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Sample records for 1h nmr relaxometry

  1. Translational diffusion in paramagnetic liquids by 1H NMR relaxometry: Nitroxide radicals in solution

    NASA Astrophysics Data System (ADS)

    Kruk, D.; Korpała, A.; Kubica, A.; Meier, R.; Rössler, E. A.; Moscicki, J.

    2013-01-01

    For nitroxide radicals in solution one can identify three frequency regimes in which 1H spin-lattice relaxation rate of solvent molecules depend linearly on square root of the 1H resonance frequency. Combining a recently developed theory of nuclear (proton) spin-lattice relaxation in solutions of nitroxide radicals [D. Kruk et al., J. Chem. Phys. 137, 044512 (2012)], 10.1063/1.4736854 with properties of the spectral density function associated with translational dynamics, relationships between the corresponding linear changes of the relaxation rate (for 14N spin probes) and relative translational diffusion coefficient of the solvent and solute molecules have been derived (in analogy to 15N spin probes [E. Belorizky et al., J. Phys. Chem. A 102, 3674 (1998)], 10.1021/jp980397h). This method allows a simple and straightforward determination of diffusion coefficients in spin-labeled systems, by means of 1H nuclear magnetic resonance (NMR) relaxometry. The approach has thoroughly been tested by applying to a large set of experimental data—1H spin-lattice relaxation dispersion results for solutions of different viscosity (decalin, glycerol, propylene glycol) of 14N and 15N spin probes. The experiments have been performed versus temperature (to cover a broad range of translational diffusion coefficients) using field cycling spectrometer which covers three decades in 1H resonance frequency, 10 kHz-20 MHz. The limitations of NMR relaxometry caused by the time scale of the translational dynamics as well as electron spin relaxation have been discussed. It has been shown that for spin-labeled systems NMR relaxometry gives access to considerably faster diffusion processes than for diamagnetic systems.

  2. The structure of polycaprolactone-clay nanocomposites investigated by 1H NMR relaxometry.

    PubMed

    Monteiro, Mariana S S B; Rodrigues, Claudia Lopes; Neto, Roberto P C; Tavares, Maria Inês Bruno

    2012-09-01

    Nanocomposites based on polycaprolactone (PCL), containing concentrations of 1, 3 and 5 wt% of sodium montmorillonite (NT-25) and organo-modified montmorillonite clay, with three different salts (Viscogel B7, Viscogel S4 and Viscogel B8), were prepared employing the solution intercalation method using chloroform. The PCL nanocomposites were characterized by relaxometry, through determination of the hydrogen spin-lattice relaxation times using low-field nuclear magnetic resonance (NMR). Conventional X-ray diffraction (XDR) was also used to measure the basal space of the nanoclay. The proton spin-lattice relaxation parameters showed that hybrid nanocomposites were formed, containing different parts of intercalated and exfoliated organoclay. The proton T1rhoH also indicated changes in the microstructure, organization and the molecular mobility of the hybrid materials. NMR relaxometry is a good way to evaluate nanomaterials because it provides complementary information, since it is measured in a different time scale. Furthermore, differential scanning calorimetry and thermogravimetric analysis were also used to investigate the crystallization and thermal behavior of the nanocomposites, respectively. All materials had low crystallization temperature (Tc) and the melting temperature (Tm) were very close to that of the PCL matrix, but the degree of crystallinity of the nanocomposites decreased. TGA analysis demonstrated that montmorillonite accelerates PCL's decomposition while unmodified montmorillonite has the opposite effect. PMID:23035469

  3. The "long tail" of the protein tumbling correlation function: observation by (1)H NMR relaxometry in a wide frequency and concentration range.

    PubMed

    Roos, Matthias; Hofmann, Marius; Link, Susanne; Ott, Maria; Balbach, Jochen; Rössler, Ernst; Saalwächter, Kay; Krushelnitsky, Alexey

    2015-12-01

    Inter-protein interactions in solution affect the auto-correlation function of Brownian tumbling not only in terms of a simple increase of the correlation time, they also lead to the appearance of a weak slow component ("long tail") of the correlation function due to a slowly changing local anisotropy of the microenvironment. The conventional protocol of correlation time estimation from the relaxation rate ratio R1/R2 assumes a single-component tumbling correlation function, and thus can provide incorrect results as soon as the "long tail" is of relevance. This effect, however, has been underestimated in many instances. In this work we present a detailed systematic study of the tumbling correlation function of two proteins, lysozyme and bovine serum albumin, at different concentrations and temperatures using proton field-cycling relaxometry combined with R1ρ and R2 measurements. Unlike high-field NMR relaxation methods, these techniques enable a detailed study of dynamics on a time scale longer than the normal protein tumbling correlation time and, thus, a reliable estimate of the parameters of the "long tail". In this work we analyze the concentration dependence of the intensity and correlation time of the slow component and perform simulations of high-field (15)N NMR relaxation data demonstrating the importance of taking the "long tail" in the analysis into account. PMID:26582718

  4. Noninvasive monitoring of moisture uptake in Ca(NO3)2 -polluted calcareous stones by 1H-NMR relaxometry.

    PubMed

    Casieri, Cinzia; Terenzi, Camilla; De Luca, Francesco

    2015-01-01

    NMR transverse relaxation time (T(2)) distribution of (1)H nuclei of water has been used to monitor the moisture condensation kinetics in Ca(NO(3))(2)  · (4)H(2)O-polluted Lecce stone, a calcareous stone with highly regular porous structure often utilized as basic material in Baroque buildings. Polluted samples have been exposed to water vapor adsorption at controlled relative humidity to mimic environmental conditions. In presence of pollutants, the T(2) distributions of water in stone exhibit a range of relaxation time values and amplitudes not observed in the unpolluted case. These characteristics could be exploited for in situ noninvasive detection of salt pollution in Lecce stone or as damage precursors in architectural buildings of cultural heritage interest. PMID:25354389

  5. Dynamics of [C3H5N2]6[Bi4Br18] by means of (1)H NMR relaxometry and quadrupole relaxation enhancement.

    PubMed

    Masierak, W; Florek-Wojciechowska, M; Oglodek, I; Jakubas, R; Privalov, A F; Kresse, B; Fujara, F; Kruk, D

    2015-05-28

    (1)H spin-lattice field cycling relaxation dispersion experiments in the intermediate phase II of the solid [C3H5N2]6[Bi4Br18] are presented. Two motional processes have been identified from the (1)H spin-lattice relaxation dispersion profiles and quantitatively described. It has been concluded that these processes are associated with anisotropic reorientations of the imidazolium ring, characterized by correlation times of the order of 10(-8) s-10(-9) s and of about 10(-5) s. Moreover, quadrupole relaxation enhancement (QRE) effects originating from slowly fluctuating (1)H-(14)N dipolar interactions have been observed. From the positions of the relaxation maxima, the quadrupole coupling parameters for the (14)N nuclei in [C3H5N2]6[Bi4Br18] have been determined. The (1)H-(14)N relaxation contribution associated with the slow dynamics has been described in terms of a theory of QRE [Kruk et al., Solid State Nucl. Magn. Reson. 40, 114 (2011)] based on the stochastic Liouville equation. The shape of the QRE maxima (often referred to as "quadrupole peaks") has been consistently reproduced for the correlation time describing the slow dynamics and the determined quadrupole coupling parameters. PMID:26026454

  6. Dynamics of [C3H5N2]6[Bi4Br18] by means of 1H NMR relaxometry and quadrupole relaxation enhancement

    NASA Astrophysics Data System (ADS)

    Masierak, W.; Florek-Wojciechowska, M.; Oglodek, I.; Jakubas, R.; Privalov, A. F.; Kresse, B.; Fujara, F.; Kruk, D.

    2015-05-01

    1H spin-lattice field cycling relaxation dispersion experiments in the intermediate phase II of the solid [C3H5N2]6[Bi4Br18] are presented. Two motional processes have been identified from the 1H spin-lattice relaxation dispersion profiles and quantitatively described. It has been concluded that these processes are associated with anisotropic reorientations of the imidazolium ring, characterized by correlation times of the order of 10-8 s-10-9 s and of about 10-5 s. Moreover, quadrupole relaxation enhancement (QRE) effects originating from slowly fluctuating 1H-14N dipolar interactions have been observed. From the positions of the relaxation maxima, the quadrupole coupling parameters for the 14N nuclei in [C3H5N2]6[Bi4Br18] have been determined. The 1H-14N relaxation contribution associated with the slow dynamics has been described in terms of a theory of QRE [Kruk et al., Solid State Nucl. Magn. Reson. 40, 114 (2011)] based on the stochastic Liouville equation. The shape of the QRE maxima (often referred to as "quadrupole peaks") has been consistently reproduced for the correlation time describing the slow dynamics and the determined quadrupole coupling parameters.

  7. Probing surface interactions by combining NMR cryoporometry and NMR relaxometry

    NASA Astrophysics Data System (ADS)

    Mitchell, J.; Stark, S. C.; Strange, J. H.

    2005-06-01

    To further expand on the understanding of surface interactions at the liquid/solid interface on pore walls, the nuclear magnetic resonance (NMR) techniques of cryoporometry and relaxometry have been combined. The combination of these techniques allows variations in NMR relaxation parameters from pore surface to volume ratio changes and from surface interaction changes to be distinguished. By studying a range of sol-gel silicas from two different sources, it was noted that the relaxation time measurements were not consistent with the pore diameters determined by cryoporometry and N2 gas adsorption. Instead distinctly different relaxivity constants were determined for each absorbate in each of the two brands of silica. It was clear that the relaxation times were modified by more than just the pore geometry. Independent experiments on the two brands of silica suggested that the relaxometry results were heavily influenced by the concentration of paramagnetic relaxation centres in the silica gels. The strength of surface interaction, and hence surface affinity, was seen to depend on the liquid in the pores. Using this difference in surface affinities, binary mixtures of alkanes placed in sol-gel silicas were separated via preferential absorption and their components identified using cryoporometry, whereas the components could not be distinguished in the bulk liquid.

  8. Multivariate analysis relating oil shale geochemical properties to NMR relaxometry

    USGS Publications Warehouse

    Birdwell, Justin E.; Washburn, Kathryn E.

    2015-01-01

    Low-field nuclear magnetic resonance (NMR) relaxometry has been used to provide insight into shale composition by separating relaxation responses from the various hydrogen-bearing phases present in shales in a noninvasive way. Previous low-field NMR work using solid-echo methods provided qualitative information on organic constituents associated with raw and pyrolyzed oil shale samples, but uncertainty in the interpretation of longitudinal-transverse (T1–T2) relaxometry correlation results indicated further study was required. Qualitative confirmation of peaks attributed to kerogen in oil shale was achieved by comparing T1–T2 correlation measurements made on oil shale samples to measurements made on kerogen isolated from those shales. Quantitative relationships between T1–T2 correlation data and organic geochemical properties of raw and pyrolyzed oil shales were determined using partial least-squares regression (PLSR). Relaxometry results were also compared to infrared spectra, and the results not only provided further confidence in the organic matter peak interpretations but also confirmed attribution of T1–T2 peaks to clay hydroxyls. In addition, PLSR analysis was applied to correlate relaxometry data to trace element concentrations with good success. The results of this work show that NMR relaxometry measurements using the solid-echo approach produce T1–T2 peak distributions that correlate well with geochemical properties of raw and pyrolyzed oil shales.

  9. (1)H NMR relaxometry and quadrupole relaxation enhancement as a sensitive probe of dynamical properties of solids--[C(NH2)3]3Bi2I9 as an example.

    PubMed

    Florek-Wojciechowska, M; Wojciechowski, M; Jakubas, R; Brym, Sz; Kruk, D

    2016-02-01

    (1)H nuclear magnetic resonance relaxometry has been applied to reveal information on dynamics and structure of Gu3Bi2I9 ([Gu = C(NH2)3] denotes guanidinium cation). The data have been analyzed in terms of a theory of quadrupole relaxation enhancement, which has been extended here by including effects associated with quadrupole ((14)N) spin relaxation caused by a fast fluctuating component of the electric field gradient tensor. Two motional processes have been identified: a slow one occurring on a timescale of about 8 × 10(-6) s which has turned out to be (almost) temperature independent, and a fast process in the range of 10(-9) s. From the (1)H-(14)N relaxation contribution (that shows "quadrupole peaks") the quadrupole parameters, which are a fingerprint of the arrangement of the anionic network, have been determined. It has been demonstrated that the magnitude of the quadrupole coupling considerably changes with temperature and the changes are not caused by phase transitions. At the same time, it has been shown that there is no evidence of abrupt changes in the cationic dynamics and the anionic substructure upon the phase transitions. PMID:26851925

  10. Dynamics of ionic liquids in bulk and in confinement by means of (1)H NMR relaxometry - BMIM-OcSO4 in an SiO2 matrix as an example.

    PubMed

    Kruk, Danuta; Wojciechowski, Milosz; Brym, Szczepan; Singh, Rajendra Kumar

    2016-08-17

    (1)H nuclear magnetic resonance relaxometry is applied to reveal information on the translational and rotational dynamics of the ionic liquid: 1-butyl-3-methyl imidazoliumoctyl sulfate (BMIM-OcSO4) in bulk and in a confinement formed by a nanoporous SiO2 matrix. The experimental studies were performed in a very broad frequency range, from 8 kHz to 40 MHz (referring to the (1)H resonance frequency), in order to probe motional processes at very different time scales using a single experiment, and in the temperature range of 243-303 K. The relaxation results for BMIM-OcSO4 in bulk are interpreted in terms of three relaxation contributions: a term associated with the translational dynamics of the ions (it has been assumed that the translational dynamics of cations and anions can be described by one diffusion coefficient) and two terms associated with the rotational motion of the anion and the cation, respectively. The relationships between the obtained dynamic parameters (rotational correlation times and translational diffusion coefficients) are thoroughly discussed and used as a "reference" for the dynamics of BMIM-OcSO4 confined in an SiO2 matrix. Analysis of the corresponding relaxation data for the confined liquid shows that the confinement does not significantly affect the rotational dynamics, but it has a considerable impact on the translational motion. It is demonstrated that the relaxation term associated with the translational dynamics stems from two contributions: a contribution from a core (bulk-like) fraction of the liquid and from a fraction moving near the pore surface and therefore being for some time adsorbed on the pore walls. The translational diffusion coefficient for the last fraction is determined and several conclusions regarding the residence lifetime of the ions on the surface are drawn. Moreover, an additional motional process on the timescale of ns or shorter is revealed in the confinement. PMID:27499198

  11. Quantitative evaluation of porous media wettability using NMR relaxometry.

    PubMed

    Fleury, M; Deflandre, F

    2003-01-01

    We propose a new method to determine wettability indices from NMR relaxometry. The new method uses the sensitivity of low field NMR relaxometry to the fluid distribution in oil-water saturated porous media. The model is based on the existence of a surface relaxivity for both oil and water, allowing the determination of the amount of surface wetted either by oil or by water. The proposed NMR wettability index requires the measurement of relaxation time distribution at four different saturation states. At the irreducible water saturation, we determine the dominant relaxation time of oil in the presence of a small amount of water, and at the oil residual saturation, we determine the dominant relaxation time of water in the presence of a small amount of oil. At 100% water and 100% oil saturation, we determine the surface relaxivity ratio. The interaction of oil with the surface is also evidenced by the comparison of the spin-lattice (T1) and spin-locking (T1rho) relaxation times. The new NMR index agrees with standard wettability measurements based on drainage-imbibition capillary pressure curves (USBM test) in the range [-0.3-1]. PMID:12850740

  12. Understanding NMR relaxometry of partially water-saturated rocks

    NASA Astrophysics Data System (ADS)

    Mohnke, O.; Jorand, R.; Nordlund, C.; Klitzsch, N.

    2015-06-01

    Nuclear magnetic resonance (NMR) relaxometry measurements are commonly used to characterize the storage and transport properties of water-saturated rocks. Estimations of these properties are based on the direct link of the initial NMR signal amplitude to porosity (water content) and of the NMR relaxation time to pore size. Herein, pore shapes are usually assumed to be spherical or cylindrical. However, the NMR response at partial water saturation for natural sediments and rocks may differ strongly from the responses calculated for spherical or cylindrical pores, because these pore shapes do not account for water menisci remaining in the corners of desaturated angular pores. Therefore, we consider a bundle of pores with triangular cross sections. We introduce analytical solutions of the NMR equations at partial saturation of these pores, which account for water menisci of desaturated pores. After developing equations that describe the water distribution inside the pores, we calculate the NMR response at partial saturation for imbibition and drainage based on the deduced water distributions. For this pore model, the NMR amplitudes and NMR relaxation times at partial water saturation strongly depend on pore shape, i.e., arising from the capillary pressure and pore shape-dependent water distribution in desaturated pores with triangular cross sections. Even so, the NMR relaxation time at full saturation only depends on the surface-to-volume ratio of the pore. Moreover, we show the qualitative agreement of the saturation-dependent relaxation-time distributions of our model with those observed for rocks and soils.

  13. A new laboratory approach to shale analysis using NMR relaxometry

    USGS Publications Warehouse

    Washburn, Kathryn E.; Birdwell, Justin E.

    2013-01-01

    Low-field nuclear magnetic resonance (LF-NMR) relaxometry is a non-invasive technique commonly used to assess hydrogen-bearing fluids in petroleum reservoir rocks. Measurements made using LF-NMR provide information on rock porosity, pore-size distributions, and in some cases, fluid types and saturations (Timur, 1967; Kenyon et al., 1986; Straley et al., 1994; Brown, 2001; Jackson, 2001; Kleinberg, 2001; Hurlimann et al., 2002). Recent improvements in LF-NMR instrument electronics have made it possible to apply methods used to measure pore fluids to assess highly viscous and even solid organic phases within reservoir rocks. T1 and T2 relaxation responses behave very differently in solids and liquids; therefore the relationship between these two modes of relaxation can be used to differentiate organic phases in rock samples or to characterize extracted organic materials. Using T1-T2 correlation data, organic components present in shales, such as kerogen and bitumen, can be examined in laboratory relaxometry measurements. In addition, implementation of a solid-echo pulse sequence to refocus T2 relaxation caused by homonuclear dipolar coupling during correlation measurements allows for improved resolution of solid-phase protons. LF-NMR measurements of T1 and T2 relaxation time distributions were carried out on raw oil shale samples from the Eocene Green River Formation and pyrolyzed samples of these shales processed by hydrous pyrolysis and techniques meant to mimic surface and in-situ retorting. Samples processed using the In Situ Simulator approach ranged from bitumen and early oil generation through to depletion of petroleum generating potential. The standard T1-T2 correlation plots revealed distinct peaks representative of solid- and liquid-like organic phases; results on the pyrolyzed shales reflect changes that occurred during thermal processing. The solid-echo T1 and T2 measurements were used to improve assessment of the solid organic phases, specifically

  14. New applications and perspectives of fast field cycling NMR relaxometry.

    PubMed

    Steele, Rebecca M; Korb, Jean-Pierre; Ferrante, Gianni; Bubici, Salvatore

    2016-06-01

    The field cycling NMR relaxometry method (also known as fast field cycling (FFC) when instruments employing fast electrical switching of the magnetic field are used) allows determination of the spin-lattice relaxation time (T1 ) continuously over five decades of Larmor frequency. The method can be exploited to observe the T1 frequency dependence of protons, as well as any other NMR-sensitive nuclei, such as (2) H, (13) C, (31) P, and (19) F in a wide range of substances and materials. The information obtained is directly correlated with the physical/chemical properties of the compound and can be represented as a 'nuclear magnetic resonance dispersion' curve. We present some recent academic and industrial applications showing the relevance of exploiting FFC NMR relaxometry in complex materials to study the molecular dynamics or, simply, for fingerprinting or quality control purposes. The basic nuclear magnetic resonance dispersion features are outlined in representative examples of magnetic resonance imaging (MRI) contrast agents, porous media, proteins, and food stuffs. We will focus on the new directions and perspectives for the FFC technique. For instance, the introduction of the latest Wide Bore FFC NMR relaxometers allows probing, for the first time, of the dynamics of confined surface water contained in the macro-pores of carbonate rock cores. We also evidence the use of the latest field cycling technology with a new cryogen-free variable-field electromagnet, which enhances the range of available frequencies in the 2D T1 -T2 correlation spectrum for separating oil and water in crude oil. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25855084

  15. NMR relaxometry measurements of Fricke gel dosimeters exposed to neutrons

    NASA Astrophysics Data System (ADS)

    Marrale, Maurizio; Brai, Maria; Longo, Anna; Gallo, Salvatore; Tomarchio, Elio; Tranchina, Luigi; Gagliardo, Cesare; D'Errico, Francesco

    2014-11-01

    Fricke infused gel matrices offer several features making them suitable for dosimetric applications; among these there are tissue equivalence, low cost and ease of preparation. Their nuclear magnetic resonance (NMR) relaxation properties can be used as a radiation detector for the dosimetry of beams used in cancer therapy. In recent years neutron capture therapy has been resumed for the treatment of various types of cancer and it requires three-dimensional mapping of the neutron fields. In this work, we investigated this particular application through NMR relaxometry and MR imaging of Fricke gels exposed to neutrons. We analyzed both the R1 and R2 relaxation rates, which relate to the longitudinal T1 and transversal T2 relaxation times. In particular, we found that the relaxation rate R2 does not depend on the neutron fluence, whereas the relaxation rate R1 increases linearly with the fluence. The magnetic resonance imaging acquisitions showed that T1-weighted images allow the characterization of samples exposed to different neutron fluences.

  16. Dynamics of [C{sub 3}H{sub 5}N{sub 2}]{sub 6}[Bi{sub 4}Br{sub 18}] by means of {sup 1}H NMR relaxometry and quadrupole relaxation enhancement

    SciTech Connect

    Masierak, W.; Florek-Wojciechowska, M.; Oglodek, I.; Jakubas, R.; Privalov, A. F.; Kresse, B.; Fujara, F.; Kruk, D.

    2015-05-28

    {sup 1}H spin-lattice field cycling relaxation dispersion experiments in the intermediate phase II of the solid [C{sub 3}H{sub 5}N{sub 2}]{sub 6}[Bi{sub 4}Br{sub 18}] are presented. Two motional processes have been identified from the {sup 1}H spin-lattice relaxation dispersion profiles and quantitatively described. It has been concluded that these processes are associated with anisotropic reorientations of the imidazolium ring, characterized by correlation times of the order of 10{sup −8} s-10{sup −9} s and of about 10{sup −5} s. Moreover, quadrupole relaxation enhancement (QRE) effects originating from slowly fluctuating {sup 1}H-{sup 14}N dipolar interactions have been observed. From the positions of the relaxation maxima, the quadrupole coupling parameters for the {sup 14}N nuclei in [C{sub 3}H{sub 5}N{sub 2}]{sub 6}[Bi{sub 4}Br{sub 18}] have been determined. The {sup 1}H-{sup 14}N relaxation contribution associated with the slow dynamics has been described in terms of a theory of QRE [Kruk et al., Solid State Nucl. Magn. Reson. 40, 114 (2011)] based on the stochastic Liouville equation. The shape of the QRE maxima (often referred to as “quadrupole peaks”) has been consistently reproduced for the correlation time describing the slow dynamics and the determined quadrupole coupling parameters.

  17. Dynamic processes and chemical composition of Lepidium sativum seeds determined by means of field-cycling NMR relaxometry and NMR spectroscopy.

    PubMed

    Rachocki, A; Latanowicz, L; Tritt-Goc, J

    2012-12-01

    Proton nuclear magnetic resonance (NMR) techniques, such as field-cycling relaxometry, wide-line NMR spectroscopy, and magic angle spinning NMR spectroscopy, were applied to study the seeds of cress, Lepidium sativum. Field-cycling NMR relaxometry was used for the first time to investigate the properties of the whole molecular system of dry cress seeds. This method not only allowed the dynamics to be studied, but was also successful in the differentiation among the solid (i.e., carbohydrates, proteins, or fats forming a solid form of lipids) and liquid-like (oil compounds) components of the seeds. The (1)H NMR relaxation dispersion of oils was interpreted as a superposition of intramolecular and intermolecular contributions. The intramolecular part was described in terms of a Lorentzian spectral density function, whereas a log-Gaussian distribution of correlation times was applied for the intermolecular dipole-dipole contribution. The models applied led to very good agreement with the experimental data and demonstrate that the contribution of the intermolecular relaxation to the overall relaxation should not be disregarded, especially at low frequencies. A power-law frequency dependence of the proton relaxation dispersion was used for the interpretation of the solid components. From the analysis of the (1)H wide-line NMR spectra of the liquid-like component of hydrated cress seeds, we can conclude that the contribution of oil protons should always be taken into account when evaluating the spin-lattice relaxation times values or measuring the moisture and oil content. The application of (1)H magic angle spinning NMR significantly improves resolution in the liquid-like spectrum of seeds and allows the determination of the chemical composition of cress seeds. PMID:23001307

  18. Effects of time and temperature of firing on Fe-rich ceramics studied by Moessbauer spectroscopy and two-dimensional {sup 1}H-nuclear magnetic resonance relaxometry

    SciTech Connect

    Casieri, Cinzia; De Luca, Francesco; Nodari, Luca; Russo, Umberto; Terenzi, Camilla; Tudisca, Valentina

    2012-10-15

    The combined effects of firing temperature and soaking time on the microstructure of iron-rich porous ceramics have been studied by {sup 57}Fe-Moessbauer spectroscopy and 2D {sup 1}H nuclear magnetic resonance (NMR) relaxometry using a single-sided probe. Examining water-saturated ceramics using the relaxation correlation method, where longitudinal (T{sub 1}) and transverse (T{sub 2}) relaxation times are measured concurrently, provides information about firing-induced changes in both porosity (related to T{sub 1}) and magnetic properties (related to T{sub 2}). Comparing the information obtained from {sup 1}H-NMR analyses with that obtained from Moessbauer spectroscopy (which characterizes changes in iron-bearing species) shows that the T{sub 1}-T{sub 2} NMR correlation technique is very sensitive to even subtle modifications in the magnetic behavior of Fe-bearing species. Moreover, the single-sided NMR approach allows us to perform millimeter-scale depth-resolved measurements, which can be used to non-invasively study the microstructural heterogeneities associated with non-uniform firing effects inside ceramics. This is in contrast to Moessbauer spectroscopy, which requires that the ceramic samples be ground.

  19. Evaluation of the surface affinity of water in three biochars using fast field cycling NMR relaxometry.

    PubMed

    Bubici, Salvatore; Korb, Jean-Pierre; Kučerik, Jiří; Conte, Pellegrino

    2016-05-01

    Many soil functions depend on the interaction of water with soil. The affinity of water for soils can be altered by applying soil amendments like stone meal, manure, or biochar (a carbonaceous material obtained by pyrolysis of biomasses). In fact, the addition of hydrophobic biochar to soil may increase soil repellency, reduce water-adsorbing capacity, inhibit microbial activity, alter soil filter, buffer, storage, and transformation functions. For this reason, it is of paramount importance to monitor water affinity for biochar surface (also referred to as 'wettability') in order to better address its applications in soil systems. In this study, we propose the use of fast field cycling NMR relaxometry technique with the application of a new mathematical model for data interpretation, as a valid alternative to the traditional contact angle (CA) measurements for biochar wettability evaluation. Either NMR or CA results revealed the same wettability trend for the biochars studied here. The advantage of NMR relaxometry over CA measurements lies in the possibility to obtain at the microscopic level a variety of different information in only one shot. In fact, while CA provides only wettability evaluation, NMR relaxometry also allows achievement of the mechanisms for water molecular dynamics on biochar surface, thereby leading to the possibility to understand better, in future research, the role of biochar in increasing soil quality and plant nutrition. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27062147

  20. NMR relaxometry and diffusometry in characterizing structural, interfacial and colloidal properties of heavy oils and oil sands.

    PubMed

    Jones, Marc; Taylor, Spencer E

    2015-10-01

    We present a discussion of the use of NMR in the characterization of heavy oils and oil sands and their interactions with water and solid surfaces. The phenomena probed by the NMR techniques take place over different length scales, ranging from molecular, through colloidal to macroscopic. During the course of the last 15 years, NMR applications have grown from their initial use in studying conventional oils in rocks to the characterization of more viscous oils in unconsolidated porous media. In particular, (1)H NMR relaxometry and diffusometry are considered with a view to the identification of oil and water in oilfield fluids and their environment. After some theoretical considerations, various topics of current significance to petroleum recovery and production are discussed, including oil viscosity (with new experimental viscosity correlations added), oil sands characterization, heavy oil emulsions, and the identification of solvent effects on oil components and asphaltene solution behaviour and interactions. We show that, increasingly, NMR is becoming an invaluable and versatile characterization tool in petroleum science, in both laboratory and field. PMID:26253810

  1. Superoxygenated Water as an Experimental Sample for NMR Relaxometry

    ERIC Educational Resources Information Center

    Nestle, Nikolaus; Dakkouri, Marwan; Rauscher, Hubert

    2004-01-01

    The increase in NMR relaxation rates as a result of dissolved paramagnetic species on the sample of superoxygenated drinking water is demonstrated. It is concluded that oxygen content in NMR samples is an important issue and can give rise to various problems in the interpretation of both spectroscopic and NMR imaging or relaxation experiments.

  2. "Solvent Effects" in 1H NMR Spectroscopy.

    ERIC Educational Resources Information Center

    Cavaleiro, Jose A. S.

    1987-01-01

    Describes a simple undergraduate experiment in chemistry dealing with the "solvent effects" in nuclear magnetic resonance (NMR) spectroscopy. Stresses the importance of having students learn NMR spectroscopy as a tool in analytical chemistry. (TW)

  3. 1H NMR relaxation in urea

    NASA Astrophysics Data System (ADS)

    Taylor, R. E.; Bacher, Alfred D.; Dybowski, C.

    2007-11-01

    Proton NMR spin-lattice relaxation times T1 were measured for urea as a function of temperature. An activation energy of 46.3 ± 4.7 kJ/mol was extracted and compared with the range of 38-65 kJ/mol previously reported in the literature as measured by different magnetic resonance techniques. In addition, proton NMR spin-lattice relaxation times in the rotating frame T1 ρ were measured as a function of temperature. These measurements provide acquisition conditions for the 13C and 15N CP/MAS spectra of pure urea in the crystalline phase.

  4. Relaxometry in soil science

    NASA Astrophysics Data System (ADS)

    Schaumann, G. E.; Jaeger, F.; Bayer, J. V.

    2009-04-01

    NMR relaxometry is a sensitive, informative and promising method to study pore size distribution in soils as well as many kinds of soil physicochemical processes, among which are wetting, swelling or changes in the macromolecular status. Further, it is a very helpful method to study interactions between molecules in soil organic matter and it can serve to study the state of binding of water or organic chemicals to soil organic matter. The method of Relaxometry excite the nuclei of interest and their relaxation kinetics are observed. The relaxation time is the time constant of this first order relaxation process. Most applications of relaxometry concentrate on protons, addressing water molecules or H-containing organic molecules. In this context, 1H-NMR relaxometry may be used as an analysis method to determine water uptake characteristics of soils, thus gaining information about water distribution and mobility as well as pore size distribution in wet and moist samples. Additionally, it can also serve as a tool to study mobility of molecular segments in biopolymers. Principally, relaxometry is not restricted to protons. In soil science, relaxometry is also applied using deuterium, xenon and other nuclei to study pore size distribution and interactions. The relaxation time depends on numerous parameters like surface relaxivity, diffusion and interactions between nuclei as well as between nuclei and the environment. One- and two-dimensional methods address the relation between relaxation time and diffusion coefficients and can give information about the interconnectivity of pores. More specific information can be gained using field cycling techniques. Although proton NMR relaxometry is a very promising method in soil science, it has been applied scarcely up to now. It was used to assess changes in molecular rigidity of humic substances. A very recent study shows the potential of NMR relaxometry to assess the pore size distribution of soils in a fast and non

  5. Simultaneous Gaussian and exponential inversion for improved analysis of shales by NMR relaxometry.

    PubMed

    Washburn, Kathryn E; Anderssen, Endre; Vogt, Sarah J; Seymour, Joseph D; Birdwell, Justin E; Kirkland, Catherine M; Codd, Sarah L

    2015-01-01

    Nuclear magnetic resonance (NMR) relaxometry is commonly used to provide lithology-independent porosity and pore-size estimates for petroleum resource evaluation based on fluid-phase signals. However in shales, substantial hydrogen content is associated with solid and fluid signals and both may be detected. Depending on the motional regime, the signal from the solids may be best described using either exponential or Gaussian decay functions. When the inverse Laplace transform, the standard method for analysis of NMR relaxometry results, is applied to data containing Gaussian decays, this can lead to physically unrealistic responses such as signal or porosity overcall and relaxation times that are too short to be determined using the applied instrument settings. We apply a new simultaneous Gaussian-Exponential (SGE) inversion method to simulated data and measured results obtained on a variety of oil shale samples. The SGE inversion produces more physically realistic results than the inverse Laplace transform and displays more consistent relaxation behavior at high magnetic field strengths. Residuals for the SGE inversion are consistently lower than for the inverse Laplace method and signal overcall at short T2 times is mitigated. Beyond geological samples, the method can also be applied in other fields where the sample relaxation consists of both Gaussian and exponential decays, for example in material, medical and food sciences. PMID:25459882

  6. Simultaneous Gaussian and exponential inversion for improved analysis of shales by NMR relaxometry

    NASA Astrophysics Data System (ADS)

    Washburn, Kathryn E.; Anderssen, Endre; Vogt, Sarah J.; Seymour, Joseph D.; Birdwell, Justin E.; Kirkland, Catherine M.; Codd, Sarah L.

    2015-01-01

    Nuclear magnetic resonance (NMR) relaxometry is commonly used to provide lithology-independent porosity and pore-size estimates for petroleum resource evaluation based on fluid-phase signals. However in shales, substantial hydrogen content is associated with solid and fluid signals and both may be detected. Depending on the motional regime, the signal from the solids may be best described using either exponential or Gaussian decay functions. When the inverse Laplace transform, the standard method for analysis of NMR relaxometry results, is applied to data containing Gaussian decays, this can lead to physically unrealistic responses such as signal or porosity overcall and relaxation times that are too short to be determined using the applied instrument settings. We apply a new simultaneous Gaussian-Exponential (SGE) inversion method to simulated data and measured results obtained on a variety of oil shale samples. The SGE inversion produces more physically realistic results than the inverse Laplace transform and displays more consistent relaxation behavior at high magnetic field strengths. Residuals for the SGE inversion are consistently lower than for the inverse Laplace method and signal overcall at short T2 times is mitigated. Beyond geological samples, the method can also be applied in other fields where the sample relaxation consists of both Gaussian and exponential decays, for example in material, medical and food sciences.

  7. Simultaneous Gaussian and exponential inversion for improved analysis of shales by NMR relaxometry

    USGS Publications Warehouse

    Washburn, Kathryn E.; Anderssen, Endre; Vogt, Sarah J.; Seymour, Joseph D.; Birdwell, Justin E.; Kirkland, Catherine M.; Codd, Sarah L.

    2014-01-01

    Nuclear magnetic resonance (NMR) relaxometry is commonly used to provide lithology-independent porosity and pore-size estimates for petroleum resource evaluation based on fluid-phase signals. However in shales, substantial hydrogen content is associated with solid and fluid signals and both may be detected. Depending on the motional regime, the signal from the solids may be best described using either exponential or Gaussian decay functions. When the inverse Laplace transform, the standard method for analysis of NMR relaxometry results, is applied to data containing Gaussian decays, this can lead to physically unrealistic responses such as signal or porosity overcall and relaxation times that are too short to be determined using the applied instrument settings. We apply a new simultaneous Gaussian-Exponential (SGE) inversion method to simulated data and measured results obtained on a variety of oil shale samples. The SGE inversion produces more physically realistic results than the inverse Laplace transform and displays more consistent relaxation behavior at high magnetic field strengths. Residuals for the SGE inversion are consistently lower than for the inverse Laplace method and signal overcall at short T2 times is mitigated. Beyond geological samples, the method can also be applied in other fields where the sample relaxation consists of both Gaussian and exponential decays, for example in material, medical and food sciences.

  8. Effects of ions on water structure: a low-field ¹H T₁ NMR relaxometry approach.

    PubMed

    Conte, Pellegrino

    2015-09-01

    Aqueous salt solutions play an important role in nature because of their effects on environmental biogeochemical processes and on structural properties of biomolecules. Upon dissolution, salts split in ions that are solvated. Water in hydration shells is subjected to molecular motions that can be monitored by (1)H T1 NMR relaxometry. This technique allowed the evaluation of the nature of the interactions between water and ions via variable temperature experiments. Examination of relaxometry properties of aqueous solutions at variable salt concentrations allowed acknowledgement of the role played by ions in either structuring or destructuring water aggregates. A mathematical model has been applied on six environmentally relevant salts: NaCl, KCl, CaCl2, CaCO3, NaNO3, and NH4NO3. It was linear only for the concentration dependence of KCl-R1. This model accorded with the one reported in literature where it has been considered valid only for diluted solutions. However, in the present study, the range of linearity for KCl was extended up to the saturation point. The model was modified for NaCl, CaCl2, and CaCO3 by using it as an exponential form in order to account for the nonlinearity of the R1-versus-concentration curves. Nonlinearity was explained by the nonnegligible ion-ion interactions occurring as concentration was increased. Finally, further modification was needed to account for the asymmetric distribution of water around nitrate (in NaNO3 and NH4NO3) and ammonium (in NH4NO3). This study is preliminary to the comprehension of the diffusion mechanisms of ions in water solutions at the equilibrium condition with solid surfaces such as soils and biochar-amended soils. PMID:25356882

  9. NMR relaxometry study of plaster mortar with polymer additives

    SciTech Connect

    Jumate, E.; Manea, D.; Moldovan, D.; Fechete, R.

