Articoli di riviste: "1H NMR quantification"

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de Graaf, Robin A., Hetty Prinsen, Cosimo Giannini, Sonia Caprio e Raimund I. Herzog. "Quantification of 1H NMR spectra from human plasma". Metabolomics 11, n. 6 (5 luglio 2015): 1702–7. http://dx.doi.org/10.1007/s11306-015-0828-1.

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Merkx, Donny W. H., Yvonne Westphal, Ewoud J. J. van Velzen, Kavish V. Thakoer, Niels de Roo e John P. M. van Duynhoven. "Quantification of food polysaccharide mixtures by 1H NMR". Carbohydrate Polymers 179 (gennaio 2018): 379–85. http://dx.doi.org/10.1016/j.carbpol.2017.09.074.

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Wang, Roy Chih Chung, David A. Campbell, James R. Green e Miroslava Čuperlović-Culf. "Automatic 1D 1H NMR Metabolite Quantification for Bioreactor Monitoring". Metabolites 11, n. 3 (9 marzo 2021): 157. http://dx.doi.org/10.3390/metabo11030157.

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High-throughput metabolomics can be used to optimize cell growth for enhanced production or for monitoring cell health in bioreactors. It has applications in cell and gene therapies, vaccines, biologics, and bioprocessing. NMR metabolomics is a method that allows for fast and reliable experimentation, requires only minimal sample preparation, and can be set up to take online measurements of cell media for bioreactor monitoring. This type of application requires a fully automated metabolite quantification method that can be linked with high-throughput measurements. In this review, we discuss the quantifier requirements in this type of application, the existing methods for NMR metabolomics quantification, and the performance of three existing quantifiers in the context of NMR metabolomics for bioreactor monitoring.

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Shumilina, Elena, Christian Andreasen, Zahra Bitarafan e Alexander Dikiy. "Determination of Glyphosate in Dried Wheat by 1H-NMR Spectroscopy". Molecules 25, n. 7 (28 marzo 2020): 1546. http://dx.doi.org/10.3390/molecules25071546.

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A wheat field was sprayed with a dosage of 1.1 kg a.i./ha Roundup PowerMax 10 days before harvest. The 1H Nuclear Magnetic Resonance (NMR) spectroscopy was used for the detection and quantification of the glyphosate (GLYP) in dried wheat spikelets, leaves, and stems. The quantification was done by the integration of the CH2-P groups doublet at 3.00 ppm with good linearity. The GLYP content varied between different samples and parts of the plant. On average, the largest content of herbicide was found in leaves (20.0 mg/kg), followed by stems (6.4 mg/kg) and spikelets (6.3 mg/kg). Our study shows that the 1H-NMR spectroscopy can be a rapid and reliable tool for GLYP detection and quantification in the field studies.

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Koptyug, Igor V., Quentin Stern, Sami Jannin e Stuart J. Elliott. "Frozen water NMR lineshape analysis enables absolute polarization quantification". Physical Chemistry Chemical Physics 24, n. 10 (2022): 5956–64. http://dx.doi.org/10.1039/d1cp05127j.

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Echo-detected 1H NMR spectra of water molecules hyperpolarized by dissolution-dynamic nuclear polarization alleviates deleterious dead time induced lineshape distortions and enables accurate nuclear spin polarization quantification.

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Kuz’mina, Natalia E., Sergey V. Moiseev, Elena Y. Severinova, Evgenii A. Stepanov e Natalia D. Bunyatyan. "Identification and Quantification by NMR Spectroscopy of the 22R and 22S Epimers in Budesonide Pharmaceutical Forms". Molecules 27, n. 7 (31 marzo 2022): 2262. http://dx.doi.org/10.3390/molecules27072262.

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The authors developed four variants of the qNMR technique (1H or 13C nucleus, DMSO-d6 or CDCl3 solvent) for identification and quantification by NMR of 22R and 22S epimers in budesonide active pharmaceutical ingredient and budesonide drugs (sprays, capsules, tablets). The choice of the qNMR technique version depends on the drug excipients. The correlation of 1H and 13C spectra signals to molecules of different budesonide epimers was carried out on the basis of a comprehensive analysis of experimental spectral NMR data (1H-1H gCOSY, 1H-13C gHSQC, 1H-13C gHMBC, 1H-1H ROESY). This technique makes it possible to identify budesonide epimers and determine their weight ratio directly, without constructing a calibration curve and using any standards. The results of measuring the 22S epimer content by qNMR are comparable with the results of measurements using the reference HPLC method.

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Sorte, Eric G., Jessica M. Rimsza e Todd M. Alam. "Computational and Experimental 1H-NMR Study of Hydrated Mg-Based Minerals". Molecules 25, n. 4 (19 febbraio 2020): 933. http://dx.doi.org/10.3390/molecules25040933.

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Magnesium oxide (MgO) can convert to different magnesium-containing compounds depending on exposure and environmental conditions. Many MgO-based phases contain hydrated species allowing 1H-nuclear magnetic resonance (NMR) spectroscopy to be used in the characterization and quantification of proton-containing phases; however, surprisingly limited examples have been reported. Here, 1H-magic angle spinning (MAS) NMR spectra of select Mg-based minerals are presented and assigned. These experimental results are combined with computational NMR density functional theory (DFT) periodic calculations to calibrate the predicted chemical shielding results. This correlation is then used to predict the NMR shielding for a series of different MgO hydroxide, magnesium chloride hydrate, magnesium perchlorate, and magnesium cement compounds to aid in the future assignment of 1H-NMR spectra for complex Mg phases.

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Hohmann, Monika, Christine Felbinger, Norbert Christoph, Helmut Wachter, Johannes Wiest e Ulrike Holzgrabe. "Quantification of taurine in energy drinks using 1H NMR". Journal of Pharmaceutical and Biomedical Analysis 93 (maggio 2014): 156–60. http://dx.doi.org/10.1016/j.jpba.2013.08.046.

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Guimarães, Diana, Jennifer Noro, Ana Loureiro, Artur Cavaco-Paulo e Eugénia Nogueira. "Quantification of drugs encapsulated in liposomes by 1H NMR". Colloids and Surfaces B: Biointerfaces 179 (luglio 2019): 414–20. http://dx.doi.org/10.1016/j.colsurfb.2019.03.039.

