different conditions are discussed.


2021 ◽  
Vol 12 ◽  
Author(s):  
Sylvana Vilca-Melendez ◽  
Malin V. Uthaug ◽  
Julian L. Griffin

While psychedelics may have therapeutic potential for treating mental health disorders such as depression, further research is needed to better understand their biological effects and mechanisms of action when considering the development of future novel therapy approaches. Psychedelic research could potentially benefit from the integration of metabonomics by proton nuclear magnetic resonance (1H NMR) spectroscopy which is an analytical chemistry-based approach that can measure the breakdown of drugs into their metabolites and their metabolic consequences from various biofluids. We have performed a systematic review with the primary aim of exploring published literature where 1H NMR analysed psychedelic substances including psilocin, lysergic acid diethylamide (LSD), LSD derivatives, N,N-dimethyltryptamine (DMT), 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and bufotenin. The second aim was to assess the benefits and limitations of 1H NMR spectroscopy-based metabolomics as a tool in psychedelic research and the final aim was to explore potential future directions. We found that the most current use of 1H NMR in psychedelic research has been for the structural elucidation and analytical characterisation of psychedelic molecules and that no papers used 1H NMR in the metabolic profiling of biofluids, thus exposing a current research gap and the underuse of 1H NMR. The efficacy of 1H NMR spectroscopy was also compared to mass spectrometry, where both metabonomics techniques have previously shown to be appropriate for biofluid analysis in other applications. Additionally, potential future directions for psychedelic research were identified as real-time NMR, in vivo1H nuclear magnetic resonance spectroscopy (MRS) and 1H NMR studies of the gut microbiome. Further psychedelic studies need to be conducted that incorporate the use of 1H NMR spectroscopy in the analysis of metabolites both in the peripheral biofluids and in vivo to determine whether it will be an effective future approach for clinical and naturalistic research.


2018 ◽  
Vol 24 (1) ◽  
pp. 31-35 ◽  
Author(s):  
Nasrin Karimi ◽  
Abolghasem Davoodnia ◽  
Mehdi Pordel

Abstract The reaction of 2-amino-4-aryl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles with excess aliphatic carboxylic acids in the presence of phosphoryl chloride (POCl3) afforded new 2-alkyl-5-aryl-8,8-dimethyl-8,9-dihydro-3H-chromeno[2,3-d]pyrimidine-4,6(5H,7H)-diones in high yields. The suggested mechanism involves a tandem intramolecular Pinner/Dimroth rearrangement. The synthesized compounds were characterized by infrared (IR), proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR) and elemental analysis.


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