    2013-11-13

    The cement mixed with water forms a plastic paste or slurry which stiffness in time and finally hardens into a resistant stone. The addition of sand aggregates, polymers (Walocel) and/or calcium carbonate will modify dramatically the final mortar mechanic and thermal properties. The hydration processes can be observed using the 1D NMR measurements of transverse T{sub 2} relaxation times distributions analysed by a Laplace inversion algorithm. These distributions were obtained for mortar pasta measured at 2 hours after preparation then at 3, 7 and 28 days after preparation. Multiple components are identified in the T{sub 2} distributions. These can be associated with the proton bounded chemical or physical to the mortar minerals characterized by a short T{sub 2} relaxation time and to water protons in pores with three different pore sizes as observed from SEM images. The evaporation process is faster in the first hours after preparation, while the mortar hydration (bonding of water molecules to mortar minerals) can be still observed after days or months from preparation. Finally, the mechanic resistance was correlated with the transverse T{sub 2} relaxation rates corresponding to the bound water.

  10. Assignments of proton populations in dough and bread using NMR relaxometry of starch, gluten, and flour model systems.

    PubMed

    Bosmans, Geertrui M; Lagrain, Bert; Deleu, Lomme J; Fierens, Ellen; Hills, Brian P; Delcour, Jan A

    2012-05-30

    Starch-water, gluten-water, and flour-water model systems as well as straight-dough bread were investigated with (1)H NMR relaxometry using free induction decay and Carr-Purcell-Meiboom-Gill pulse sequences. Depending on the degree of interaction between polymers and water, different proton populations could be distinguished. The starch protons in the starch-water model gain mobility owing to amylopectin crystal melting, granule swelling, and amylose leaching, whereas water protons lose mobility due to increased interaction with starch polymers. Heating of the gluten-water sample induces no pronounced changes in proton distributions. Heating changes the proton distributions of the flour-water and starch-water models in a similar way, implying that the changes are primarily attributable to starch gelatinization. Proton distributions of the heated flour-water model system and those of fresh bread crumb are very similar. This allows identifying the different proton populations in bread on the basis of the results from the model systems. PMID:22553963

  11. Dynamics of Molecular Crystals by Means of (1) H NMR Relaxometry: Dynamical Heterogeneity versus Homogenous Motion.

    PubMed

    Kruk, Danuta; Florek-Wojciechowska, Małgorzata; Jakubas, Ryszard; Chaurasia, Sujeet K; Brym, Szczepan

    2016-08-01

    (1) H NMR relaxometry was used to reveal information on the dynamical properties of the molecular crystal (PyH)5 Bi2 Br11 (PyH=C5 H6 N, pyridinium cation), chosen as an example of a solid that exhibits a complex structure and rotational-like dynamics. Experimental studies were performed over a very broad frequency range, from 4 kHz to 40 MHz (referring to the (1) H resonance frequency) versus temperature. The extensive set of data was thoroughly analyzed in terms of two motional models differing with respect to the assumed mechanism (heterogeneous versus homogenous) of the motion of the PyH cations. A Cole-Davidson distribution of the correlation times describing the assumed motional heterogeneity was tested against a concept of two correlation times characterizing the rotation-like dynamics of the PyH cation around the perpendicular axes differing by about one order of magnitude. The parameters describing the dynamics of the cation, obtained by means of both models, were compared and discussed. PMID:27264005

  12. Laundering and Deinking Applications of 1H NMR Imaging

    NASA Astrophysics Data System (ADS)

    Tutunjian, P. N.; Borchardt, J. K.; Prieto, N. E.; Raney, K. H.; Ferris, J. A.

    One-dimensional 1H NMR imaging techniques are used to visualize oil removal from fabrics and paper fibers immersed in aqueous solutions of nonionic detergents. The method provides a unique approach to the study of oil-removal kinetics in nonionic detergent systems where traditional optical techniques fail due to solution turbidity. The only requirement of the NMR experiment is the use of deuterated water in order to selectively image the hydrocarbon phase. Preliminary applications to laundering and paper deinking are discussed.

  13. Localized double-quantum-filtered 1H NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Thomas, M. A.; Hetherington, H. P.; Meyerhoff, D. J.; Twieg, D. B.

    The image-guided in vivo spectroscopic (ISIS) pulse sequence has been combined with a double-quantum-filter scheme in order to obtain localized and water-suppressed 1H NMR spectra of J-coupled metabolites. The coherence-transfer efficiency associated with the DQ filter for AX and A 3X spin systems is described. Phantom results of carnosine, alanine, and ethanol in aqueous solution are presented. For comparison, the 1H NMR spectrum of alanine in aqueous solution with the binomial (1331, 2662) spin-echo sequence is also shown.

  14. Applications of 1H-NMR to Biodiesel Research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodiesel is an alternative diesel fuel derived from vegetable oils, animal fats, or used cooking oils. It is produced by reacting these materials with an alcohol in the presence of a catalyst to give the corresponding mono-alkyl esters. 1H-NMR is a routine analytical method that has been used for...

  15. Nanoparticle dispersion in polymer nanocomposites by spin-diffusion-averaged paramagnetic enhanced NMR relaxometry: scaling relations and applications.

    PubMed

    Xu, Bo; Leisen, Johannes; Beckham, Haskell W

    2014-08-21

    Scaling relationships are identified between NMR longitudinal relaxation times and clay dispersion quality in polymer-paramagnetic clay nanocomposites. Derived from a previously published analytical relationship developed from a lamella-based model, the scaling relationships are based on the enhancement of NMR relaxation rates with increasing exfoliation and dispersion homogeneity. The paramagnetic contribution to the NMR relaxation rate is inversely proportional to the square of the clay interparticle spacing, and directly proportional to the square of the clay weight fraction. These scaling relationships allow the prediction of relative exfoliation of clay particles for a given series of polymer-clay nanocomposites. With independent knowledge of clay exfoliation in a single sample (e.g., from transmission electron microscopy), NMR relaxometry data may be converted into absolute measures of exfoliation. These scaling relations are confirmed with samples of fully exfoliated poly(vinyl alcohol)-montmorillonite nanocomposites, and then used to reveal exfoliation and dispersion quality in a series of nylon-6-montmorillonite nanocomposites. This characterization route is advantageous because NMR relaxometry can more rapidly provide clay dispersion information that is averaged over larger sample volumes than transmission electron microscopy. PMID:25000915

  16. Rapid method for monitoring chitosan coagulation using low-field NMR relaxometry.

    PubMed

    Kock, Flávio Vinicius Crizóstomo; Colnago, Luiz Alberto

    2016-10-01

    Time-domain NMR relaxometry was proposed as a simple, rapid method to monitor chitosan (CS) coagulation as a function of pH. The longitudinal (T1) and transverse (T2) relaxation times of three CS concentrations (0.022, 0.22, and 2.2gL(-1)) were simultaneously measured by CP-CWFPx-x pulse sequences in a 0.47T spectrometer. T1 and T2 were shown to be independent of pH as well as to assume values similar to the relaxation time of water (2.7s) at the lowest tested CS concentration. At the highest concentration, T1 increased whereas T2 decreased as pH varied from 6.0 to 7.0. This indicates a remarkable effect of CS on water relaxation at pH values higher than the pKa of CS amino groups (6.5). Therefore, CS reduced the water mobility at the highest CS concentration and greatest pH values, suggesting a CS supramolecular structure (gel) that entraps the solvent in confined regions. The method proposed here can be further used to study the coagulation of other polysaccharides. PMID:27312606

  17. Ultrafast two-dimensional NMR relaxometry for investigating molecular processes in real time.

    PubMed

    Ahola, Susanna; Telkki, Ville-Veikko

    2014-06-01

    Nuclear spin-lattice (T1) and spin-spin (T2) relaxation times provide versatile information about the dynamics and structure of substances, such as proteins, polymers, porous media, and so forth. Multidimensional experiments increase the information content and resolution of NMR relaxometry, but they also multiply the measurement time. To overcome this issue, we present an efficient strategy for a single-scan measurement of a 2D T1-T2 correlation map. The method shortens the experimental time by one to three orders of magnitude as compared to the conventional method, offering an unprecedented opportunity to study molecular processes in real-time. We demonstrate that, despite the tremendous speed-up, the T1-T2 correlation maps determined by the single-scan method are in good agreement with the maps measured by the conventional method. The concept of the single-scan T1-T2 correlation experiment is applicable to a broad range of other multidimensional relaxation and diffusion experiments. PMID:24634359

  18. Cooperative polymer dynamics under nanoscopic pore confinements probed by field-cycling NMR relaxometry

    NASA Astrophysics Data System (ADS)

    Fatkullin, Nail; Kausik, Ravinath; Kimmich, Rainer

    2007-03-01

    Reptational dynamics of bulk polymer chains on a time scale between the Rouse mode relaxation time and the so-called disengagement time is not compatible with the basic thermodynamic law of fluctuations of the number of segments in a given volume. On the other hand, experimental field-cycling NMR relaxometry data of perfluoropolyether melts confined in Vycor, a porous silica glass of nominal pore dimension of 4nm, closely display the predicted signatures for the molecular weight and frequency dependences of the spin-lattice relaxation time in this particular limit, namely T1∝M-1/2ν1/2. It is shown that this contradiction is an apparent one. In this paper a formalism is developed suggesting cooperative chain dynamics under nanoscopic pore confinements. The result is a cooperative reptational displacement phenomenon reducing the root-mean-squared displacement rate correspondingly but showing the same characteristic dependences as the ordinary reptation model. The tube diameter effective for cooperative reptation is estimated on this basis for the sample system under consideration and is found to be of the same order of magnitude as the nominal pore diameter of Vycor.

  19. Dynamic 1H NMR Studies of Schiff Base Derivatives

    NASA Astrophysics Data System (ADS)

    Köylü, M. Z.; Ekinci, A.; Böyükata, M.; Temel, H.

    2016-01-01

    The spin-lattice relaxation time T 1 and the spin-spin relaxation time T 2 of two Schiff base derivatives, N,N'-ethylenebis(salicylidene)-1,2-diaminoethane (H2L1) and N,N'-ethylenebis (salicylidene)-1,3-diaminopropane (H2L2), in DMSO-d6 solvent were studied as a function of temperature in the range of 20-50°C using a Bruker Avance 400.132 MHz 1H NMR spectrometer. Based on the activation energy ( E a) and correlation time (τc), we believe that the Schiff base derivatives perform a molecular tumbling motion.

  20. High resolution 1H solid state NMR studies of polyethyleneterephthalate

    NASA Astrophysics Data System (ADS)

    Cheung, T. T. P.; Gerstein, B. C.; Ryan, L. M.; Taylor, R. E.; Dybowski, D. R.

    1980-12-01

    Molecular motions and spatial properties of the solid polymer polyethyleneterephthalate have been investigated using high resolution 1H solid state NMR techniques. The longitudinal spin relaxation time T1ρ of protons (1H) in the rotating frame was measured for a spin locking field ranging from 5 to 20 G. The decay of the 1H magnetization indicated the existence of two distinct T1ρ's and their field dependence shows that they are associated with two mobile phases of the polymer. The 1H magnetization also relaxes under the dipolar narrowed Carr-Purcell (DNCP) multipulse sequence with two dintinct T1y relaxation times. The ratios T1y's and T1ρ's deviate significantly from the expected theoretical values. The combined experiment with magic angle spinning and the DNCP sequence followed by homonuclear dipolar decoupling reveals the individual T1y relaxation of the resolved methylene and aromatic protons. These two species of protons were found to relax with the same T1y's, thus implying that spin diffusion must have taken place under the homonuclear dipolar decoupling multipulse. The qualitative description of spin diffusion under homonuclear decoupling is given. The combined experiment with spin locking and the DNCP sequence yields the correspondence between the two T1ρ's and the two T1y's. The long T1ρ corresponds to the short T1y whereas the short T1ρ corresponds to the long T1y. Communication between the two spatial phases via spin diffusion was also observed in this experiment by monitoring the recovery of the 1H magnitization associated with the short T1ρ after it has been eliminated during the spin locking. The total 1H magnetization is allowed to equilibrate in the laboratory frame for a variable time much shorter than T1 after the spin locking field has been turned off. The spatial relationship between the two phases is discussed.

  1. Dynamics of water solutions of natural polysaccharides by fast field cycling nmr relaxometry

    NASA Astrophysics Data System (ADS)

    Prusova, Alena; Conte, Pellegrino; Kucerik, Jiri; de Pasquale, Claudio; Alonzo, Giuseppe

    2010-05-01

    Cryobiology studies the effect of low temperatures on living systems such as microorganisms and plants. In particular, plants growing in cold or frozen environments can survive such extreme conditions due to the cold hardening process. Hardening is a three step process during which, first, translocation of polysaccharides to the plant roots affects water structure in the cell-soil surface. For this reason, increase of cell-membrane permeability and resistance to temperatures from -5°C to -10°C is achieved. In a second step, chemical alteration of cell membrane arises and resistance to temperatures up to -20°C is obtained. The last hardening step consists in the vitrification of the plant tissues which allow plants to survive at temperatures as low as -50°C. Since polysaccharides play a very important role in the initial part of the cold hardening process, it is of paramount importance to study the effect of such natural biopolymers on water structure. Here, we present preliminary data obtained by fast field cycling NMR relaxometry on the effect of hyaluronan (an anionic, non-sulfated glycosaminoglycan) on water structure at different concentrations of the polysaccharide. Although hyaluronan is a polysaccharide found exceptionally in animal, human or bacterial bodies, in the present work it was used as a model "pilot" compound. In fact, it has an unique ability to hold water and it contains both polysaccharide and protein-like acetamido functionalities. For this reason, hyaluronan promotes the future research on other plant biopolymers such as, for instance, starch and other very specific proteins. Results revealed that different water-structure systems surround the molecule of hyaluronan in diluted and semidiluted systems. Namely, at the lowest hyaluronan concentration, three hydration shells can be recognized. The first hydration shell is made by bound water (BW) which is strongly fixed to the hyaluronan surface mainly through electrostatic interactions. A

  2. On the macromolecular cellulosic network of paper: changes induced by acid hydrolysis studied by NMR diffusometry and relaxometry.

    PubMed

    Conti, Allegra; Poggi, Giovanna; Baglioni, Piero; De Luca, Francesco

    2014-05-14

    The cellulosic network of artificially acidified paper has been studied by 2D NMR relaxometry, NMR diffusometry and NMR diffusion-diffraction. Results show that the acidifying treatment enlarges the macropore structure of paper increasing the pore connectivity and modifying the exchange between water populations localized in amorphous cellulose. Acidification damage suggests that simple breaking of the amorphous portion of fibrils occurs. Nevertheless, under a specific acidifying condition, a rearrangement in the cellulose network seems to take place, with a reduction of the average macropore size and a loss of pore connectivity. The identification of water populations by 2D relaxation maps allows for monitoring the changes in cellulose water mobility due to the depolymerization process. In general the relaxation and self-diffusion results confirm that water mobility increases with acidification. PMID:24663146

  3. The 1H NMR Profile of Healthy Dog Cerebrospinal Fluid

    PubMed Central

    Musteata, Mihai; Nicolescu, Alina; Solcan, Gheorghe; Deleanu, Calin

    2013-01-01

    The availability of data for reference values in cerebrospinal fluid for healthy humans is limited due to obvious practical and ethical issues. The variability of reported values for metabolites in human cerebrospinal fluid is quite large. Dogs present great similarities with humans, including in cases of central nervous system pathologies. The paper presents the first study on healthy dog cerebrospinal fluid metabolomic profile using 1H NMR spectroscopy. A number of 13 metabolites have been identified and quantified from cerebrospinal fluid collected from a group of 10 mix breed healthy dogs. The biological variability as resulting from the relative standard deviation of the physiological concentrations of the identified metabolites had a mean of 18.20% (range between 9.3% and 44.8%). The reported concentrations for metabolites may be used as normal reference values. The homogeneity of the obtained results and the low biologic variability show that the 1H NMR analysis of the dog’s cerebrospinal fluid is reliable in designing and interpreting clinical and therapeutic trials in dogs with central nervous system pathologies. PMID:24376499

  4. Application of Solid-State NMR Relaxometry for Characterization and Formulation Optimization of Grinding-Induced Drug Nanoparticle.

    PubMed

    Ueda, Keisuke; Higashi, Kenjirou; Moribe, Kunikazu

    2016-03-01

    The formation mechanism of drug nanoparticles was investigated using solid-state nuclear magnetic resonance (NMR) techniques for the efficient discovery of an optimized nanoparticle formulation. The cogrinding of nifedipine (NIF) with polymers, including hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP), and sodium dodecyl sulfate (SDS) was performed to prepare the NIF nanoparticle formulations. Then, solid-state NMR relaxometry was used for the nanometer-order characterization of NIF in the polymer matrix. Solid-state NMR measurements revealed that the crystal size of NIF was reduced to several tens of nanometers with amorphization of NIF by cogrinding with HPMC and SDS for 100 min. Similarly, the size of the NIF crystal was reduced to less than 90 nm in the 40 min ground mixture of NIF/PVP/SDS. Furthermore, 100 min grinding of NIF/PVP/SDS induced amorphization of almost all the NIF crystals followed by nanosizing. The hydrogen bond between NIF and PVP led to the efficient amorphization of NIF in the NIF/PVP/SDS system compared with NIF/HPMC/SDS system. The efficient nanosizing of the NIF crystal in the solid state, revealed by the solid-state NMR relaxation time measurements, enabled the formation of large amounts of NIF nanoparticles in water followed by the polymer dissolution. In contrast, excess amorphization of the NIF crystals failed to efficiently prepare the NIF nanoparticles. The solid-state characterization of the crystalline NIF revealed good correlation with the NIF nanoparticles formation during aqueous dispersion. Furthermore, the solid-state NMR measurements including relaxometry successfully elucidated the nanometer-order dispersion state of NIF in polymer matrix, leading to the discovery of optimized conditions for the preparation of suitable drug nanoparticles. PMID:26855230

  5. Perspectives of Deuteron Field-Cycling NMR Relaxometry for Probing Molecular Dynamics in Soft Matter.

    PubMed

    Flämig, M; Becher, M; Hofmann, M; Körber, T; Kresse, B; Privalov, A F; Willner, L; Kruk, D; Fujara, F; Rössler, E A

    2016-08-11

    Due to the single-particle character of the quadrupolar interaction in molecular systems, (2)H NMR poses a unique method for probing reorientational dynamics. Spin-lattice relaxation gives access to the spectral density, and its frequency dependency can be monitored by field-cycling (FC) techniques. However, most FC NMR studies employ (1)H; the use of (2)H is still rare. We report on the application of (2)H FC NMR for investigating the dynamics in molecular liquids and polymers. Commercial as well as home-built relaxometers are employed accessing a frequency range from 30 Hz to 6 MHz. Due to low gyromagnetic ratio, high coupling constants, and finite FC switching times, current (2)H FC NMR does not reach the dispersion region in liquids (toluene and glycerol), yet good agreement with the results from conventional high-field (HF) relaxation studies is demonstrated. The pronounced difference at low frequencies between (2)H and (1)H FC NMR data shows the relevance of intermolecular relaxation in the case of (1)H NMR. In the case of the polymers polybutadiene and poly(ethylene-alt-propylene), very similar relaxation dispersion is observed and attributed to Rouse and entanglement dynamics. Combination with HF (2)H relaxation data via applying frequency-temperature superposition allows the reconstruction of the full spectral density reflecting both polymer as well as glassy dynamics. Transformation into the time domain yields the reorientational correlation function C2(t) extending over nine decades in time with a long-time power law, C2(t) ∝ t(-0.45±0.05), which does not conform to the prediction of the tube-reptation model, for which ∝ t(-0.25) is expected. Entanglement sets in below C2(t = τe) ≅ S(2) = 0.001, where τe is the entanglement time and S the corresponding order parameter. Finally, we discuss the future prospects of the (2)H FC NMR technique. PMID:27420118

  6. Synthesis of LaF{sub 3} nanosheets with high fluorine mobility investigated by NMR relaxometry and diffusometry

    SciTech Connect

    Gulina, L. B.; Tolstoy, V. P.; Murin, I. V.; Schäfer, M.; Privalov, A. F.

    2015-12-21

    Ionically conducting lanthanum fluoride (LaF{sub 3}), displaying a nanoscopic lamellar structure, has been synthesized at the surface of an aqueous solution of LaCl{sub 3} and HF. The structure and the chemical composition of the conductor have been analyzed by SEM, electron probe microanalysis, X-ray powder diffraction, FTIR, and {sup 19}F magic angle spinning nuclear magnetic resonance (NMR) spectroscopy. The fluorine dynamics have been studied by NMR diffusometry and relaxometry in a temperature range from room temperature up to 875 K. The fluorine self-diffusion coefficient of the nanostructured LaF{sub 3} is about two orders of magnitude larger than that of bulk LaF{sub 3}. This novel material is highly promising for many typical applications of fluorine ionic systems.

  7. Changes in porosity and organic matter phase distribution monitored by NMR relaxometry following hydrous pyrolysis under uniaxial confinement

    USGS Publications Warehouse

    Washburn, Kathryn E.; Birdwell, Justin E.; Lewan, Michael D.; Miller, Michael

    2013-01-01

    Artificial maturation methods are used to induce changes in source rock thermal maturity without the uncertainties that arise when comparing natural samples from a particular basin that often represent different levels of maturation and different lithofacies. A novel uniaxial confinement clamp was used on Woodford Shale cores in hydrous pyrolysis experiments to limit sample expansion by simulating the effect of overburden present during thermal maturation in natural systems. These samples were then subjected to X-ray computed tomography (X-CT) imaging and low-field nuclear magnetic resonance (LF-NMR) relaxometry measurements. LF-NMR relaxometry is a noninvasive technique commonly used to measure porosity and pore-size distributions in fluid-filled porous media, but may also measure hydrogen present in hydrogen-bearing organic solids. Standard T1 and T2 relaxation distributions were determined and two dimensional T1-T2 correlation measurements were performed on the Woodford Shale cores. The T1-T2 correlations facilitate resolution of organic phases in the system. The changes observed in NMR-relaxation times correspond to bitumen and lighter hydrocarbon production that occur as source rock organic matter matures. The LF-NMR porosities of the core samples at maximum oil generation are significantly higher than porosities measured by other methods. This discrepancy likely arises from the measurement of highly viscous organic constituents in addition to fluid-filled porosity. An unconfined sample showed shorter relaxation times and lower porosity. This difference is attributed to the lack of fractures observed in the unconfined sample by X-CT.

  8. Observation of 1H-13C and 1H-1H proximities in a paramagnetic solid by NMR at high magnetic field under ultra-fast MAS.

    PubMed

    Li, Shenhui; Trébosc, Julien; Lafon, Olivier; Zhou, Lei; Shen, Ming; Pourpoint, Frédérique; Amoureux, Jean-Paul; Deng, Feng

    2015-02-01

    The assignment of NMR signals in paramagnetic solids is often challenging since: (i) the large paramagnetic shifts often mask the diamagnetic shifts specific to the local chemical environment, and (ii) the hyperfine interactions with unpaired electrons broaden the NMR spectra and decrease the coherence lifetime, thus reducing the efficiency of usual homo- and hetero-nuclear NMR correlation experiments. Here we show that the assignment of (1)H and (13)C signals in isotopically unmodified paramagnetic compounds with moderate hyperfine interactions can be facilitated by the use of two two-dimensional (2D) experiments: (i) (1)H-(13)C correlations with (1)H detection and (ii) (1)H-(1)H double-quantum↔single-quantum correlations. These methods are experimentally demonstrated on isotopically unmodified copper (II) complex of l-alanine at high magnetic field (18.8 T) and ultra-fast Magic Angle Spinning (MAS) frequency of 62.5 kHz. Compared to (13)C detection, we show that (1)H detection leads to a 3-fold enhancement in sensitivity for (1)H-(13)C 2D correlation experiments. By combining (1)H-(13)C and (1)H-(1)H 2D correlation experiments with the analysis of (13)C longitudinal relaxation times, we have been able to assign the (1)H and (13)C signals of each l-alanine ligand. PMID:25557861

  9. 1H NMR metabolomics study of age profiling in children

    PubMed Central

    Gu, Haiwei; Pan, Zhengzheng; Xi, Bowei; Hainline, Bryan E.; Shanaiah, Narasimhamurthy; Asiago, Vincent; Nagana Gowda, G. A.; Raftery, Daniel

    2014-01-01

    Metabolic profiling of urine provides a fingerprint of personalized endogenous metabolite markers that correlate to a number of factors such as gender, disease, diet, toxicity, medication, and age. It is important to study these factors individually, if possible to unravel their unique contributions. In this study, age-related metabolic changes in children of age 12 years and below were analyzed by 1H NMR spectroscopy of urine. The effect of age on the urinary metabolite profile was observed as a distinct age-dependent clustering even from the unsupervised principal component analysis. Further analysis, using partial least squares with orthogonal signal correction regression with respect to age, resulted in the identification of an age-related metabolic profile. Metabolites that correlated with age included creatinine, creatine, glycine, betaine/TMAO, citrate, succinate, and acetone. Although creatinine increased with age, all the other metabolites decreased. These results may be potentially useful in assessing the biological age (as opposed to chronological) of young humans as well as in providing a deeper understanding of the confounding factors in the application of metabolomics. PMID:19441074

  10. 1H NMR Metabolomics Analysis of Glioblastoma Subtypes

    PubMed Central

    Cuperlovic-Culf, Miroslava; Ferguson, Dean; Culf, Adrian; Morin, Pier; Touaibia, Mohamed

    2012-01-01

    Glioblastoma multiforme (GBM) is the most common form of malignant glioma, characterized by unpredictable clinical behaviors that suggest distinct molecular subtypes. With the tumor metabolic phenotype being one of the hallmarks of cancer, we have set upon to investigate whether GBMs show differences in their metabolic profiles. 1H NMR analysis was performed on metabolite extracts from a selection of nine glioblastoma cell lines. Analysis was performed directly on spectral data and on relative concentrations of metabolites obtained from spectra using a multivariate regression method developed in this work. Both qualitative and quantitative sample clustering have shown that cell lines can be divided into four groups for which the most significantly different metabolites have been determined. Analysis shows that some of the major cancer metabolic markers (such as choline, lactate, and glutamine) have significantly dissimilar concentrations in different GBM groups. The obtained lists of metabolic markers for subgroups were correlated with gene expression data for the same cell lines. Metabolic analysis generally agrees with gene expression measurements, and in several cases, we have shown in detail how the metabolic results can be correlated with the analysis of gene expression. Combined gene expression and metabolomics analysis have shown differential expression of transporters of metabolic markers in these cells as well as some of the major metabolic pathways leading to accumulation of metabolites. Obtained lists of marker metabolites can be leveraged for subtype determination in glioblastomas. PMID:22528487

  11. High resolution 1H NMR of a lipid cubic phase using a solution NMR probe

    NASA Astrophysics Data System (ADS)

    Boyle-Roden, E.; Hoefer, N.; Dey, K. K.; Grandinetti, P. J.; Caffrey, M.

    2007-11-01

    The cubic mesophase formed by monoacylglycerols and water is an important medium for the in meso crystallogenesis of membrane proteins. To investigate molecular level lipid and additive interactions within the cubic phase, a method was developed for improving the resolution of 1H NMR spectra when using a conventional solution state NMR probe. Using this approach we obtained well-resolved J-coupling multiplets in the one-dimensional NMR spectrum of the cubic-Ia3d phase prepared with hydrated monoolein. A high resolution t-ROESY two-dimensional 1H NMR spectrum of the cubic-Ia3d phase is also reported. Using this new methodology, we have investigated the interaction of two additive molecules, L-tryptophan and ruthenium-tris(2,2-bipyridyl) dichloride (rubipy), with the cubic mesophase. Based on the measured chemical shift differences when changing from an aqueous solution to the cubic phase, we conclude that L-tryptophan experiences specific interactions with the bilayer interface, whereas rubipy remains in the aqueous channels and does not associate with the lipid bilayer.

  12. Cross Polarization for 1H NMR Image Contrast in Solids

    NASA Astrophysics Data System (ADS)

    Nakai, Toshihito; Fukunaga, Yasuhiro; Nonaka, Masayuki; Matsui, Shigeru; Inouye, Tamon

    1998-09-01

    A novel1H imaging method for solids, yielding images reflecting1H-13C dipolar interactions through cross relaxation timeTIS, is presented. Phase-alternating multiple-contact cross polarization (PAMC CP) was incorporated into the magic-echo frequency-encoding imaging scheme; the PAMC CP sequence may partly but efficiently destroy the initial1H magnetization depending on theTISvalues. A theory describing the effects of the PAMC CP sequence was developed, which was used for the assessment of the sequence as well as the analysis for the experimental results. It was demonstrated that theTIS-weighted1H image and theTISmapping for a phantom, constituted of adamantane and ferrocene, can distinguish these compounds clearly.

  13. 1H and 13C Solid-state NMR of G. barbadense (Pima) Cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The interaction of water with cellulose and its influence on the nuclear spin dynamics in G. barbadense (Pima) cotton were investigated with 1H and 13C solid-state NMR techniques. 1H spin diffusion results from a Goldman-Shen experiment indicate that the water is multilayered. 1H MAS experiment...

  14. 1H and 13C Solid-state NMR of Gossypium barbadense (Pima) Cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The interaction of water with cellulose and its influence on the nuclear spin dynamics in G. barbadense (Pima) cotton were investigated by 1H and 13C solid-state NMR techniques. 1H spin diffusion results from a Goldman-Shen experiment indicate that the water is multilayered. 1H MAS experiments pro...

  15. Diffusional Properties of Methanogenic Granular Sludge: 1H NMR Characterization

    PubMed Central

    Lens, Piet N. L.; Gastesi, Rakel; Vergeldt, Frank; van Aelst, Adriaan C.; Pisabarro, Antonio G.; Van As, Henk

    2003-01-01

    The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were performed at 22°C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Self-diffusion coefficients of H2O in the investigated series of mesophilic aggregates were found to be 51 to 78% lower than the self-diffusion coefficient of free water. Interestingly, self-diffusion coefficients of H2O were independent of the aggregate size for the size fractions investigated. Diffusional transport occurred faster in aggregates growing under nutrient-rich conditions (e.g., the bottom of a reactor) or at high (55°C) temperatures than in aggregates cultivated in nutrient-poor conditions or at low (10°C) temperatures. Exposure of aggregates to 2.5% glutaraldehyde or heat (70 or 90°C for 30 min) modified the diffusional transport up to 20%. In contrast, deactivation of aggregates by HgCl2 did not affect the H2O self-diffusion coefficient in aggregates. Analysis of NMR images of a single aggregate shows that methanogenic aggregates possess a spin-spin relaxation time and self-diffusion coefficient distribution, which are due to both physical (porosity) and chemical (metal sulfide precipitates) factors. PMID:14602624

  16. Dynamics of the Chiral Liquid Crystal 4'-Butyl-4-(S)-(2-methylbutoxy)azoxybenzene in the Isotropic, Cholesteric, and Solid Phases: A Fast Field-Cycling NMR Relaxometry Study.

    PubMed

    Carignani, Elisa; Calucci, Lucia; Juszyńska-Gałązka, Ewa; Gałązka, Mirosław; Massalska-Arodź, Maria; Forte, Claudia; Geppi, Marco

    2016-06-01

    (1)H NMR relaxometry was applied to investigate dynamic processes in the isotropic liquid, cholesteric, and crystalline phases of the chiral mesogen 4'-butyl-4-(S)-(2-methylbutoxy)azoxybenzene (4ABO5*). To this aim, (1)H longitudinal relaxation rates were measured as a function of temperature (between 257 and 319 K) and Larmor frequency (from 10 kHz to 35 MHz by a fast field-cycling relaxometer and at 400 MHz by an NMR spectrometer). The NMR relaxation dispersion (NMRD) curves so obtained were analyzed in terms of models suitable for the description of dynamic processes in the different phases, thus quantitatively determining values of characteristic motional parameters. In particular, internal and overall rotations/reorientations, molecular translational diffusion, and collective motions contribute to relaxation in the isotropic and cholesteric phases, whereas, in the crystalline phase, relaxation is mainly determined by internal motions and molecular reorientations. The results were discussed and compared with those previously obtained on the same compound by dielectric relaxation spectroscopy. PMID:27186864

  17. Effects of organic amendments on natural organic matter in bulk soils from an italian agricultural area as assessed by Fast Field Cycling NMR relaxometry

    NASA Astrophysics Data System (ADS)

    Scotti, Riccardo; Conte, Pellegrino; Alonzo, Giuseppe; Rao, Maria A.

    2010-05-01

    Losses of soil organic carbon often occur in soil because of intensive agricultural practices. This is due both to removal of organic carbon following harvest production and to insufficient inputs of organic amendments. Natural organic matter (NOM) can be a very appropriate material for enhancing organic carbon content in very stressed agricultural soils. In general, NOM plays an important role in environmental matrices due, for example, to its capacity in retaining water, in interacting with organic and inorganic pollutants, and in enhancing nutrient availability to plants. For this reason, the understanding of the mechanisms with which NOM interacts with other chemicals in the environment is of paramount importance. Structural and conformational NOM characteristics can be analysed by high field (HF) nuclear magnetic resonance (NMR) spectroscopy either in the solid or in the liquid state. In both cases, information on the chemical nature of NOM can be achieved. Moreover, relaxometry studies can be also conducted to provide information on the molecular dynamics of natural organic matter. However, HF-NMR relaxometry limitations are related to the strength of the magnetic fields which limits the range of relaxation rates that can be investigated. In fact, high magnetic fields (e.g. ≥108 Hz) reduce the possibilities to observe molecular dynamics at very low frequencies such as those between 106 and 103 Hz. To this aim, nuclear magnetic resonance relaxometry at low fields and in the fast field cycling (FFC) setup is the most powerful way to retrieve information on the dynamics at low frequencies. Here, FFC-NMR relaxometry studies on soils subjected to different organic amendements are presented. Two farms, in an important agricultural area of Campania Region, Italy, were selected in order to study the effect of different organic amendments on bulk soils. Namely, a compost from municipal solid wastes and wood-wastes (scraps of poplars pruning) were applied in

  18. Methane Storage in Nanoporous Media as Observed via High-Field NMR Relaxometry

    NASA Astrophysics Data System (ADS)

    Papaioannou, A.; Kausik, R.

    2015-08-01

    The storage properties of methane gas in Vycor porous glass (5.7 nm) are characterized in a wide pressure range from 0.7 to 89.7 MPa using nuclear magnetic resonance. We demonstrate the capability of high-field nuclear-magnetic-resonance relaxometry for the determination of the methane-gas storage capacity and the measurement of the hydrogen index, to a high degree of accuracy. This helps determine the excess gas in the pore space which can be identified to exhibit Langmuir properties in the low pressure regime of 0.7 to 39.6 MPa. The Langmuir model enables us to determine the equilibrium density of the monolayer of adsorbed gas to be 8.5% lower than that of liquid methane. We also identify the signatures of multilayer adsorption at the high pressure regime from 39.6 to 89.7 MPa and use the Brunauer-Emmet-Teller theory to determine the number of adsorbed layers of methane gas. We show how these measurements help us differentiate the gas stored in the Vycor pore space into free and adsorbed fractions for the entire pressure range paving way for similar applications such as studying natural-gas storage in gas shale rock or hydrogen storage in carbon nanotubes.

  19. 1H NMR spectra part 31: 1H chemical shifts of amides in DMSO solvent.

    PubMed

    Abraham, Raymond J; Griffiths, Lee; Perez, Manuel

    2014-07-01

    The (1)H chemical shifts of 48 amides in DMSO solvent are assigned and presented. The solvent shifts Δδ (DMSO-CDCl3 ) are large (1-2 ppm) for the NH protons but smaller and negative (-0.1 to -0.2 ppm) for close range protons. A selection of the observed solvent shifts is compared with calculated shifts from the present model and from GIAO calculations. Those for the NH protons agree with both calculations, but other solvent shifts such as Δδ(CHO) are not well reproduced by the GIAO calculations. The (1)H chemical shifts of the amides in DMSO were analysed using a functional approach for near ( ≤ 3 bonds removed) protons and the electric field, magnetic anisotropy and steric effect of the amide group for more distant protons. The chemical shifts of the NH protons of acetanilide and benzamide vary linearly with the π density on the αN and βC atoms, respectively. The C=O anisotropy and steric effect are in general little changed from the values in CDCl3. The effects of substituents F, Cl, Me on the NH proton shifts are reproduced. The electric field coefficient for the protons in DMSO is 90% of that in CDCl3. There is no steric effect of the C=O oxygen on the NH proton in an NH…O=C hydrogen bond. The observed deshielding is due to the electric field effect. The calculated chemical shifts agree well with the observed shifts (RMS error of 0.106 ppm for the data set of 257 entries). PMID:24824670

  20. Lemna minor L. as a model organism for ecotoxicological studies performing 1H NMR fingerprinting.

    PubMed

    Aliferis, Konstantinos A; Materzok, Sylwia; Paziotou, Georgia N; Chrysayi-Tokousbalides, Maria

    2009-08-01

    A validated method applying (1)H NMR fingerprinting for the study of metabolic changes caused in Lemna minor L. by various phytotoxic substances is presented. (1)H NMR spectra of crude extracts from untreated and treated colonies with the herbicides glyphosate, mesotrione, norflurazon, paraquat and the phytotoxin pyrenophorol were subjected to multivariate analyses for detecting differences between groups of treatments. Partial least squares-discriminant analysis (PLS-DA) and hierarchical cluster analysis (HCA) were carried out in order to discriminate and classify treatments according to the observed changes in the metabolome of the plant. Although the compounds at the concentrations used did not cause macroscopically observable symptoms of phytotoxicity, characteristic metabolic changes were detectable by analyzing (1)H NMR spectra. Analyses results revealed that metabonomics applying (1)H NMR fingerprinting is a potential method for the investigation of toxicological effects of xenobiotics on L. minor, and possibly on other duckweed species, helping in the understanding of such interactions. PMID:19443011

  1. Parallel NMR spectroscopy with simultaneous detection of (1) H and (19) F nuclei.

    PubMed

    Kovacs, Helena; Kupče, Ēriks

    2016-07-01

    Recording NMR signals of several nuclear species simultaneously by using parallel receivers provides more information from a single measurement and at the same time increases the measurement sensitivity per unit time. Here we present a comprehensive series of the most frequently used NMR experiments modified for simultaneous direct detection of two of the most sensitive NMR nuclei - (1) H and (19) F. We hope that the presented material will stimulate interest in and further development of this technique. PMID:27021630

  2. Proton Fingerprints Portray Molecular Structures: Enhanced Description of the 1H NMR Spectra of Small Molecules

    PubMed Central

    Napolitano, José G.; Lankin, David C.; McAlpine, James B.; Niemitz, Matthias; Korhonen, Samuli-Petrus; Chen, Shao-Nong; Pauli, Guido F.