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D’eon, Jessica C., Brian P. Lankadurai, André J. Simpson, Eric J. Reiner, David G. Poirier, Greg C. Vanlerberghe e Myrna J. Simpson. "Cross-Platform Comparison of Amino Acid Metabolic Profiling in Three Model Organisms Used in Environmental Metabolomics". Metabolites 13, n. 3 (8 marzo 2023): 402. http://dx.doi.org/10.3390/metabo13030402.

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Environmental metabolomics is a promising approach to study pollutant impacts to target organisms in both terrestrial and aquatic environments. To this end, both nuclear magnetic resonance (NMR)- and mass spectrometry (MS)-based methods are used to profile amino acids in different environmental metabolomic studies. However, these two methods have not been compared directly which is an important consideration for broader comparisons in the environmental metabolomics field. We compared the quantification of 18 amino acids in the tissue extracts of Daphnia magna, a common model organism used in both ecotoxicology and ecology, using both 1H NMR spectroscopy and liquid chromatography with tandem MS (LC-MS/MS). 1H NMR quantification of amino acids agreed with the LC-MS/MS quantification for 17 of 18 amino acids measured. We also tested both quantitative methods in a D. magna sub-lethal exposure study to copper and lithium. Again, both NMR and LC-MS/MS measurements showed agreement. We extended our analyses with extracts from the earthworm Eisenia fetida and the plant model Nicotiana tabacum. The concentrations of amino acids by both 1H NMR and LC-MS/MS, agreed and demonstrated the robustness of both techniques for quantitative metabolomics. These findings demonstrate the compatibility of these two analytical platforms for amino acid profiling in environmentally relevant model organisms and emphasizes that data from either method is robust for comparisons across studies to further build the knowledge base related to pollutant exposure impacts and toxic responses of diverse environmental organisms.

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Gadape, H. H., e K. S. Parikh. "Quantitative Determination and Validation of Metformin Hydrochloride in Pharmaceutical Using Quantitative Nuclear Magnetic Resonance Spectroscopy". E-Journal of Chemistry 8, n. 2 (2011): 767–81. http://dx.doi.org/10.1155/2011/461898.

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Rapid, specific and accurate proton nuclear magnetic resonance spectroscopy (1H NMR) method was developed to determine metformin hydrochloride antidiabetic drug in pharmaceutical tablet formulation. The method was based on quantitative NMR spectroscopy (qNMR) using maleic acid as an internal standard and deuterium oxide (D2O) as a diluent. For the quantification of the drug, the (1H NMR signals at 2.91 ppm and 6.25 ppm corresponding to the analyte proton of metformin hydrochloride and maleic acid internal reference standard (IS) respectively were used. The method was validated for the parameters of specificity and selectivity, precision and intermediate precision, linearity, range, limit of detection (LOD) and limit of quantification (LOQ), accuracy, solution stability and robustness. The linearity of the calibration curve for analyte in the desired concentration range was good (R2=0.9993). The method was accurate and precise with good recoveries. Range study was also performed up to saturation level (152.67 mg/0.60 mL) in D2O. The advantage of the method is that no reference standard of analyte drug is required for quantification. The method is nondestructive and can be applied for quantification of metformin hydrochloride in commercial formulation products.

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Moing, Annick, Mickaël Maucourt, Christel Renaud, Monique Gaudillère, Renaud Brouquisse, Bénédicte Lebouteiller, Aurélie Gousset-Dupont et al. "Quantitative metabolic profiling by 1-dimensional 1H-NMR analyses: application to plant genetics and functional genomics". Functional Plant Biology 31, n. 9 (2004): 889. http://dx.doi.org/10.1071/fp04066.

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Metabolic profiling by 1-dimensional (1-D) 1H-nuclear magnetic resonance (NMR) was tested for absolute quantification of soluble sugars, organic acids, amino acids and some secondary metabolites in fruit, roots and leaves. The metabolite responsible for each peak of the 1H-NMR spectra was identified from spectra of pure compounds. Peak identity was confirmed by the addition of a small amount of commercially-available pure substance. 1H-NMR spectra acquisition was automated. 1H-NMR absolute quantification was performed with a synthesised electronic reference signal and validated by comparison with enzymatic or HPLC analyses; the correlation coefficients between 1H-NMR data and enzymatic or HPLC data were highly significant. Depending on the species and tissues, 14–17 metabolites could be quantified with 15–25 min acquisition time. The detection limit was approximately 1–9 µg in the NMR tube, depending on the compound. Quantitative data were used for (1) a genetic study of strawberry fruit quality, (2) a functional study of tomato transformants overexpressing hexokinase and (3) a study of Arabidopsis phosphoenolpyruvate carboxylase transformants with several lines showing decreased activity of the enzyme. Biochemical phenotyping of the fruits of a strawberry offspring allowed the detection of quantitative trait loci (QTL) controlling fruit quality. Comparison of the roots of wild types and hexokinase tomato transformants using principal component analysis of metabolic profiles revealed that environmental factors, i.e. culture conditions, can significantly modify the metabolic status of plants and thus hide or emphasise the expression of a given genetic background. The decrease in phosphoenolpyruvate carboxylase activity (up to 75%) in Arabidopsis transformants impacted on the metabolic profiles without compromising plant growth, thus supporting the idea that the enzyme has a low influence on the carbon flux through the anaplerotic pathway.

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Weitzel, Alexander, Claudia Samol, Peter J. Oefner e Wolfram Gronwald. "Robust Metabolite Quantification from J-Compensated 2D 1H-13C-HSQC Experiments". Metabolites 10, n. 11 (7 novembre 2020): 449. http://dx.doi.org/10.3390/metabo10110449.