    2013-01-01

    The characteristic signals observed in NMR spectra encode essential information on the structure of small molecules. However, extracting all of this information from complex signal patterns is not trivial. This report demonstrates how computer-aided spectral analysis enables the complete interpretation of 1D 1H NMR data. The effectiveness of this approach is illustrated with a set of organic molecules, for which replicas of their 1H NMR spectra were generated. The potential impact of this methodology on organic chemistry research is discussed. PMID:24007197

  3. Preliminary 1H NMR study on archaeological waterlogged wood.

    PubMed

    Maccotta, Antonella; Fantazzini, Paola; Garavaglia, Carla; Donato, Ines D; Perzia, Patrizia; Brai, Maria; Morreale, Filippa

    2005-01-01

    Magnetic Resonance Relaxation (MRR) and Magnetic Resonance Imaging (MRI) are powerful tools to obtain detailed information on the pore space structure that one is unlikely to obtain in other ways. These techniques are particularly suitable for Cultural Heritage materials, because they use water 1H nuclei as a probe. Interaction with water is one of the main causes of deterioration of materials. Porous structure in wood, for example, favours the penetration of water, which can carry polluting substances and promote mould growth. A particular case is waterlogged wood from underwater discoveries and moist sites; in fact, these finds are very fragile because of chemical, physical and biological decay from the long contact with the water. When wood artefacts are brought to the surface and directly dried in air, there is the collapse of the cellular structures, and wood loses its original form and dimensions and cannot be used for study and museum exhibits. In this work we have undertaken the study of some wood finds coming from Ercolano's harbour by MRR and MRI under different conditions, and we have obtained a characterization of pore space in wood and images of the spatial distribution of the confined water in the wood. PMID:16485652

  4. Intermolecular Interactions between Eosin Y and Caffeine Using 1H-NMR Spectroscopy

    PubMed Central

    Okuom, Macduff O.; Wilson, Mark V.; Jackson, Abby; Holmes, Andrea E.

    2014-01-01

    DETECHIP has been used in testing analytes including caffeine, cocaine, and tetrahydrocannabinol (THC) from marijuana, as well as date rape and club drugs such as flunitrazepam, gamma-hydroxybutyric acid (GHB), and methamphetamine. This study investigates the intermolecular interaction between DETECHIP sensor eosin Y (DC1) and the analyte (caffeine) that is responsible for the fluorescence and color changes observed in the actual array. Using 1H-NMR, 1H-COSY, and 1H-DOSY NMR methods, a proton exchange from C-8 of caffeine to eosin Y is proposed. PMID:25018772

  5. Intermolecular Interactions between Eosin Y and Caffeine Using (1)H-NMR Spectroscopy.

    PubMed

    Okuom, Macduff O; Wilson, Mark V; Jackson, Abby; Holmes, Andrea E

    2013-12-31

    DETECHIP has been used in testing analytes including caffeine, cocaine, and tetrahydrocannabinol (THC) from marijuana, as well as date rape and club drugs such as flunitrazepam, gamma-hydroxybutyric acid (GHB), and methamphetamine. This study investigates the intermolecular interaction between DETECHIP sensor eosin Y (DC1) and the analyte (caffeine) that is responsible for the fluorescence and color changes observed in the actual array. Using (1)H-NMR, (1)H-COSY, and (1)H-DOSY NMR methods, a proton exchange from C-8 of caffeine to eosin Y is proposed. PMID:25018772

  6. Characterisation of the 1H and 13C NMR spectra of methylcitric acid

    NASA Astrophysics Data System (ADS)

    Krawczyk, Hanna; Martyniuk, Tomasz

    2007-06-01

    Methylcitric acid (MCA) was synthesised in Reformatsky reaction (2 RS, 3 RS stereoisomers) and in the nucleophilic addition (2 RS, 3 SR stereoisomers). The stereoselectivity of these reactions was analysed. 1H and 13C NMR spectra of diastereoisomers of methylcitric acid were recorded and interpreted. The values of 1H chemical shifts and 1H- 1H coupling constants were analysed. Proton-decoupled high-resolution 13C NMR spectra of MCA diastereoisomers were measured in a series of dilute water solutions of various acidities. These data may provide a basis for unequivocal determination of the presence of MCA in the urine samples of patients' suffering from propionic acidemia, methylmalonic aciduria, or holocarboxylase synthetase deficiency. NMR spectroscopy enables determination of MCA diastereoisomers in body fluids and can be a complementary and useful diagnostic tool.

  7. Digital NMR Profiles as Building Blocks: Assembling 1H Fingerprints of Steviol Glycosides

    PubMed Central

    Napolitano, José G.; Simmler, Charlotte; McAlpine, James B.; Lankin, David C.; Chen, Shao-Nong; Pauli, Guido F.

    2015-01-01

    This report describes a fragment-based approach to the examination of congeneric organic compounds by NMR spectroscopy. The method combines the classic interpretation of 1D- and 2D-NMR data sets with contemporary computer-assisted NMR analysis. Characteristic NMR profiles of key structural motifs were generated by 1H iterative full spin analysis and then joined together as building blocks to recreate the 1H NMR spectra of increasingly complex molecules. To illustrate the methodology described, a comprehensive analysis of steviol (1), seven steviol glycosides (2–8) and two structurally related isosteviol compounds (9, 10) was carried out. The study also assessed the potential impact of this method on relevant aspects of natural product research including structural verification, chemical dereplication, and mixture analysis. PMID:25714117

  8. Liquid crystal 8CB in random porous glass: NMR relaxometry study of molecular diffusion and director fluctuations

    SciTech Connect

    Vilfan, M.; Apih, T.; Lahajnar, G.; Sebastiao, P. J.; Zumer, S.

    2007-11-15

    We present the measurements of the proton spin-lattice relaxation time T{sub 1} of liquid crystal 4-n-octyl-4{sup '}-cyanobiphenyl (8CB) confined into randomly oriented {approx}15 nm pores of untreated porous glass. In the low kilohertz range the spin-lattice relaxation rate in the nanoconfined 8CB is about ten times larger than in the bulk. We show that the increase is mainly due to molecular reorientations mediated by translational displacements (RMTD). In the paranematic phase the power law describing the RMTD dispersion, (T{sub 1}{sup -1}){sub RMTD}{proportional_to}{omega}{sup -p}, is well characterized by the exponent p=0.5{+-}0.06 and suggests an equipartition of diffusion modes with different wavelengths. The largest distance related to the decay of the orientational correlation function is about twice the diameter of the cavity. The situation is different in the nematic phase, where the orientational correlation is eventually lost at {approx}60 nm in the direction along the pore, a distance corresponding roughly to the length of a pore segment in the glassy matrix. The exponent p is between 0.65 and 0.9, depending on the temperature, which implies that in the nematic phase long wavelength modes are relatively more important--a consequence of the uniform director field along the pore. These observations are in agreement with the model of mutually independent pores with nematic director parallel to the pore axis in each segment. We point out that in strongly confined liquid crystals the proton NMR relaxometry does not provide the evidence of director fluctuations correlated over micrometer distances as was suggested earlier. The local translational diffusion of molecules within the cavities is found about as fast as in bulk.

  9. Hydrogen concentration dependence of 1H Knight shift in NbH x studied by 1H MAS NMR

    NASA Astrophysics Data System (ADS)

    Ueda, Takahiro; Hayashi, Shigenobu; Hayamizu, Kikuko

    1993-08-01

    Hydrogen concentration dependence of the Knight shift of protons in NbH x(0.05≤×≤1.05) has been studied by means of 1H MAS (magic angle sample spinning) NMR. In the mixed-phase samples of the α and β phases (0.05<×≤0.7), it is found that the 1H Knight shift of β-NbH x depends on the phase fraction. The shift variation in the β phase can be correlated with the unit cell volume, being explained by the variation of the density of electronic states at the Fermi level N(0) due to the compression of the crystal lattice. On the other hand, in the single β-phase samples (0.7<×≤1.05), the 1H Knight shift becomes smaller as the hydrogen concentration increases. This variation can be explained by increase in the number of electrons in the unit cell with the hydrogen concentration, resulting in the N(0) increase.

  10. Evaluation Of Automated Low-Field Nuclear Magnetic Resonance (NMR) Relaxometry For Analysis Of Silicone Polymers

    SciTech Connect

    M. H. Wilson

    2009-10-02

    Screening studies and Design of Experiments (DoE) were performed to evaluate measurement variation of a new, non-destructive Nuclear Magnetic Resonance (NMR) test system designed to assess age-induced degradation of Outer Pressure Pads (OPP). The test method and results from 54,275 measurements are described. A reduction in measurement error was obtained after metal support struts were replaced with plastic support struts adjacent to the front position of the test chamber. However, remaining interference and a lack of detecting any age-related degradation prevent the use of the NMR system as a non-destructive surveillance test for OPPs. A cursory evaluation of the system with cellular silicone samples obtained more uniform results with increased error as measurements approached the sample’s edge.

  11. Metabolomic differentiation of Cannabis sativa cultivars using 1H NMR spectroscopy and principal component analysis.

    PubMed

    Choi, Young Hae; Kim, Hye Kyong; Hazekamp, Arno; Erkelens, Cornelis; Lefeber, Alfons W M; Verpoorte, Robert

    2004-06-01

    The metabolomic analysis of 12 Cannabis sativa cultivars was carried out by 1H NMR spectroscopy and multivariate analysis techniques. Principal component analysis (PCA) of the 1H NMR spectra showed a clear discrimination between those samples by principal component 1 (PC1) and principal component 3 (PC3) in cannabinoid fraction. The loading plot of PC value obtained from all 1)H NMR signals shows that Delta9-tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA) are important metabolites to differentiate the cultivars from each other. The discrimination of the cultivars could also be obtained from a water extract containing carbohydrates and amino acids. The level of sucrose, glucose, asparagine, and glutamic acid are found to be major discriminating metabolites of these cultivars. This method allows an efficient differentiation between cannabis cultivars without any prepurification steps. PMID:15217272

  12. 1H NMR determination of urinary betaine in patients with premature vascular disease and mild homocysteinemia.

    PubMed

    Lundberg, P; Dudman, N P; Kuchel, P W; Wilcken, D E

    1995-02-01

    Urinary N,N,N-trimethylglycine (betaine) and N,N-dimethylglycine (DMG) have been identified and quantified for clinical purposes by proton nuclear magnetic resonance (1H NMR) measurement in previous studies. We have assessed these procedures by using both one-dimensional (1-D) and 2-D NMR spectroscopy, together with pH titration of urinary extracts to help assign 1H NMR spectral peaks. The betaine calibration curve linearity was excellent (r = 0.997, P = 0.0001) over the concentration range 0.2-1.2 mmol/L, and CVs for replicate betaine analyses ranged from 7% (n = 10) at the lowest concentration to 1% (n = 9) at the highest. The detection limit for betaine was < 15 mumol/L. Urinary DMG concentrations were substantially lower than those of betaine. Urinary betaine and DMG concentrations measured by 1H NMR spectroscopy from 13 patients with premature vascular disease and 17 normal controls provided clinically pertinent data. We conclude that 1H NMR provides unique advantages as a research tool for determination of urinary betaine and DMG concentrations. PMID:7533065

  13. Binding of Sulfonamide Antibiotics to CTABr Micelles Characterized Using (1)H NMR Spectroscopy.

    PubMed

    Sarker, Ashish K; Cashin, Patrick J; Balakrishnan, Vimal K; Exall, Kirsten; Buncel, Erwin; Brown, R Stephen

    2016-08-01

    Interactions of nine sulfonamide antibiotics (sulfadoxine, sulfathiazole, sulfamethoxazole, sulfamerazine, sulfadiazine, sulfamethazine, sulfacetamide, sulfaguanidine, and sulfanilamide) with cetyltrimethylamonium bromide (CTABr) micelles were examined using (1)H NMR spectroscopy. Seven of the nine provided a significant change in the (1)H NMR chemical shift such that the magnitude and direction (upfield vs downfield) of the chemical shift could be used to propose a locus and orientation of the sulfonamide within the micelle structure. The magnitude of the chemical shift was used to estimate the binding constant for seven sulfonamides with CTABr micelles, providing values and an overall pattern consistent with previous studies of these sulfonamides. PMID:27391918

  14. Fruit juice authentication by 1H NMR spectroscopy in combination with different chemometrics tools.

    PubMed

    Cuny, M; Vigneau, E; Le Gall, G; Colquhoun, I; Lees, M; Rutledge, D N

    2008-01-01

    To discriminate orange juice from grapefruit juice in a context of fraud prevention, (1)H NMR data were submitted to different treatments to extract informative variables which were then analysed using multivariate techniques. Averaging contiguous data points of the spectrum followed by logarithmic transformation improved the results of the data analysis. Moreover, supervised variable selection methods gave better rates of classification of the juices into the correct groups. Last, independent-component analysis gave better classification results than principal-component analysis. Hence, ICA may be an efficient chemometric tool to detect differences in the (1)H NMR spectra of similar samples, and so may be useful for authentication of foods. PMID:18026939

  15. Evaluation of Automated Low-Field NMR Relaxometry For Analysis of Polymers

    SciTech Connect

    Wilson, Mark

    2008-12-04

    Screening studies and a Design of Experiment were performed to evaluate measurement variation of a new, non-destructive NMR test system designed to assess age induced degradation of Outer Pressure Pads. The test method and results from 76,746 measurements are described indicating that a metal support strut adjacent to the front position of the test chamber interferes with the measurements and that there is a measurement property gradient from the front to the back of the chamber. Also, obvious compression set areas on a surveillance OPP were not detected, but hidden, internal voids within a newly molded OPP were detected.

  16. Probing degradation in complex engineering silicones by 1H multiple quantum NMR

    SciTech Connect

    Maxwell, R S; Chinn, S C; Giuliani, J; Herberg, J L

    2007-09-05

    Static {sup 1}H Multiple Quantum Nuclear Magnetic Resonance (MQ NMR) has recently been shown to provide detailed insight into the network structure of pristine silicon based polymer systems. The MQ NMR method characterizes the residual dipolar couplings of the silicon chains that depend on the average molecular weight between physical or chemical constraints. Recently, we have employed MQ NMR methods to characterize the changes in network structure in a series of complex silicone materials subject to numerous degradation mechanisms, including thermal, radiative, and desiccative. For thermal degradation, MQ NMR shows that a combination of crosslinking due to post-curing reactions as well as random chain scissioning reactions occurs. For radiative degradation, the primary mechanisms are via crosslinking both in the network and at the interface between the polymer and the inorganic filler. For samples stored in highly desiccating environments, MQ NMR shows that the average segmental dynamics are slowed due to increased interactions between the filler and the network polymer chains.

  17. Importance of Purity Evaluation and the Potential of Quantitative 1H NMR as a Purity Assay

    PubMed Central

    2015-01-01

    In any biomedical and chemical context, a truthful description of chemical constitution requires coverage of both structure and purity. This qualification affects all drug molecules, regardless of development stage (early discovery to approved drug) and source (natural product or synthetic). Purity assessment is particularly critical in discovery programs and whenever chemistry is linked with biological and/or therapeutic outcome. Compared with chromatography and elemental analysis, quantitative NMR (qNMR) uses nearly universal detection and provides a versatile and orthogonal means of purity evaluation. Absolute qNMR with flexible calibration captures analytes that frequently escape detection (water, sorbents). Widely accepted structural NMR workflows require minimal or no adjustments to become practical 1H qNMR (qHNMR) procedures with simultaneous qualitative and (absolute) quantitative capability. This study reviews underlying concepts, provides a framework for standard qHNMR purity assays, and shows how adequate accuracy and precision are achieved for the intended use of the material. PMID:25295852

  18. Dynamics of ferroelectric bis(imidazolium) pentachloroantimonate(III) by means of nuclear magnetic resonance 1H relaxometry and dielectric spectroscopy.

    PubMed

    Piecha-Bisiorek, A; Jakubas, R; Medycki, W; Florek-Wojciechowska, M; Wojciechowski, M; Kruk, D

    2014-05-22

    Some of haloantimonates(III) and halobismuthates(III) are ferroelectric. Bis(imidazolium) pentachloroantimonate(III), (C3N2H5)2SbCl5 (abbreviation: ICA) is the first example of such compounds with a one-dimensional anionic chain which exhibits ferroelectric properties. The relation between the ionic dynamics and network structure and the ferroelectric features is not clear. Here Nuclear Magnetic Resonance (NMR) (1)H spin-lattice relaxation experiments at 25 MHz are reported for ICA in the temperature range of 80 K-360 K, covering ferroelectric-paraelectric and structural phase transitions of the compound occurring at 180 and 342 K, respectively. The relaxation process is biexponential in the whole temperature range indicating two dynamically nonequivalent types of imidazolium cations. Temperature dependences of both relaxation contributions allow for identifying three motional processes. Two of them are cation-specific - i.e. they are attributed to the two types of imidazolium cations, respectively. The third process involves both types of cations, and it is characterized by much lower activation energy. Moreover, the relaxation data (combined with (1)H second moment measurements) show that the ferroelectric-paraelectric phase transition mechanism is governed, to a large extent, by the anionic network arrangement. The NMR studies are complemented by dielectric spectroscopy experiments performed in the vicinity of the Curie temperature, TC = 180 K, to get insight into the mechanism of the ferroelectric-paraelectric phase transition. The dielectric dispersion data show critical slowing down of the macroscopic relaxation time, τ, in ICA when approaching TC from the paraelectric side, indicating an order-disorder type of ferroelectrics. PMID:24804840

  19. An NMR relaxometry and gravimetric study of gelatin-free aqueous polyacrylamide dosimeters

    NASA Astrophysics Data System (ADS)

    Babic, Steven; Schreiner, L. John

    2006-09-01

    In conformal radiation therapy, a high dose of radiation is given to a target volume to increase the probability of cure, and care is taken to minimize the dose to surrounding healthy tissue. The techniques used to achieve this are very complicated and the precise verification of the resulting three-dimensional (3D) dose distribution is required. Polyacrylamide gelatin (PAG) dosimeters with magnetic resonance imaging and optical computed tomography scanning provide the required 3D dosimetry with high spatial resolution. Many basic studies have characterized these chemical dosimeters that polymerize under irradiation. However, the investigation of the fundamental properties of the radiation-induced polymerization in PAG dosimeters is complicated by the presence of the background gelatin matrix. In this work, a gelatin-free model system for the study of the basic radiation-induced polymerization in PAG dosimeters has been developed. Experiments were performed on gelatin-free dosimeters, named aqueous polyacrylamide (APA) dosimeters, containing equal amounts of acrylamide and N,N'-methylene-bisacrylamide. The APA dosimeters were prepared with four different total monomer concentrations (2, 4, 6 and 8% by weight). Nuclear magnetic resonance (NMR) spin-spin and spin-lattice proton relaxation measurements at 20 MHz, and gravimetric analyses performed on all four dosimeters, show a continuous degree of polymerization over the dose range of 0-25 Gy. The developed NMR model explains the relationship observed between the relaxation data and the amount of crosslinked polymer formed at each dose. This model can be extended with gelatin relaxation data to provide a fundamental understanding of radiation-induced polymerization in the conventional PAG dosimeters.

  20. A 1H/19F minicoil NMR probe for solid-state NMR: application to 5-fluoroindoles.

    PubMed

    Graether, Steffen P; DeVries, Jeffrey S; McDonald, Robert; Rakovszky, Melissa L; Sykes, Brian D

    2006-01-01

    We show that it is feasible to use a minicoil for solid-state 19F 1H NMR experiments that has short pulse widths, good RF homogeneity, and excellent signal-to-noise for small samples while using low power amplifiers typical to liquid-state NMR. The closely spaced resonant frequencies of 1H and 19F and the ubiquitous use of fluorine in modern plastics and electronic components present two major challenges in the design of a high-sensitivity, high-field 1H/19F probe. Through the selection of specific components, circuit design, and pulse sequence, we were able to build a probe that has low 19F background and excellent separation of 1H and 19F signals. We determine the principle components of the chemical shift anisotropy tensor of 5-fluoroindole-3-acetic acid (5FIAA) and 5-fluorotryptophan. We also solve the crystal structure of 5FIAA, determine the orientation dependence of the chemical shift of a single crystal of 5FIAA, and predict the 19F chemical shift based on the orientation of the fluorine in the crystal. The results show that this 1H/19F probe is suitable for solid-state NMR experiments with low amounts of biological molecules that have been labeled with 19F. PMID:16198131

  1. Simultaneous (19)F-(1)H medium resolution NMR spectroscopy for online reaction monitoring.

    PubMed

    Zientek, Nicolai; Laurain, Clément; Meyer, Klas; Kraume, Matthias; Guthausen, Gisela; Maiwald, Michael

    2014-10-18

    Medium resolution nuclear magnetic resonance (MR-NMR) spectroscopy is currently a fast developing field, which has an enormous potential to become an important analytical tool for reaction monitoring, in hyphenated techniques, and for systematic investigations of complex mixtures. The recent developments of innovative MR-NMR spectrometers are therefore remarkable due to their possible applications in quality control, education, and process monitoring. MR-NMR spectroscopy can beneficially be applied for fast, non-invasive, and volume integrating analyses under rough environmental conditions. Within this study, a simple 1/16″ fluorinated ethylene propylene (FEP) tube with an ID of 0.04″ (1.02mm) was used as a flow cell in combination with a 5mm glass Dewar tube inserted into a benchtop MR-NMR spectrometer with a (1)H Larmor frequency of 43.32MHz and 40.68MHz for (19)F. For the first time, quasi-simultaneous proton and fluorine NMR spectra were recorded with a series of alternating (19)F and (1)H single scan spectra along the reaction time coordinate of a homogeneously catalysed esterification model reaction containing fluorinated compounds. The results were compared to quantitative NMR spectra from a hyphenated 500MHz online NMR instrument for validation. Automation of handling, pre-processing, and analysis of NMR data becomes increasingly important for process monitoring applications of online NMR spectroscopy and for its technical and practical acceptance. Thus, NMR spectra were automatically baseline corrected and phased using the minimum entropy method. Data analysis schemes were designed such that they are based on simple direct integration or first principle line fitting, with the aim that the analysis directly revealed molar concentrations from the spectra. Finally, the performance of 1/16″ FEP tube set-up with an ID of 1.02mm was characterised regarding the limit of detection (LOQ ((1)H)=0.335molL(-1) and LOQ ((19)F)=0.130molL(-1) for trifluoroethanol

  2. Simultaneous 19F-1H medium resolution NMR spectroscopy for online reaction monitoring

    NASA Astrophysics Data System (ADS)

    Zientek, Nicolai; Laurain, Clément; Meyer, Klas; Kraume, Matthias; Guthausen, Gisela; Maiwald, Michael

    2014-12-01

    Medium resolution nuclear magnetic resonance (MR-NMR) spectroscopy is currently a fast developing field, which has an enormous potential to become an important analytical tool for reaction monitoring, in hyphenated techniques, and for systematic investigations of complex mixtures. The recent developments of innovative MR-NMR spectrometers are therefore remarkable due to their possible applications in quality control, education, and process monitoring. MR-NMR spectroscopy can beneficially be applied for fast, non-invasive, and volume integrating analyses under rough environmental conditions. Within this study, a simple 1/16″ fluorinated ethylene propylene (FEP) tube with an ID of 0.04″ (1.02 mm) was used as a flow cell in combination with a 5 mm glass Dewar tube inserted into a benchtop MR-NMR spectrometer with a 1H Larmor frequency of 43.32 MHz and 40.68 MHz for 19F. For the first time, quasi-simultaneous proton and fluorine NMR spectra were recorded with a series of alternating 19F and 1H single scan spectra along the reaction time coordinate of a homogeneously catalysed esterification model reaction containing fluorinated compounds. The results were compared to quantitative NMR spectra from a hyphenated 500 MHz online NMR instrument for validation. Automation of handling, pre-processing, and analysis of NMR data becomes increasingly important for process monitoring applications of online NMR spectroscopy and for its technical and practical acceptance. Thus, NMR spectra were automatically baseline corrected and phased using the minimum entropy method. Data analysis schemes were designed such that they are based on simple direct integration or first principle line fitting, with the aim that the analysis directly revealed molar concentrations from the spectra. Finally, the performance of 1/16″ FEP tube set-up with an ID of 1.02 mm was characterised regarding the limit of detection (LOQ (1H) = 0.335 mol L-1 and LOQ (19F) = 0.130 mol L-1 for trifluoroethanol in

  3. Synthesis of stereospecifically deuterated desoxypodophyllotoxins and 1H-nmr assignment of desoxypodophyllotoxin

    NASA Technical Reports Server (NTRS)

    Pullockaran, A. J.; Kingston, D. G.; Lewis, N. G.

    1989-01-01

    [4 beta- 2H1]Desoxypodophyllotoxin [3], [4 alpha- 2H1]desoxypodophyllotoxin [4], and [4, 4- 2 H2]desoxypodophyllotoxin [9] were prepared from podophyllotoxin [1] via its chloride [5]. A complete assignment of the 1H-nmr spectrum of desoxypodophyllotoxin [2] was made on the basis of the spectra of the deuterated compounds [3] and [4].

  4. Scalable synthesis of quaterrylene: solution-phase 1H NMR spectroscopy of its oxidative dication.

    PubMed

    Thamatam, Rajesh; Skraba, Sarah L; Johnson, Richard P

    2013-10-14

    Quaterrylene is prepared in a single reaction and high yield by Scholl-type coupling of perylene, utilizing trifluoromethanesulfonic acid as catalyst and DDQ or molecular oxygen as oxidant. Dissolution in 1 M triflic acid/dichloroethane with sonication yields the aromatic quaterrylene oxidative dication, which is characterized by its (1)H NMR spectrum. PMID:23999880

  5. Molecular Structures from [superscript 1]H NMR Spectra: Education Aided by Internet Programs

    ERIC Educational Resources Information Center

    Debska, Barbara; Guzowska-Swider, Barbara

    2007-01-01

    The article presents the way in which freeware Internet programs can be applied to teach [superscript 1]H NMR spectroscopy. The computer programs described in this article are part of the educational curriculum that explores spectroscopy and spectra interpretation. (Contains 6 figures.)

  6. 1H NMR detection of small molecules in human urine with a deep cavitand synthetic receptor.

    PubMed

    Ryan, Daniel A; Rebek, Julius

    2013-02-21

    A water-soluble deep cavitand recognized alkylammonium salts, including the drug amantadine hydrochloride, in spiked samples of human urine. The signals of the guests are detected by (1)H NMR upfield of 0 ppm and so occur in a spectroscopic window that is outside of the normal region and distinct from the signals of the biofluid components. PMID:23304698

  7. Solid state field-cycling NMR relaxometry: instrumental improvements and new applications.

    PubMed

    Fujara, Franz; Kruk, Danuta; Privalov, Alexei F

    2014-10-01

    The paper reviews recent progress in field cycling (FC) NMR instrumentation and its application to solid state physics. Special emphasis is put on our own work during the last 15years on instrumentation, theory and applications. As far as instrumentation is concerned we report on our development of two types of electronical FC relaxometers, a mechanical FC relaxometer and a combination of FC and one-dimensional microimaging. Progress has been achieved with respect to several parameters such as the accessible field and temperature range as well as the incorporation of sample spinning. Since an appropriate analysis of FC data requires a careful consideration of relaxation theory, we include a theory section discussing the most relevant aspects of relaxation in solids which are related to residual dipolar and quadrupolar interactions. The most important limitations of relaxation theory are also discussed. With improved instrumentation and with the help of relaxation theory we get access to interesting new applications such as ionic motion in solid electrolytes, structure determination in molecular crystals, ultraslow polymer dynamics and rotational resonance phenomena. PMID:25444698

  8. Improved Carbohydrate Structure Generalization Scheme for (1)H and (13)C NMR Simulations.

    PubMed

    Kapaev, Roman R; Toukach, Philip V

    2015-07-21

    The improved Carbohydrate Structure Generalization Scheme has been developed for the simulation of (13)C and (1)H NMR spectra of oligo- and polysaccharides and their derivatives, including those containing noncarbohydrate constituents found in natural glycans. Besides adding the (1)H NMR calculations, we improved the accuracy and performance of prediction and optimized the mathematical model of the precision estimation. This new approach outperformed other methods of chemical shift simulation, including database-driven, neural net-based, and purely empirical methods and quantum-mechanical calculations at high theory levels. It can process structures with rarely occurring and noncarbohydrate constituents unsupported by the other methods. The algorithm is transparent to users and allows tracking used reference NMR data to original publications. It was implemented in the Glycan-Optimized Dual Empirical Spectrum Simulation (GODESS) web service, which is freely available at the platform of the Carbohydrate Structure Database (CSDB) project ( http://csdb.glycoscience.ru). PMID:26087011

  9. Study on 1H-NMR fingerprinting of Rhodiolae Crenulatae Radix et Rhizoma.

    PubMed

    Wen, Shi-yuan; Zhou, Jiang-tao; Chen, Yan-yan; Ding, Li-qin; Jiang, Miao-miao

    2015-07-01

    Nuclear magnetic resonance (1H-NMR) fingerprint of Rhodiola rosea medicinal materials was established, and used to distinguish the quality of raw materials from different sources. Pulse sequence for water peak inhibition was employed to acquire 1H-NMR spectra with the temperature at 298 K and spectrometer frequency of 400.13 MHz. Through subsection integral method, the obtained NMR data was subjected to similarity analysis and principal component analysis (PCA). 10 batches raw materials of Rhodiola rosea from different origins were successfully distinguished by PCA. The statistical results indicated that rhodiola glucoside, butyl alcohol, maleic acid and alanine were the main differential ingredients. This method provides an auxiliary method of Chinese quality approach to evaluate the quality of Rhodiola crenulata without using natural reference substances. PMID:26697690

  10. (1) H and (13) C NMR data on natural and synthetic capsaicinoids.

    PubMed

    Gómez-Calvario, Víctor; Garduño-Ramírez, María Luisa; León-Rivera, Ismael; Rios, María Yolanda

    2016-04-01

    Capsaicinoids are the compounds responsible for the pungency of chili peppers. These substances have attracted the attention of many research groups in recent decades because of their antinociceptive, analgesic, anti-inflammatory, and anti-obesity properties, among others. There are nearly 160 capsaicinoids reported in the literature. Approximately 25 of them are natural products, while the rest are synthetic or semi-synthetic products. A large amount of NMR data for the capsaicinoids is dispersed throughout literature. Therefore, there is a need to organize all this NMR data in a systematic and orderly way. This review summarizes the (1) H and (13) C NMR data on 159 natural and synthetic capsaicinoids, with a brief discussion of some typical and relevant aspects of these NMR data. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26626418

  11. An efficient spectra processing method for metabolite identification from 1H-NMR metabolomics data.

    PubMed

    Jacob, Daniel; Deborde, Catherine; Moing, Annick

    2013-06-01

    The spectra processing step is crucial in metabolomics approaches, especially for proton NMR metabolomics profiling. During this step, noise reduction, baseline correction, peak alignment and reduction of the 1D (1)H-NMR spectral data are required in order to allow biological information to be highlighted through further statistical analyses. Above all, data reduction (binning or bucketing) strongly impacts subsequent statistical data analysis and potential biomarker discovery. Here, we propose an efficient spectra processing method which also provides helpful support for compound identification using a new data reduction algorithm that produces relevant variables, called buckets. These buckets are the result of the extraction of all relevant peaks contained in the complex mixture spectra, rid of any non-significant signal. Taking advantage of the concentration variability of each compound in a series of samples and based on significant correlations that link these buckets together into clusters, the method further proposes automatic assignment of metabolites by matching these clusters with the spectra of reference compounds from the Human Metabolome Database or a home-made database. This new method is applied to a set of simulated (1)H-NMR spectra to determine the effect of some processing parameters and, as a proof of concept, to a tomato (1)H-NMR dataset to test its ability to recover the fruit extract compositions. The implementation code for both clustering and matching steps is available upon request to the corresponding author. PMID:23525538

  12. {sup 1}H NMR spectroscopic studies establish that heparanase is a retaining glycosidase

    SciTech Connect

    Wilson, Jennifer C.; Laloo, Andrew Elohim; Singh, Sanjesh; Ferro, Vito

    2014-01-03

    Highlights: •{sup 1}H and {sup 13}C NMR chemical shifts of fondaparinux were fully assigned by 1D and 2D NMR techniques. •Hydrolysis of fondaparinux by heparanase was monitored by {sup 1}H NMR spectroscopy. •Heparanase is established to be a retaining glycosidase. -- Abstract: Heparanase is an endo-β-glucuronidase that cleaves heparan sulfate side chains of proteoglycans in basement membranes and the extracellular matrix (ECM). Heparanase is implicated in several diverse pathological processes associated with ECM degradation such as metastasis, inflammation and angiogenesis and is thus an important target for anti-cancer and anti-inflammatory drug discovery. Heparanase has been classed as belonging to the clan A glycoside hydrolase family 79 based on sequence analysis, secondary structure predictions and mutagenic analysis, and thus it has been inferred that it is a retaining glycosidase. However, there has been no direct experimental evidence to support this conclusion. Herein we describe {sup 1}H NMR spectroscopic studies of the hydrolysis of the pentasaccharide substrate fondaparinux by heparanase, and provide conclusive evidence that heparanase hydrolyses its substrate with retention of configuration and is thus established as a retaining glycosidase. Knowledge of the mechanism of hydrolysis may have implications for future design of inhibitors for this important drug target.

  13. NMR resonance splitting of urea in stretched hydrogels: proton exchange and (1)H/(2)H isotopologues.

    PubMed

    Kuchel, Philip W; Naumann, Christoph; Chapman, Bogdan E; Shishmarev, Dmitry; Håkansson, Pär; Bacskay, George; Hush, Noel S

    2014-10-01

    Urea at ∼12 M in concentrated gelatin gel, that was stretched, gave (1)H and (2)H NMR spectral splitting patterns that varied in a predictable way with changes in the relative proportions of (1)H2O and (2)H2O in the medium. This required consideration of the combinatorics of the two amide groups in urea that have a total of four protonation/deuteration sites giving rise to 16 different isotopologues, if all the atoms were separately identifiable. The rate constant that characterized the exchange of the protons with water was estimated by back-transformation analysis of 2D-EXSY spectra. There was no (1)H NMR spectral evidence that the chiral gelatin medium had caused in-equivalence in the protons bonded to each amide nitrogen atom. The spectral splitting patterns in (1)H and (2)H NMR spectra were accounted for by intra-molecular scalar and dipolar interactions, and quadrupolar interactions with the electric field gradients of the gelatin matrix, respectively. PMID:25241007

  14. Identifying metabolites related to nitrogen mineralisation using 1H NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    . T McDonald, Noeleen; Graham, Stewart; Watson, Catherine; Gordon, Alan; Lalor, Stan; Laughlin, Ronnie; Elliott, Chris; . P Wall, David

    2015-04-01

    Exploring new analysis techniques to enhance our knowledge of the various metabolites within our soil systems is imperative. Principally, this knowledge would allow us to link key metabolites with functional influences on critical nutrient processes, such as the nitrogen (N) mineralisation in soils. Currently there are few studies that utilize proton nuclear magnetic resonance spectroscopy (1H NMR) to characterize multiple metabolites within a soil sample. The aim of this research study was to examine the effectiveness of 1H NMR for isolating multiple metabolites that are related to the mineralizable N (MN) capacity across a range of 35 Irish grassland soils. Soils were measured for MN using the standard seven day anaerobic incubation (AI-7). Additionally, soils were also analysed for a range of physio-chemical properties [e.g. total N, total C, mineral N, texture and soil organic matter (SOM)]. Proton NMR analysis was carried on these soils by extracting with 40% methanol:water, lyophilizing and reconstituting in deuterium oxide and recording the NMR spectra on a 400MHz Bruker AVANCE III spectrometer. Once the NMR data were spectrally processed and analysed using multivariate statistical analysis, seven metabolites were identified as having significant relationships with MN (glucose, trimethylamine, glutamic acid, serine, aspartic acid, 4-aminohippuirc acid and citric acid). Following quantification, glucose was shown to explain the largest percentage variability in MN (72%). These outcomes suggest that sources of labile carbon are essential in regulating N mineralisation and the capacity of plant available N derived from SOM-N pools in these soils. Although, smaller in concentration, the amino acids; 4-aminohippuirc acid, glutamic acid and serine also significantly (P<0.05) explained 43%, 27% and 19% of the variability in MN, respectively. This novel study highlights the effectiveness of using 1H NMR as a practical approach to profile multiple metabolites in

  15. The (1) H NMR spectrum of pyrazole in a nematic phase.

    PubMed

    Provasi, Patricio; Jimeno, María Luisa; Alkorta, Ibon; Reviriego, Felipe; Elguero, José; Jokisaari, Jukka

    2016-08-01

    The experimental (1) H nuclear magnetic resonance (NMR) spectrum of 1H-pyrazole was recorded in thermotropic nematic liquid crystal N-(p-ethoxybenzylidene)-p-butylaniline (EBBA) within the temperature range of 299-308 K. Two of three observable dipolar DHH -couplings appeared to be equal at each temperature because of fast prototropic tautomerism. Analysis of the Saupe orientational order parameters using fixed geometry determined by computations and experimental dipolar couplings results in a situation in which the molecular orientation relative to the magnetic field (and the liquid crystal director) can be described exceptionally by a single parameter. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26947581

  16. (1)H-NMR-based discrimination of thermal and vinegar treated ginseng roots.

    PubMed

    Kim, So-Hyun; Hyun, Sun-Hee; Yang, Seung-Ok; Choi, Hyung-Kyoon; Lee, Boo-Yong

    2010-08-01

    To investigate the changes in nonvolatile metabolites of thermal and/or vinegar treated ginseng (TVG), samples prepared using various treatment conditions were analyzed using an (1)H-NMR-based metabolomics technique. The processing conditions of the ginseng in this study were 100, 140, and 180 degrees C with and without vinegar and the duration of exposure to each temperature was 10, 30, and 50 min, respectively. There was a clear separation in the score plots among various treatment conditions. Major compounds contributing to the separation of 50% methanol extracts of TVG with various process conditions were valine, lactate, alanine, arginine, glucose, fructose, and sucrose. As temperature increased, valine, arginine, glucose, fructose, and sucrose concentrations decreased, whereas lactate, glucose, and fructose increased in the vinegar-treated samples compared to non-vinegar-treated samples. The present study suggests the usefulness of an (1)H-NMR-based metabolomics approach to discriminate TVG samples, subjected to different processing conditions. PMID:20722913

  17. Evaluation of saffron (Crocus sativus L.) adulteration with plant adulterants by (1)H NMR metabolite fingerprinting.

    PubMed

    Petrakis, Eleftherios A; Cagliani, Laura R; Polissiou, Moschos G; Consonni, Roberto

    2015-04-15

    In the present work, a preliminary study for the detection of adulterated saffron and the identification of the adulterant used by means of (1)H NMR and chemometrics is reported. Authentic Greek saffron and four typical plant-derived materials utilised as bulking agents in saffron, i.e., Crocus sativus stamens, safflower, turmeric, and gardenia were investigated. A two-step approach, relied on the application of both OPLS-DA and O2PLS-DA models to the (1)H NMR data, was adopted to perform authentication and prediction of authentic and adulterated saffron. Taking into account the deficiency of established methodologies to detect saffron adulteration with plant adulterants, the method developed resulted reliable in assessing the type of adulteration and could be viable for dealing with extensive saffron frauds at a minimum level of 20% (w/w). PMID:25466103

  18. Total (1)H NMR assignment of 3β-acetoxypregna-5,16-dien-20-one.

    PubMed

    Becerra-Martinez, Elvia; Ramírez-Gualito, Karla E; Pérez-Hernández, Nury; Joseph-Nathan, Pedro

    2015-12-01

    This work describes the total and unambiguous assignment of the 750 MHz (1)H NMR spectrum of 3β-acetoxypregna-5,16-dien-20-one or 16-DPA (1), the well-known intermediate utilized in the synthesis of biological important commercial steroids. The task was accomplished by extracting the coupling constant values in the overlapped spectrum region by HSQC, and using these values in the (1)H iterative full spin analysis integrated in the PERCH NMR software. Comparison of the experimental vicinal coupling constants of 1 with the values calculated using Altona provides an excellent correlation. The same procedure, when applied to the published data of progesterone (2) and testosterone (3), afforded an acceptable correlation for 2 and a poor correlation for 3. In the last case, this suggested the reassignment of all four vicinal coupling constants for the methylene signals at the C-15 and C-16 positions, demonstrating the utility of this methodology. PMID:26476187

  19. 1H NMR profiling as an approach to differentiate conventionally and organically grown tomatoes.

    PubMed

    Hohmann, Monika; Christoph, Norbert; Wachter, Helmut; Holzgrabe, Ulrike

    2014-08-20

    This study describes the approach of (1)H NMR profiling for the authentication of organically produced tomatoes (Solanum lycopersicum). Overall, 361 tomato samples of two different cultivars and four different producers were regularly analyzed during a 7 month period. The results of principal component analysis showed a significant trend for the separation between organically and conventionally produced tomatoes (p < 0.001 using the t test). Linear discriminant analysis demonstrated good discrimination between the growing regimens, and external validation showed 100% correctly classified tomato samples. Further validation studies, however, also disclosed unexpected differences between individual producers, which interfere with the aim of predicting the cultivation method, yet the results indicate significant differences between (1)H NMR spectra of organically and conventionally grown tomatoes. PMID:25066078

  20. 1H-NMR METABONOMICS ANALYSIS OF SERA DIFFERENTIATES BETWEEN MAMMARY TUMOR-BEARING MICE AND HEALTHY CONTROLS

    EPA Science Inventory

    Global analysis of 1H-NMR spectra of serum is an appealing approach for the rapid detection of cancer. To evaluate the usefulness of this method in distinguishing between mammary tumor-bearing mice and healthy controls, we conducted 1H-NMR metabonomic analyses on serum samples ob...

  1. Application of 1H-NMR metabolomic profiling for reef-building corals.

    PubMed

    Sogin, Emilia M; Anderson, Paul; Williams, Philip; Chen, Chii-Shiarng; Gates, Ruth D

    2014-01-01

    In light of global reef decline new methods to accurately, cheaply, and quickly evaluate coral metabolic states are needed to assess reef health. Metabolomic profiling can describe the response of individuals to disturbance (i.e., shifts in environmental conditions) across biological models and is a powerful approach for characterizing and comparing coral metabolism. For the first time, we assess the utility of a proton-nuclear magnetic resonance spectroscopy (1H-NMR)-based metabolomics approach in characterizing coral metabolite profiles by 1) investigating technical, intra-, and inter-sample variation, 2) evaluating the ability to recover targeted metabolite spikes, and 3) assessing the potential for this method to differentiate among coral species. Our results indicate 1H-NMR profiling of Porites compressa corals is highly reproducible and exhibits low levels of variability within and among colonies. The spiking experiments validate the sensitivity of our methods and showcase the capacity of orthogonal partial least squares discriminate analysis (OPLS-DA) to distinguish between profiles spiked with varying metabolite concentrations (0 mM, 0.1 mM, and 10 mM). Finally, 1H-NMR metabolomics coupled with OPLS-DA, revealed species-specific patterns in metabolite profiles among four reef-building corals (Pocillopora damicornis, Porites lobata, Montipora aequituberculata, and Seriatopora hystrix). Collectively, these data indicate that 1H-NMR metabolomic techniques can profile reef-building coral metabolomes and have the potential to provide an integrated picture of the coral phenotype in response to environmental change. PMID:25354140

  2. Application of 1H-NMR Metabolomic Profiling for Reef-Building Corals

    PubMed Central

    Sogin, Emilia M.; Anderson, Paul; Williams, Philip; Chen, Chii-Shiarng; Gates, Ruth D.

    2014-01-01

    In light of global reef decline new methods to accurately, cheaply, and quickly evaluate coral metabolic states are needed to assess reef health. Metabolomic profiling can describe the response of individuals to disturbance (i.e., shifts in environmental conditions) across biological models and is a powerful approach for characterizing and comparing coral metabolism. For the first time, we assess the utility of a proton-nuclear magnetic resonance spectroscopy (1H-NMR)-based metabolomics approach in characterizing coral metabolite profiles by 1) investigating technical, intra-, and inter-sample variation, 2) evaluating the ability to recover targeted metabolite spikes, and 3) assessing the potential for this method to differentiate among coral species. Our results indicate 1H-NMR profiling of Porites compressa corals is highly reproducible and exhibits low levels of variability within and among colonies. The spiking experiments validate the sensitivity of our methods and showcase the capacity of orthogonal partial least squares discriminate analysis (OPLS-DA) to distinguish between profiles spiked with varying metabolite concentrations (0 mM, 0.1 mM, and 10 mM). Finally, 1H-NMR metabolomics coupled with OPLS-DA, revealed species-specific patterns in metabolite profiles among four reef-building corals (Pocillopora damicornis, Porites lobata, Montipora aequituberculata, and Seriatopora hystrix). Collectively, these data indicate that 1H-NMR metabolomic techniques can profile reef-building coral metabolomes and have the potential to provide an integrated picture of the coral phenotype in response to environmental change. PMID:25354140

  3. A 1H NMR assay for measuring the photostationary States of photoswitchable ligands.

    PubMed

    Banghart, Matthew R; Trauner, Dirk

    2013-01-01

    Incorporation of photoisomerizable chromophores into small molecule ligands represents a general approach for reversibly controlling protein function with light. Illumination at different wavelengths produces photostationary states (PSSs) consisting of different ratios of photoisomers. Thus optimal implementation of photoswitchable ligands requires knowledge of their wavelength sensitivity. Using an azobenzene-based ion channel blocker as an example, this protocol describes a (1)H NMR assay that can be used to precisely determine the isomeric content of photostationary states (PSSs) as a function of illumination wavelength. Samples of the photoswitchable ligand are dissolved in deuterated water and analyzed by UV/VIS spectroscopy to identify the range of illumination wavelengths that produce PSSs. The PSSs produced by these wavelengths are quantified using (1)H NMR spectroscopy under continuous irradiation through a monochromator-coupled fiber-optic cable. Because aromatic protons of azobenzene trans and cis isomers exhibit sufficiently different chemical shifts, their relative abundances at each PSS can be readily determined by peak integration. Constant illumination during spectrum acquisition is essential to accurately determine PSSs from molecules that thermally relax on the timescale of minutes or faster. This general protocol can be readily applied to any photoswitch that exhibits distinct (1)H NMR signals in each photoisomeric state. PMID:23494375

  4. Complete 1H NMR assignments of pyrrolizidine alkaloids and a new eudesmanoid from Senecio polypodioides.

    PubMed

    Villanueva-Cañongo, Claudia; Pérez-Hernández, Nury; Hernández-Carlos, Beatriz; Cedillo-Portugal, Ernestina; Joseph-Nathan, Pedro; Burgueño-Tapia, Eleuterio

    2014-05-01

    Chemical investigation of the aerial parts of Senecio polypodioides lead to the isolation of the new eudesmanoid 1β-angeloyloxyeudesm-7-ene-4β,9α-diol (1) and the known dirhamnosyl flavonoid lespidin (3), while from roots, the known 7β-angeloyloxy-1-methylene-8α-pyrrolizidine (5) and sarracine N-oxide (6), as well as the new neosarracine N-oxide (8), were obtained. The structure of 1 and 8 was elucidated by spectral means. Complete assignments of the (1)H NMR data for 5, 6, sarracine (7), and 8 were made using one-dimensional and two-dimensional NMR experiments and by application of the iterative full spin analysis of the PERCH NMR software. PMID:24574143

  5. Investigating brain metabolism at high fields using localized 13C NMR spectroscopy without 1H decoupling.

    PubMed

    Deelchand, Dinesh Kumar; Uğurbil, Kâmil; Henry, Pierre-Gilles

    2006-02-01

    Most in vivo 13C NMR spectroscopy studies in the brain have been performed using 1H decoupling during acquisition. Decoupling imposes significant constraints on the experimental setup (particularly for human studies at high magnetic field) in order to stay within safety limits for power deposition. We show here that incorporation of the 13C label from 13C-labeled glucose into brain amino acids can be monitored accurately using localized 13C NMR spectroscopy without the application of 1H decoupling. Using LCModel quantification with prior knowledge of one-bond and multiple-bond J(CH) coupling constants, the uncertainty on metabolites concentrations was only 35% to 91% higher (depending on the carbon resonance of interest) in undecoupled spectra compared to decoupled spectra in the rat brain at 9.4 Tesla. Although less sensitive, 13C NMR without decoupling dramatically reduces experimental constraints on coil setup and pulse sequence design required to keep power deposition within safety guidelines. This opens the prospect of safely measuring 13C NMR spectra in humans at varied brain locations (not only the occipital lobe) and at very high magnetic fields above 4 Tesla. PMID:16345037

  6. Wastewater Colloidal Organic Carbon: Characterization of Filtration Fractions Using 1H NMR.

    PubMed

    McPhedran, Kerry N; Seth, Rajesh

    2016-04-01

    The current study separates colloidal organic carbon (COC) of municipal wastewater using membrane and ultrafiltration filters followed by characterization using 1H nuclear magnetic resonance (NMR) and UV absorbance with the goal of determination of size-specific characteristics, which may be used to correlate contaminant partitioning to natural COC. Passing fractions included 49.7, 44.8, 39.3, and 33.1 mg/L COC for filter sizes 1.5 μm, 0.45 μm, 100 kDa, and 1 kDa, respectively. The methodology used for processing COC prior to 1H NMR characterization was novel and successful in concentrating COC without modification of structures, which is the general drawback of other separation techniques such as resin extractions. This concentration technique is quite simple (i.e., not dependent on specialized instrumentation) and allows much shorter NMR experimental durations saving time and cost of analysis. Further work using NMR techniques will allow for greater understanding of COC molecular characteristics and be valuable for use in predictive modeling improvements. PMID:27131054

  7. Automated structure verification based on a combination of 1D (1)H NMR and 2D (1)H - (13)C HSQC spectra.

    PubMed

    Golotvin, Sergey S; Vodopianov, Eugene; Pol, Rostislav; Lefebvre, Brent A; Williams, Antony J; Rutkowske, Randy D; Spitzer, Timothy D

    2007-10-01

    A method for structure validation based on the simultaneous analysis of a 1D (1)H NMR and 2D (1)H - (13)C single-bond correlation spectrum such as HSQC or HMQC is presented here. When compared with the validation of a structure by a 1D (1)H NMR spectrum alone, the advantage of including a 2D HSQC spectrum in structure validation is that it adds not only the information of (13)C shifts, but also which proton shifts they are directly coupled to, and an indication of which methylene protons are diastereotopic. The lack of corresponding peaks in the 2D spectrum that appear in the 1D (1)H spectrum, also gives a clear picture of which protons are attached to heteroatoms. For all these benefits, combined NMR verification was expected and found by all metrics to be superior to validation by 1D (1)H NMR alone. Using multiple real-life data sets of chemical structures and the corresponding 1D and 2D data, it was possible to unambiguously identify at least 90% of the correct structures. As part of this test, challenging incorrect structures, mostly regioisomers, were also matched with each spectrum set. For these incorrect structures, the false positive rate was observed as low as 6%. PMID:17694570

  8. Preparation of the UNDERC 200 MHz /sup 1/H NMR spectral catalog, Volume II

    SciTech Connect

    Gaides, G.E.; Farnum, S.A.; Wolfson, A.C.; Farnum, B.W.

    1984-01-01

    High resolution 200 MHz /sup 1/H NMR is used extensively to identify the components of complex low-rank coal-derived materials. We have compiled a catalog of 302 spectra of standards: (1) and are compiling a second, similar volume of 125 additional spectra. Many of these new compounds have only recently become available from commercial suppliers, or by synthesis. Like the previous catalog, Volume II is divided into two sections: a tabular section of all the compounds with their correct names, structure, and a line list of the chemical shifts, and a section which contains the actual spectra. Each section is arranged by functional group, for example, alkanes, phenols, etc. in order of their chromatographic elution. There is also an appendix which lists the suppliers of all the compounds in the catalog. Volume II contains several features not incorporated in the original catalog. We have added an alphabetical listing of all the compounds in both NMR catalogs, as well as formula and molecular weight indices. An added feature of this volume is the expanded coverage of nitrogen-containing compounds. Though there are many /sup 1/H NMR spectral catalogs in print, there are none that contain spectra run on 200 MHz spectrometers. Many spectra that appear complex at 60 MHz become first order at 200 MHz, facilitating their interpretation. At the UNDERC the majority of our samples are extremely complex mixtures. The simplification of the spectra of the individual components is necessary to characterize these coal-derived liquids. Another advantage of /sup 1/H NMR spectra run at 200 MHz is the greater than eleven-fold increase in sensitivity over those run at 60 MHz (2). Smaller, or more dilute samples may therefore be utilized. 2 references, 1 figure.

  9. Identification of fucans from four species of sea cucumber by high temperature 1H NMR

    NASA Astrophysics Data System (ADS)

    Wu, Nian; Chen, Shiguo; Ye, Xingqian; Li, Guoyun; Yin, Li'ang; Xue, Changhu

    2014-10-01

    Acidic polysaccharide, which has various biological activities, is one of the most important components of sea cucumber. In the present study, crude polysaccharide was extracted from four species of sea cucumber from three different geographical zones, Pearsonothuria graeffei ( Pg) from Indo-Pacific, Holothuria vagabunda ( Hv) from Norwegian Coast, Stichopus tremulu ( St) from Western Indian Ocean, and Isostichopus badionotu ( Ib) from Western Atlantic. The polysaccharide extract was separated and purified with a cellulose DEAE anion-exchange column to obtain corresponding sea cucumber fucans (SC-Fucs). The chemical property of these SC-Fucs, including molecular weight, monosaccharide composition and sulfate content, was determined. Their structure was compared simply with fourier infrared spectrum analyzer and identified with high temperature 1H nuclear magnetic resonance spectrum analyzer (NMR) and room temperature 13C NMR. The results indicated that Fuc- Pg obtained from the torrid zone mainly contained 2,4-O-disulfated and non-sulfated fucose residue, whereas Fuc- Ib from the temperate zone contained non-, 2-O- and 2,4-O-disulfated fucose residue; Fuc- St from the frigid zone and Fuc- Hv from the torrid zone contained mainly non-sulfated fucose residue. The proton of SC-Fucs was better resolved via high temperature 1H NMR than via room temperature 1H NMR. The fingerprint of sea cucumber in different sea regions was established based on the index of anomer hydrogen signal in SC-Fucs. Further work will help to understand whether there exists a close relationship between the geographical area of sea cucumber and the sulfation pattern of SC-Fucs.

  10. 1H NMR structure of the heme pocket of HNO-myoglobin.

    PubMed

    Sulc, Filip; Fleischer, Everly; Farmer, Patrick J; Ma, Dejian; La Mar, Gerd N

    2003-02-01

    The unique (1)H NMR signal of nitrosyl hydride at 14.8 ppm is used to obtain a solution structure of the distal pocket of Mb-HNO, a rare nitroxyl adduct with a half-life of several months at room temperature. (1)H NMR, NOESY and TOCSY data were obtained under identical experimental conditions on solutions of the diamagnetic HNO and CO complexes of equine Mb, allowing direct comparison of NMR data to a crystallographically characterized structure. Twenty NOEs between the nitrosyl hydride and protein and heme-based signals were observed. The HNO orientation obtained by modeling the experimental (1)H NMR NOESY data yielded an orientation of ca. -104 degrees referenced to the N-Fe-N vector between alpha and beta mesoprotons. An essentially identical orientation was obtained by simple energy minimization of the HNO adduct using ESFF potentials, suggesting steric control of the orientation. Differences in chemical shifts are seen for protons on residues Phe43(CD1) and Val68(E11), but both exhibit virtually identical NOESY contacts to other residues, and thus are attributed to small movements of ca. 0.1 A within the strong ring current. The most significant differences are seen in the NOESY peak intensities and chemical shifts for the ring non-labile protons of the distal His64(E7). The orientation of the His64(E7) in Mb-HNO was analyzed on the basis of the NOESY cross-peak changes and chemical shift changes, predicting a ca. 20 degrees rotation about the beta-gamma bond. The deduced HNO and His64(E7) orientations result in geometry where the His64(E7) ring can serve as the donor for a significant H-bond to the oxygen atom of the bound HNO. PMID:12589571

  11. Probing structure and dynamics of bulk and confined crude oils by multiscale NMR spectroscopy, diffusometry, and relaxometry.

    PubMed

    Korb, Jean-Pierre; Louis-Joseph, Alain; Benamsili, Lyès

    2013-06-13

    We propose using a set of noninvasive multiscale NMR techniques for probing the structure and dynamics of bulk and confined crude oils with and without asphaltene. High-field 1D (1)H and (13)C NMR spectroscopies evidence the proton species and the amount of asphaltene and give an average chain length for the hydrocarbon aliphatic chains. Two-dimensional (1)H diffusion-ordered NMR spectroscopy (DOSY) spectra allow us to identify two populations of hydrocarbons characterized by two distributions of translational diffusion coefficients in the presence of asphaltene and a single one without asphaltene. A detailed analysis of the distributions of longitudinal, T1, relaxation times measured at different magnetic fields is proposed in terms of highly skewed bimodal (or monomodal) log-normal distributions, confirming the two environments in the presence of asphaltene and a single one without asphaltene. We show that these distributions are similar to the gas and gel permeation chromatography distributions, thus showing a connection of the hydrocarbon dynamics with their chain lengths. The remarkable observed features of the nuclear magnetic relaxation dispersion (NMRD) profiles of <1/T1> for bulk and confined crude oils with and without asphaltene are interpreted with an original relaxation model of intermittent surface dynamics of proton species at the proximity of asphaltene nanoaggregates and bulk dynamics in between clusters of these nanoaggregates. This allows us to probe the 2D translational diffusion correlation time and the time of residence of hydrocarbons in the proximity of the asphaltene nanoaggregates. Provided that the diffusion of the hydrocarbons close to the asphaltene nanoaggregates is three times smaller than the bulk diffusion, as the DOSY experiments show, this time of residence gives an average radius of exploration for the 2D hydrocarbon diffusion, r2D ≈ 3.9 nm, of the same order of magnitude as the aggregate sizes found by J. Eyssautier with SAXS

  12. Hyphenated low-field NMR techniques: combining NMR with NIR, GPC/SEC and rheometry.

    PubMed

    Räntzsch, Volker; Wilhelm, Manfred; Guthausen, Gisela

    2016-06-01

    Hyphenated low-field NMR techniques are promising characterization methods for online process analytics and comprehensive offline studies of soft materials. By combining different analytical methods with low-field NMR, information on chemical and physical properties can be correlated with molecular dynamics and complementary chemical information. In this review, we present three hyphenated low-field NMR techniques: a combination of near-infrared spectroscopy and time-domain NMR (TD-NMR) relaxometry, online (1) H-NMR spectroscopy measured directly after size exclusion chromatographic (SEC, also known as GPC) separation and a combination of rheometry and TD-NMR relaxometry for highly viscous materials. Case studies are reviewed that underline the possibilities and challenges of the different hyphenated low-field NMR methods. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25854997

  13. 2D 1H and 3D 1H-15N NMR of zinc-rubredoxins: contributions of the beta-sheet to thermostability.

    PubMed Central

    Richie, K. A.; Teng, Q.; Elkin, C. J.; Kurtz, D. M.

    1996-01-01

    Based on 2D 1H-1H and 2D and 3D 1H-15N NMR spectroscopies, complete 1H NMR assignments are reported for zinc-containing Clostridium pasteurianum rubredoxin (Cp ZnRd). Complete 1H NMR assignments are also reported for a mutated Cp ZnRd, in which residues near the N-terminus, namely, Met 1, Lys 2, and Pro 15, have been changed to their counterparts, (-), Ala and Glu, respectively, in rubredoxin from the hyperthermophilic archaeon, Pyrococcus furiosus (Pf Rd). The secondary structure of both wild-type and mutated Cp ZnRds, as determined by NMR methods, is essentially the same. However, the NMR data indicate an extension of the three-stranded beta-sheet in the mutated Cp ZnRd to include the N-terminal Ala residue and Glu 15, as occurs in Pf Rd. The mutated Cp Rd also shows more intense NOE cross peaks, indicating stronger interactions between the strands of the beta-sheet and, in fact, throughout the mutated Rd. However, these stronger interactions do not lead to any significant increase in thermostability, and both the mutated and wild-type Cp Rds are much less thermostable than Pf Rd. These correlations strongly suggest that, contrary to a previous proposal [Blake PR et al., 1992, Protein Sci 1:1508-1521], the thermostabilization mechanism of Pf Rd is not dominated by a unique set of hydrogen bonds or electrostatic interactions involving the N-terminal strand of the beta-sheet. The NMR results also suggest that an overall tighter protein structure does not necessarily lead to increased thermostability. PMID:8732760

  14. Methodology of 1H NMR Spectroscopy of the Human Brain at Very High Magnetic Fields

    PubMed Central

    Tkáč, I.; Gruetter, R.

    2009-01-01

    An ultrashort-echo-time stimulated echo-acquisition mode (STEAM) pulse sequence with interleaved outer volume suppression and VAPOR (variable power and optimized relaxation delays) water suppression was redesigned and optimized for human applications at 4 and 7 T, taking into account the specific requirements for spectroscopy at high magnetic fields and limitations of currently available hardware. In combination with automatic shimming, automated parameter adjustments and data processing, this method provided a user-friendly tool for routine 1H nuclear magnetic resonance (NMR) spectroscopy of the human brain at very high magnetic fields. Effects of first- and second-order shimming, single-scan averaging, frequency and phase corrections, and eddy currents were described. LCModel analysis of an in vivo 1H NMR spectrum measured from the human brain at 7 T allowed reliable quantification of more than fifteen metabolites noninvasively, illustrating the potential of high-field NMR spectroscopy. Examples of spectroscopic studies performed at 4 and 7 T demonstrated the high reproducibility of acquired spectra quality. PMID:20179773

  15. Chemical Origins of Permanent Set in a Peroxide Cured Filled Silicone Elastomer - Tensile and 1H NMR Analysis

    SciTech Connect

    Chinn, S; Deteresa, S; Shields, A; Sawvel, A; Balazs, B; Maxwell, R S

    2004-10-29

    The aging of a commercial filled siloxane polymeric composite in states of high stress and Co-60 {gamma}-radiation exposure has been studied. DC-745 is a commercially available silicone elastomer consisting of dimethyl, methyl-phenyl, and vinyl-methyl siloxane monomers crosslinked with a peroxide vinyl specific curing agent. It is filled with {approx}30 wt.% mixture of high and low surface area silicas. This filled material is shown to be subject to permanent set if exposed to radiation while under tensile stress. Tensile modulus measurements show that the material gets marginally softer with combined radiation exposure and tensile strain as compared to material exposed to radiation without tensile strain. In addition, the segmental dynamics as measured by both uniaxial NMR relaxometry and Multiple Quantum NMR methods indicate that the material is undergoes radiatively-induced crosslinking in the absence of tensile strain and a combination of crosslinking and strain dependent increase in dynamic order parameter for the network chains. The MQ-NMR also suggests a small change in the number of polymer chains associated with the silica filler surface. Comparison of the prediction of the relative change in crosslink density from the NMR data as well as solvent swelling data and from that predicted from the Tobolsky model suggest that degradation leads to a deviation from Gaussian chain statistics and the formation of increased numbers of elastically ineffective network chains.

  16. 1H to 13C Energy Transfer in Solid State NMR Spectroscopy of Natural Organic Systems

    NASA Astrophysics Data System (ADS)

    Berns, Anne E.; Conte, Pellegrino

    2010-05-01

    Cross polarization (CP) magic angle spinning (MAS) 13C-NMR spectroscopy is a solid state NMR technique widely used to study chemical composition of organic materials with low or no solubility in the common deuterated solvents used to run liquid state NMR experiments. Based on the magnetization transfer from abundant nuclei (with spin of 1 -2) having a high gyromagnetic ratio (γ), such as protons, to the less abundant 13C nuclei with low γ values, 13C-CPMAS NMR spectroscopy is often applied in environmental chemistry to obtain quantitative information on the chemical composition of natural organic matter (NOM) (Conte et al., 2004), although its quantitative assessment is still matter of heavy debates. Many authors (Baldock et al., 1997; Conte et al., 1997, 2002; Dria et al., 2002; Kiem et al., 2000; Kögel-Knabner, 2000; Preston, 2001), reported that the application of appropriate instrument setup as well as the use of special pulse sequences and correct spectra elaboration may provide signal intensities that are directly proportional to the amount of nuclei creating a NMR signal. However, many other papers dealt with the quantitative unsuitability of 13C-CPMAS NMR spectroscopy. Among those, Mao et al. (2000), Smernik and Oades (2000 a,b), and Preston (2001) reported that cross-polarized NMR techniques may fail in a complete excitation of the 13C nuclei. In fact, the amount of observable carbons via 13C-CPMAS NMR spectroscopy appeared, in many cases, lower than that measured by a direct observation of the 13C nuclei. As a consequence, cross-polarized NMR techniques may provide spectra where signal distribution may not be representative of the quantitative distribution of the different natural organic matter components. Cross-polarization is obtained after application of an initial 90° x pulse on protons and a further spin lock pulse (along the y axis) having a fixed length (contact time) for both nuclei (1H and 13C) once the Hartmann-Hahn condition is matched

  17. Automatic 1H-NMR Screening of Fatty Acid Composition in Edible Oils

    PubMed Central

    Castejón, David; Fricke, Pascal; Cambero, María Isabel; Herrera, Antonio

    2016-01-01

    In this work, we introduce an NMR-based screening method for the fatty acid composition analysis of edible oils. We describe the evaluation and optimization needed for the automated analysis of vegetable oils by low-field NMR to obtain the fatty acid composition (FAC). To achieve this, two scripts, which automatically analyze and interpret the spectral data, were developed. The objective of this work was to drive forward the automated analysis of the FAC by NMR. Due to the fact that this protocol can be carried out at low field and that the complete process from sample preparation to printing the report only takes about 3 min, this approach is promising to become a fundamental technique for high-throughput screening. To demonstrate the applicability of this method, the fatty acid composition of extra virgin olive oils from various Spanish olive varieties (arbequina, cornicabra, hojiblanca, manzanilla, and picual) was determined by 1H-NMR spectroscopy according to this protocol. PMID:26891323

  18. Pore size distribution calculation from 1H NMR signal and N2 adsorption-desorption techniques

    NASA Astrophysics Data System (ADS)

    Hassan, Jamal

    2012-09-01

    The pore size distribution (PSD) of nano-material MCM-41 is determined using two different approaches: N2 adsorption-desorption and 1H NMR signal of water confined in silica nano-pores of MCM-41. The first approach is based on the recently modified Kelvin equation [J.V. Rocha, D. Barrera, K. Sapag, Top. Catal. 54(2011) 121-134] which deals with the known underestimation in pore size distribution for the mesoporous materials such as MCM-41 by introducing a correction factor to the classical Kelvin equation. The second method employs the Gibbs-Thompson equation, using NMR, for melting point depression of liquid in confined geometries. The result shows that both approaches give similar pore size distribution to some extent, and also the NMR technique can be considered as an alternative direct method to obtain quantitative results especially for mesoporous materials. The pore diameter estimated for the nano-material used in this study was about 35 and 38 Å for the modified Kelvin and NMR methods respectively. A comparison between these methods and the classical Kelvin equation is also presented.

  19. Quantitative (1)H NMR method for hydrolytic kinetic investigation of salvianolic acid B.

    PubMed

    Pan, Jianyang; Gong, Xingchu; Qu, Haibin

    2013-11-01

    This work presents an exploratory study for monitoring the hydrolytic process of salvianolic acid B (Sal B) in low oxygen condition using a simple quantitative (1)H NMR (Q-NMR) method. The quantity of the compounds was calculated by the relative ratio of the integral values of the target peak for each compound to the known amount of the internal standard trimethylsilyl propionic acid (TSP). Kinetic runs have been carried out on different initial concentrations of Sal B (5.00, 10.0, 20.0mg/mL) and temperatures of 70, 80, 90°C. The effect of these two factors during the transformation process of Sal B was investigated. The hydrolysis followed pseudo-first-order kinetics and the apparent degradation kinetic constant at 80°C decreased when concentration of Sal B increased. Under the given conditions, the rate constant of overall hydrolysis as a function of temperature obeyed the Arrhenius equation. Six degradation products were identified by NMR and mass spectrometric analysis. Four of these degradation products, i.e. danshensu (DSS), protocatechuic aldehyde (PRO), salvianolic acid D (Sal D) and lithospermic acid (LA) were further identified by comparing the retention times with standard compounds. The advantage of this Q-NMR method was that no reference compounds were required for calibration curves, the quantification could be directly realized on hydrolyzed samples. It was proved to be simple, convenient and accurate for hydrolytic kinetic study of Sal B. PMID:23867115

  20. Survey and qualification of internal standards for quantification by 1H NMR spectroscopy.

    PubMed

    Rundlöf, Torgny; Mathiasson, Marie; Bekiroglu, Somer; Hakkarainen, Birgit; Bowden, Tim; Arvidsson, Torbjörn

    2010-09-01

    In quantitative NMR (qNMR) selection of an appropriate internal standard proves to be crucial. In this study, 25 candidate compounds considered to be potent internal standards were investigated with respect to the ability of providing unique signal chemical shifts, purity, solubility, and ease of use. The (1)H chemical shift (delta) values, assignments, multiplicities and number of protons (for each signal), appropriateness (as to be used as internal standards) in four different deuterated solvents (D(2)O, DMSO-d(6), CD(3)OD, CDCl(3)) were studied. Taking into account the properties of these 25 internal standards, the most versatile eight compounds (2,4,6-triiodophenol, 1,3,5-trichloro-2-nitrobenzene, 3,4,5-trichloropyridine, dimethyl terephthalate, 1,4-dinitrobenzene, 2,3,5-triiodobenzoic acid, maleic acid and fumaric acid) were qualified using both differential scanning calorimetry (DSC) and NMR spectroscopy employing highly pure acetanilide as the reference standard. The data from these two methods were compared as well as utilized in the quality assessment of the compounds as internal standards. Finally, the selected internal standards were tested and evaluated in a real case of quantitative NMR analysis of a paracetamol pharmaceutical product. PMID:20207092

  1. (1)H NMR spectroscopy in the diagnosis of Pseudomonas aeruginosa-induced urinary tract infection.

    PubMed

    Gupta, Ashish; Dwivedi, Mayank; Nagana Gowda, G A; Ayyagari, Archana; Mahdi, A A; Bhandari, M; Khetrapal, C L

    2005-08-01

    The utility of (1)H NMR spectroscopy is suggested and demonstrated for the diagnosis of Pseudomonas aeruginosa in urinary tract infection (UTI). The specific property of P. aeruginosa of metabolizing nicotinic acid to 6-hydroxynicotinic acid (6-OHNA) is exploited. The quantity of 6-OHNA produced correlates well with the viable bacterial count. Other common bacteria causing UTI such as Escherichia coli, Klebsiella pneumonia, Enterobacter aerogenes, Acinetobacter baumanii, Proteus mirabilis, Citrobacter frundii, Enterococcus faecalis, Streptococcus gp B and Staphylococcus aureus do not metabolize nicotinic acid under similar conditions. The method provides a single-step documentation of P. aeruginosa qualitatively as well as quantitatively. The NMR method is demonstrated on urine samples from 30 patients with UTI caused by P. aeruginosa. PMID:15759292

  2. Interaction of Daunomycin with Dipalmitoylphosphatidylcholine Model Membranes. A 1H NMR Study

    NASA Astrophysics Data System (ADS)

    Calzolai, Luigi; Gaggelli, Elena; Maccotta, Antonella; Valensin, Gianni

    1996-09-01

    1H NMR parameters were obtained for daunomycin in water solution in the free state as well as in the presence of dipalmitoylphosphatidylcholine model membranes. Spin-lattice relaxation rates were measured under nonselective, single-selective, and double-selective irradiation modes, and 2D NOESY spectra were obtained at several values of the mixing time. Proton-proton distances were calculated and the motional correlation time was evaluated in both the free and bound states. NMR parameters were used to show that ring A and the glucosamine moiety of daunomycin strongly interact with the external surface of the bilayer, while the rest of the molecule penetrates the membrane without crossing it. The structures of both free and bound daunomycin were obtained and compared by using molecular modeling.

  3. 1H, 13C and 15N NMR assignments of phenazopyridine derivatives.

    PubMed

    Burgueño-Tapia, Eleuterio; Mora-Pérez, Yolanda; Morales-Ríos, Martha S; Joseph-Nathan, Pedro

    2005-03-01

    Phenazopyridine hydrochloride (1), a drug in clinical use for many decades, and some derivatives were studied by one- and two-dimensional (1)H, (13)C and (15)N NMR methodology. The assignments, combined with DFT calculations, reveal that the preferred protonation site of the drug is the pyridine ring nitrogen atom. The chemoselective acetylation of phenazopyridine (2) and its influence on the polarization of the azo nitrogen atoms were evidenced by the (15)N NMR spectra. Molecular calculations of the phenazopyridines 2-4 show that the pyridine and phenyl groups are oriented in an antiperiplanar conformation with intramolecular hydrogen bonding between the N-b atom and the C-2 amino group preserving the E-azo stereochemistry. PMID:15625718

  4. 1H-NMR study of the three low temperature phases of DPPC-water systems.