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The spectral resolution of 2D 1H-13C heteronuclear single quantum coherence (1H-13C-HSQC) nuclear magnetic resonance (NMR) spectra facilitates both metabolite identification and quantification in nuclear magnetic resonance-based metabolomics. However, quantification is complicated by variations in magnetization transfer, which among others originate mainly from scalar coupling differences. Methods that compensate for variation in scalar coupling include the generation of calibration factors for individual signals or the use of additional pulse sequence schemes such as quantitative HSQC (Q-HSQC) that suppress the JCH-dependence by modulating the polarization transfer delays of HSQC or, additionally, employ a pure-shift homodecoupling approach in the 1H dimension, such as Quantitative, Perfected and Pure Shifted HSQC (QUIPU-HSQC). To test the quantitative accuracy of these three methods, employing a 600 MHz NMR spectrometer equipped with a helium cooled cryoprobe, a Latin-square design that covered the physiological concentration ranges of 10 metabolites was used. The results show the suitability of all three methods for the quantification of highly abundant metabolites. However, the substantially increased residual water signal observed in QUIPU-HSQC spectra impeded the quantification of low abundant metabolites located near the residual water signal, thus limiting its utility in high-throughput metabolite fingerprinting studies.

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F. da Costa, Luana, Silvia Keli B. Alcanfor e Aline L. de Oliveira. "Development and Validation of Furosemide Quantification Method By 1H NMR". Revista Virtual de Química 8, n. 5 (2016): 1683–92. http://dx.doi.org/10.21577/1984-6835.20160111.

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Lv, Jinxiao, Cong Wang, Xiuli Zhang, Zhihua Lv e Mingming Yu. "1H NMR Quantification of DHA and EPA in Fish Oil". Journal of Ocean University of China 19, n. 5 (2 settembre 2020): 1193–97. http://dx.doi.org/10.1007/s11802-020-4395-3.

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Forshed, Jenny, Bengt Erlandsson e Sven P. Jacobsson. "Quantification of aldehyde impurities in poloxamer by 1H NMR spectrometry". Analytica Chimica Acta 552, n. 1-2 (novembre 2005): 160–65. http://dx.doi.org/10.1016/j.aca.2005.07.050.

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Bharti, Santosh Kumar, Neeraj Sinha, Bhawani Shankar Joshi, Sudhir Kumar Mandal, Raja Roy e Chunni Lal Khetrapal. "Improved quantification from 1H-NMR spectra using reduced repetition times". Metabolomics 4, n. 4 (14 settembre 2008): 367–76. http://dx.doi.org/10.1007/s11306-008-0130-6.

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Yousefi, Farzad, Shital Kandel e Nancy Pleshko. "Infrared Spectroscopic Quantification of Methacrylation of Hyaluronic Acid: A Scaffold for Tissue Engineering Applications". Applied Spectroscopy 72, n. 10 (10 agosto 2018): 1455–66. http://dx.doi.org/10.1177/0003702818785353.

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Methacrylated hyaluronic acid (MeHA) has been used extensively in tissue engineering and drug delivery applications. The degree of methacrylation (DM) of HA impacts hydrogel crosslinking, which is of pivotal importance for cell interactions. The methacrylation reaction occurs over several hours, and DM is currently assessed post reaction and after dialysis of the solution, using nuclear magnetic resonance (1H NMR) data. Thus, there is little control over exact DM in a specific reaction. Here, infrared (IR) spectroscopy in attenuated total reflection (ATR) mode was investigated as an alternate modality for assessment of the DM of HA hydrogels, including during the reaction progression. Attenuated total reflection is a low-cost technique that is widely available in research and industry labs that can be used online during the reaction process. Strong correlations were achieved with IR-derived peak heights from dialyzed and lyophilized samples at 1708 cm−1 (from the methacrylic ester carbonyl vibration), and 1H NMR values ( R = 0.92, P = 6.56E-11). Additional IR peaks of importance were identified using principal component analysis and resulted in significant correlations with the 1H NMR DM parameter: 1454 cm−1 ( R = 0.85, P = 2.81E-8), 1300 cm−1 ( R = 0.95, P = 4.50E-14), 950 ( R = 0.85, P = 3.55E-8), 856 cm−1 ( R = 0.94, P = 1.20E-12), and 809 cm−1 ( R = 0.93, P = 3.54E-12). A multiple linear regression model to predict 1H NMR-derived DM using the 1708, 1300, and 1200 cm−1 peak heights as independent variables resulted in prediction with an error of 3.2% using dialyzed and lyophilized samples ( P < 0.001). Additionally, a multilinear regression model to predict the DM in undialyzed liquid MeHA samples obtained during the reaction process using similar peak height positions as independent variables resulted in a prediction error of 0.81% ( P < 0.05). Thus, IR spectroscopy can be utilized as an alternate modality to 1H NMR for quantification of the DM of MeHA while sampling either on-line during the methacrylation reaction as well as in post-lyophilized products. This could greatly simplify workflow for tissue engineering and other applications.

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Linton, Elisabeth, Asif Rahman, Sridhar Viamajala, Ronald C. Sims e Charles D. Miller. "Polyhydroxyalkanoate quantification in organic wastes and pure cultures using a single-step extraction and 1H NMR analysis". Water Science and Technology 66, n. 5 (1 settembre 2012): 1000–1006. http://dx.doi.org/10.2166/wst.2012.273.

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In this study, a proton nuclear magnetic resonance (1H NMR) method was developed to quantitatively analyze polyhydroxyalkanoate (PHA) content in Cupriavidus necator H16, Azotobacter vinelandii AvOP, and mixed microbial cultures from the effluent of an agricultural waste treatment anaerobic digester. In contrast to previous methods, a single-step PHA extractive method using deuterated chloroform was established, thereby facilitating direct 1H NMR analysis. The accuracy of the method was verified through comparison with well-established gas chromatography (GC) methanolysis techniques. Nile blue fluorescence staining was also carried out to serve as an independent and qualitative indicator of intracellular PHA content. The results indicate that the 1H NMR method is appropriate for rapid and non-destructive quantification of overall PHA content and determination of PHA copolymer composition in a variety of cultures. Notably, this technique was effective in measuring PHA content in full-strength waste samples where high concentrations of background impurities and organic compounds are present. The straightforward procedures minimize error-introducing steps, require less time and materials, and result in an accurate method suitable for routine analyses.

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Wei, Feifei, Minoru Fukuchi, Kengo Ito, Kenji Sakata, Taiga Asakura, Yasuhiro Date e Jun Kikuchi. "Large-Scale Evaluation of Major Soluble Macromolecular Components of Fish Muscle from a Conventional 1H-NMR Spectral Database". Molecules 25, n. 8 (23 aprile 2020): 1966. http://dx.doi.org/10.3390/molecules25081966.