    PubMed

    Trahms, L; Klabe, W D; Boroske, E

    1983-06-01

    The three phases of dipalmitoylphosphatidylcholine-water dispersions, occurring below the main transition are studied by a moment analysis of 1H-nuclear magnetic resonance (NMR) spectra. The subtransition, recently detected by Chen, S. C., J. M. Sturtevant, and B. J. Gaffney, 1980, Pro. Natl. Acad. Sci. USA, 77:5060-5063, is characterized by a sharp drop in the second moment at 12 degrees C as a result of increasing the temperature. Interesting features of this phase transition are a hysteresis of 11 K and extremely slow kinetics. It is interpreted as the onset of a flip-flop of the hydrocarbon chains about their long axis. At the pretransition, this type of motion is assumed to change into a fast rotation. The proposed models for the three phases are confirmed by computer calculations of theoretical values for the second and fourth moments of the corresponding NMR signals. PMID:6688190

  5. Determination of metabolite profiles in tropical wines by 1H NMR spectroscopy and chemometrics.

    PubMed

    da Silva Neto, Humberto G; da Silva, João B P; Pereira, Giuliano E; Hallwass, Fernando

    2009-12-01

    Traditionally, wines are produced in temperate climate zones, with one harvest per year. Tropical wines are a new concept of vitiviniculture that is being developed, principally in Brazil. The new Brazilian frontier is located in the northeast region (São Francisco River Valley) in Pernambuco State, close to the equator, between 8 and 9 degrees S. Compared with other Brazilian and worldwide vineyards, the grapes of this region possess peculiar characteristics. The aim of this work is a preliminary study of commercial São Francisco River Valley wines, analyzing their metabolite profiles by (1)H NMR and chemometric methods. PMID:19810052

  6. 1H NMR investigation of self-association of vanillin in aqueous solution

    NASA Astrophysics Data System (ADS)

    Bogdan, Mircea; Floare, Calin G.; Pîrnau, Adrian

    2009-08-01

    A self-association of vanillin have been studied by 1H NMR spectroscopy using the analysis of proton chemical shifts changes in aqueous solution as a function of concentration. The experimental results have been analysed using indefinite non-cooperative and cooperative models of molecular self-association, enabling the determination of equilibrium constants, parameters of cooperativity and the limiting values of vanillin proton chemical shifts in the complex. It was found that the dimer formation creates energetically favourable conditions for subsequent molecular association.

  7. Cucurbitacins from Cayaponia racemosa: isolation and total assignment of 1H and 13C NMR spectra.

    PubMed

    Chaves, Davina C; Assunção, João Carlos C; Braz-Filho, Raimundo; Lemos, Telma L G; Monte, Francisco J Q

    2007-05-01

    Two new cucurbitane-type triterpenoids, 2beta,3beta,16alpha,20(R),25-pentahydroxy-9-methyl-19-norlanost-5-en-7,22-dione and 2beta,3beta,16alpha,20(R),25-pentahydroxy-9-methyl-19-norlanost-5-en-7,11,22-trione, were isolated from fruits of Cayaponia racemosa. The total (1)H and (13)C chemical shift assignment of these two closely related compounds is described, making use of one- and two-dimensional NMR techniques. PMID:17372957

  8. 1H-NMR study of the spin dynamics of fine superparamagnetic nanoparticles

    SciTech Connect

    Bordonali, L.; Furukawa, Y.; Kraken, M.; Litterst, F.J.; Sangregorio, C.; Casula, M.F.; Lascialfari, A.

    2012-05-25

    We report a broadband 1H-NMR study of the temperature spin dynamics of nearly monodisperse dextran-coated γ-Fe2O3 magnetic nanoparticles. We observed a maximum in T1−1(T) that decreases in amplitude and shifts toward higher temperatures with increasing field. We suggest that this is related to the progressive superparamagnetic spin blocking of the ferrite core. The data can be explained by assuming a single electronic spin-spin correlation time and introducing a field-dependent distribution of anisotropy energy barriers.

  9. 1H and 13C resonance designation of antimycin A1 by two-dimensional NMR spectroscopy

    USGS Publications Warehouse

    Abidi, S.L.; Adams, B.R.

    1987-01-01

    Complete 1H and 13C resonance assignments of antimycin A1 were accomplished by two-dimensional NMR techniques, viz. 1H homonuclear COSY correlation, heteronuclear 13C-1H chemical shift correlation and long-range heteronuclear 13C-1H COLOC correlation. Antimycin A1 was found to consist of two isomeric components in a 2:1 ratio based on NMR spectroscopic evidence. The structure of the major component was newly assigned as the 8-isopentanoic acid ester. The spectra of the minor component were consistent with the known structure of antimycin A1.

  10. Toxicity assessment of Arisaematis Rhizoma in rats by a (1)H NMR-based metabolomics approach.

    PubMed

    Dong, Ge; Wang, Junsong; Guo, Pingping; Wei, Dandan; Yang, Minghua; Kong, Lingyi

    2015-02-01

    Arisaematis Rhizoma (AR), a famous traditional Chinese medicine, has been widely used in Asia over thousands of years. Documented with noticeable toxicity in ancient books, AR has been used to treat various diseases in the clinic. Therefore, it is important to assess the toxicity of AR dynamically and holistically. In this study, a (1)H NMR-based metabolomics approach complemented with serum chemistry and histopathology has been applied to investigate the toxicity of AR. Rats were intragastrically administered with AR (0, 0.5 and 1 g kg(-1) body weight) for 30 days, and serum and urine samples were collected. Their (1)H NMR profiles were analyzed by multivariate pattern recognition techniques to denote metabolic variations induced by AR, and 13 metabolites in urine and 6 metabolites in serum were significantly altered, which suggested that disturbances in energy metabolism, perturbation of the gut microflora environment, membrane damage, folate deficiency and injury of kidneys are produced by AR. Histopathology showed a slight vacuolization of the glomerular matrix and edema of renal tubular epithelial cells in kidneys of AR administered rats, which were evidenced by increased levels of blood urea nitrogen and creatinine in serum chemistry. Our results indicated that oral administration of crude AR was found to induce slight renal toxicity. Therefore, precautions should be made to monitor the potential nephrotoxicity of AR in clinical use. The metabolomics approach provided a promising tool for the study and better understanding of TCM-induced toxicity dynamically and holistically. PMID:25407163

  11. Broad identification of bacterial type in urinary tract infection using (1)h NMR spectroscopy.

    PubMed

    Gupta, Ashish; Dwivedi, Mayank; Mahdi, Abbas Ali; Khetrapal, Chunni Lal; Bhandari, Mahendra

    2012-03-01

    To address the shortcomings of urine culture for the rapid identification of urinary tract infection (UTI), we applied (1)H-nuclear magnetic resonance (NMR) spectroscopy as a surrogate method for fast screening of microorganisms. Study includes 682 urine samples from suspected UTI patients, 50 healthy volunteers, and commercially available standard strains of gram negative bacilli (GNB) (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Enterobacter, Acinetobacter, Proteus mirabilis, Citrobacter frundii) and gram positive cocci (GPC) (Enterococcus faecalis, Streptococcus group B, Staphylococcus saprophyticus). Acetate, lactate, ethanol, succinate, creatinine, trimethylamine (TMA), citrate, trimethylamin-N-oxide, glycine, urea, and hippurate were measured by (1)H NMR spectroscopy. All urine specimens were evaluated with culture method. Multivariate discriminant function analysis (DFA) reveals that acetate, lactate, succinate, and formate were able to differentiate, with high accuracy (99.5%), healthy controls from UTI patients. This statistical analysis was also able to classify GNB to GPC infected urine samples with high accuracy (96%). This technique appears to be a promising, rapid, and noninvasive approach to probing GNB and GPC infected urine specimens with its distinguishing metabolic profile. The determination of infection will be very important for rapidly and efficiently measuring the efficacy of a tailored treatment, leading to prompt and appropriate care of UTI patients. PMID:22292465

  12. UV-visible and (1)H-(15)N NMR spectroscopic studies of colorimetric thiosemicarbazide anion sensors.

    PubMed

    Farrugia, Kristina N; Makuc, Damjan; Podborska, Agnieszka; Szaciłowski, Konrad; Plavec, Janez; Magri, David C

    2015-02-14

    Four model thiosemicarbazide anion chemosensors containing three N-H bonds, substituted with phenyl and/or 4-nitrophenyl units, were synthesised and studied for their anion binding abilities with hydroxide, fluoride, acetate, dihydrogen phosphate and chloride. The anion binding properties were studied in DMSO and 9 : 1 DMSO-H2O by UV-visible absorption and (1)H/(13)C/(15)N NMR spectroscopic techniques and corroborated with DFT studies. Significant changes were observed in the UV-visible absorption spectra with all anions, except for chloride, accompanied by dramatic colour changes visible to the naked eye. These changes were determined to be due to the deprotonation of the central N-H proton and not due to hydrogen bonding based on (1)H/(15)N NMR titration studies with acetate in DMSO-d6-0.5% water. Direct evidence for deprotonation was confirmed by the disappearance of the central thiourea proton and the formation of acetic acid. DFT and charge distribution calculations suggest that for all four compounds the central N-H proton is the most acidic. Hence, the anion chemosensors operate by a deprotonation mechanism of the central N-H proton rather than by hydrogen bonding as is often reported. PMID:25451865

  13. Low Temperature 1H MAS NMR Spectroscopy Studies of Proton Motion in Zeolite

    SciTech Connect

    Huo, H.; Peng, L; Grey, C

    2009-01-01

    Low temperature {sup 1}H MAS NMR spectroscopy is used to study protonic motion in zeolite HZSM-5 in both samples that have been dried using procedures that are standard in the literature and samples that have been more carefully dehydrated. A significant enhancement of proton mobility is seen for the ''standard'' dehydrated HZSM-5 sample in comparison to that seen for the much drier sample. This is ascribed to a vehicle-hopping mechanism involving the residual water that is present in these zeolites. A gradual change of the framework structure is observed on cooling to approximately 213 K, as monitored via the change in {sup 1}H chemical shift values of the Broensted acid resonances and by X-ray diffraction. A more sudden change in structure is seen by differential scanning calorimetry and NMR at approximately 220?230 K, which is associated with changes in both the mobility and the modes of binding of the residual water to the Broensted acid sites and the zeolite framework.

  14. Authentication of beef versus horse meat using 60 MHz 1H NMR spectroscopy.

    PubMed

    Jakes, W; Gerdova, A; Defernez, M; Watson, A D; McCallum, C; Limer, E; Colquhoun, I J; Williamson, D C; Kemsley, E K

    2015-05-15

    This work reports a candidate screening protocol to distinguish beef from horse meat based upon comparison of triglyceride signatures obtained by 60 MHz (1)H NMR spectroscopy. Using a simple chloroform-based extraction, we obtained classic low-field triglyceride spectra from typically a 10 min acquisition time. Peak integration was sufficient to differentiate samples of fresh beef (76 extractions) and horse (62 extractions) using Naïve Bayes classification. Principal component analysis gave a two-dimensional "authentic" beef region (p=0.001) against which further spectra could be compared. This model was challenged using a subset of 23 freeze-thawed training samples. The outcomes indicated that storing samples by freezing does not adversely affect the analysis. Of a further collection of extractions from previously unseen samples, 90/91 beef spectra were classified as authentic, and 16/16 horse spectra as non-authentic. We conclude that 60 MHz (1)H NMR represents a feasible high-throughput approach for screening raw meat. PMID:25577043

  15. Metabolic characterization of natural and cultured Ophicordyceps sinensis from different origins by 1H NMR spectroscopy.

    PubMed

    Zhang, Jianshuang; Zhong, Xin; Li, Shaosong; Zhang, Guren; Liu, Xin

    2015-11-10

    Ophicordyceps sinensis is a well-known traditional Chinese medicine and cultured mycelium is a substitute for wild O. sinensis. Metabolic profiles of wild O. sinensis from three geographical locations and cultivated mycelia derived from three origins were investigated using (1)H nuclear magnetic resonance (NMR) analysis combined with multivariate statistical analysis. A total of 56 primary metabolites were identified and quantified from O. sinensis samples. The principle component analysis (PCA) showed significant differences between natural O. sinensis and fermentation mycelia. Seven metabolites responsible for differentiation were screened out by orthogonal partial least squares discriminant analysis (OPLS-DA). The concentrations of mannitol, trehalose, arginine, trans-4-hydroxyproline, alanine and glucitol were significantly different between wild and cultured groups. The variation in metabolic profiling among artificial mycelia was greater than that among wild O. sinensis. Furthermore, wild samples from different origins were clearly distinguished by the levels of mannitol, trehalose and some amino acids. This study indicates that (1)H NMR-based metabolomics is useful for fingerprinting and discriminating O. sinensis of different geographical regions and cultivated mycelia of different strains. The present study provided an efficient approach for investigating chemical compositions and evaluating the quality of medicine and health food derived from O. sinensis. PMID:26279370

  16. (1)H NMR Spectroscopy of Fecal Extracts Enables Detection of Advanced Colorectal Neoplasia.

    PubMed

    Amiot, Aurelien; Dona, Anthony C; Wijeyesekera, Anisha; Tournigand, Christophe; Baumgaertner, Isabelle; Lebaleur, Yann; Sobhani, Iradj; Holmes, Elaine

    2015-09-01

    Colorectal cancer (CRC) is a growing cause of mortality in developing countries, warranting investigation into its etiopathogenesis and earlier diagnosis. Here, we investigated the fecal metabolic phenotype of patients with advanced colorectal neoplasia and controls using (1)H-nuclear magnetic resonance (NMR) spectroscopy and multivariate modeling. The fecal microbiota composition was assessed by quantitative real-time PCR as well as Wif-1 methylation levels in stools, serum, and urine and correlated to the metabolic profile of each patient. The predictivity of the model was 0.507 (Q(2)Y), and the explained variance was 0.755 (R(2)Y). Patients with advanced colorectal neoplasia demonstrated increased fecal concentrations of four short-chain fatty acids (valerate, acetate, propionate, and butyrate) and decreased signals relating to β-glucose, glutamine, and glutamate. The predictive accuracy of the multivariate (1)H NMR model was higher than that of the guaiac-fecal occult blood test and the Wif-1 methylation test for predicting advanced colorectal neoplasia. Correlation analysis between fecal metabolites and bacterial profiles revealed strong associations between Faecalibacterium prausnitzii and Clostridium leptum species with short-chain fatty acids concentration and inverse correlation between Faecalibacterium prausnitzii and glucose. These preliminary results suggest that fecal metabonomics may potentially have a future role in a noninvasive colorectal screening program and may contribute to our understanding of the role of these dysregulated molecules in the cross-talk between the host and its bacterial microbiota. PMID:26211820

  17. Authentication of beef versus horse meat using 60 MHz 1H NMR spectroscopy

    PubMed Central

    Jakes, W.; Gerdova, A.; Defernez, M.; Watson, A.D.; McCallum, C.; Limer, E.; Colquhoun, I.J.; Williamson, D.C.; Kemsley, E.K.

    2015-01-01

    This work reports a candidate screening protocol to distinguish beef from horse meat based upon comparison of triglyceride signatures obtained by 60 MHz 1H NMR spectroscopy. Using a simple chloroform-based extraction, we obtained classic low-field triglyceride spectra from typically a 10 min acquisition time. Peak integration was sufficient to differentiate samples of fresh beef (76 extractions) and horse (62 extractions) using Naïve Bayes classification. Principal component analysis gave a two-dimensional “authentic” beef region (p = 0.001) against which further spectra could be compared. This model was challenged using a subset of 23 freeze–thawed training samples. The outcomes indicated that storing samples by freezing does not adversely affect the analysis. Of a further collection of extractions from previously unseen samples, 90/91 beef spectra were classified as authentic, and 16/16 horse spectra as non-authentic. We conclude that 60 MHz 1H NMR represents a feasible high-throughput approach for screening raw meat. PMID:25577043

  18. Two-dimensional /sup 1/H NMR studies on cyclophilin, a cytosolic cyclosporin A binding protein

    SciTech Connect

    Dalgarno, D.C.; Harding, M.W.; Lazarides, A.; Handschumacher, R.E.; Armitage, I.M.

    1986-05-01

    Cyclophilin (CyP) is a specific cytosolic cyclosporin A (CsA) binding protein (163 residues) that has been implicated in the pharmacological action of this potent immunosuppressant. One and two-dimensional /sup 1/H NMR methods are being employed to elucidate the solution structural properties of CyP particularly as they relate to the binding site of CsA. The focal point for these studies is the single Trp (residue number120) in CyP which, in the 1:1 CyP:CsA complex (K/sub d/approx.2 x 10/sup -7/M), shows a 2 fold enhancement in its intrinsic fluorescence. Using 2D /sup 1/H NMR methods, a low resolution structure has been derived for a very hydrophobic domain containing the Trp residue using interresidue n.O.e. data between assigned spin systems and a distance geometry algorithm. The structure of this hydrophobic domain will be discussed in relation to the predicted ..cap alpha../..beta.. secondary structure of this protein and comparisons made between its structure in the drug free and complexed form of the protein.

  19. Method for determining molar concentrations of metabolites in complex solutions from two-dimensional 1H-13C NMR spectra.

    PubMed

    Lewis, Ian A; Schommer, Seth C; Hodis, Brendan; Robb, Kate A; Tonelli, Marco; Westler, William M; Sussman, Michael R; Markley, John L

    2007-12-15

    One-dimensional (1D) (1)H nuclear magnetic resonance (NMR) spectroscopy is used extensively for high-throughput analysis of metabolites in biological fluids and tissue extracts. Typically, such spectra are treated as multivariate statistical objects rather than as collections of quantifiable metabolites. We report here a two-dimensional (2D) (1)H-(13)C NMR strategy (fast metabolite quantification, FMQ, by NMR) for identifying and quantifying the approximately 40 most abundant metabolites in biological samples. To validate this technique, we prepared mixtures of synthetic compounds and extracts from Arabidopsis thaliana, Saccharomyces cerevisiae, and Medicago sativa. We show that accurate (technical error 2.7%) molar concentrations can be determined in 12 min using our quantitative 2D (1)H-(13)C NMR strategy. In contrast, traditional 1D (1)H NMR analysis resulted in 16.2% technical error under nearly ideal conditions. We propose FMQ by NMR as a practical alternative to 1D (1)H NMR for metabolomics studies in which 50-mg (extract dry weight) samples can be obtained. PMID:17985927

  20. Topotecan dynamics, tautomerism and reactivity--1H/13C NMR and ESI MS study.

    PubMed

    Hyz, Karolina; Kawecki, Robert; Bednarek, Elzbieta; Bocian, Wojciech; Sitkowski, Jerzy; Kozerski, Lech

    2010-08-01

    Topotecan (TPT) is in clinical use as an antitumor agent, hycamtin. Because of this, it requires both biologically and chemically useful information to be available. TPT acts by binding to the covalent complex formed by nicked DNA and topoisomerase I. This has a poisonous effect since inserted into the single-strand nick and TPT inhibits its religation. We used NMR to trace TPT dynamics, tautomerism and solvolysis products in various solvents and conditions. Chemical stability was assessed in methanol and DMSO as compared to water, and the regioselectivity of the N- and O-methylation was studied using various alkylating agents. The reaction products of quaternization of the nitrogen atom and methylation of the oxygen atom were characterized by means of ESI MS, (1)H/(13)C-HMBC and -HSQCAD NMR. We have focused on the NMR characterization of TPT with an anticipation that its aggregation, tumbling properties and the intramolecular dipolar interactions will be a common feature for other compounds described in this article. These features can also be useful in tracing the interactions of this class of topoisomerase I (TopoI) poisons with DNA. Moreover, the results explained shed light on the recently disclosed problem of lack of stability of TPT in the heart tissue homogenate samples using the analytical assays developed for this class of compounds carried out in the presence of methanol. PMID:20623719

  1. Qualitative and Quantitative Control of Carbonated Cola Beverages Using 1H NMR Spectroscopy

    PubMed Central

    2012-01-01

    1H Nuclear magnetic resonance (NMR) spectroscopy (400 MHz) was used in the context of food surveillance to develop a reliable analytical tool to differentiate brands of cola beverages and to quantify selected constituents of the soft drinks. The preparation of the samples required only degassing and addition of 0.1% of TSP in D2O for locking and referencing followed by adjustment of pH to 4.5. The NMR spectra obtained can be considered as “fingerprints” and were analyzed by principal component analysis (PCA). Clusters from colas of the same brand were observed, and significant differences between premium and discount brands were found. The quantification of caffeine, acesulfame-K, aspartame, cyclamate, benzoate, hydroxymethylfurfural (HMF), sulfite ammonia caramel (E 150D), and vanillin was simultaneously possible using external calibration curves and applying TSP as internal standard. Limits of detection for caffeine, aspartame, acesulfame-K, and benzoate were 1.7, 3.5, 0.8, and 1.0 mg/L, respectively. Hence, NMR spectroscopy combined with chemometrics is an efficient tool for simultaneous identification of soft drinks and quantification of selected constituents. PMID:22356160

  2. Characterization of water-soluble organic matter in urban aerosol by 1H-NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Chalbot, Marie-Cecile G.; Chitranshi, Priyanka; Gamboa da Costa, Gonçalo; Pollock, Erik; Kavouras, Ilias G.

    2016-03-01

    The functional and 13C isotopic compositions of water-soluble organic carbon (WSOC) in atmospheric aerosol were determined by nuclear magnetic resonance (1H-NMR) and isotope ratio mass spectrometry (IRMS) in an urban location in the Southern Mississippi Valley. The origin of WSOC was resolved using the functional distribution of organic hydrogen, δ13C ratio, and positive matrix factorization (PMF). Three factors were retained based on NMR spectral bins loadings. Two factors (factors 1 and 3) demonstrated strong associations with the aliphatic region in the NMR spectra and levoglucosan resonances. Differences between the two factors included the abundance of the aromatic functional group for factor 1, indicating fresh emissions and, for factor 3, the presence of resonances attributed to secondary ammonium nitrate and low δ13C ratio values that are indicative of secondary organic aerosol. Factors 1 and 3 added 0.89 and 1.08 μgC m-3, respectively, with the highest contribution in the summer and fall. Factor 2 retained resonances consistent with saccharides and was attributed to pollen particles. Its contribution to WSOC varied from 0.22 μgC m-3 in winter to 1.04 μgC m-3 in spring.

  3. 60 MHz (1)H NMR spectroscopy for the analysis of edible oils.

    PubMed

    Parker, T; Limer, E; Watson, A D; Defernez, M; Williamson, D; Kemsley, E Kate

    2014-05-01

    We report the first results from a new 60 MHz (1)H nuclear magnetic resonance (NMR) bench-top spectrometer, Pulsar, in a study simulating the adulteration of olive oil with hazelnut oil. There were qualitative differences between spectra from the two oil types. A single internal ratio of two isolated groups of peaks could detect hazelnut oil in olive oil at the level of ∼13%w/w, whereas a whole-spectrum chemometric approach brought the limit of detection down to 11.2%w/w for a set of independent test samples. The Pulsar's performance was compared to that of Fourier transform infrared (FTIR) spectroscopy. The Pulsar delivered comparable sensitivity and improved specificity, making it a superior screening tool. We also mapped NMR onto FTIR spectra using a correlation-matrix approach. Interpretation of this heat-map combined with the established annotations of the NMR spectra suggested a hitherto undocumented feature in the IR spectrum at ∼1130 cm(-1), attributable to a double-bond vibration. PMID:24850979

  4. 1H Solid-State NMR Imaging by TREV-CRAMPS

    NASA Astrophysics Data System (ADS)

    Buszko, M. L.; Maciel, G. E.

    A proton NMR imaging experiment based on line narrowing by TREV-CRAMPS with a time-dependent magnetic field gradient has been demonstrated on a solid adamantane phantom. With the magnetic field gradient applied as 16 μs pulses in the windows of the RF pulse sequence, a spatial resolution of about 100 μm is experimentally achieved (based on linewidth and gradient strength), with a digital resolution of 40 μm, qualitatively similar to what is achieved in liquid-sample NMR imaging. The technique benefits from a favorable time average of the magnetic field gradient, relatively wide windows between the magic-echo sandwiches, and the good off-resonance line-narrowing characteristics of the TREV technique. High-resolution chemical-shift information is retained and hence potentially attainable. The low MAS rate, compared to what is used in imaging experiments in which MAS is the only line-narrowing procedure used, may be of importance if one wishes to apply 1H NMR imaging to certain types of samples, e.g., biological tissue.

  5. Thermal degradation in a trimodal PDMS network by 1H Multiple Quantum NMR

    SciTech Connect

    Giuliani, J R; Gjersing, E L; Chinn, S C; Jones, T V; Wilson, T S; Alviso, C T; Herberg, J L; Pearson, M A; Maxwell, R S

    2007-06-06

    Thermal degradation of a filled, crosslinked siloxane material synthesized from PDMS chains of three different average molecular weights and with two different crosslinking species has been studied by {sup 1}H Multiple Quantum (MQ) NMR methods. Multiple domains of polymer chains were detected by MQ NMR exhibiting Residual Dipolar Coupling (<{Omega}{sub d}>) values of 200 Hz and 600 Hz, corresponding to chains with high average molecular weight between crosslinks and chains with low average molecular weight between crosslinks or near the multifunctional crosslinking sites. Characterization of the <{Omega}{sub d}> values and changes in <{Omega}{sub d}> distributions present in the material were studied as a function of time at 250 C and indicates significant time dependent degradation. For the domains with low <{Omega}{sub d}>, a broadening in the distribution was observed with aging time. For the domain with high <{Omega}{sub d}>, increases in both the mean <{Omega}{sub d}> and the width in <{Omega}{sub d}> were observed with increasing aging time. Isothermal Thermal Gravimetric Analysis (TGA) reveals a 3% decrease in weight over 20 hours of aging at 250 C. Degraded samples also were analyzed by traditional solid state {sup 1}H NMR techniques and offgassing products were identified by Solid Phase MicroExtraction followed by Gas Chromatography-Mass Spectrometry (SPME GC-MS). The results, which will be discussed here, suggest that thermal degradation proceeds by complex competition between oxidative chain scissioning and post-curing crosslinking that both contribute to embrittlement.

  6. 1H and 13C NMR investigation of 20-hydroxyecdysone dioxolane derivatives, a novel group of MDR modulator agents.

    PubMed

    Balázs, Attila; Hunyadi, Attila; Csábi, József; Jedlinszki, Nikoletta; Martins, Ana; Simon, András; Tóth, Gábor

    2013-12-01

    The synthesis, structure elucidation and the complete (1)H and (13)C signal assignment of a series of dioxolane derivatives of 20-hydroxyecdysone, synthesized as novel modulators of multidrug resistance, are presented. The structures and NMR signal assignment were established by comprehensive one-dimensional and two-dimensional NMR spectroscopy supported by mass spectrometry. PMID:24114927

  7. Response to the Letter to the Editor regarding "Determination of the fatty acid profile by 1H-NMR spectroscopy."

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In expansion of previous work (G. Knothe, J.A. Kenar, Determination of the fatty acid profile by 1H-NMR spectroscopy, Eur. J. Lipid Sci. Technol. 2004, 106, 88-96), an additional approach is discussed for quantitating saturated fatty acids in the fatty acid profiles of common vegetable oils by 1H-NM...

  8. Ovariectomized rats' femur treated with fibrates and statins. Assessment of pore-size distribution by ¹H-NMR relaxometry.

    PubMed

    Şipoş, Remus Sebastian; Fechete, Radu; Chelcea, Ramona Ioana; Moldovan, Dumitriţa; Pap, Zsuzsánna; Pávai, Zoltán; Demco, Dan Eugen

    2015-01-01

    The effects of two wonder drugs, simvastatins and fenofibrates on the proximal part of the femoris of a series of ovariectomized and non-ovariectomized Wistar albino rats was estimated qualitatively and semi-quantitatively by the modern method of 1D 1H-NMR T2-distribution. The 72 rats subjected to this study were divided in six groups and were sacrificed at two, four, six and eight weeks after ovariectomy and the proximal part of femoris was harvested. The CPMG (Carr-Purcell-Meiboom-Gill) echoes train curves were measured for the bones fully saturated with water during two months after two months of natural drying. These decays were analyzed by Laplace inversion and an average of normalized T2-distributions was considered for all rat's groups. The 1D averaged T2-distributions present four peaks, which were associated with protons in four major environments, from which the free water protons are used as spy molecules to explore the boundaries of cavities. In the approximation of spherical pores, the averaged T2-distributions were transformed in distributions of pores diameters. These were found in the range from 2 μm up to 2 mm. The relative amplitudes, widths and position of deconvoluted distributions of small, medium and large cavities are used for a qualitatively analysis of the effect of our lipid-lowering drugs. For a semi-quantitatively analysis, we chose the diameter d of proximal part of femoris' trabecular cavities. We show that the positive or negative effects of treatments with simvastatins and fenofibrates are strongly dependent on the duration of treatment. Moreover, the treatment of healthy bone is generally counter-indicated. PMID:26429167

  9. Automated data evaluation and modelling of simultaneous (19) F-(1) H medium-resolution NMR spectra for online reaction monitoring.

    PubMed

    Zientek, Nicolai; Laurain, Clément; Meyer, Klas; Paul, Andrea; Engel, Dirk; Guthausen, Gisela; Kraume, Matthias; Maiwald, Michael

    2016-06-01

    Medium-resolution nuclear magnetic resonance spectroscopy (MR-NMR) currently develops to an important analytical tool for both quality control and process monitoring. In contrast to high-resolution online NMR (HR-NMR), MR-NMR can be operated under rough environmental conditions. A continuous re-circulating stream of reaction mixture from the reaction vessel to the NMR spectrometer enables a non-invasive, volume integrating online analysis of reactants and products. Here, we investigate the esterification of 2,2,2-trifluoroethanol with acetic acid to 2,2,2-trifluoroethyl acetate both by (1) H HR-NMR (500 MHz) and (1) H and (19) F MR-NMR (43 MHz) as a model system. The parallel online measurement is realised by splitting the flow, which allows the adjustment of quantitative and independent flow rates, both in the HR-NMR probe as well as in the MR-NMR probe, in addition to a fast bypass line back to the reactor. One of the fundamental acceptance criteria for online MR-MNR spectroscopy is a robust data treatment and evaluation strategy with the potential for automation. The MR-NMR spectra are treated by an automated baseline and phase correction using the minimum entropy method. The evaluation strategies comprise (i) direct integration, (ii) automated line fitting, (iii) indirect hard modelling (IHM) and (iv) partial least squares regression (PLS-R). To assess the potential of these evaluation strategies for MR-NMR, prediction results are compared with the line fitting data derived from the quantitative HR-NMR spectroscopy. Although, superior results are obtained from both IHM and PLS-R for (1) H MR-NMR, especially the latter demands for elaborate data pretreatment, whereas IHM models needed no previous alignment. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25854892

  10. Discovering [superscript 13]C NMR, [superscript 1]H NMR, and IR Spectroscopy in the General Chemistry Laboratory through a Sequence of Guided-Inquiry Exercises

    ERIC Educational Resources Information Center

    Iler, H. Darrell; Justice, David; Brauer, Shari; Landis, Amanda

    2012-01-01

    This sequence of three guided-inquiry labs is designed for a second-semester general chemistry course and challenges students to discover basic theoretical principles associated with [superscript 13]C NMR, [superscript 1]H NMR, and IR spectroscopy. Students learn to identify and explain basic concepts of magnetic resonance and vibrational…

  11. Low-field (1)H NMR spectroscopy for distinguishing between arabica and robusta ground roast coffees.

    PubMed

    Defernez, Marianne; Wren, Ella; Watson, Andrew D; Gunning, Yvonne; Colquhoun, Ian J; Le Gall, Gwénaëlle; Williamson, David; Kemsley, E Kate

    2017-02-01

    This work reports a new screening protocol for addressing issues of coffee authenticity using low-field (60MHz) bench-top (1)H NMR spectroscopy. Using a simple chloroform-based extraction, useful spectra were obtained from the lipophilic fraction of ground roast coffees. It was found that 16-O-methylcafestol (16-OMC, a recognized marker compound for robusta beans) gives rise to an isolated peak in the 60MHz spectrum, which can be used as an indicator of the presence of robusta beans in the sample. A total of 81 extracts from authenticated coffees and mixtures were analysed, from which the detection limit of robusta in arabica was estimated to be between 10% and 20% w/w. Using the established protocol, a surveillance exercise was conducted of 27 retail samples of ground roast coffees which were labelled as "100% arabica". None were found to contain undeclared robusta content above the estimated detection limit. PMID:27596398

  12. {sup 1}H NMR electron-nuclear cross relaxation in thin films of hydrogenated amorphous silicon

    SciTech Connect

    Su Tining; Taylor, P. C.; Ganguly, G.; Carlson, D. E.; Bobela, D. C.; Hari, P.

    2007-12-15

    We investigate the spin-lattice relaxation of the dipolar order in {sup 1}H NMR in hydrogenated amorphous silicon (a-Si:H). We find that the relaxation is dominated by the cross relaxation between the hydrogen nuclei and the paramagnetic states. The relaxation is inhomogeneous, and can be described as a stretched exponential function. We proposed a possible mechanism for this relaxation. This mechanism applies to a rather broad range of paramagnetic states, including the deep neutral defects (dangling bonds), the light-induced metastable defects, the defects created by doping, and the singly occupied, localized band-tail states populated by light at low temperatures. The cross relaxation is only sensitive to the bulk spin density, and the surface spins have a negligible effect on the relaxation.

  13. Single-Quantum Coherence Filter for Strongly Coupled Spin Systems for Localized 1H NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Trabesinger, Andreas H.; Mueller, D. Christoph; Boesiger, Peter

    2000-08-01

    A pulse sequence for localized in vivo1H NMR spectroscopy is presented, which selectively filters single-quantum coherence built up by strongly coupled spin systems. Uncoupled and weakly coupled spin systems do not contribute to the signal output. Analytical calculations using a product operator description of the strongly coupled AB spin system as well as in vitro tests demonstrate that the proposed filter produces a signal output for a strongly coupled AB spin system, whereas the resonances of a weakly coupled AX spin system and of uncoupled spins are widely suppressed. As a potential application, the detection of the strongly coupled AA‧BB‧ spin system of taurine at 1.5 T is discussed.

  14. 1H NMR Relaxation Investigation of Inhibitors Interacting with Torpedo californica Acetylcholinesterase

    NASA Astrophysics Data System (ADS)

    Delfini, Maurizio; Gianferri, Raffaella; Dubbini, Veronica; Manetti, Cesare; Gaggelli, Elena; Valensin, Gianni

    2000-05-01

    Two naphthyridines interacting with Torpedo californica acetylcholinesterase (AChE) were investigated. 1H NMR spectra were recorded and nonselective, selective, and double-selective spin-lattice relaxation rates were measured. The enhancement of selective relaxation rates could be titrated by different ligand concentrations at constant AChE (yielding 0.22 and 1.53 mM for the dissociation constants) and was providing evidence of a diverse mode of interaction. The double-selective relaxation rates were used to evaluate the motional correlation times of bound ligands at 34.9 and 36.5 ns at 300 K. Selective relaxation rates of bound inhibitors could be interpreted also in terms of dipole-dipole interactions with protons in the enzyme active site.

  15. 1H NMR study of the complexation of aromatic drugs with dimethylxanthine derivatives

    NASA Astrophysics Data System (ADS)

    Hernandez Santiago, A. A.; Gonzalez Flores, M.; Rosas Castilla, S. A.; Cervantes Tavera, A. M.; Gutierrez Perez, R.; Khomich, V. V.; Ovchinnikov, D. V.; Parkes, H. G.; Evstigneev, M. P.

    2012-02-01

    With an aim of searching efficient interceptors of aromatic drugs, the self- and hetero-association of dimethylxanthine derivatives with different structures, selected according to Strategy 1 (variation of the position of methyl groups) and Strategy 2 (variation of the length of sbnd (CH2)nsbnd COOH group), with aromatic drug molecules: Ethidium Bromide, Proflavine and Daunomycin, were studied using 1H NMR spectroscopy. It was found that the association proceeds in a form of stacking-type complexation and its energetics is relatively independent on the structure of the dimethylxanthines. However, on average, the dimethylxanthines possess higher hetero-association constant and, hence, higher interceptor ability as compared to the trimethylxanthine, Caffeine, used during the past two decades as a typical interceptor molecule.

  16. 1H NMR Cryoporometry Study of the Melting Behavior of Water in White Cement

    NASA Astrophysics Data System (ADS)

    Boguszyńska, Joanna; Tritt-Goc, Jadwiga

    2004-09-01

    The pore size of white cement samples is studied by the melting behaviour of water confined in it, using 1H NMR cryopormetry. The influence of the preparing method and antifreeze admixture on the pore size and distribution in cement samples is investigated at 283 K. The addition of an antifreeze admixture [containing 1% Sika Rapid 2 by weight of the dry cement] influences the porosity. In wet prepared samples we observed a significant increase in the quantity of mesopores between 0.8 and 5 nm and a smaller increase of mesopores between 5 and 10 nm, when compared to cement without admixture. The compressive strength is related to the porosity of the cement. Therefore the cement with Sika Rapid 2, wet prepared at 278 K shows a higher strength than all other measured samples.

  17. Quantitative 1H NMR: Development and Potential of an Analytical Method – an Update

    PubMed Central

    Pauli, Guido F.; Gödecke, Tanja; Jaki, Birgit U.; Lankin, David C.

    2012-01-01

    Covering the literature from mid-2004 until the end of 2011, this review continues a previous literature overview on quantitative 1H NMR (qHNMR) methodology and its applications in the analysis of natural products (NPs). Among the foremost advantages of qHNMR is its accurate function with external calibration, the lack of any requirement for identical reference materials, a high precision and accuracy when properly validated, and an ability to quantitate multiple analytes simultaneously. As a result of the inclusion of over 170 new references, this updated review summarizes a wealth of detailed experiential evidence and newly developed methodology that supports qHNMR as a valuable and unbiased analytical tool for natural product and other areas of research. PMID:22482996

  18. 1H NMR metabolomics of earthworm responses to polychlorinated biphenyl (PCB) exposure in soil.