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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.

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Valim, Thays Cardoso, Danyelle Alves Cunha, Carla Santana Francisco, Wanderson Romão, Paulo Roberto Filgueiras, Reginaldo Bezerra dos Santos, Warley de Souza Borges, Raphael Conti, Valdemar Lacerda e Alvaro Cunha Neto. "Quantification of capsaicinoids from chili peppers using 1H NMR without deuterated solvent". Analytical Methods 11, n. 14 (2019): 1939–50. http://dx.doi.org/10.1039/c9ay00292h.

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ANDO, Itiro, Kazuhisa TAKEUCHI, Shiro OGUMA, Hiroshi SATO, Hiroshi SEKINO, Yutaka IMAI e Masako FUJIWARA. "1H NMR Spectroscopic Quantification of Plasma Metabolites in Dialysate during Hemodialysis". Magnetic Resonance in Medical Sciences 12, n. 2 (2013): 129–35. http://dx.doi.org/10.2463/mrms.2012-0076.

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Ohtsuki, Takashi, Kyoko Sato, Yutaka Abe, Naoki Sugimoto e Hiroshi Akiyama. "Quantification of acesulfame potassium in processed foods by quantitative 1H NMR". Talanta 131 (gennaio 2015): 712–18. http://dx.doi.org/10.1016/j.talanta.2014.08.002.

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Rosselgong, Julien, e Steven P. Armes. "Quantification of Intramolecular Cyclization in Branched Copolymers by 1H NMR Spectroscopy". Macromolecules 45, n. 6 (13 marzo 2012): 2731–37. http://dx.doi.org/10.1021/ma3002609.

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Ghadban, Ali, Luca Albertin, Eric Condamine, Rédéo W. Moussavou Mounguengui e Alain Heyraud. "NMR and MS study of the formation of β-d-glucopyranosylamine uronic acid in aqueous solution". Canadian Journal of Chemistry 89, n. 8 (agosto 2011): 987–1000. http://dx.doi.org/10.1139/v11-064.

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The products of the reaction of d-glucuronic acid with various combinations of ammonia and volatile ammonium salts in water were studied by NMR and MS spectroscopy. For long reaction times (~24 h), the expected products β-d-glucopyranosylamine uronic acid and ammonium N-(β-d-glucopyranosyluronic acid)carbamate were obtained in good-to-high yield, whereas seven intermediate species were identified in samples taken at earlier reaction times. 1H–1H homonuclear and 1H–13C heteronuclear correlation experiments enabled a complete assignment of the 1H and 13C NMR spectra of the starting and final compounds, and a partial assignment of the peaks of intermediate species. Based on these results, a 1H NMR protocol for the quantification of the different compounds taking part in the reaction was developed, which was used to monitor the evolution of the composition of an early reaction sample redissolved in D2O. It was thus established that two of the observed intermediate species are actually the α anomer of the main products, whereas the others are precursors to the formation of α/β-d-glucopyranosylamine uronic acid and ammonium N-(α/β-d-glucopyranosyluronic acid)carbamate. The correct assignments for the 1H and 13C spectra of d-glucuronic acid in D2O are also reported.

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Nemzer, Boris, John Edwards e Diganta Kalita. "Matrix-Specific Effects on Caffeine and Chlorogenic Acid Complexation in a Novel Extract of Whole Coffea arabica Coffee Cherry by NMR Spectroscopy". Molecules 27, n. 22 (12 novembre 2022): 7803. http://dx.doi.org/10.3390/molecules27227803.

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Coffee cherry is a rich source of caffeine and chlorogenic acids. In this study we investigate the structural analysis of caffeine-enriched whole coffee cherry extracts, CEWCCE by using 1H and 13C NMR spectroscopy. The changes in 1H chemical shift data in NMR spectra of CEWCCE compared to pure caffeine indicated the formation of complexes between caffeine and chlorogenic acids in aqueous solution. The effect of complexation on the peak position of caffeoylquinic acid and caffeine resonance with increasing addition of caffeine was investigated. 2D NOESY experiments show the presence of cross-peaks that are due to the proximity of chlorogenic acid and caffeine molecules in stable complexes in protic solvents. The quantification data of caffeine by 1H qNMR was found to be in close agreement with the data obtained by HPLC analysis.

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Silwood, C. J. L., E. Lynch, A. W. D. Claxson e M. C. Grootveld. "1H and 13C NMR Spectroscopic Analysis of Human Saliva". Journal of Dental Research 81, n. 6 (giugno 2002): 422–27. http://dx.doi.org/10.1177/154405910208100613.

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We have explored the ability of high-resolution NMR techniques to (1) index salivary biomolecules and (2) provide valuable data regarding intra- and inter-subject variability in the concentrations of a series of components readily determinable by this technique (organic acids and malodorous amines). Experiments were conducted on ‘whole’ saliva samples collected from 20 patients, either randomly during their daily activities, or, for investigations involving the quantification of salivary biomolecules, immediately after they woke in the morning throughout a three-day period. These NMR techniques permitted us to detect greater than 60 metabolites, together with agents arising from dietary, oral health care product, and pharmaceutical sources. Highly significant “between-subject” differences in the a.m. waking salivary metabolite concentrations were found for 9 out of 11 components monitored. It is concluded that NMR spectroscopy serves as a powerful technique for the multicomponent analysis of human saliva.

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Hung, Hsin-Yi, Shih-Min Lin, Chia-Ying Li, Sio-Hong Lam, Yu-Yi Chan, Meei-Jen Liou, Po-Chuen Shieh, Fu-An Chen, Ping-Chung Kuo e Tian-Shung Wu. "A Rapid and Feasible 1H-NMR Quantification Method of Ephedrine Alkaloids in Ephedra Herbal Preparations". Molecules 26, n. 6 (13 marzo 2021): 1599. http://dx.doi.org/10.3390/molecules26061599.

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A highly specific and sensitive proton nuclear magnetic resonance (1H-NMR) method has been developed for the quantification of ephedrine alkaloid derivatives in Ephedra herbal commercial prescriptions. At the region of δ 4.0 to 5.0 ppm in the 1H NMR spectrum, the characteristic signals are separated well from each other, and six analogues in total, methylephedrine (ME), ephedrine (EP), norephedrine (NE), norpseudoephedrine (NP), pseudoephedrine (PE), and methylpseudoephedrine (MP) could be identified. The quantities of these compounds are calculated by the relative ratio of the integral values of the target peak for each compound to the known concentrations of the internal standard anthracene. The present method allows for a rapid and simple quantification of ephedrine alkaloid derivatives in Ephedra-related commercial prescriptions without any preliminary purification steps and standard compounds, and accordingly it can be a powerful tool to verify different Ephedra species. In comparison to conventional chromatographic methods, the advantages of this method include the fact that no standard compounds are required, the quantification can be directly performed on the crude extracts, a better selectivity for various ephedrine alkaloid derivatives, and the fact that a very significant time-gain may be achieved.

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Lefort, Gaëlle, Laurence Liaubet, Cécile Canlet, Patrick Tardivel, Marie-Christine Père, Hélène Quesnel, Alain Paris, Nathalie Iannuccelli, Nathalie Vialaneix e Rémi Servien. "ASICS: an R package for a whole analysis workflow of 1D 1H NMR spectra". Bioinformatics 35, n. 21 (12 aprile 2019): 4356–63. http://dx.doi.org/10.1093/bioinformatics/btz248.

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Abstract Motivation In metabolomics, the detection of new biomarkers from Nuclear Magnetic Resonance (NMR) spectra is a promising approach. However, this analysis remains difficult due to the lack of a whole workflow that handles spectra pre-processing, automatic identification and quantification of metabolites and statistical analyses, in a reproducible way. Results We present ASICS, an R package that contains a complete workflow to analyse spectra from NMR experiments. It contains an automatic approach to identify and quantify metabolites in a complex mixture spectrum and uses the results of the quantification in untargeted and targeted statistical analyses. ASICS was shown to improve the precision of quantification in comparison to existing methods on two independent datasets. In addition, ASICS successfully recovered most metabolites that were found important to explain a two level condition describing the samples by a manual and expert analysis based on bucketing. It also found new relevant metabolites involved in metabolic pathways related to risk factors associated with the condition. Availability and implementation ASICS is distributed as an R package, available on Bioconductor. Supplementary information Supplementary data are available at Bioinformatics online.

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Amiel, Aurélien, Marie Tremblay-Franco, Roselyne Gautier, Simon Ducheix, Alexandra Montagner, Arnaud Polizzi, Laurent Debrauwer, Hervé Guillou, Justine Bertrand-Michel e Cécile Canlet. "Proton NMR Enables the Absolute Quantification of Aqueous Metabolites and Lipid Classes in Unique Mouse Liver Samples". Metabolites 10, n. 1 (21 dicembre 2019): 9. http://dx.doi.org/10.3390/metabo10010009.

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Abstract (sommario):

Hepatic metabolites provide valuable information on the physiological state of an organism, and thus, they are monitored in many clinical situations. Typically, monitoring requires several analyses for each class of targeted metabolite, which is time consuming. The present study aimed to evaluate a proton nuclear magnetic resonance (1H-NMR) method for obtaining quantitative measurements of aqueous and lipidic metabolites. We optimized the extraction protocol, the standard samples, and the organic solvents for the absolute quantification of lipid species. To validate the method, we analyzed metabolic profiles in livers of mice fed three different diets. We compared our results with values obtained with conventional methods and found strong correlations. The 1H-NMR protocol enabled the absolute quantification of 29 aqueous metabolites and eight lipid classes. Results showed that mice fed a diet enriched in saturated fatty acids had higher levels of triglycerides, cholesterol ester, monounsaturated fatty acids, lactate, 3-hydroxy-butyrate, and alanine and lower levels of glucose, compared to mice fed a control diet. In conclusion, proton NMR provided a rapid overview of the main lipid classes (triglycerides, cholesterol, phospholipids, fatty acids) and the most abundant aqueous metabolites in liver.

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Liu, Jia, Lawrence Litt, Mark R. Segal, Mark JS Kelly, Hikari AI Yoshihara e Thomas L. James. "Outcome-Related Metabolomic Patterns from 1H/31P NMR after Mild Hypothermia Treatments of Oxygen—Glucose Deprivation in a Neonatal Brain Slice Model of Asphyxia". Journal of Cerebral Blood Flow & Metabolism 31, n. 2 (18 agosto 2010): 547–59. http://dx.doi.org/10.1038/jcbfm.2010.125.

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Abstract (sommario):

Human clinical trials using 72 hours of mild hypothermia (32°C–34°C) after neonatal asphyxia have found substantially improved neurologic outcomes. As temperature changes differently modulate numerous metabolite fluxes and concentrations, we hypothesized that 1H/31P nuclear magnetic resonance (NMR) spectroscopy of intracellular metabolites can distinguish different insults, treatments, and recovery stages. Three groups of superfused neonatal rat brain slices underwent 45 minutes oxygen–glucose deprivation (OGD) and then were: treated for 3 hours with mild hypothermia (32°C) that began with OGD, or similarly treated with hypothermia after a 15-minute delay, or not treated (normothermic control group, 37°C). Hypothermia was followed by 3 hours of normothermic recovery. Slices collected at different predetermined times were processed, respectively, for 14.1 Tesla NMR analysis, enzyme-linked immunosorbent assay (ELISA) cell-death quantification, and superoxide production. Forty-nine NMR-observable metabolites underwent a multivariate analysis. Separated clustering in scores plots was found for treatment and outcome groups. Final ATP (adenosine triphosphate) levels, severely decreased at normothermia, were restored equally by immediate and delayed hypothermia. Cell death was decreased by immediate hypothermia, but was equally substantially greater with normothermia and delayed hypothermia. Potentially important biomarkers in the 1H spectra included PCr-1H (phosphocreatine in the 1H spectrum), ATP-1H (adenosine triphosphate in the 1H spectrum), and ADP-1H (adenosine diphosphate in the 1H spectrum). The findings suggest a potential role for metabolomic monitoring during therapeutic hypothermia.

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Monakhova, Yulia B., Gabriele Randel e Bernd W. K. Diehl. "Automated Control of the Organic and Inorganic Composition of Aloe vera Extracts Using 1H NMR Spectroscopy". Journal of AOAC INTERNATIONAL 99, n. 5 (1 settembre 2016): 1213–18. http://dx.doi.org/10.5740/jaoacint.16-0020.