    PubMed

    Whitfield Åslund, Melissa L; Simpson, André J; Simpson, Myrna J

    2011-06-01

    (1)H NMR-based metabolomics was used to examine the metabolic profile of D(2)O-buffer extracted tissues of Eisenia fetida earthworms exposed for 2 days to an artificial soil spiked with sub-lethal concentrations of polychlorinated biphenyls (PCBs) (0, 0.5, 1, 5, 10, or 25 mg/kg Aroclor 1254). Univariate statistical analysis of the identified metabolites revealed a significant increase in ATP concentration in earthworms exposed to the highest soil PCB concentration, but detected no significant changes in other metabolites. However, a multivariate approach which considers alterations in multiple metabolites simultaneously, identified a significant linear relationship between earthworm metabolic profiles and PCB concentration (cross-validated PLS-regression with 7 components, R(2)X = 0.99, R(2)Y = 0.77, Q(2)Y = 0.45, P < 0.001). Significant changes in pair-wise metabolic correlations were also detected as PCB concentration increased. For example, lysine and ATP concentrations showed no apparent correlation in control earthworms (r = 0.22, P = 0.54), but were positively correlated in earthworms from the 25 mg/kg treatment (r = 0.87, P = 0.001). Overall, the observed metabolic responses suggest that PCBs disrupted both carbohydrate (energy) metabolism and membrane (osmolytic) function in E. fetida. The ability of (1)H NMR-based metabolomics to detect these responses suggests that this method offers significant potential for direct assessment of sub-lethal PCB toxicity in soil. PMID:21424327

  19. Essential Parameters for Structural Analysis and Dereplication by 1H NMR Spectroscopy

    PubMed Central

    2015-01-01

    The present study demonstrates the importance of adequate precision when reporting the δ and J parameters of frequency domain 1H NMR (HNMR) data. Using a variety of structural classes (terpenoids, phenolics, alkaloids) from different taxa (plants, cyanobacteria), this study develops rationales that explain the importance of enhanced precision in NMR spectroscopic analysis and rationalizes the need for reporting Δδ and ΔJ values at the 0.1–1 ppb and 10 mHz level, respectively. Spectral simulations paired with iteration are shown to be essential tools for complete spectral interpretation, adequate precision, and unambiguous HNMR-driven dereplication and metabolomic analysis. The broader applicability of the recommendation relates to the physicochemical properties of hydrogen (1H) and its ubiquity in organic molecules, making HNMR spectra an integral component of structure elucidation and verification. Regardless of origin or molecular weight, the HNMR spectrum of a compound can be very complex and encode a wealth of structural information that is often obscured by limited spectral dispersion and the occurrence of higher order effects. This altogether limits spectral interpretation, confines decoding of the underlying spin parameters, and explains the major challenge associated with the translation of HNMR spectra into tabulated information. On the other hand, the reproducibility of the spectral data set of any (new) chemical entity is essential for its structure elucidation and subsequent dereplication. Handling and documenting HNMR data with adequate precision is critical for establishing unequivocal links between chemical structure, analytical data, metabolomes, and biological activity. Using the full potential of HNMR spectra will facilitate the general reproducibility for future studies of bioactive chemicals, especially of compounds obtained from the diversity of terrestrial and marine organisms. PMID:24895010

  20. Age-Related 1H NMR Characterization of Cerebrospinal Fluid in Newborn and Young Healthy Piglets

    PubMed Central

    Barone, Francesca; Elmi, Alberto; Romagnoli, Noemi; Bacci, Maria Laura

    2016-01-01

    When it comes to neuroscience, pigs represent an important animal model due to their resemblance with humans’ brains for several patterns including anatomy and developmental stages. Cerebrospinal fluid (CSF) is a relatively easy-to-collect specimen that can provide important information about neurological health and function, proving its importance as both a diagnostic and biomedical monitoring tool. Consequently, it would be of high scientific interest and value to obtain more standard physiological information regarding its composition and dynamics for both swine pathology and the refinement of experimental protocols. Recently, proton nuclear magnetic resonance (1H NMR) spectroscopy has been applied in order to analyze the metabolomic profile of this biological fluid, and results showed the technique to be highly reproducible and reliable. The aim of the present study was to investigate in both qualitative and quantitative manner the composition of Cerebrospinal Fluid harvested form healthy newborn (5 days old-P5) and young (30-P30 and 50-P50 days old) piglets using 1H NMR Spectroscopy, and to analyze any possible difference in metabolites concentration between age groups, related to age and Blood-Brain-Barrier maturation. On each of the analyzed samples, 30 molecules could be observed above their limit of quantification, accounting for 95–98% of the total area of the spectra. The concentrations of adenine, tyrosine, leucine, valine, 3-hydroxyvalerate, 3-methyl-2-oxovalerate were found to decrease between P05 and P50, while the concentrations of glutamine, creatinine, methanol, trimethylamine and myo-inositol were found to increase. The P05-P30 comparison was also significant for glutamine, creatinine, adenine, tyrosine, leucine, valine, 3-hydroxyisovalerate, 3-methyl-2-oxovalerate, while for the P30-P50 comparison we found significant differences for glutamine, myo-inositol, leucine and trimethylamine. None of these molecules showed at P30 concentrations

  1. Essential parameters for structural analysis and dereplication by (1)H NMR spectroscopy.

    PubMed

    Pauli, Guido F; Chen, Shao-Nong; Lankin, David C; Bisson, Jonathan; Case, Ryan J; Chadwick, Lucas R; Gödecke, Tanja; Inui, Taichi; Krunic, Aleksej; Jaki, Birgit U; McAlpine, James B; Mo, Shunyan; Napolitano, José G; Orjala, Jimmy; Lehtivarjo, Juuso; Korhonen, Samuli-Petrus; Niemitz, Matthias

    2014-06-27

    The present study demonstrates the importance of adequate precision when reporting the δ and J parameters of frequency domain (1)H NMR (HNMR) data. Using a variety of structural classes (terpenoids, phenolics, alkaloids) from different taxa (plants, cyanobacteria), this study develops rationales that explain the importance of enhanced precision in NMR spectroscopic analysis and rationalizes the need for reporting Δδ and ΔJ values at the 0.1-1 ppb and 10 mHz level, respectively. Spectral simulations paired with iteration are shown to be essential tools for complete spectral interpretation, adequate precision, and unambiguous HNMR-driven dereplication and metabolomic analysis. The broader applicability of the recommendation relates to the physicochemical properties of hydrogen ((1)H) and its ubiquity in organic molecules, making HNMR spectra an integral component of structure elucidation and verification. Regardless of origin or molecular weight, the HNMR spectrum of a compound can be very complex and encode a wealth of structural information that is often obscured by limited spectral dispersion and the occurrence of higher order effects. This altogether limits spectral interpretation, confines decoding of the underlying spin parameters, and explains the major challenge associated with the translation of HNMR spectra into tabulated information. On the other hand, the reproducibility of the spectral data set of any (new) chemical entity is essential for its structure elucidation and subsequent dereplication. Handling and documenting HNMR data with adequate precision is critical for establishing unequivocal links between chemical structure, analytical data, metabolomes, and biological activity. Using the full potential of HNMR spectra will facilitate the general reproducibility for future studies of bioactive chemicals, especially of compounds obtained from the diversity of terrestrial and marine organisms. PMID:24895010

  2. 1H Nuclear Magnetic Resonance (NMR) Metabolomic Study of Chronic Organophosphate Exposure in Rats

    PubMed Central

    Alam, Todd M.; Neerathilingam, Muniasamy; Alam, M. Kathleen; Volk, David E.; Ansari, G. A. Shakeel; Sarkar, Swapna; Luxon, Bruce A.

    2012-01-01

    1H NMR spectroscopy and chemometric analysis were used to characterize rat urine obtained after chronic exposure to either tributyl phosphate (TBP) or triphenyl phosphate (TPP). In this study, the daily dose exposure was 1.5 mg/kg body weight for TBP, or 2.0 mg/kg body weight for TPP, administered over a 15-week period. Orthogonal signal correction (OSC) -filtered partial least square discriminant analysis (OSC-PLSDA) was used to predict and classify exposure to these organophosphates. During the development of the model, the classification error was evaluated as a function of the number of latent variables. NMR spectral regions and corresponding metabolites important for determination of exposure type were identified using variable importance in projection (VIP) coefficients obtained from the OSC-PLSDA analysis. As expected, the model for classification of chronic (1.5–2.0 mg/kg body weight daily) TBP or TPP exposure was not as strong as the previously reported model developed for identifying acute (15–20 mg/kg body weight) exposure. The set of majorly impacted metabolites identified for chronic TBP or TPP exposure was slightly different than those metabolites previously identified for acute exposure. These metabolites were then mapped to different metabolite pathways and ranked, allowing the metabolic response to chronic organophosphate exposure to be addressed. PMID:24957643

  3. Effects of high fructose and salt feeding on systematic metabonome probed via (1) H NMR spectroscopy.

    PubMed

    Yang, Yongxia; Zheng, Lingyun; Wang, Linlin; Wang, Shumei; Wang, Yaling; Han, Zhihui

    2015-04-01

    Diets rich in high fructose and salt are increasingly popular in our daily life. A combination consumption of excessive fructose and salt can induce insulin resistance (IR) and hypertension (HT), which are major public health problems around the world. However, the effects of high fructose and salt on systematic metabonome remain unknown, which is very important for revealing the molecular mechanism of IR and HT induced by this dietary pattern. The metabolic profiling in urine, plasma, and fecal extracts from high fructose and salt-fed rats was investigated by use of (1) H nuclear magnetic resonance (NMR)-based metabonomics approach in this study. Multivariate analysis of NMR data showed the effects of high fructose and salt on the global metabonome. The metabolite analysis in urine and fecal extracts showed the time-dependent metabolic changes, which displayed metabonomic progression axes from normal to IR and HT status. The changes of 2-oxoglutarate, creatine and creatinine, citrate, hippurate, trimethylamine N-oxide (TMAO), and betaine in urine, together with gut microbiota disorder in feces, were observed at the preliminary formation stage of IR and HT (fourth week). At the severe stage (eighth week), the previously mentioned metabolic changes were aggravated, and the changes of lipid and choline metabolism in plasma suggested the increased risk of cardiovascular diseases. These findings provide an overview of biochemistry consequences of high fructose and salt feeding and comprehensive insights into the progression of systematic metabonome for IR and HT induced by this dietary pattern. PMID:25641270

  4. Combined Analysis of Stable Isotope, (1)H NMR, and Fatty Acid To Verify Sesame Oil Authenticity.

    PubMed

    Kim, Jeongeun; Jin, Gyungsu; Lee, Yunhee; Chun, Hyang Sook; Ahn, Sangdoo; Kim, Byung Hee

    2015-10-14

    The aim of this study was to verify the authenticity of sesame oils using combined analysis of stable isotope ratio, (1)H NMR spectroscopy, and fatty acid profiles of the oils. Analytical data were obtained from 35 samples of authentic sesame oils and 29 samples of adulterated sesame oils currently distributed in Korea. The orthogonal projection to latent structure discriminant analysis technique was used to select variables that most effectively verify the sesame oil authenticity. The variables include δ(13)C value, integration values of NMR peaks that signify the CH3 of n-3 fatty acids, CH2 between two C═C, protons from sesamin/sesamolin, and 18:1n-9, 18:3n-3, 18:2t, and 18:3t content values. The authenticity of 65 of 70 blind samples was correctly verified by applying the range of the eight variables found in the authentic sesame oil samples, suggesting that triple analysis is a useful approach to verify sesame oil authenticity. PMID:26395416

  5. Secondary structure determination of human. beta. -endorphin by /sup 1/H NMR spectroscopy

    SciTech Connect

    Lichtarge, O.; Jardetzky, O.; Li, C.H.

    1987-09-08

    The /sup 1/H NMR spectra of human ..beta..-endorphin indicate that the peptide exists in random-coil form in aqueous solution but becomes helical in mixed solvent. Thermal denaturation NMR experiments show that in water there is no transition between 24 and 75/sup 0/C, while a slow noncooperative thermal unfolding is observed in a 60% methanol-40% water mixed solvent in the same temperature range. These findings are consistent with circular dichroism studies by other workers concluding that ..beta..-endorphin is a random coil in water but that it forms 50% ..cap alpha..-helix or more in mixed solvents. The peptide in the mixed water-methanol solvent was further studied by correlated spectroscopy (COSY) and nuclear Overhauser effect spectroscopy (NOESY) experiments. These allow a complete set of assignments to be made and establish two distinct stretches over which the solvent induces formation of ..cap alpha..-helices: the first occurs between Tyr-1 and Thr-12 and the second between Leu-14 and extending to Lys-28. There is evidence that the latter is capped by a turn occurring between Lys-28 and Glu-31. These helices form at the enkephalin receptor binding site, which is at the amino terminus, and at the morphine receptor binding site, located at the carboxyl terminus. The findings suggest that these two receptors may specifically recognize ..cap alpha..-helices.

  6. Discrimination of the geographical origin of beef by (1)H NMR-based metabolomics.

    PubMed

    Jung, Youngae; Lee, Jueun; Kwon, Joseph; Lee, Kwang-Sik; Ryu, Do Hyun; Hwang, Geum-Sook

    2010-10-13

    The geographical origin of beef is of increasing interest to consumers and producers due to "mad cow" disease and the implementation of the Free Trade Agreement (FTA). In this study, (1)H NMR spectroscopy coupled with multivariate statistical analyses was used to differentiate the geographical origin of beef samples. Principal component analysis (PCA) and orthogonal projection to latent structure-discriminant analysis (OPLS-DA) showed significant separation between extracts of beef originating from four countries: Australia, Korea, New Zealand, and the United States. The major metabolites responsible for differentiation in OPLS-DA loading plots were succinate and various amino acids including isoleucine, leucine, methionine, tyrosine, and valine. A one-way ANOVA was performed to statistically certify the difference in metabolite levels. The data suggest that NMR-based metabolomics is an efficient method to distinguish fingerprinting difference between raw beef samples, and several metabolites including various amino acids and succinate can be possible biomarkers for discriminating the geographical origin of beef. PMID:20831251

  7. 1H NMR-based metabolic profiling for evaluating poppy seed rancidity and brewing.

    PubMed

    Jawień, Ewa; Ząbek, Adam; Deja, Stanisław; Łukaszewicz, Marcin; Młynarz, Piotr

    2015-12-01

    Poppy seeds are widely used in household and commercial confectionery. The aim of this study was to demonstrate the application of metabolic profiling for industrial monitoring of the molecular changes which occur during minced poppy seed rancidity and brewing processes performed on raw seeds. Both forms of poppy seeds were obtained from a confectionery company. Proton nuclear magnetic resonance (1H NMR) was applied as the analytical method of choice together with multivariate statistical data analysis. Metabolic fingerprinting was applied as a bioprocess control tool to monitor rancidity with the trajectory of change and brewing progressions. Low molecular weight compounds were found to be statistically significant biomarkers of these bioprocesses. Changes in concentrations of chemical compounds were explained relative to the biochemical processes and external conditions. The obtained results provide valuable and comprehensive information to gain a better understanding of the biology of rancidity and brewing processes, while demonstrating the potential for applying NMR spectroscopy combined with multivariate data analysis tools for quality control in food industries involved in the processing of oilseeds. This precious and versatile information gives a better understanding of the biology of these processes. PMID:26540222

  8. Organic solute changes with acidification in Lake Skjervatjern as shown by 1H-NMR spectroscopy

    USGS Publications Warehouse

    Malcolm, R.L.; Hayes, T.

    1994-01-01

    1H-NMR spectroscopy has been found to be a useful tool to establish possible real differences and trends between all natural organic solute fractions (fulvic acids, humic acids, and XAD-4 acids) after acid-rain additions to the Lake Skjervatjern watershed. The proton NMR technique used in this study determined the spectral distribution of nonexchangeable protons among four peaks (aliphatic protons; aliphatic protons on carbon ?? or attached to electronegative groups; protons on carbons attached to O or N heteroatoms; and aromatic protons). Differences of 10% or more in the respective peak areas were considered to represent a real difference. After one year of acidification, fulvic acids decreased 13% (relative) in Peak 3 protons on carbon attached to N and O heteratoms and exhibited a decrease in aromatic protons between 27% and 31%. Humic acids also exhibited an 11% relative decrease in aromatic protons as a result of acidification. After one year of acidification, real changes were shown in three of the four proton assignments in XAD-4 acids. Peak 1 aliphatic protons increased by 14% (relative), Peak 3 protons on carbons attached to O and N heteroatoms decreased by 13% (relative), and aromatic protons (Peak 4) decreased by 35% (relative). Upon acidification, there was a trend in all solutes for aromatic protons to decrease and aliphatic protons to increase. The natural variation in organic solutes as shown in the Control Side B of the lake from 1990 to 1991 is perhaps a small limitation to the same data interpretations of acid rain changes at the Lake Skjervatjern site, but the proton NMR technique shows great promise as an independent scientific tool to detect and support other chemical techniques in establishing organic solute changes with different treatments (i.e., additions of acid rain).

  9. Determining diffusion coefficients of ionic liquids by means of field cycling nuclear magnetic resonance relaxometry.

    PubMed

    Kruk, D; Meier, R; Rachocki, A; Korpała, A; Singh, R K; Rössler, E A

    2014-06-28

    Field Cycling Nuclear Magnetic Resonance (FC NMR) relaxation studies are reported for three ionic liquids: 1-ethyl-3- methylimidazolium thiocyanate (EMIM-SCN, 220-258 K), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4, 243-318 K), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6, 258-323 K). The dispersion of (1)H spin-lattice relaxation rate R1(ω) is measured in the frequency range of 10 kHz-20 MHz, and the studies are complemented by (19)F spin-lattice relaxation measurements on BMIM-PF6 in the corresponding frequency range. From the (1)H relaxation results self-diffusion coefficients for the cation in EMIM-SCN, BMIM-BF4, and BMIM-PF6 are determined. This is done by performing an analysis considering all relevant intra- and intermolecular relaxation contributions to the (1)H spin-lattice relaxation as well as by benefiting from the universal low-frequency dispersion law characteristic of Fickian diffusion which yields, at low frequencies, a linear dependence of R1 on square root of frequency. From the (19)F relaxation both anion and cation diffusion coefficients are determined for BMIM-PF6. The diffusion coefficients obtained from FC NMR relaxometry are in good agreement with results reported from pulsed- field-gradient NMR. This shows that NMR relaxometry can be considered as an alternative route of determining diffusion coefficients of both cations and anions in ionic liquids. PMID:24985656

  10. Determining diffusion coefficients of ionic liquids by means of field cycling nuclear magnetic resonance relaxometry

    NASA Astrophysics Data System (ADS)

    Kruk, D.; Meier, R.; Rachocki, A.; Korpała, A.; Singh, R. K.; Rössler, E. A.

    2014-06-01

    Field Cycling Nuclear Magnetic Resonance (FC NMR) relaxation studies are reported for three ionic liquids: 1-ethyl-3- methylimidazolium thiocyanate (EMIM-SCN, 220-258 K), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4, 243-318 K), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6, 258-323 K). The dispersion of 1H spin-lattice relaxation rate R1(ω) is measured in the frequency range of 10 kHz-20 MHz, and the studies are complemented by 19F spin-lattice relaxation measurements on BMIM-PF6 in the corresponding frequency range. From the 1H relaxation results self-diffusion coefficients for the cation in EMIM-SCN, BMIM-BF4, and BMIM-PF6 are determined. This is done by performing an analysis considering all relevant intra- and intermolecular relaxation contributions to the 1H spin-lattice relaxation as well as by benefiting from the universal low-frequency dispersion law characteristic of Fickian diffusion which yields, at low frequencies, a linear dependence of R1 on square root of frequency. From the 19F relaxation both anion and cation diffusion coefficients are determined for BMIM-PF6. The diffusion coefficients obtained from FC NMR relaxometry are in good agreement with results reported from pulsed- field-gradient NMR. This shows that NMR relaxometry can be considered as an alternative route of determining diffusion coefficients of both cations and anions in ionic liquids.

  11. CHHC and 1H-1H Magnetization Exchange: Analysis by Experimental Solid-State NMR and 11-Spin Density-Matrix Simulations

    PubMed Central

    Aluas, Mihaela; Tripon, Carmen; Griffin, John M.; Filip, Xenia; Ladizhansky, Vladimir; Griffin, Robert G.; Brown, Steven P.; Filip, Claudiu

    2009-01-01

    A protocol is presented for correcting the effect of non-specific cross polarization in CHHC solid-state MAS NMR experiments, thus allowing the recovery of the 1H-1H magnetization exchange functions from the mixing-time dependent buildup of experimental CHHC peak intensity. The presented protocol also incorporates a scaling procedure to take into account the effect of multiplicity of a CH2 or CH3 moiety. Experimental CHHC buildup curves are presented for L-Tyrosine.HCl samples where either all or only one in ten molecules are U-13C labeled. Good agreement between experiment and 11-spin SPINEVOLUTION simulation (including only isotropic 1H chemical shifts) is demonstrated for the initial buildup (tmix < 100 μs) of CHHC peak intensity corresponding to an intramolecular close (2.5 Å) H-H proximity. Differences in the initial CHHC buildup are observed between the 1 in 10 dilute and 100 % samples for cases where there is a close intermolecular H-H proximity in addition to a close intramolecular H-H proximity. For the dilute sample, CHHC cross peak intensities tended to significantly lower values for long mixing times (500 μs) as compared to the 100 % sample. This difference is explained as being due to the dependence of the limiting total magnetization on the ratio Nobs/Ntot between the number of protons that are directly attached to a 13C nucleus and hence contribute significantly to the observed 13C CHHC NMR signal, and the total number of 1H spins into the system. 1H-1H magnetization exchange curves extracted from CHHC spectra for the 100 % L-Tyrosine.HCl sample exhibit a clear sensitivity to the root sum squared dipolar coupling, with fast build-up being observed for the shortest intramolecular distances (2.5 Å) and slower, yet observable build-up for the longer intermolecular distances (up to 5 Å). PMID:19467890

  12. Towards high resolution ^1H NMR spectra of tannin colloidal aggregates

    NASA Astrophysics Data System (ADS)

    Mirabel, M.; Glories, Y.; Pianet, I.; Dufourc, E. J.

    1999-10-01

    The time dependent colloidal formation of tannins in hydro-alcoholic medium has been studied by 1H-NMR. Line broadening observed with time can be cancelled by making use of magic angle sample spinning (MASS) thus yielding sharp lines that allow structural studies. We used as an example catechin, a constitutive monomer of Bordeaux young red wine tannins. Chemical shift variations of polyphenol protons allow monitoring the time course of aggregation. La formation de tanins colloïdaux au cours du temps, en milieu hydroalcoolique, a été suivie par RMN-^1H. Un élargissement marqué des résonances est observé et peut être supprimé par la rotation de l'échantillon à l'angle magique ce qui ouvre tout un champ d'études structurales sur ces composés colloïdaux. L'exemple proposé est celui de la catéchine, monomère constitutif de tannins présents en grande quantité dans les vins rouges jeunes de Bordeaux. Des variations du déplacement chimique de certains protons polyphénoliques permettent de suivre l'évolution temporelle de l'agrégation.

  13. Spatially localized sup 1 H NMR spectra of metabolites in the human brain

    SciTech Connect

    Hanstock, C.C. ); Rothman, D.L.; Jue, T.; Shulman, R.G. ); Prichard, J.W. )

    1988-03-01

    Using a surface coil, the authors have obtained {sup 1}H NMR spectra from metabolites in the human brain. Localization was achieved by combining depth pulses with image-selected in vivo spectroscopy magnetic field gradient methods. {sup 1}H spectra in which total creatine (3.03 ppm) has a signal/noise ratio of 95:1 were obtained in 4 min from 14 ml of brain. A resonance at 2.02 ppm consisting predominantly of N-acetylaspartate was measured relative to the creatine peak in gray and white matter, and the ratio was lower in the white matter. The spin-spin relaxation times of N-acetylaspartate and creatine were measured in white and gray matter and while creatine relaxation times were the same in both, the N-acetylaspartate relaxation time was longer in white matter. Lactate was detected in the normoxic brain and the average of three measurements was {approx}0.5 mM from comparison with the creatine plus phosphocreatine peak, which was assumed to be 10.5 mM.

  14. New Insights on Human Skeletal Muscle Tissue Compartments Revealed by In Vivo T2 NMR Relaxometry

    PubMed Central

    Araujo, Ericky C.A.; Fromes, Yves; Carlier, Pierre G.

    2014-01-01

    The spin-spin (T2) relaxation of 1H-NMR signals in human skeletal muscle has been previously hypothesized to reveal information about myowater compartmentation. Although experimental support has been provided, no consensus has yet emerged concerning the attribution of specific anatomical compartments to the observed T2 components. Potential application of a noninvasive tool that might offer such information urges the quest for a definitive answer to this question. The purpose of this work was to obtain new information that might help elucidate the mechanism of T2 distribution in muscle. To do so, in vivo T2 relaxation data was acquired from the soleus of eight healthy volunteers using a localized Carr-Purcell-Meiboom-Gill technique. Each acquisition contained 1000 echoes with an interecho spacing of 1 ms. Data were acquired from each subject under different vascular filling preparations expected to change exclusively the extracellular water fraction. Two exponential components were systematically observed: an intermediate component (T2 ∼ 32 ms) and a long component (100 < T2 < 210 ms). The relative fraction and T2 value characterizing the long component systematically increased after progressive augmentation of extracellular water volume. Characteristic relaxation behavior for each vascular filling condition was analyzed with a two-site exchange model and a three-site two-exchange model. We show that a two-site exchange model can only predict the observations for small exchange rates, much more representative of transendothelial than transcytolemmal exchange regimes. The three-site two-exchange model representing the intracellular, interstitial, and vascular spaces was capable of precisely predicting the observations for realistic transcytolemmal and transendothelial exchange rates. The estimated intrinsic relative fractions of each of these compartments corroborate with estimations from previous works and strongly suggest that the T2 relaxation from

  15. Improving Assessment of Lipoprotein Profile in Type 1 Diabetes by 1H NMR Spectroscopy

    PubMed Central

    Brugnara, Laura; Mallol, Roger; Ribalta, Josep; Vinaixa, Maria; Murillo, Serafín; Casserras, Teresa; Guardiola, Montse; Vallvé, Joan Carles; Kalko, Susana G.; Correig, Xavier; Novials, Anna

    2015-01-01

    Patients with type 1 diabetes (T1D) present increased risk of cardiovascular disease (CVD). The aim of this study is to improve the assessment of lipoprotein profile in patients with T1D by using a robust developed method 1H nuclear magnetic resonance spectroscopy (1H NMR), for further correlation with clinical factors associated to CVD. Thirty patients with T1D and 30 non-diabetes control (CT) subjects, matched for gender, age, body composition (DXA, BMI, waist/hip ratio), regular physical activity levels and cardiorespiratory capacity (VO2peak), were analyzed. Dietary records and routine lipids were assessed. Serum lipoprotein particle subfractions, particle sizes, and cholesterol and triglycerides subfractions were analyzed by 1H NMR. It was evidenced that subjects with T1D presented lower concentrations of small LDL cholesterol, medium VLDL particles, large VLDL triglycerides, and total triglycerides as compared to CT subjects. Women with T1D presented a positive association with HDL size (p<0.005; R = 0.601) and large HDL triglycerides (p<0.005; R = 0.534) and negative (p<0.005; R = -0.586) to small HDL triglycerides. Body fat composition represented an important factor independently of normal BMI, with large LDL particles presenting a positive correlation to total body fat (p<0.005; R = 0.505), and total LDL cholesterol and small LDL cholesterol a positive correlation (p<0.005; R = 0.502 and R = 0.552, respectively) to abdominal fat in T1D subjects; meanwhile, in CT subjects, body fat composition was mainly associated to HDL subclasses. VO2peak was negatively associated (p<0.005; R = -0.520) to large LDL-particles only in the group of patients with T1D. In conclusion, patients with T1D with adequate glycemic control and BMI and without chronic complications presented a more favourable lipoprotein profile as compared to control counterparts. In addition, slight alterations in BMI and/or body fat composition showed to be relevant to provoking alterations in

  16. An FTIR Calibration for Structural Hydrogen in Feldspars Using 1H MAS NMR

    NASA Astrophysics Data System (ADS)

    Johnson, E. A.; Rossman, G. R.

    2002-05-01

    It is important to know how to determine the speciation and concentration of H in feldspars because this information could be used to determine primary magmatic water activity or to estimate the degree of hydrothermal alteration in igneous rocks. FTIR spectroscopy is sensitive to changes in speciation of hydrogen, and can be calibrated for quantitative determination of H concentration using 1H MAS (magic-angle spinning) NMR spectroscopy. Three pegmatitic albites, one metamorphic albite, three volcanic plagioclases (albite, andesine, and anorthite) and one pegmatite oligoclase were used in this study to provide a range of plagioclase compositions. Two pegmatitic microclines and one sanidine were also studied. Polarized infrared spectra were obtained in the three principal optical directions for each specimen. Samples were prepared for 1H MAS NMR experiments at 12 kHz spinning speed in a dry box, without the use of a liquid grinding aid. A spectrum from anhydrous synthetic corundum was used as a baseline for feldspar NMR spectra. The pegmatitic and metamorphic albites are transparent, but contain submicroscopic fluid inclusions as evidenced by a broad band at 3400 cm-1 and an asymmetric band at 5200 cm-1 in the IR spectra that shift to bands characteristic of ice upon cooling to 77 K. These albites have a very sharp band at 4.7 ppm (relative to TMS) in their NMR spectra consistent with fluid inclusion water. In addition to the broad fluid inclusion band, the pegmatitic albites have sharp bands in the mid-IR similar the OH bands found in quartz. All other plagioclases have broad, anisotropic bands around 3200 cm-1 in the mid-IR and MOH combination stretch-bend bands near 4500 cm-1 in the near-IR, indicative of structural OH. The NMR spectra of these plagioclases have a broad band at 4.7 to 4.9 ppm TMS. The OH vector in plagioclases is preferentially aligned parallel to the a crystallographic axis. The concentration of structural OH in the plagioclases ranges from 50

  17. Are nucleus-independent (NICS) and 1H NMR chemical shifts good indicators of aromaticity in π-stacked polyfluorenes?

    NASA Astrophysics Data System (ADS)

    Osuna, Sílvia; Poater, Jordi; Bofill, Josep M.; Alemany, Pere; Solà, Miquel

    2006-09-01

    We have analyzed the change of local aromaticity in a series of polyfluorene compounds with the increase of the number of π-stacked layers. The local aromaticity of the aromatic and non-aromatic rings of polyfluorenes remains unchanged when going from one to four layers of π-stacked rings according to HOMA, PDI, and FLU aromaticity descriptors. On the contrary, experimental 1H NMR chemical shifts indicate a reduction of the aromaticity of π-stacked rings with the increase of the number of layers. Calculated NICS also show a change of aromaticity, but opposite to the tendency given by the 1H NMR chemical shifts. We show that this increase (decrease) of local aromaticity in superimposed aromatic rings indicated by NICS ( 1H NMR) is not real but the result of the coupling between the magnetic fields generated by the π-stacked rings.

  18. Fatty acids profile of Sacha Inchi oil and blends by 1H NMR and GC-FID.

    PubMed

    Vicente, Juarez; de Carvalho, Mario Geraldo; Garcia-Rojas, Edwin E

    2015-08-15

    This study aimed at the characterization of blends of Sacha Inchi oil (SIO) with different ratios of SO (soybean oil) and CO (corn oil) by nuclear magnetic resonance ((1)H NMR), compared with the data obtained by gas chromatography with a flame ionization detector (GC-FID). The (1)H NMR and GC-FID data from different ratios of SIO were adjusted by a second order polynomial equation. The two techniques were highly correlated (R(2) values ranged from 0.995 to 0.999), revealing that (1)H NMR is an efficient methodology for the quantification of omega-3 fatty acids in oils rich in omega-6 fatty acids or vice versa such as SO and CO and, on the other hand, can be used to quantify ω-6 in oils rich in ω-3, such as SIO. PMID:25794742

  19. Observation by flow sup 1 H NMR and dimerization kinetics and products of reactive ortho-quinodimethanes and benzocyclobutadiene

    SciTech Connect

    Fischer, D.

    1990-09-21

    The reactive o-quinodimethanes, 1,2-dimethylene-1,2-dihydronaphthalene (9) and o-xylylene (1) were observed by flow {sup 1}H NMR spectroscopy at room temperature. The {sup 1}H NMR spectrum of 9 was obtained in the absence of precursor and dimers. However, the {sup 1}H NMR spectrum of the more reactive 1, generated in a similar manner from (o-((trimethylsilyl)methyl)benzyl)trimethylammonium iodide (5.) could be obtained only in the presence of its stable (4 + 2) and (4 + 4) dimers. The dimerization kinetics of 3-methyl- (5{prime}), 3,6-dimethyl- (11), 3-isopropyl- (12), and 3,6-diisoproply-1,2-xylylene (13) in acetonitrile (CH{sub 3}CN) were studied by stopped-flow UV-visible spectroscopy. Fluoride ion induced 1,2-elimination from 2-elimination from 2-trimethylsilylbenzocyclobutenyl-1 mesylate (26) was used to generate the reactive molecule benzocyclobutadiene (1{prime}) in CD{sub 3}CN, which was observed by flow {sup 1}H NMR spectroscopy at room temperature. The {sup 1}H NMR spectrum (in CD{sub 3}CN) of 1,2-dimethylene-1,2-dihydrothiophene (1{double prime}), obtained by fluoride ion induced 1,4-elimination from 3-(trimethylammoniummethyl)-2-(trimethylsilylmethyl)thiophene iodine was observed by flow {sup 1}H NMR spectroscopy at room temperature. The dimerization rate of 1{double prime} in CH{sub 3}CN, generated in the same manner, was measured by UV-visible spectroscopy. 166 refs., 7 figs., 7 tabs.

  20. The secondary structure of echistatin from 1H-NMR, circular-dichroism and Raman spectroscopy.

    PubMed

    Saudek, V; Atkinson, R A; Lepage, P; Pelton, J T

    1991-12-01

    Detailed biophysical studies have been carried out on echistatin, a member of the disintegrin family of small, cysteine-rich, RGD-containing proteins, isolated from the venom of the saw-scaled viper Echis carinatus. Analysis of circular-dichroism spectra indicates that, at 20 degrees C, echistatin contains no alpha-helix but contains mostly beta-turns and beta-sheet. Two isobestic points are observed as the temperature is raised, the conformational changes associated with that observed between 40 degrees C and 72 degrees C being irreversible. Raman spectra also indicate considerable beta-turn and beta-sheet (20%) structure and an absence of alpha-helical structure. Three of the four disulphide bridges are shown to be in an all-gauche conformation, while the fourth adopts a trans-gauche-gauche conformation. The 1H-NMR spectrum of echistatin has been almost fully assigned. A single conformation was observed at 27 degrees C with the four proline residues adopting only the trans conformation. A large number of backbone amide protons were found to exchange slowly, but no segments of the backbone were found to be in either alpha-helical or beta-sheet conformation. A number of turns could be characterised. An irregular beta-hairpin contains the RGD sequence in a mobile loop at its tip. Two of the four disulphide cross-links have been identified from the NMR spectra. The data presented in this paper will serve to define the structure of echistatin more closely in subsequent studies. PMID:1761037

  1. 1H NMR studies of insulin: histidine residues, metal binding, and dissociation in alkaline solution.

    PubMed

    Ramesh, V; Bradbury, J H

    1987-10-01

    The shifts of the H2 histidine B5 and B10 resonances of 2-Zn insulin hexamer were followed in 2H2O by 1H NMR spectroscopy at 270 MHz from pH 9.85 to 7. The two resonances present at high pH, previously assigned to H2 histidine B5 and B10 residues, moved slightly downfield and split into four resonances at pH 8.95 and also at pH 7. By use of a paramagnetic broadening probe (Mn2+) and the addition of Zn2+ to metal-free insulin, it was deduced that the four resonances arose from histidines B10 and B5 in two different magnetic environments, probably either bound to Zn2+ or not bound to Zn2+. The pK' values of the B5 and B10 histidines were determined in 60% 2H2O-40% dioxan, in which insulin was soluble throughout the pH range, to be 7.1 and 6.8, respectively at 37 degrees C. Studies at higher pH indicated that at a concentration level suitable for 1H NMR (approximately 1 mM) at 37 degrees C in 2H2O the 2-Zn hexamer was largely dissociated to dimer at pH 10.3 and to monomer at pH 10.8. Addition of paramagnetic shift probe Ni2+ to metal-free insulin caused changes to the spectrum similar to those produced on addition of diamagnetic Zn2+. Addition of Co2+ gave a different result, but there was no paramagnetic shift of the H2 histidine B10 resonance, probably because of rapid exchange at the binding site. Addition of Cd2+ and of Cd2+ and Ca2+ produced changes that were similar to each other but were different from those observed on addition of Zn2+, probably due to the binding of Cd2+ and Ca2+ at glutamate B13. PMID:3310894

  2. /sup 1/H NMR studies of insulin: histidine residues, metal binding, and dissociation in alkaline solution

    SciTech Connect

    Ramesh, V.; Bradbury, J.H.

    1987-10-01

    The shifts of the H2 histidine B5 and B10 resonances of 2-Zn insulin hexamer were followed in /sup 2/H/sub 2/O by /sup 1/H NMR spectroscopy at 270 MHz from pH 9.85 to 7. The two resonances present at high pH, previously assigned to H2 histidine B5 and B10 residues, moved slightly downfield and split into four resonances at pH 8.95 and also at pH 7. By use of a paramagnetic broadening probe (Mn/sup 2 +/) and the addition of Zn/sup 2 +/ to metal-free insulin, it was deduced that the four resonances arose from histidines B10 and B5 in two different magnetic environments, probably either bound to Zn/sup 2 +/ or not bound to Zn/sup 2 +/. The pK' values of the B5 and B10 histidines were determined in 60% /sup 2/H/sub 2/O-40% dioxan, in which insulin was soluble throughout the pH range, to be 7.1 and 6.8, respectively at 37 degrees C. Studies at higher pH indicated that at a concentration level suitable for /sup 1/H NMR (approximately 1 mM) at 37 degrees C in /sup 2/H/sub 2/O the 2-Zn hexamer was largely dissociated to dimer at pH 10.3 and to monomer at pH 10.8. Addition of paramagnetic shift probe Ni/sup 2 +/ to metal-free insulin caused changes to the spectrum similar to those produced on addition of diamagnetic Zn/sup 2 +/. Addition of Co/sup 2 +/ gave a different result, but there was no paramagnetic shift of the H2 histidine B10 resonance, probably because of rapid exchange at the binding site. Addition of Cd/sup 2 +/ and of Cd/sup 2 +/ and Ca/sup 2 +/ produced changes that were similar to each other but were different from those observed on addition of Zn/sup 2 +/, probably due to the binding of Cd/sup 2 +/ and Ca/sup 2 +/ at glutamate B13.