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Abstract (sommario):

Abstract Recent classification of Aloe vera whole-leaf extract by the International Agency for Research and Cancer as a possible carcinogen to humans as well as the continuous adulteration of A. vera's authentic material have generated renewed interest in controlling A. vera. The existing NMR spectroscopic method for the analysis of A. vera, which is based on a routine developed at Spectral Service, was extended. Apart from aloverose, glucose, malic acid, lactic acid, citric acid, whole-leaf material (WLM), acetic acid, fumaric acid, sodium benzoate, and potassium sorbate, the quantification of Mg2+, Ca2+, and fructose is possible with the addition of a Cs-EDTA solution to sample. The proposed methodology was automated, which includes phasing, baseline-correction, deconvolution (based on the Lorentzian function), integration, quantification, and reporting. The NMR method was applied to 41 A. vera preparations in the form of liquid A. vera juice and solid A. vera powder. The advantages of the new NMR methodology over the previous method were discussed. Correlation between the new and standard NMR methodologies was significant for aloverose, glucose, malic acid, lactic acid, citric acid, and WLM (P < 0.0001, R2 = 0.99). NMR was found to be suitable for the automated simultaneous quantitative determination of 13 parameters in A. vera.

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Barnett, Brian R., Fariba Fathi, Paulo Falco Cobra, Sue Y. Yi, Jacqueline M. Anderson, Hamid R. Eghbalnia, John L. Markley e John-Paul J. Yu. "Metabolic Changes in Synaptosomes in an Animal Model of Schizophrenia Revealed by 1H and 1H,13C NMR Spectroscopy". Metabolites 10, n. 2 (23 febbraio 2020): 79. http://dx.doi.org/10.3390/metabo10020079.

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Abstract (sommario):

Synaptosomes are isolated nerve terminals that contain synaptic components, including neurotransmitters, metabolites, adhesion/fusion proteins, and nerve terminal receptors. The essential role of synaptosomes in neurotransmission has stimulated keen interest in understanding both their proteomic and metabolic composition. Mass spectrometric (MS) quantification of synaptosomes has illuminated their proteomic composition, but the determination of the metabolic composition by MS has been met with limited success. In this study, we report a proof-of-concept application of one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy for analyzing the metabolic composition of synaptosomes. We utilize this approach to compare the metabolic composition synaptosomes from a wild-type rat with that from a newly generated genetic rat model (Disc1 svΔ2), which qualitatively recapitulates clinically observed early DISC1 truncations associated with schizophrenia. This study demonstrates the feasibility of using NMR spectroscopy to identify and quantify metabolites within synaptosomal fractions.

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Di Pietro, Maria Enrica, Alberto Mannu e Andrea Mele. "NMR Determination of Free Fatty Acids in Vegetable Oils". Processes 8, n. 4 (31 marzo 2020): 410. http://dx.doi.org/10.3390/pr8040410.

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Abstract (sommario):

The identification and quantification of free fatty acids (FFA) in edible and non-edible vegetable oils, including waste cooking oils, is a crucial index to assess their quality and drives their use in different application fields. NMR spectroscopy represents an alternative tool to conventional methods for the determination of FFA content, providing us with interesting advantages. Here the approaches reported in the literature based on 1H, 13C and 31P NMR are illustrated and compared, highlighting the pros and cons of the suggested strategies.

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Burkhardtsmaier, Pia, Kristina Pavlovskaja, Dennis Maier, Stephanie Schäfer, Ulrike Salat e Magnus S. Schmidt. "Quantitative Monitoring of the Fermentation Process of a Barley Malt Mash by Benchtop 1H NMR Spectroscopy". Food Analytical Methods 14, n. 7 (20 febbraio 2021): 1425–31. http://dx.doi.org/10.1007/s12161-021-01991-9.

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Abstract (sommario):

AbstractIn order to investigate benchtop NMR spectroscopy as a monitoring tool for fermentation processes, we used a barley malt mash and took various samples over time and analysed them by NMR spectroscopy with 3-(trimethylsilyl)-2,2,3,3-tetradeuteropropionic acid sodium salt (TSP-d4) as an internal standard for the quantification of ethanol and validated the results by two different enzymatic standard test kits for ethanol analysis. We could show that the results between NMR spectroscopy and test kits were consistent with NMR having a much lower standard deviation. Finally, we discussed the applicability of the method as well as the possibility to quantify various other substances.

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Ohmenhaeuser, Marc, Yulia B. Monakhova, Thomas Kuballa e Dirk W. Lachenmeier. "Qualitative and Quantitative Control of Honeys Using NMR Spectroscopy and Chemometrics". ISRN Analytical Chemistry 2013 (12 maggio 2013): 1–9. http://dx.doi.org/10.1155/2013/825318.

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Abstract (sommario):

400 MHz nuclear magnetic resonance (NMR) spectroscopy and multivariate data analysis techniques were used in the context of food surveillance to measure 328 honey samples with 1H and 13C NMR. Using principal component analysis (PCA), clusters of honeys from the same botanical origin were observed. The chemical shifts of the principal monosaccharides (glucose and fructose) were found to be mostly responsible for this differentiation. Furthermore, soft independent modeling of class analogy (SIMCA) and partial least squares discriminant analysis (PLS-DA) could be used to automatically classify spectra according to their botanical origin with 95–100% accuracy. Direct quantification of 13 compounds (carbohydrates, aldehydes, aliphatic and aromatic acids) was additionally possible using external calibration curves and applying TSP as internal standard. Hence, NMR spectroscopy combined with chemometrics is an efficient tool for simultaneous identification of botanical origin and quantification of selected constituents of honeys.

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Ciampa, Alessandra, Luca Laghi e Gianfranco Picone. "Validation of a 1H-NMR Spectroscopy Quantitative Method to Quantify Trimethylamine Content and K-Index Value in Different Species of Fish". Journal of Food Quality 2022 (31 agosto 2022): 1–9. http://dx.doi.org/10.1155/2022/3612095.