  3. Mapping hypoxia-induced bioenergetic rearrangements and metabolic signaling by 18O-assisted 31P NMR and 1H NMR spectroscopy.

    PubMed

    Pucar, Darko; Dzeja, Petras P; Bast, Peter; Gumina, Richard J; Drahl, Carmen; Lim, Lynette; Juranic, Nenad; Macura, Slobodan; Terzic, Andre

    2004-01-01

    Brief hypoxia or ischemia perturbs energy metabolism inducing paradoxically a stress-tolerant state, yet metabolic signals that trigger cytoprotection remain poorly understood. To evaluate bioenergetic rearrangements, control and hypoxic hearts were analyzed with 18O-assisted 31P NMR and 1H NMR spectroscopy. The 18O-induced isotope shift in the 31P NMR spectrum of CrP, betaADP and betaATP was used to quantify phosphotransfer fluxes through creatine kinase and adenylate kinase. This analysis was supplemented with determination of energetically relevant metabolites in the phosphomonoester (PME) region of 31P NMR spectra, and in both aromatic and aliphatic regions of 1H NMR spectra. In control conditions, creatine kinase was the major phosphotransfer pathway processing high-energy phosphoryls between sites of ATP consumption and ATP production. In hypoxia, creatine kinase flux was dramatically reduced with a compensatory increase in adenylate kinase flux, which supported heart energetics by regenerating and transferring beta- and gamma-phosphoryls of ATP. Activation of adenylate kinase led to a build-up of AMP, IMP and adenosine, molecules involved in cardioprotective signaling. 31P and 1H NMR spectral analysis further revealed NADH and H+ scavenging by alpha-glycerophosphate dehydrogenase (alphaGPDH) and lactate dehydrogenase contributing to maintained glycolysis under hypoxia. Hypoxia-induced accumulation of alpha-glycerophosphate and nucleoside 5'-monophosphates, through alphaGPDH and adenylate kinase reactions, respectively, was mapped within the increased PME signal in the 31P NMR spectrum. Thus, 18O-assisted 31P NMR combined with 1H NMR provide a powerful approach in capturing rearrangements in cardiac bioenergetics, and associated metabolic signaling that underlie the cardiac adaptive response to stress. PMID:14977188

  4. Probing Structure Property Relationships in Complex Engineering Silicones by 1H NMR

    SciTech Connect

    Chinn, S C; Gjersing, E L; Maxwell, R S; Eastwood, E; Bowen, D; Stephens, T

    2006-07-14

    It is generally accepted that the properties of polymeric materials are controlled by the network structure and the reactions by which they have been constructed. These properties include the bulk moduli at creation, but also the properties as a function of age during use. In order to interpret mechanical properties and predict the time dependent changes in these properties, detailed knowledge of the effect of structural changes must be obtained. The degree and type of crosslinking, the molecular weight between crosslinks, the number of elastically ineffective chains (loops, dangling chain ends, sol-fraction) must be characterized. A number of theoretical and experimental efforts have been reported in the last few years on model networks prepared by endlinking reactions and the relationships of those structures with the ultimate mechanical properties. A range of experimental methods have been used to investigate structure including rheometric, scattering, infrared, {sup 29}Si MAS and CPMAS, {sup 1}H relaxation measurements, and recently {sup 1}H multiple quantum methods. Characterization of the growth of multiple quantum coherences have recently been shown to provide detailed insight into silicone network structure by the ability to selective probe the individual components of the polymer network, such as the polymer-filler interface or network chains. We have employed recently developed MQ methods to investigate the structure-property relationships in a series of complex, endlinked filled-PDMS blends. Here, a systematic study of the relationship between the molecular formulation, as dictated by the amount and type of crosslinks present and by the remaining network chains, and the segmental dynamics as observed by MQ NMR was performed.

  5. Determination of glucan phosphorylation using heteronuclear 1H, 13C double and 1H, 13C, 31P triple-resonance NMR spectra.

    PubMed

    Schmieder, Peter; Nitschke, Felix; Steup, Martin; Mallow, Keven; Specker, Edgar

    2013-10-01

    Phosphorylation and dephosphorylation of starch and glycogen are important for their physicochemical properties and also their physiological functions. It is therefore desirable to reliably determine the phosphorylation sites. Heteronuclear multidimensional NMR-spectroscopy is in principle a straightforward analytical approach even for complex carbohydrate molecules. With heterogeneous samples from natural sources, however, the task becomes more difficult because a full assignment of the resonances of the carbohydrates is impossible to obtain. Here, we show that the combination of heteronuclear (1) H,(13) C and (1) H,(13) C,(31) P techniques and information derived from spectra of a set of reference compounds can lead to an unambiguous determination of the phosphorylation sites even in heterogeneous samples. PMID:23913630

  6. NMR Relaxometry for the Thermal Stability and Phase Transition Mechanism of Flower-like Micelles from Linear and Cyclic Amphiphilic Block Copolymers.

    PubMed

    Wada, Haruna; Kitazawa, Yu; Kuroki, Shigeki; Tezuka, Yasuyuki; Yamamoto, Takuya

    2015-08-18

    Linear and cyclic amphiphilic block copolymers consisting of poly(ethylene oxide) (PEO) as the hydrophilic segment and poly(methyl acrylate) or poly(ethyl acrylate) as the hydrophobic segments were synthesized and self-assembled to form flower-like micelles. The micelles from linear (methyl acrylate)12(ethylene oxide)73(methyl acrylate)12 (Mn = 1000-3200-1000, l-MOM) showed a cloud point (Tc) at 46 °C by the transmittance of the micellar solution, whereas that of cyclic (methyl acrylate)30(ethylene oxide)79 (Mn = 2600-3500, c-MO) increased to 72 °C, as previously reported. DLS showed comparable diameters (l-MOM, 14 nm; c-MO, 12 nm) and Tc values (l-MOM, 48 °C; c-MO, 75 °C). For the investigation of the difference in Tc and the phase transition mechanism based on the polymer topology, NMR relaxometry was performed to determine the spin-lattice (T1) and spin-spin (T2) relaxation times. A decrease in T2 of the PEO segment in both l-MOM and c-MO was observed above Tc, suggesting that slow large-scale motions, such as the detachment of a chain end from the core, bridging, and interpenetration of the micelles, were inhibited. T1 of the PEO segment in l-MOM continuously increased in the experimental temperature range, indicating that the segment is hydrated even above its Tc. On the other hand, that of c-MO reached a ceiling above its Tc, likely due to the prevention of the rotation of the PEO main chain bonds caused by dehydration. Similar results were obtained for linear (ethyl acrylate)8(ethylene oxide)79(ethyl acrylate)8 (Mn = 800-3500-800, l-EOE) and its cyclic (ethyl acrylate)15(ethylene oxide)78 (Mn = 1500-3400, c-EO). PMID:26230670

  7. Using magnetic coupling to implement 1H, 19F, 13C experiments in routine high resolution NMR probes

    NASA Astrophysics Data System (ADS)

    Bowyer, Paul; Finnigan, Jim; Marsden, Brian; Taber, Bob; Zens, Albert

    2015-12-01

    We report in this paper the design of 1H, 19F, 13C circuitry using magnetic coupling which can do on demand experiments where one of the three nuclei is observed and the other two are decoupled. The implementation of this circuitry in routine NMR probes is compared with capacitive coupling methods where it was found that by using magnetic coupling the performance of the routine NMR probe was not impacted by the addition of this circuitry. It is surmised that using this type of circuitry would be highly desirable for those chemists doing routine 19F NMR.

  8. Differential osmotic behavior of water components in living skeletal muscle resolved by 1H-NMR.

    PubMed

    Kimura, Masako; Takemori, Shigeru; Yamaguchi, Maki; Umazume, Yoshiki

    2005-08-01

    Using frog sartorius muscle, we observed transverse relaxation processes of (1)H-NMR signals from myowater. The process could be well described by four characteristic exponentials: the extremely slow exponential of relaxation time constant T(2) > 0.4 s, the slow one of T(2) approximately 0.15 s, the intermediate one of 0.03 s < T(2) < 0.06 s, and the rapid one of T(2) < 0.03 s. Addition of isotonic extracellular solution affected only the extremely slow exponential, linearly increasing its amplitude and gradually increasing its T(2) toward that of the bulk solution (1.7 s). Therefore, this exponential should represent extracellular surplus solution independently of the other exponentials. At two thirds to three times the isotonicity, the amplitude of the intermediate exponential showed normal osmotic behavior in parallel with the volume change of the myofilament lattice measured with x-ray diffraction. In the same tonicity range, the amplitude of the rapid exponential showed converse osmotic behavior. Lower tonicities increased the amplitude of only the slow exponential. Studied tonicities did not affect the T(2) values. The distinct osmotic behavior indicated that each characteristic exponential could be viewed as a distinct water group. In addition, the converse osmotic behavior suggested that the rapid exponential would not be a static water layer on the macromolecule surface. PMID:15894647

  9. 1H NMR spectra of humic and fulvic acids and their peracetic oxidation products

    NASA Astrophysics Data System (ADS)

    Ruggiero, P.; Interesse, F. S.; Cassidei, L.; Sciacovelli, O.

    1980-04-01

    1H NMR spectra of humic (HA) and fulvic (FA) acids and their oxidative degradation products are reported. The HA shows the presence of -( CH2) n - CH3 ( n > 6) chemical fragments belonging to n-alkanes and/or n-fatty acids physically adsorbed onto the macromolecule structure. These fragments are absent in the FA fraction. Both humic fractions reveal the presence of similar amounts of aromatic protons which partly undergo exchange phenomena. The importance of this experimental observation is discussed. Oxidative degradation seems to cause partial cleavage of aromatic rings, more pronounced in the FA than in the HA. The degraded FA shows a higher total acidity and a higher phenolic OH content than the degraded HA. Both degraded fractions display some sharp singlet signals at 1.9 and 3.9 ppm arising from protons belonging to repetitive chemical fragments probably formed during the oxidation reaction. Tentative assignments of these signals are given. A general analysis of the HA and FA degraded spectra seems to indicate that the chemical fragments which undergo peracetic oxidation are substantially similar. The extent of oxidation of the two humic fractions is different. The HA degradation products reveal the presence of oligomeric structures, whereas the degraded FA appears less resistant to the oxidizing agent.

  10. 1H NMR Spectroscopy and MVA Analysis of Diplodus sargus Eating the Exotic Pest Caulerpa cylindracea

    PubMed Central

    De Pascali, Sandra A.; Del Coco, Laura; Felline, Serena; Mollo, Ernesto; Terlizzi, Antonio; Fanizzi, Francesco P.

    2015-01-01

    The green alga Caulerpa cylindracea is a non-autochthonous and invasive species that is severely affecting the native communities in the Mediterranean Sea. Recent researches show that the native edible fish Diplodus sargus actively feeds on this alga and cellular and physiological alterations have been related to the novel alimentary habits. The complex effects of such a trophic exposure to the invasive pest are still poorly understood. Here we report on the metabolic profiles of plasma from D. sargus individuals exposed to C. cylindracea along the southern Italian coast, using 1H NMR spectroscopy and multivariate analysis (Principal Component Analysis, PCA, Orthogonal Partial Least Square, PLS, and Orthogonal Partial Least Square Discriminant Analysis, OPLS-DA). Fish were sampled in two seasonal periods from three different locations, each characterized by a different degree of algal abundance. The levels of the algal bisindole alkaloid caulerpin, which is accumulated in the fish tissues, was used as an indicator of the trophic exposure to the seaweed and related to the plasma metabolic profiles. The profiles appeared clearly influenced by the sampling period beside the content of caulerpin, while the analyses also supported a moderate alteration of lipid and choline metabolism related to the Caulerpa-based diet. PMID:26058009

  11. 1H NMR Metabolic Profiling of Biofluids from Rats with Gastric Mucosal Lesion and Electroacupuncture Treatment

    PubMed Central

    Xu, Jingjing; Cheng, Kian-Kai; Yang, Zongbao; Wang, Chao; Shen, Guiping; Wang, Yadong; Liu, Qiong; Dong, Jiyang

    2015-01-01

    Gastric mucosal lesion (GML) is a common gastrointestinal disorder with multiple pathogenic mechanisms in clinical practice. In traditional Chinese medicine (TCM), electroacupuncture (EA) treatment has been proven as an effective therapy for GML, although the underlying healing mechanism is not yet clear. Here, we used proton nuclear magnetic resonance- (1H NMR-) based metabolomic method to investigate the metabolic perturbation induced by GML and the therapeutic effect of EA treatment on stomach meridian (SM) acupoints. Clear metabolic differences were observed between GML and control groups, and related metabolic pathways were discussed by means of online metabolic network analysis toolbox. By comparing the endogenous metabolites from GML and GML-SM groups, the disturbed pathways were partly recovered towards healthy state via EA treated on SM acupoints. Further comparison of the metabolic variations induced by EA stimulated on SM and the control gallbladder meridian (GM) acupoints showed a quite similar metabolite composition except for increased phenylacetylglycine, 3,4-dihydroxymandelate, and meta-hydroxyphenylacetate and decreased N-methylnicotinamide in urine from rats with EA treated on SM acupoints. The current study showed the potential application of metabolomics in providing further insight into the molecular mechanism of acupuncture. PMID:26170882

  12. Polypharmacotherapy in rheumatology: 1H NMR analysis of binding of phenylbutazone and methotrexate to serum albumin

    NASA Astrophysics Data System (ADS)

    Maciążek-Jurczyk, M.; Sułkowska, A.; Równicka-Zubik, J.; Bojko, B.; Szkudlarek-Haśnik, A.; Knopik, M.; Sułkowski, W. W.

    2011-05-01

    The influence of phenylbutazone (Phe) and methotrexate (MTX) on binding of MTX and Phe to human (HSA) and bovine (BSA) serum albumin in the low-affinity binding sites is investigated. The strength and kind of interactions between serum albumin (SA) and drugs used in combination therapy were found using 1H NMR spectroscopy. A stoichiometric molar ratios for Phe-SA and MTX-SA complexes are 36:1 and 31:1, respectively. It appeared these molar ratios are higher for the ternary systems than it were in the binary ones. The presence of the additional drug (MTX or Phe) causes the increase of an affinity of albumin towards Phe and MTX. It was found that the aliphatic groups of MTX are more resistant to the influence of Phe on the MTX-SA complex than the aromatic rings. The results showed the important impact of another drug (MTX or Phe) on the affinity of SA towards Phe and MTX in the low-affinity binding sites. This work is a subsequent part of the spectroscopic study on Phe-MTX-SA interactions (Maciążek-Jurczyk, 2009 [1]).

  13. Resolution Improvements in in Vivo1H NMR Spectra with Increased Magnetic Field Strength

    NASA Astrophysics Data System (ADS)

    Gruetter, Rolf; Weisdorf, Sally A.; Rajanayagan, Vasantham; Terpstra, Melissa; Merkle, Hellmut; Truwit, Charles L.; Garwood, Michael; Nyberg, Scott L.; Ugurbil, Kâmil

    1998-11-01

    The measurement of cerebral metabolites using highly homologous localization techniques and similar shimming methods was performed in the human brain at 1.5 and 4 T as well as in the dog and rat brain at 9.4 T. In rat brain, improved resolution was achieved by shimming all first- and second-order shim coils using a fully adiabatic FASTMAP sequence. The spectra showed a clear improvement in spectral resolution for all metabolite resonances with increased field strength. Changes in cerebral glutamine content were clearly observed at 4 T compared to 1.5 T in patients with hepatic encephalopathy. At 9.4 T, glutamine H4 at 2.46 ppm was fully resolved from glutamate H4 at 2.37 ppm, as was the potential resonance from γ-amino-butyric acid at 2.30 ppm and N-acetyl-aspartyl-glutamate at 2.05 ppm. Singlet linewidths were found to be as low as 6 Hz (0.015 ppm) at 9.4 T, indicating a substantial decrease in ppm linewidth with field strength. Furthermore, the methylene peak of creatine was partially resolved from phosphocreatine, indicating a close to 1:1 relationship in gray matter. We conclude that increasing the magnetic field strength increases spectral resolution also for1H NMR, which can lead to more than linear sensitivity gains.

  14. Relaxation of water protons in highly concentrated aqueous protein systems studied by 1H NMR spectroscopy.

    PubMed

    Szuminska, K; Gutsze, A; Kowalczyk, A

    2001-01-01

    Concentrated Aqueous Protein Systems, Proton Relaxation Times, Slow Chemical Exchange In this paper we present proton spin-lattice (T1) and spin-spin (T2) relaxation times measured vs. concentration, temperature, pulse interval (tauCPMG) as well as 1H NMR spectral measurements in a wide range of concentrations of bovine serum albumin (BSA) solutions. The anomalous relaxation behaviour of the water protons, similar to that observed in mammalian lenses, was found in the two most concentrated solutions (44% and 46%). The functional dependence of the spin-spin relaxation time vs. tauCPMG pulse interval and the values of the motional activation parameters obtained from the temperature dependencies of spin-lattice relaxation times suggest that the water molecule mobility is reduced in these systems. The slow exchange process on the T2 time scale is proposed to explain the obtained data. The proton spectral measurements support the hypothesis of a slow exchange mechanism in the highest concentrated solutions. From the analysis of the shape of the proton spectra the mean exchange times between bound and bulk water proton groups (tauex) have been estimated for the range of the highest concentrations (30%-46%). The obtained values are of the order of milliseconds assuring that the slow exchange condition is fulfilled in the most concentrated samples. PMID:11837660

  15. 1H NMR global metabolic phenotyping of acute pancreatitis in the emergency unit.

    PubMed

    Villaseñor, Alma; Kinross, James M; Li, Jia V; Penney, Nicholas; Barton, Richard H; Nicholson, Jeremy K; Darzi, Ara; Barbas, Coral; Holmes, Elaine

    2014-12-01

    We have investigated the urinary and plasma metabolic phenotype of acute pancreatitis (AP) patients presenting to the emergency room at a single center London teaching hospital with acute abdominal pain using (1)H NMR spectroscopy and multivariate modeling. Patients were allocated to either the AP (n = 15) or non-AP patients group (all other causes of abdominal pain, n = 21) on the basis of the national guidelines. Patients were assessed for three clinical outcomes: (1) diagnosis of AP, (2) etiology of AP caused by alcohol consumption and cholelithiasis, and (3) AP severity based on the Glasgow score. Samples from AP patients were characterized by high levels of urinary ketone bodies, glucose, plasma choline and lipid, and relatively low levels of urinary hippurate, creatine and plasma-branched chain amino acids. AP could be reliably identified with a high degree of sensitivity and specificity (OPLS-DA model R(2) = 0.76 and Q(2)Y = 0.59) using panel of discriminatory biomarkers consisting of guanine, hippurate and creatine (urine), and valine, alanine and lipoproteins (plasma). Metabolic phenotyping was also able to distinguish between cholelithiasis and colonic inflammation among the heterogeneous non-AP group. This work has demonstrated that combinatorial biomarkers have a strong diagnostic and prognostic potential in AP with relevance to clinical decision making in the emergency unit. PMID:25160714

  16. 1H-NMR metabolite profiles of different strains of Plasmodium falciparum.

    PubMed

    Teng, Rongwei; Lehane, Adele M; Winterberg, Markus; Shafik, Sarah H; Summers, Robert L; Martin, Rowena E; van Schalkwyk, Donelly A; Junankar, Pauline R; Kirk, Kiaran

    2014-01-01

    Although efforts to understand the basis for inter-strain phenotypic variation in the most virulent malaria species, Plasmodium falciparum, have benefited from advances in genomic technologies, there have to date been few metabolomic studies of this parasite. Using 1H-NMR spectroscopy, we have compared the metabolite profiles of red blood cells infected with different P. falciparum strains. These included both chloroquine-sensitive and chloroquine-resistant strains, as well as transfectant lines engineered to express different isoforms of the chloroquine-resistance-conferring pfcrt (P. falciparum chloroquine resistance transporter). Our analyses revealed strain-specific differences in a range of metabolites. There was marked variation in the levels of the membrane precursors choline and phosphocholine, with some strains having >30-fold higher choline levels and >5-fold higher phosphocholine levels than others. Chloroquine-resistant strains showed elevated levels of a number of amino acids relative to chloroquine-sensitive strains, including an approximately 2-fold increase in aspartate levels. The elevation in amino acid levels was attributable to mutations in pfcrt. Pfcrt-linked differences in amino acid abundance were confirmed using alternate extraction and detection (HPLC) methods. Mutations acquired to withstand chloroquine exposure therefore give rise to significant biochemical alterations in the parasite. PMID:25405893

  17. 1H, 13C and 29Si NMR of tetramethylsilane in liquid crystals

    NASA Astrophysics Data System (ADS)

    Hiltunen, Y.; Jokisaari, J.

    1990-12-01

    The 1H, 13C and 29Si NMR spectra of tetramethylsilane (TMS) dissolved in two nematic liquid crystals (LC) and in their three mixtures were recorded. The proton—proton, proton—carbon and proton—silicon dipolar couplings, which arise from molecular deformation in the LC environment, were determined. The results for the 2DHH, 4DHH, 3DCH and 2DSiH couplings show only a small variation as a function of the composition of the LC mixture. On the contrary, the one-bond CH dipolar coupling is markedly solvent dependent: it varies from -6.22 Hz (in ZLI 1167) to +3.63 Hz (in phase IV). The 1DCH coupling of TMS vanishes in a certain mixture of the two liquid crystals; this mixture, however, is not the same as that in which the corresponding coupling of methane was earlier observed to vanish. This different behaviour of TMS and methane may be due to the additional torques which act on the SiC bonds of TMS.

  18. Relativistic force field: parametric computations of proton-proton coupling constants in (1)H NMR spectra.

    PubMed

    Kutateladze, Andrei G; Mukhina, Olga A

    2014-09-01

    Spin-spin coupling constants in (1)H NMR carry a wealth of structural information and offer a powerful tool for deciphering molecular structures. However, accurate ab initio or DFT calculations of spin-spin coupling constants have been very challenging and expensive. Scaling of (easy) Fermi contacts, fc, especially in the context of recent findings by Bally and Rablen (Bally, T.; Rablen, P. R. J. Org. Chem. 2011, 76, 4818), offers a framework for achieving practical evaluation of spin-spin coupling constants. We report a faster and more precise parametrization approach utilizing a new basis set for hydrogen atoms optimized in conjunction with (i) inexpensive B3LYP/6-31G(d) molecular geometries, (ii) inexpensive 4-31G basis set for carbon atoms in fc calculations, and (iii) individual parametrization for different atom types/hybridizations, not unlike a force field in molecular mechanics, but designed for the fc's. With the training set of 608 experimental constants we achieved rmsd <0.19 Hz. The methodology performs very well as we illustrate with a set of complex organic natural products, including strychnine (rmsd 0.19 Hz), morphine (rmsd 0.24 Hz), etc. This precision is achieved with much shorter computational times: accurate spin-spin coupling constants for the two conformers of strychnine were computed in parallel on two 16-core nodes of a Linux cluster within 10 min. PMID:25158224

  19. Quantification of acesulfame potassium in processed foods by quantitative 1H NMR.

    PubMed

    Ohtsuki, Takashi; Sato, Kyoko; Abe, Yutaka; Sugimoto, Naoki; Akiyama, Hiroshi

    2015-01-01

    Acesulfame potassium (AceK), a high-intensity and non-caloric artificial sweetener, is used in various processed foods as a food additive. In this study, we established and validated a method for determining the AceK content in various processed foods by solvent extraction and quantitative (1)H NMR, using a certified reference material as the internal standard. In the recovery test, the proposed method gave satisfactory recoveries (88.4-99.6%) and repeatabilities (0.6-5.6%) for various processed foods. The limit of quantification was confirmed as 0.13 g kg(-1), which was sufficiently low for the purposes of monitoring AceK levels. In the analysis of commercially processed foods containing AceK, all AceK contents determined by the proposed method were in good agreement with those obtained by a conventional method based on dialysis and HPLC. Moreover, this method can achieve rapid quantification and yields analytical data with traceability to the International System of Units (SI) without the need for an authentic analyte standard. Therefore, the proposed method is a useful and practical tool for the determination of AceK in processed foods. PMID:25281163

  20. 1H NMR Spectroscopy and MVA Analysis of Diplodus sargus Eating the Exotic Pest Caulerpa cylindracea.

    PubMed

    De Pascali, Sandra A; Del Coco, Laura; Felline, Serena; Mollo, Ernesto; Terlizzi, Antonio; Fanizzi, Francesco P

    2015-06-01

    The green alga Caulerpa cylindracea is a non-autochthonous and invasive species that is severely affecting the native communities in the Mediterranean Sea. Recent researches show that the native edible fish Diplodus sargus actively feeds on this alga and cellular and physiological alterations have been related to the novel alimentary habits. The complex effects of such a trophic exposure to the invasive pest are still poorly understood. Here we report on the metabolic profiles of plasma from D. sargus individuals exposed to C. cylindracea along the southern Italian coast, using 1H NMR spectroscopy and multivariate analysis (Principal Component Analysis, PCA, Orthogonal Partial Least Square, PLS, and Orthogonal Partial Least Square Discriminant Analysis, OPLS-DA). Fish were sampled in two seasonal periods from three different locations, each characterized by a different degree of algal abundance. The levels of the algal bisindole alkaloid caulerpin, which is accumulated in the fish tissues, was used as an indicator of the trophic exposure to the seaweed and related to the plasma metabolic profiles. The profiles appeared clearly influenced by the sampling period beside the content of caulerpin, while the analyses also supported a moderate alteration of lipid and choline metabolism related to the Caulerpa-based diet. PMID:26058009

  1. Intra- and extracellular carbohydrates in plant cell cultures investigated by (1)H-NMR.

    PubMed

    Schripsema, J; Erkelens, C; Verpoorte, R

    1991-01-01

    With the aim of quantifying intra- and extracellular carbohydrates media and cell-extracts from a Tabernaemontana divaricata plant cell-suspension culture were investigated with (1)H-NMR.For suppression of the solvent peak the Meiboom-Gill modification of the Carr-Purcell (CPMG) spin-echo sequence was used after addition of a paramagnetic relaxation agent (Mn(2+)) to the sample. Several aspects of this method were optimized (the manganese concentration, the interpulse delay and the number of spin-echo cycles) so as to obtain a rapid and easy method in which no pretreatment of media or cell-extracts was needed. Besides the speed and ease of the method, also the direct identification of carbohydrates and other main components is an advantage.The exhaustion of extracellular carbohydrates was found to coincide with the maximum amount of intracellular carbohydrates. The intracellular carbohydrates, i.e. glucose and fructose, were consumed at a low rate, during several weeks. PMID:24213796

  2. Studies of Secondary Melanoma on C57BL/6J Mouse Liver Using 1H NMR Metabolomics

    SciTech Connect

    Feng, Ju; Isern, Nancy G.; Burton, Sarah D.; Hu, Jian Z.

    2013-10-31

    NMR metabolomics, consisting of solid state high resolution (hr) magic angle spinning (MAS) 1H NMR (1H hr-MAS), liquid state high resolution 1H-NMR, and principal components analysis (PCA) has been used to study secondary metastatic B16-F10 melanoma in C57BL/6J mouse liver . The melanoma group can be differentiated from its control group by PCA analysis of the absolute concentrations or by the absolute peak intensities of metabolites from either 1H hr-MAS NMR data on intact liver tissues or liquid state 1H-NMR spectra on liver tissue extracts. In particular, we found that the absolute concentrations of alanine, glutamate, creatine, creatinine, fumarate and cholesterol are elevated in the melanoma group as compared to controls, while the absolute concentrations of succinate, glycine, glucose, and the family of linear lipids including long chain fatty acids, total choline and acylglycerol are decreased. The ratio of glycerophosphocholine to phosphocholine is increased by about 1.5 fold in the melanoma group, while the absolute concentration of total choline is actually lower in melanoma mice. These results suggest the following picture in secondary melanoma metastasis: Linear lipid levels are decreased by beta oxidation in the melanoma group, which contributes to an increase in the synthesis of cholesterol, and also provides an energy source input for TCA cycle. These findings suggest a link between lipid oxidation, the TCA cycle and the hypoxia-inducible factors (HIF) signal pathway in tumor metastases. Thus this study indicates that the metabolic profile derived from NMR analysis can provide a valuable bio-signature of malignancy and cell hypoxia in metastatic melanoma.

  3. Dolphin: a tool for automatic targeted metabolite profiling using 1D and 2D (1)H-NMR data.

    PubMed

    Gómez, Josep; Brezmes, Jesús; Mallol, Roger; Rodríguez, Miguel A; Vinaixa, Maria; Salek, Reza M; Correig, Xavier; Cañellas, Nicolau

    2014-12-01

    One of the main challenges in nuclear magnetic resonance (NMR) metabolomics is to obtain valuable metabolic information from large datasets of raw NMR spectra in a high throughput, automatic, and reproducible way. To date, established software packages used to match and quantify metabolites in NMR spectra remain mostly manually operated, leading to low resolution results and subject to inconsistencies not attributable to the NMR technique itself. Here, we introduce a new software package, called Dolphin, able to automatically quantify a set of target metabolites in multiple sample measurements using an approach based on 1D and 2D NMR techniques to overcome the inherent limitations of 1D (1)H-NMR spectra in metabolomics. Dolphin takes advantage of the 2D J-resolved NMR spectroscopy signal dispersion to avoid inconsistencies in signal position detection, enhancing the reliability and confidence in metabolite matching. Furthermore, in order to improve accuracy in quantification, Dolphin uses 2D NMR spectra to obtain additional information on all neighboring signals surrounding the target metabolite. We have compared the targeted profiling results of Dolphin, recorded from standard biological mixtures, with those of two well established approaches in NMR metabolomics. Overall, Dolphin produced more accurate results with the added advantage of being a fully automated and high throughput processing package. PMID:25370160

  4. NMR profiling of biomolecules at natural abundance using 2D 1H-15N and 1H-13C multiplicity-separated (MS) HSQC spectra

    NASA Astrophysics Data System (ADS)

    Chen, Kang; Freedberg, Darón I.; Keire, David A.

    2015-02-01

    2D NMR 1H-X (X = 15N or 13C) HSQC spectra contain cross-peaks for all XHn moieties. Multiplicity-edited1H-13C HSQC pulse sequences generate opposite signs between peaks of CH2 and CH/CH3 at a cost of lower signal-to-noise due to the 13C T2 relaxation during an additional 1/1JCH period. Such CHn-editing experiments are useful in assignment of chemical shifts and have been successfully applied to small molecules and small proteins (e.g. ubiquitin) dissolved in deuterated solvents where, generally, peak overlap is minimal. By contrast, for larger biomolecules, peak overlap in 2D HSQC spectra is unavoidable and peaks with opposite phases cancel each other out in the edited spectra. However, there is an increasing need for using NMR to profile biomolecules at natural abundance dissolved in water (e.g., protein therapeutics) where NMR experiments beyond 2D are impractical. Therefore, the existing 2D multiplicity-edited HSQC methods must be improved to acquire data on nuclei other than 13C (i.e.15N), to resolve more peaks, to reduce T2 losses and to accommodate water suppression approaches. To meet these needs, a multiplicity-separated1H-X HSQC (MS-HSQC) experiment was developed and tested on 500 and 700 MHz NMR spectrometers equipped with room temperature probes using RNase A (14 kDa) and retroviral capsid (26 kDa) proteins dissolved in 95% H2O/5% D2O. In this pulse sequence, the 1/1JXH editing-period is incorporated into the semi-constant time (semi-CT) X resonance chemical shift evolution period, which increases sensitivity, and importantly, the sum and the difference of the interleaved 1JXH-active and the 1JXH-inactive HSQC experiments yield two separate spectra for XH2 and XH/XH3. Furthermore we demonstrate improved water suppression using triple xyz-gradients instead of the more widely used z-gradient only water-suppression approach.

  5. (1)H, (13)C and (15)N NMR assignments of a calcium-binding protein from Entamoeba histolytica.

    PubMed

    Verma, Deepshikha; Bhattacharya, Alok; Chary, Kandala V R

    2016-04-01

    We report almost complete sequence specific (1)H, (13)C and (15)N NMR assignments of a 150-residue long calmodulin-like calcium-binding protein from Entamoeba histolytica (EhCaBP6), as a prelude to its structural and functional characterization. PMID:26377206

  6. Application of (1)h NMR profiling to assess seed metabolomic diversity. A case study on a soybean era population.

    PubMed

    Harrigan, George G; Skogerson, Kirsten; MacIsaac, Susan; Bickel, Anna; Perez, Tim; Li, Xin

    2015-05-13

    (1)H NMR spectroscopy offers advantages in metabolite quantitation and platform robustness when applied in food metabolomics studies. This paper provides a (1)H NMR-based assessment of seed metabolomic diversity in conventional and glyphosate-resistant genetically modified (GM) soybean from a genetic lineage representing ∼35 years of breeding and differing yield potential. (1)H NMR profiling of harvested seed allowed quantitation of 27 metabolites, including free amino acids, sugars, and organic acids, as well as choline, O-acetylcholine, dimethylamine, trigonelline, and p-cresol. Data were analyzed by canonical discriminant analysis (CDA) and principal variance component analysis (PVCA). Results demonstrated that (1)H NMR spectroscopy was effective in highlighting variation in metabolite levels in the genetically diverse sample set presented. The results also confirmed that metabolite variability is influenced by selective breeding and environment, but not genetic modification. Therefore, metabolite variability is an integral part of crop improvement that has occurred for decades and is associated with a history of safe use. PMID:25940152

  7. Microscale Synthesis and (super 1)H NMR Analysis of Zn(super II) and Ni(super II) Tetraphenylporphyrins

    ERIC Educational Resources Information Center

    Saucedo, Laura; Mink, Larry M.

    2005-01-01

    A multisection undergraduate laboratory involving the microscale synthesis and spectroscopic analysis of unmetalled porphyrins and their corresponding metalloporphyins is described. The microscale synthesis involving the isolation of the metalloporphyrins as solids and their corresponding (super 1)H NMR spectra are presented.

  8. 1H NMR studies of aerosol-OT reverse micelles with alkali and magnesium counterions: preparation and analysis of MAOTs.

    PubMed

    Stahla, Michelle L; Baruah, Bharat; James, Dustin M; Johnson, Michael D; Levinger, Nancy E; Crans, Debbie C

    2008-06-17

    Simple procedures and characterization of a series of well-defined precursors are described for preparation of a unique microenvironment in nanoreactors, reverse micelles. The Na(+), K(+), Rb(+), Cs(+), and Mg(2+) surfactants were prepared using liquid-liquid ion exchange using chloride and nitrate salts. The surfactants were characterized using (1)H NMR spectroscopy and a variety of other techniques. (1)H NMR spectroscopy was found to be a sensitive probe for characterization of the size of the nanoreactor as well as its water content. (1)H NMR spectra can be used for detailed characterization of reactions in confined environments when counterion effects are likely to be important. (1)H NMR spectroscopy revealed two separate peaks corresponding to water in Mg(AOT)2 samples; one peak arises from water coordinated to the Mg(2+) ion while the other peak arises from bulk water. The two water signals arise directly from the slow exchange of the water coordinated to Mg(2+) in these microemulsions with water in the water pool, and provide an opportunity to study hydration of Mg(2+). This work thus extends the potential use of MAOT microemulsions for applications such as in green chemistry. PMID:18484757

  9. LC-MS and 1H NMR as an improved dereplication tool to identify antifungal diterpenoids from Sagittaria latifolia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A dereplication strategy using a combination of liquid chromatography-mass spectrometry (LC-MS) and proton nuclear magnetic resonance spectroscopy (1H NMR) to facilitate compound identification towards antifungal natural product discovery is presented. This analytical approach takes advantage of th...

  10. An optimized and validated (1)H NMR method for the quantification of α-pinene in essentials oils.

    PubMed

    Cerceau, Cristiane I; Barbosa, Luiz C A; Filomeno, Claudinei A; Alvarenga, Elson S; Demuner, Antônio J; Fidencio, Paulo H

    2016-04-01

    The authenticity and composition of commercial essential oils requires strict quality control. Due to the importance of α-pinene containing essential oils, a rapid and efficient method for quantification of this terpene in oils of eucalyptus, pink pepper and turpentine using (1)H NMR was developed and validated. All evaluated parameters (selectivity, linearity, accuracy/precision, repeatability, robustness, stability of analyte and internal standard in solutions) showed satisfactory results. The limit of detection (LOD) and limit of quantification (LOQ) were 0.1 and 2.5mg respectively. These values indicated that α-pinene was detected in 35 mg samples containing at least 0.3% of this compound. In addition, a minimum of 8% of α-pinene in the sample was required for quantification. Furthermore, the standard deviations found in the (1)H NMR methodology were less than 1% and were lower than those obtained by gas chromatographic analysis. Statistical tests have shown that the results obtained by (1)H NMR methodology are similar to those obtained by GC-FID technique using external and internal standardization and normalization within 95% confidence. R&R values lower than 10% have shown that all the methods are appropriate and the (1)H NMR method is suitable for quantification of α-pinene in samples of essential oils since this method possessed the smallest R&R (1.81) value. PMID:26838386

  11. Application of a quantitative (1)H-NMR method for the determination of paeonol in Moutan cortex, Hachimijiogan and Keishibukuryogan.