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Abstract (sommario):

The chemical analysis that is frequently employed for the evaluation of the freshness of fish includes (i) the quantification of trimethylamine (TMA) and (ii) the estimation of the K-Index, based on the ratio between the concentrations of adenosine triphosphate (ATP) and its breakdown products. TMA is quantified using a colorimetric reference method (AOAC), while the K-Index is usually determined by HPLC. The present work proposes a method for the above freshness biomarkers based on HR 1H-NMR as an alternative method able to assess both indexes simultaneously on aqueous fish extracts. To validate the proposed 1H-NMR method, a large set of validation checks has been addressed, such as accuracy, precision, specificity, limits of detection, linearity, and range of linearity and quantification according to EuroChem guidelines. The results show that the methodology satisfies all the validation requirements at the same level as the most frequently used methods, with the advantage of being faster and more repeatable, avoiding the use of solvents, such as toluene and formaldehyde, or dangerous reagents such as picric acid.

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Sharma, Neha, Mahendra K. Verma, Devinder K. Gupta, Naresh K. Satti e Ravi K. Khajuria. "Isolation and quantification of pinitol in Argyrolobium roseum plant, by 1H-NMR". Journal of Saudi Chemical Society 20, n. 1 (gennaio 2016): 81–87. http://dx.doi.org/10.1016/j.jscs.2014.07.002.

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Rundlöf, Torgny, Marie Mathiasson, Somer Bekiroglu, Birgit Hakkarainen, Tim Bowden e Torbjörn Arvidsson. "Survey and qualification of internal standards for quantification by 1H NMR spectroscopy". Journal of Pharmaceutical and Biomedical Analysis 52, n. 5 (settembre 2010): 645–51. http://dx.doi.org/10.1016/j.jpba.2010.02.007.

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40

Tojo, E., e J. Prado. "A simple 1H NMR method for the quantification of carrageenans in blends". Carbohydrate Polymers 53, n. 3 (agosto 2003): 325–29. http://dx.doi.org/10.1016/s0144-8617(03)00080-8.

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41

Crucho, Carina I. C., Carlos Baleizão e José Paulo S. Farinha. "Functional Group Coverage and Conversion Quantification in Nanostructured Silica by 1H NMR". Analytical Chemistry 89, n. 1 (20 dicembre 2016): 681–87. http://dx.doi.org/10.1021/acs.analchem.6b03117.

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42

Liang, Tingfu, Takuya Miyakawa, Jinwei Yang, Tsutomu Ishikawa e Masaru Tanokura. "Quantification of terpene trilactones in Ginkgo biloba with a 1H NMR method". Journal of Natural Medicines 72, n. 3 (22 marzo 2018): 793–97. http://dx.doi.org/10.1007/s11418-018-1203-0.

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43

Asllani, I., E. Shankland, T. Pratum e M. Kushmerick. "Double Quantum Filtered 1H NMR Spectroscopy Enables Quantification of Lactate in Muscle". Journal of Magnetic Resonance 152, n. 2 (ottobre 2001): 195–202. http://dx.doi.org/10.1006/jmre.2001.2407.

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Ohtsuki, Takashi, Kyoko Sato, Noriko Furusho, Hiroki Kubota, Naoki Sugimoto e Hiroshi Akiyama. "Absolute quantification of dehydroacetic acid in processed foods using quantitative 1H NMR". Food Chemistry 141, n. 2 (novembre 2013): 1322–27. http://dx.doi.org/10.1016/j.foodchem.2013.04.005.

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45

Chen, Yi-Ting, Wei-Ting Hung, Shwu-Huey Wang, Jim-Min Fang e Wei-Bin Yang. "Quantitative analysis of sugar ingredients in beverages and food crops by an effective method combining naphthimidazole derivatization and 1H-NMR spectrometry". Functional Foods in Health and Disease 7, n. 7 (31 luglio 2017): 494. http://dx.doi.org/10.31989/ffhd.v7i7.348.

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Abstract (sommario):

Background: Though carbohydrates are needed for health, excessive uptake of sugar may induce obesity, decayed teeth, and chronic diseases. The Taiwan Food and Drug Administration has recently proposed to regulate common sugars, a list that includes glucose, galactose, fructose, lactose, maltose, and sucrose in beverages and dietary foods. Accordingly, rapid and effective methods are needed for the quantitative analysis of sugar ingredients in beverages and foods.Objective: To establish a convenient method of quantifying sugar ingredients in beverages and foods by using one-dimensional 1H-NMR spectroscopy via a simple treatment with naphthimidazole (NAIM) labeling kit.Methods: The sample of beverages or the hydrolysate of food crops were treated with an NAIM labeling kit that contains 2,3-naphthalenediamine and iodine in acetic acid solution. After the complete conversion of the reducing sugars to sugar-NAIM derivatives, the mixture solution was subjected to rotary evaporation under reduced pressure, and the residue was dissolved in D2O solution with dimethylsulfoxide (DMSO) as an internal standard for the 1H-NMR spectrometric analysis. Results: An aldose existing in two anomeric isomers is completely converted to the corresponding NAIM derivative that shows a single characteristic vinyl proton at a distinct position to facilitate the quantitative analysis by NMR spectrometry. Even 10 μmol of common sugar ingredients in 50 μL of beverage or in the hydrolysate prepared from 1 mg of food crop can be quantified.Conclusions: The results suggest that a simple treatment of beverage with the NAIM labeling kit provides a convenient method for the quantification of sugar ingredients by 1H-NMR spectrometry. This method combining NAIM derivatization and 1H-NMR analysis is also useful for the profiling and fingerprinting of food crops.Keywords: sugar, beverage, food crop, naphthimidazole, 1H-NMR spectrometry, quantitative analysis

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46

Jones, Ian C., Gary J. Sharman e Julia Pidgeon. "1H and13C NMR data to aid the identification and quantification of residual solvents by NMR spectroscopy". Magnetic Resonance in Chemistry 43, n. 6 (2005): 497–509. http://dx.doi.org/10.1002/mrc.1578.

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DUȚĂ, Denisa Eglantina, Alina CULEȚU, Mioara NEGOIȚĂ e Valentin Ionescu. "Quantification of Anethole in Fennel and Anise Essential Oils using Gas Chromatography and 1H-NMR-Spectroscopy". Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Food Science and Technology 76, n. 2 (23 novembre 2019): 105. http://dx.doi.org/10.15835/buasvmcn-fst:2019.0020.

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Abstract (sommario):

Nine essential oils from fennel (seeds and herbs) and anise (seeds) from different origins were analysed for density, refractive index and for a complete composition through GC-MS and 1H-NMR-spectroscopy. Anethole was the main compound identified in fennel and anise essential oils. Anethole content varied between 30 – 90% in fennel oils and between 80 – 99% in anise oils; anethole is often used as flavouring substance in foods with a good antimicrobial activity also. A positive correlation was found between anethole content determined by GC-MS and 1H-NMR (r = 0.8567 for fennel oils and r = 0.6986 for anise oils). The results showed different levels of anethole in oils (values ranged between 30.66 % and 99.24 %). Electronic nose was a very good and rapid method for discrimination of essential oils based on PCA (Principal Component Analysis) with discrimination index above 90 for both essential oils.

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Teipel, Jan C., Thomas Hausler, Katharina Sommerfeld, Andreas Scharinger, Stephan G. Walch, Dirk W. Lachenmeier e Thomas Kuballa. "Application of 1H Nuclear Magnetic Resonance Spectroscopy as Spirit Drinks Screener for Quality and Authenticity Control". Foods 9, n. 10 (24 settembre 2020): 1355. http://dx.doi.org/10.3390/foods9101355.

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Abstract (sommario):

Due to legal regulations, the rise of globalised (online) commerce and the need for public health protection, the analysis of spirit drinks (alcoholic beverages >15% vol) is a task with growing importance for governmental and commercial laboratories. In this article a newly developed method using nuclear magnetic resonance (NMR) spectroscopy for the simultaneous determination of 15 substances relevant to assessing the quality and authenticity of spirit drinks is described. The new method starts with a simple and rapid sample preparation and does not need an internal standard. For each sample, a group of 1H-NMR spectra is recorded, among them a two-dimensional spectrum for analyte identification and one-dimensional spectra with suppression of solvent signals for quantification. Using the Pulse Length Based Concentration Determination (PULCON) method, concentrations are calculated from curve fits of the characteristic signals for each analyte. The optimisation of the spectra, their evaluation and the transfer of the results are done fully automatically. Glucose, fructose, sucrose, acetic acid, citric acid, formic acid, ethyl acetate, ethyl lactate, acetaldehyde, methanol, n-propanol, isobutanol, isopentanol, 2-phenylethanol and 5-(hydroxymethyl)furfural (HMF) can be quantified with an overall accuracy better than 8%. This new NMR-based targeted quantification method enables the simultaneous and efficient quantification of relevant spirit drinks ingredients in their typical concentration ranges in one process with good accuracy. It has proven to be a reliable method for all kinds of spirit drinks in routine food control.

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Mohale, Keletso C., Olusola Bodede, Hintsa T. Araya e Fhatuwani N. Mudau. "Metabolomic Analysis for Compositional Differences of Bush Tea (Athrixia phylicoides DC.) Subjected to Seasonal Dynamics". Agronomy 10, n. 6 (23 giugno 2020): 892. http://dx.doi.org/10.3390/agronomy10060892.

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Abstract (sommario):

Bush tea (Athrixia phylicoides DC.) is a South African indigenous herbal tea rich in secondary metabolites with medicinal significance. However, studies on the effects of seasonal changes on bush tea and quantification of its metabolites using untargeted approach have not been explored. Therefore, this study’s objective was to investigate the effects of seasonal variation on the metabolites of bush tea using LC-MS/MS (Liquid Chromatography with Tandem Mass Spectrometry) and 1H NMR (High-Resolution Proton Nuclear Magnetic Resonance) techniques. Bush tea leaves were plucked once in each season namely, autumn (March to May), winter (June to August), spring (September to November), and summer (December to February). The primary metabolites including non-essential amino acids, organic acids, and vitamins in bush tea were predominantly elevated during summer and spring. The 1H NMR-based metabolomic analysis revealed that bush tea metabolome was strongly affected by seasonal variations, using the partial least squares-discriminant analysis (PLS-DA) which demonstrated four distinct groups of seasons. Similarly, the 1H NMR based metabolic profiling of bush tea subjected to different seasons resulted in putative annotation of six phenolic compounds which included rutin, 4-(hydroxyphenyl) propyl coumarate, caffeic acid, hymenoxin, quercetin, and kaempferol. The phenolics and primary metabolites differed remarkably per season with enhanced accumulation observed in the summer and spring harvested bush tea. The LC-MS and 1H NMR metabolomics analysis suggests that summer and spring can be recommended as preferred plucking seasons for bush tea leaves and twigs.

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Zhang, Bo, Robert Powers e Elizabeth M. O’Day. "Evaluation of Non-Uniform Sampling 2D 1H–13C HSQC Spectra for Semi-Quantitative Metabolomics". Metabolites 10, n. 5 (16 maggio 2020): 203. http://dx.doi.org/10.3390/metabo10050203.

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Abstract (sommario):

Metabolomics is the comprehensive study of metabolism, the biochemical processes that sustain life. By comparing metabolites between healthy and disease states, new insights into disease mechanisms can be uncovered. NMR is a powerful analytical method to detect and quantify metabolites. Standard one-dimensional (1D) 1H-NMR metabolite profiling is informative but challenged by significant chemical shift overlap. Multi-dimensional NMR can increase resolution, but the required long acquisition times lead to limited throughput. Non-uniform sampling (NUS) is a well-accepted mode of acquiring multi-dimensional NMR data, enabling either reduced acquisition times or increased sensitivity in equivalent time. Despite these advantages, the technique is not widely applied to metabolomics. In this study, we evaluated the utility of NUS 1H–13C heteronuclear single quantum coherence (HSQC) for semi-quantitative metabolomics. We demonstrated that NUS improved sensitivity compared to uniform sampling (US). We verified that the NUS measurement maintains linearity, making it possible to detect metabolite changes across samples and studies. Furthermore, we calculated the lower limit of detection and quantification (LOD/LOQ) of common metabolites. Finally, we demonstrate that the measurements are repeatable on the same system and across different systems. In conclusion, our results detail the analytical capability of NUS and, in doing so, empower the future use of NUS 1H–13C HSQC in metabolomic studies.

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