    PubMed

    Tanaka, Rie; Shibata, Hikari; Sugimoto, Naoki; Akiyama, Hiroshi; Nagatsu, Akito

    2016-10-01

    Quantitative (1)H-NMR ((1)H-qNMR) was applied to the determination of paeonol concentration in Moutan cortex, Hachimijiogan, and Keishibukuryogan. Paeonol is a major component of Moutan cortex, and its purity was calculated from the ratio of the intensity of the paeonol H-3' signal at δ 6.41 ppm in methanol-d 4 or 6.40 ppm in methanol-d 4 + TFA-d to that of a hexamethyldisilane (HMD) signal at 0 ppm. The concentration of HMD was corrected with SI traceability by using potassium hydrogen phthalate of certified reference material grade. As a result, the paeonol content in two lots of Moutan cortex as determined by (1)H-qNMR was found to be 1.59 % and 1.62 %, respectively, while the paeonol content in Hachimijiogan and Keishibukuryogan was 0.15 % and 0.22 %, respectively. The present study demonstrated that the (1)H-NMR method is useful for the quantitative analysis of crude drugs and Kampo formulas. PMID:27164909

  12. Combined (1)H NMR and LSER study for the compound-specific interactions between organic contaminants and organobentonites.

    PubMed

    Ruan, Xiuxiu; Zhu, Lizhong; Chen, Baoliang; Qian, Guangren; Frost, Ray L

    2015-12-15

    The compound-specific mechanisms for the sorption of organic contaminants onto cetyltrimethylammonium-saturated bentonite (i.e., CTMA-Bentonite) in water were evaluated by (1)H NMR study and Linear Solvation Energy Relationship (LSER) approach. In (1)H NMR study, comparing with pure CTMAB, the up-field shifts of hydrogen peaks for CH2N(+) and CH3N(+) of CTMA(+) in CTMAB-aromatics (1-naphtylamine, aniline and phenol) mixtures are much greater than that in CTMAB-aliphatics (cyclohexanone and cyclohexanol) mixtures. Meanwhile, the peak position of hydrogen on amino- and hydroxyl-groups of aromatic compounds also changes greatly. (1)H NMR data demonstrated the strong molecular interaction between the positive ammonium group of CTMA(+) and the delocalized π-systems of aromatic solutes, whereas the interactions of CTMA(+) with aliphatic compounds having electron-donating groups (such as cyclohexanol and cyclohexanone) or aromatic ring substituted by electron-withdrawing groups (i.e., nitrobenzene) or nonpolar aromatic compounds with single phenyl ring (i.e., toluene) are weak. The derived LSER equation was obtained by a multiple regression of the solid-water sorption coefficients (Kd) of 16 probe solutes upon their solvation parameters, and demonstrates aromatics sorption onto CTMA-Bentonite is concurrently governed by the π-/n-electron pair donor-accepter interaction and the cavity/dispersion interaction, while the predominant mechanism for aliphatic compounds is the cavity/dispersion interaction, consisting with the (1)H NMR results. PMID:26319328

  13. Extraction and [superscript 1]H NMR Analysis of Fats from Convenience Foods: A Laboratory Experiment for Organic Chemistry

    ERIC Educational Resources Information Center

    Hartel, Aaron M.; Moore, Amy C.

    2014-01-01

    The extraction and analysis of fats from convenience foods (crackers, cookies, chips, candies) has been developed as an experiment for a second-year undergraduate organic chemistry laboratory course. Students gravimetrically determine the fat content per serving and then perform a [superscript 1]H NMR analysis of the recovered fat to determine the…

  14. Complete assignment of (1)H and (13)C NMR spectra of standard neo-iota-carrabiose oligosaccharides.

    PubMed

    Jouanneau, Diane; Boulenguer, Patrick; Mazoyer, Jacques; Helbert, William

    2010-02-26

    Standard Eucheuma denticulatum iota-carrageenan was degraded with the Alteromonas fortis iota-carrageenase. The most abundant products, the neo-iota-carratetraose and neo-iota-carrahexaose were purified by permeation gel chromatography, and their corresponding (1)H and (13)C NMR spectra were fully assigned. PMID:20038459

  15. Spinning-frequency-dependent linewidths in 1H-decoupled 13C magic-angle spinning NMR spectra

    NASA Astrophysics Data System (ADS)

    Nakai, Toshihito; McDowell, Charles A.

    1994-09-01

    The broadenings observed in 13C MAS NMR spectra, which depend on the sample-spinning speed, were studied, using polycrystalline adamantane. Not only was a monotonic increase of the linewidths with the increase of the spinning frequency observed, but also a novel resonant feature was found. The phenomena were interpreted as originating from rotary-resonance 13C 1H recoupling.

  16. Discrimination of Basal Cell Carcinoma from Normal Skin Tissue Using High-Resolution Magic Angle Spinning 1H NMR Spectroscopy

    PubMed Central

    Mun, Je-Ho; Lee, Heonho; Yoon, Dahye; Kim, Byung-Soo; Kim, Moon-Bum; Kim, Shukmann

    2016-01-01

    High-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy is a useful tool for investigating the metabolism of various cancers. Basal cell carcinoma (BCC) is the most common skin cancer. However, to our knowledge, data on metabolic profiling of BCC have not been reported in the literature. The objective of the present study was to investigate the metabolic profiling of cutaneous BCC using HR-MAS 1H NMR spectroscopy. HR-MAS 1H NMR spectroscopy was used to analyze the metabolite profile and metabolite intensity of histopathologically confirmed BCC tissues and normal skin tissue (NST) samples. The metabolic intensity normalized to the total spectral intensities in BCC and NST was compared, and multivariate analysis was performed with orthogonal partial least-squares discriminant analysis (OPLS-DA). P values < 0.05 were considered statistically significant. Univariate analysis revealed 9 metabolites that showed statistically significant difference between BCC and NST. In multivariate analysis, the OPLS-DA models built with the HR-MAS NMR metabolic profiles revealed a clear separation of BCC from NST. The receiver operating characteristic curve generated from the results revealed an excellent discrimination of BCC from NST with an area under the curve (AUC) value of 0.961. The present study demonstrated that the metabolite profile and metabolite intensity differ between BCC and NST, and that HR-MAS 1H NMR spectroscopy can be a valuable tool in the diagnosis of BCC. PMID:26934749

  17. Bonding in hard and elastic amorphous carbon nitride films investigated using 15N, 13C, and 1H NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Gammon, W. J.; Hoatson, G. L.; Holloway, B. C.; Vold, R. L.; Reilly, A. C.

    2003-11-01

    The nitrogen bonding in hard and elastic amorphous carbon nitride (a-CNx) films is examined with 15N, 13C, and 1H nuclear magnetic resonance (NMR) spectroscopy. Films were deposited by dc magnetron sputtering, in a pure nitrogen discharge on Si(001) substrates at 300 °C. Nanoindentation tests revealed an elastic recovery of 80%, a hardness of 5 GPa, and an elastic modulus of 47 GPa. The NMR results show that nitrogen bonding in this material is consistent with sp2 hybridized nitrogen incorporated in an aromatic carbon environment. The data also indicate that the a-CNx prepared for this study has very low hydrogen content and is hydrophilic. Specifically, analysis of 15N and 13C cross polarization magic angle spinning and 1H NMR experiments suggests that water preferentially protonates nitrogen sites.

  18. Selective excitation enables assignment of proton resonances and {sup 1}H-{sup 1}H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy

    SciTech Connect

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-07-21

    Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of {sup 1}H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as {sup 13}C or {sup 15}N. In this method, after the initial preparation of proton magnetization and cross-polarization to {sup 13}C nuclei, transverse magnetization of desired {sup 13}C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific {sup 13}C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of {sup 1}H-{sup 1}H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids.

  19. Selective excitation enables assignment of proton resonances and (1)H-(1)H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy.

    PubMed

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-07-21

    Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of (1)H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as (13)C or (15)N. In this method, after the initial preparation of proton magnetization and cross-polarization to (13)C nuclei, transverse magnetization of desired (13)C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific (13)C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of (1)H-(1)H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids. PMID:26203019

  20. Selective excitation enables assignment of proton resonances and 1H-1H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-07-01

    Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of 1H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as 13C or 15N. In this method, after the initial preparation of proton magnetization and cross-polarization to 13C nuclei, transverse magnetization of desired 13C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific 13C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of 1H-1H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids.

  1. 1H NMR-based metabolomics combined with HPLC-PDA-MS-SPE-NMR for investigation of standardized Ginkgo biloba preparations

    PubMed Central

    Agnolet, Sara; Jaroszewski, Jerzy W.; Verpoorte, Robert

    2010-01-01

    Commercial preparations of Ginkgo biloba are very complex mixtures prepared from raw leaf extracts by a series of extraction and prepurification steps. The pharmacological activity is attributed to a number of flavonoid glycosides and unique terpene trilactones (TTLs), with largely uncharacterized pharmacological profiles on targets involved in neurological disorders. It is therefore important to complement existing targeted analytical methods for analysis of Ginkgo biloba preparations with alternative technology platforms for their comprehensive and global characterization. In this work, 1H NMR-based metabolomics and hyphenation of high-performance liquid chromatography, photo-diode array detection, mass spectrometry, solid-phase extraction, and nuclear magnetic resonance spectroscopy (HPLC-PDA-MS-SPE-NMR) were used for investigation of 16 commercially available preparations of Ginkgo biloba. The standardized extracts originated from Denmark, Italy, Sweden, and United Kingdom, and the results show that 1H NMR spectra allow simultaneous assessment of the content as well as identity of flavonoid glycosides and TTLs based on a very simple sample-preparation procedure consisting of extraction, evaporation and reconstitution in acetone-d6. Unexpected or unwanted extract constituents were also easily identified in the 1H NMR spectra, which contrasts traditional methods that depend on UV absorption or MS ionizability and usually require availability of reference standards. Automated integration of 1H NMR spectral segments (buckets or bins of 0.02 ppm width) provides relative distribution plots of TTLs based on their H-12 resonances. The present study shows that 1H NMR-based metabolomics is an attractive method for non-selective and comprehensive analysis of Ginkgo extracts. Electronic supplementary material The online version of this article (doi:10.1007/s11306-009-0195-x) contains supplementary material, which is available to authorized users. PMID:20526353

  2. Detailed 1H and 13C NMR structural assignment and relative stereochemistry determination for three new and one known semi-synthetic sesquiterpene lactones

    NASA Astrophysics Data System (ADS)

    Sass, Daiane Cristina; Heleno, Vladimir Constantino Gomes; Soares, Ana Carolina Ferreira; Lopes, João Luis Callegari; Constantino, Mauricio Gomes

    2012-01-01

    In this work is described a complete 1H and 13C NMR analysis for a group of four sesquiterpene lactones, three previously unknown. The unequivocal assignments were achieved by 1H NMR, 13C{ 1H} NMR, J-resolved, gCOSY, gHMQC, gHMBC and NOESY experiments and no ambiguities were left behind. All hydrogen coupling constants were measured, clarifying all hydrogen signals multiplicities.

  3. Qualification of Automated Low-Field NMR Relaxometry for Quality Control of Polymers in a Production Setting

    SciTech Connect

    Chinn, S; Cook-Tendulkar, A; Maxwell, R; Wheeler, H; Wilson, M; Xie, Z

    2007-05-11

    Implementation of a low field time-domain NMR scanner as a diagnostic tool in the production of new polymer components is described in the context of qualification of a new QA/QC device. A study to determine the optimal experimental parameters was performed and a robotic autosampler was built to enable scanning of multiple pads. Relationships between T{sub 2} values and physical properties of DC745 slabs were investigated, and the appropriate sampling parameters for the production setting were determined. Two versions of a robotic autosampler were built, and for the component described here a fourth radial axis was required in addition to traditional X, Y, and Z movement to eliminate the large variability in T{sub 2} due to inconsistent sample coverage caused by complex rib geometry of the component. Data show that with appropriate choice of experimental conditions of the NMR detector and the detection geometry of the robotic autosampler, sufficient resolution of variations in crosslink density on the millimeter scale could be determined. All data to date demonstrates that low-field NMR devices are a feasible tool for use in production settings for non-destructive quality control of polymer components.

  4. The use of IRMS, (1)H NMR and chemical analysis to characterise Italian and imported Tunisian olive oils.

    PubMed

    Camin, Federica; Pavone, Anita; Bontempo, Luana; Wehrens, Ron; Paolini, Mauro; Faberi, Angelo; Marianella, Rosa Maria; Capitani, Donatella; Vista, Silvia; Mannina, Luisa

    2016-04-01

    Isotope Ratio Mass Spectrometry (IRMS), (1)H Nuclear Magnetic Resonance ((1)H NMR), conventional chemical analysis and chemometric elaboration were used to assess quality and to define and confirm the geographical origin of 177 Italian PDO (Protected Denomination of Origin) olive oils and 86 samples imported from Tunisia. Italian olive oils were richer in squalene and unsaturated fatty acids, whereas Tunisian olive oils showed higher δ(18)O, δ(2)H, linoleic acid, saturated fatty acids β-sitosterol, sn-1 and 3 diglyceride values. Furthermore, all the Tunisian samples imported were of poor quality, with a K232 and/or acidity values above the limits established for extra virgin olive oils. By combining isotopic composition with (1)H NMR data using a multivariate statistical approach, a statistical model able to discriminate olive oil from Italy and those imported from Tunisia was obtained, with an optimal differentiation ability arriving at around 98%. PMID:26593470

  5. High-field localized 1H NMR spectroscopy in the anesthetized and in the awake monkey.

    PubMed

    Pfeuffer, Josef; Juchem, Christoph; Merkle, Hellmut; Nauerth, Arno; Logothetis, Nikos K

    2004-12-01

    Localized cerebral in vivo 1H NMR spectroscopy (MRS) was performed in the anesthetized as well as the awake monkey using a novel vertical 7 T/60 cm MR system. The increased sensitivity and spectral dispersion gained at high field enabled the quantification of up to 16 metabolites in 0.1- to 1-ml volumes. Quantification was accomplished by using simulations of 18 metabolite spectra and a macromolecule (MM) background spectrum consisting of 12 components. Major cerebral metabolites (concentrations >3 mM) such as glutamate (Glu), N-acetylaspartate (NAA), creatine (Cr)/phosphocreatine (PCr) and myo-inositol (Ins) were identified with an error below 3%; most other metabolites were quantified with errors in the order of 10%. Metabolite ratios were 1.39:1 for total NAA, 1.38:1 for glutamate (Glu)/glutamine (Gln) and 0.09:1 for cholines (Cho) relative to total Cr. Taurine (Tau) was detectable at concentrations lower than 1 mM, while lactate (Lac) remained below the detection limit. The spectral dispersion was sufficient to separate metabolites of similar spectral patterns, such as Gln and Glu, N-acetylaspartylglutamate (NAAG) and NAA, and PCr-Cr. MRS in the awake monkey required the development and refinement of acquisition and correction strategies to minimize magnetic susceptibility artifacts induced by respiration and movement of the mouth or body. Periods with major motion artifacts were rejected, while a frequency/phase correction was performed on the remaining single spectra before averaging. In resting periods, both spectral amplitude and line width, that is, the voxel shim, were unaffected permitting reliable measurements. The corrected spectra obtained from the awake monkey afforded the reliable detection of 6-10 cerebral metabolites of 1-ml volumes. PMID:15707786

  6. Metabonomic signature analysis of cervical carcinoma and precancerous lesions in women by 1H NMR spectroscopy

    PubMed Central

    HASIM, AYSHAMGUL; ALI, MAYINUER; MAMTIMIN, BATUR; MA, JUN-QI; LI, QIAO-ZHI; ABUDULA, ABULIZI

    2012-01-01

    1H nuclear magnetic resonance (NMR)-based metabonomics has been used to characterize the metabolic profiles of cervical intraepithelial neoplasia (CIN) and cervical squamous cell carcinoma (CSCC). Principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLS-DA) were used to model the systematic variation related to patients with CIN or CSCC with healthy controls. Potential metabolic biomarkers were identified using database comparisons, and the one-way analysis of variance (ANOVA) test was used to examine the significance of the metabolites. Compared with plasma obtained from the healthy controls, plasma from patients with CIN had higher levels of very-low density lipoprotein (VLDL), acetone, unsaturated lipid and carnitine, together with lower levels of creatine, lactate, isoleucine, leucine, valine, alanine, glutamine, histidine, glycine, acetylcysteine, myo-inositol, choline and glycoprotein. Plasma from patients with CSCC had higher levels of acetate and formate, together with lower levels of creatine, lactate, isoleucine, leucine, valine, alanine, glutamine, histidine and tyrosine compared with the plasma of the healthy controls. In addition, compared with the plasma of patients with CIN, the plasma of CSCC patients had higher levels of acetate, formate, lactate, isoleucine, leucine, valine, alanine, glutamine, histidine, tyrosine, acetylcysteine, myo-inositol, glycoprotein, α-glucose and β-glucose, together with lower levels of acetone, unsaturated lipid and carnitine. Moreover, the profiles showed high feasibility and specificity by statistical analysis with OPLS-DA compared to the Thinprep cytology test (TCT) by setting the histopathological outcome as standard. The metabolic profile obtained for cervical cancer is significant, even for the precancerous disease. This suggests a systemic metabolic response to cancer, which may be used to identify potential early diagnostic biomarkers of the cancer and to establish

  7. (1)H NMR based metabolomic profiling revealed doxorubicin-induced systematic alterations in a rat model.

    PubMed

    Niu, Qian-Yun; Li, Zhen-Yu; Du, Guan-Hua; Qin, Xue-Mei

    2016-01-25

    Doxorubicin (DOX) is used as a chemotherapy drug with severe carditoxicity. In this study, an integrated echocardiography along with pathological examination and (1)H NMR analysis of multiple biological matrices (urine, serum, heart, and kidney) was employed to systemically assess the toxicity of DOX. Echocardiographic results showed that impaired left ventricular contractility and degenerative pathology lesions in DOX group, which were in consistent with pathology. The endogenous metabolites in the urine, serum, heart and kidney was identified by comparison with the data from the literature and databases. Multivariate analysis, including PCA and OPLS, revealed 8 metabolites in urine, including succinate, 2-ketoglutarate, citrate, hippurate, methylamine, benzoate, allantion, and acetate were the potential changed biomarkers. In serum, perturbed metabolites include elevation of leucine, β-glucose, O-acetyl-glycoprotein, creatine, lysine, glycerin, dimethylglycine, trimethylamine-N-oxide, myo-inositol, and N-acetyl-glycoprotein, together with level decreases of acetone, lipid, lactate, glutamate, phosphocholine, acetoacetate and pyruvate. For heart, DOX exposure caused decline of lipid, lactate, leucine, alanine, glutamate, choline, xanthine, glycerin, carnitine, and fumarate, together with elevation of glutamine, creatine, inosine, taurine and malate. Metabolic changes of kidney were mainly involved in the accumulation of α-glucose, lactate, phosphocholine, betaine, threonine, choline, taurine, glycine, urea, hypoxanthine, glutamate, and nicotinamide, coupled with reduction of asparagine, valine, methionine, tyrosine, lysine, alanine, leucine, ornithine, creatine, lipid, and acetate. In addition, alterations of urinary metabolites exhibited a time-dependent manner. Complementary evidences by multiple matrices revealed disturbed pathways concerning energy metabolism, fatty acids oxidation, amino acids and purine metabolism, choline metabolism, and gut microbiota

  8. 1H NMR- based metabolomics approaches as non- invasive tools for diagnosis of endometriosis

    PubMed Central

    Ghazi, Negar; Arjmand, Mohammad; Akbari, Ziba; Mellati, Ali Owsat; Saheb-Kashaf, Hamid; Zamani, Zahra

    2016-01-01

    Background: So far, non-invasive diagnostic approaches such as ultrasound, magnetic resonance imaging, or blood tests do not have sufficient diagnostic power for endometriosis disease. Lack of a non-invasive diagnostic test contributes to the long delay between onset of symptoms and diagnosis of endometriosis. Objective: The present study focuses on the identification of predictive biomarkers in serum by pattern recognition techniques and uses partial least square discriminant analysis, multi-layer feed forward artificial neural networks (ANNs) and quadratic discriminant analysis (QDA) modeling tools for the early diagnosis of endometriosis in a minimally invasive manner by 1H- NMR based metabolomics. Materials and Methods: This prospective cohort study was done in Pasteur Institute, Iran in June 2013. Serum samples of 31 infertile women with endometriosis (stage II and III) who confirmed by diagnostic laparoscopy and 15 normal women were collected and analyzed by nuclear magnetic resonance spectroscopy. The model was built by using partial least square discriminant analysis, QDA, and ANNs to determine classifier metabolites for early prediction risk of disease. Results: The levels of 2- methoxyestron, 2-methoxy estradiol, dehydroepiandrostion androstendione, aldosterone, and deoxy corticosterone were enhanced significantly in infertile group. While cholesterol and primary bile acids levels were decreased. QDA model showed significant difference between two study groups. Positive and negative predict value levels obtained about 71% and 78%, respectively. ANNs provided also criteria for detection of endometriosis. Conclusion: The QDA and ANNs modeling can be used as computational tools in noninvasive diagnose of endometriosis. However, the model designed by QDA methods is more efficient compared to ANNs in diagnosis of endometriosis patients. PMID:27141542

  9. Metabonomic signature analysis of cervical carcinoma and precancerous lesions in women by (1)H NMR spectroscopy.

    PubMed

    Hasim, Ayshamgul; Ali, Mayinuer; Mamtimin, Batur; Ma, Jun-Qi; Li, Qiao-Zhi; Abudula, Abulizi

    2012-06-01

    (1)H nuclear magnetic resonance (NMR)-based metabonomics has been used to characterize the metabolic profiles of cervical intraepithelial neoplasia (CIN) and cervical squamous cell carcinoma (CSCC). Principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLS-DA) were used to model the systematic variation related to patients with CIN or CSCC with healthy controls. Potential metabolic biomarkers were identified using database comparisons, and the one-way analysis of variance (ANOVA) test was used to examine the significance of the metabolites. Compared with plasma obtained from the healthy controls, plasma from patients with CIN had higher levels of very-low density lipoprotein (VLDL), acetone, unsaturated lipid and carnitine, together with lower levels of creatine, lactate, isoleucine, leucine, valine, alanine, glutamine, histidine, glycine, acetylcysteine, myo-inositol, choline and glycoprotein. Plasma from patients with CSCC had higher levels of acetate and formate, together with lower levels of creatine, lactate, isoleucine, leucine, valine, alanine, glutamine, histidine and tyrosine compared with the plasma of the healthy controls. In addition, compared with the plasma of patients with CIN, the plasma of CSCC patients had higher levels of acetate, formate, lactate, isoleucine, leucine, valine, alanine, glutamine, histidine, tyrosine, acetylcysteine, myo-inositol, glycoprotein, α-glucose and β-glucose, together with lower levels of acetone, unsaturated lipid and carnitine. Moreover, the profiles showed high feasibility and specificity by statistical analysis with OPLS-DA compared to the Thinprep cytology test (TCT) by setting the histopathological outcome as standard. The metabolic profile obtained for cervical cancer is significant, even for the precancerous disease. This suggests a systemic metabolic response to cancer, which may be used to identify potential early diagnostic biomarkers of the cancer and to establish

  10. Evaluation of 1H NMR metabolic profiling using biofluid mixture design.

    PubMed

    Athersuch, Toby J; Malik, Shahid; Weljie, Aalim; Newton, Jack; Keun, Hector C

    2013-07-16

    A strategy for evaluating the performance of quantitative spectral analysis tools in conditions that better approximate background variation in a metabonomics experiment is presented. Three different urine samples were mixed in known proportions according to a {3, 3} simplex lattice experimental design and analyzed in triplicate by 1D (1)H NMR spectroscopy. Fifty-four urinary metabolites were subsequently quantified from the sample spectra using two methods common in metabolic profiling studies: (1) targeted spectral fitting and (2) targeted spectral integration. Multivariate analysis using partial least-squares (PLS) regression showed the latent structure of the spectral set recapitulated the experimental mixture design. The goodness-of-prediction statistic (Q(2)) of each metabolite variable in a PLS model was calculated as a metric for the reliability of measurement, across the sample compositional space. Several metabolites were observed to have low Q(2) values, largely as a consequence of their spectral resonances having low s/n or strong overlap with other sample components. This strategy has the potential to allow evaluation of spectral features obtained from metabolic profiling platforms in the context of the compositional background found in real biological sample sets, which may be subject to considerable variation. We suggest that it be incorporated into metabolic profiling studies to improve the estimation of matrix effects that confound accurate metabolite measurement. This novel method provides a rational basis for exploiting information from several samples in an efficient manner and avoids the use of multiple spike-in authentic standards, which may be difficult to obtain. PMID:23730812

  11. Impact of Adenovirus infection in host cell metabolism evaluated by (1)H-NMR spectroscopy.

    PubMed

    Silva, Ana Carina; P Teixeira, Ana; M Alves, Paula

    2016-08-10

    Adenovirus-based vectors are powerful vehicles for gene transfer applications in vaccination and gene therapy. Although highly exploited in the clinical setting, key aspects of the adenovirus biology are still not well understood, in particular the subversion of host cell metabolism during viral infection and replication. The aim of this work was to gain insights on the metabolism of two human cell lines (HEK293 and an amniocyte-derived cell line, 1G3) after infection with an adenovirus serotype 5 vector (AdV5). In order to profile metabolic alterations, we used (1)H-NMR spectroscopy, which allowed the quantification of 35 metabolites in cell culture supernatants with low sample preparation and in a relatively short time. Significant differences between both cell lines in non-infected cultures were identified, namely in glutamine and acetate metabolism, as well as by-product secretion. The main response to AdV5 infection was an increase in glucose consumption and lactate production rates. Moreover, cultures performed with or without glutamine supplementation confirmed the exhaustion of this amino acid as one of the main causes of lower AdV5 production at high cell densities (10- and 1.5-fold less specific yields in HEK293 and 1G3 cells, respectively), and highlighted different degrees of glutamine dependency of adenovirus replication in each cell line. The observed metabolic alterations associated with AdV5 infection and specificity of the host cell line can be useful for targeted bioprocess optimization. PMID:27215342

  12. Identification and quantification of the main organic components of vinegars by high resolution 1H NMR spectroscopy.

    PubMed

    Caligiani, A; Acquotti, D; Palla, G; Bocchi, V

    2007-02-28

    A detailed analysis of the proton high-field NMR spectra of vinegars (in particular of Italian balsamic vinegars) is reported. A large number of organic substances belonging to different classes, such as carbohydrates, alcohols, organic acids, volatile compounds and amino acids, were assigned. The possibility of quantification of the substances identified in the whole vinegar sample, without extraction or pre-concentration steps, was also tested. The data validity was demonstrated in terms of precision, accuracy, repeatability and inter-day reproducibility. The effects of the most critical experimental parameters (sample concentration, water suppression and relaxation time) on the analysis response were also discussed. (1)H NMR results were compared with those obtained by traditional techniques (GC-MS, titrations), and good correlations were obtained. The results showed that (1)H NMR with water suppression allows a rapid, simultaneous determination of carbohydrates (glucose and fructose), organic acids (acetic, formic, lactic, malic, citric, succinic and tartaric acids), alcohols and polyols (ethanol, acetoin, 2,3-butanediol, hydroxymethylfurfural), and volatile substances (ethyl acetate) in vinegar samples. On the contrary, the amino acid determination without sample pre-concentration was critical. The (1)H NMR method proposed was applied to different samples of vinegars, allowing, in particular, the discrimination of vinegars and balsamic vinegars. PMID:17386654

  13. Lateral diffusion of PEG-Lipid in magnetically aligned bicelles measured using stimulated echo pulsed field gradient 1H NMR.

    PubMed

    Soong, Ronald; Macdonald, Peter M

    2005-01-01

    Lateral diffusion measurements of PEG-lipid incorporated into magnetically aligned bicelles are demonstrated using stimulated echo (STE) pulsed field gradient (PFG) proton (1H) nuclear magnetic resonance (NMR) spectroscopy. Bicelles were composed of dimyristoyl phosphatidylcholine (DMPC) plus dihexanoyl phosphatidylcholine (DHPC) (q = DMPC/DHPC molar ratio = 4.5) plus 1 mol % (relative to DMPC) dimyristoyl phosphatidylethanolamine-N-[methoxy(polyethylene glycol)-2000] (DMPE-PEG 2000) at 25 wt % lipid. 1H NMR STE spectra of perpendicular aligned bicelles contained only resonances assigned to residual HDO and to overlapping contributions from a DMPE-PEG 2000 ethoxy headgroup plus DHPC choline methyl protons. Decay of the latter's STE intensity in the STE PFG 1H NMR experiment (g(z) = 244 G cm(-1)) yielded a DMPE-PEG 2000 (1 mol %, 35 degrees C) lateral diffusion coefficient D = 1.35 x 10(-11) m2 s(-1). Hence, below the "mushroom-to-brush" transition, DMPE-PEG 2000 lateral diffusion is dictated by its DMPE hydrophobic anchor. D was independent of the diffusion time, indicating unrestricted lateral diffusion over root mean-square diffusion distances of microns, supporting the "perforated lamellae" model of bicelle structure under these conditions. Overall, the results demonstrate the feasibility of lateral diffusion measurements in magnetically aligned bicelles using the STE PFG NMR technique. PMID:15475584

  14. Complexation of oxygen ligands with dimeric rhodium(II) tetrakistrifluoroacetate in chloroform: 1H, 13C NMR and DFT studies

    NASA Astrophysics Data System (ADS)

    Głaszczka, Rafał; Jaźwiński, Jarosław

    2013-03-01

    The complexation of dimeric rhodium(II) tetrakistrifluoroacetylate with 25 ligands containing oxygen atoms: alcohols, ethers, ketones, aldehydes, carboxylic acids and esters in chloroform solution have been investigated by 1H and 13C NMR spectroscopy and Density Functional Theory (DFT) methods. Investigated ligands form 1:1 adducts in our experimental conditions, with stability constants in the order of several hundred mol-1. The exchange of ligands in solution is fast on the NMR spectroscopic timescale. The decrease of longitudinal relaxation times T1 in ligands in the presence of rhodium salt has been tested as the means of determination of the complexation site in ligands. The influence of complexation on chemical shifts in ligands was evaluated by a parameter complexation shift Δδ (Δδ = δadd - δlig). These parameters were positive (>0 ppm) and did not exceed 1 ppm for 1H NMR; and varied from ca. -5 to +15 ppm in the case of 13C NMR. The calculation by DFT methods using the B3LYP functional (structure optimization, electronic energy) and B3PW91 functional (shielding), and combinations of the (6-31G(2d), 6-311G++(2d,p), and LANL2DZ basis sets, followed by scaling procedures reproduced satisfactorily 1H and 13C chemical shifts and, with some limitations, allowed to estimate Δδ parameters.

  15. Spin-echo sup 1 H NMR studies of differential mobility in gizzard myosin and its subfragments

    SciTech Connect

    Sommervile, L.E. ); Henry, G.D.; Sykes, B.D. ); Harshorne, D.J. )

    1990-12-01

    The unexpectedly narrow resonances in the {sup 1}H NMR spectra of gizzard myosin, heavy meromyosin, and subfragment 1 were examined by spin-echo NMR spectroscopy. These resonances originated predominantly in the myosin heads, or subfragment 1 units. Smooth muscle myosin undergoes a dramatic change in hydrodynamic properties and can exist either as a folded (10S) or as an extended (6S) species. Factors that influence this transition, namely, ionic strength and phosphorylation (or thiophosphorylation), were varied in the NMR experiments. T{sub 2} relaxation experiments on dephosphorylated myosin indicated several components of different relaxation times that were not influenced by changes in ionic strength. The experiments focused on the components with longer relaxation times, i.e., corresponding to nuclei with more mobility, and these were observed selectively in a spin-echo experiment. With dephosphorylated myosin and HMM, increases in ionic strength caused an increased intensity in several of the narrower resonances. The ionic strength dependence of these changes paralleled that for the 10S and 6S transition. With thiophosphorylated myosin and HMM, changes in ionic strength also influenced the intensities of the narrower resonances, and in addition changes in the {sup 1}H NMR spectrum due to thiophosphorylation were observed. These results suggest that a fraction of the {sup 1}H resonances in smooth muscle myosin and its fragments originates from both aliphatic and aromatic residues of increased mobility compared to the mobility expected from hydrodynamic properties of these proteins.

  16. A closer look at the nitrogen next door: 1H-15N NMR methods for glycosaminoglycan structural characterization

    NASA Astrophysics Data System (ADS)

    Langeslay, Derek J.; Beni, Szabolcs; Larive, Cynthia K.

    2012-03-01

    Recently, experimental conditions were presented for the detection of the N-sulfoglucosamine (GlcNS) NHSO3- or sulfamate 1H and 15N NMR resonances of the pharmaceutically and biologically important glycosaminoglycan (GAG) heparin in aqueous solution. In the present work, we explore further the applicability of nitrogen-bound proton detection to provide structural information for GAGs. Compared to the detection of 15N chemical shifts of aminosugars through long-range couplings using the IMPACT-HNMBC pulse sequence, the more sensitive two-dimensional 1H-15N HSQC-TOCSY experiments provided additional structural data. The IMPACT-HNMBC experiment remains a powerful tool as demonstrated by the spectrum measured for the unsubstituted amine of 3-O-sulfoglucosamine (GlcN(3S)), which cannot be observed with the 1H-15N HSQC-TOCSY experiment due to the fast exchange of the amino group protons with solvent. The 1H-15N HSQC-TOCSY NMR spectrum reported for the mixture of model compounds GlcNS and N-acetylglucosamine (GlcNAc) demonstrate the broad utility of this approach. Measurements for the synthetic pentasaccharide drug Arixtra® (Fondaparinux sodium) in aqueous solution illustrate the power of this NMR pulse sequence for structural characterization of highly similar N-sulfoglucosamine residues in GAG-derived oligosaccharides.

  17. NMRmix: A Tool for the Optimization of Compound Mixtures in 1D 1H NMR Ligand Affinity Screens

    PubMed Central

    2016-01-01

    NMR ligand affinity screening is a powerful technique that is routinely used in drug discovery or functional genomics to directly detect protein–ligand binding events. Binding events can be identified by monitoring differences in the 1D 1H NMR spectrum of a compound with and without protein. Although a single NMR spectrum can be collected within a short period (2—10 min per sample), one-by-one screening of a protein against a library of hundreds or thousands of compounds requires a large amount of spectrometer time and a large quantity of protein. Therefore, compounds are usually evaluated in mixtures ranging in size from 3 to 20 compounds to improve the efficiency of these screens in both time and material. Ideally, the NMR signals from individual compounds in the mixture should not overlap so that spectral changes can be associated with a particular compound. We have developed a software tool, NMRmix, to assist in creating ideal mixtures from a large panel of compounds with known chemical shifts. Input to NMRmix consists of an 1H NMR peak list for each compound, a user-defined overlap threshold, and additional user-defined parameters if default settings are not used. NMRmix utilizes a simulated annealing algorithm to optimize the composition of the mixtures to minimize spectral peak overlaps so that each compound in the mixture is represented by a maximum number of nonoverlapping chemical shifts. A built-in graphical user interface simplifies data import and visual evaluation of the results. PMID:26965640

  18. State-of-the-Art Direct 13C and Indirect 1H-[13C] NMR Spectroscopy In Vivo

    PubMed Central

    de Graaf, Robin A.; Rothman, Douglas L.; Behar, Kevin L.

    2013-01-01

    Carbon-13 NMR spectroscopy in combination with 13C-labeled substrate infusion is a powerful technique to measure a large number of metabolic fluxes non-invasively in vivo. It has been used to quantify glycogen synthesis rates, establish quantitative relationships between energy metabolism and neurotransmission and evaluate the importance of different substrates. All measurements can, in principle, be performed through direct 13C NMR detection or via indirect 1H-[13C] NMR detection of the protons attached to 13C nuclei. The choice for detection scheme and pulse sequence depends on the magnetic field strength, whereas substrate selection depends on the metabolic pathways that are studied. 13C NMR spectroscopy remains a challenging technique that requires several non-standard hardware modifications, infusion of 13C-labeled substrates and sophisticated processing and metabolic modeling. Here the various aspects of direct 13C and indirect 1H-[13C] NMR are reviewed with the aim of providing a practical guide. PMID:21919099

  19. NMRmix: A Tool for the Optimization of Compound Mixtures in 1D (1)H NMR Ligand Affinity Screens.

    PubMed

    Stark, Jaime L; Eghbalnia, Hamid R; Lee, Woonghee; Westler, William M; Markley, John L

    2016-04-01

    NMR ligand affinity screening is a powerful technique that is routinely used in drug discovery or functional genomics to directly detect protein-ligand binding events. Binding events can be identified by monitoring differences in the 1D (1)H NMR spectrum of a compound with and without protein. Although a single NMR spectrum can be collected within a short period (2-10 min per sample), one-by-one screening of a protein against a library of hundreds or thousands of compounds requires a large amount of spectrometer time and a large quantity of protein. Therefore, compounds are usually evaluated in mixtures ranging in size from 3 to 20 compounds to improve the efficiency of these screens in both time and material. Ideally, the NMR signals from individual compounds in the mixture should not overlap so that spectral changes can be associated with a particular compound. We have developed a software tool, NMRmix, to assist in creating ideal mixtures from a large panel of compounds with known chemical shifts. Input to NMRmix consists of an (1)H NMR peak list for each compound, a user-defined overlap threshold, and additional user-defined parameters if default settings are not used. NMRmix utilizes a simulated annealing algorithm to optimize the composition of the mixtures to minimize spectral peak overlaps so that each compound in the mixture is represented by a maximum number of nonoverlapping chemical shifts. A built-in graphical user interface simplifies data import and visual evaluation of the results. PMID:26965640

  20. Data fusion between high resolution (1)H-NMR and mass spectrometry: a synergetic approach to honey botanical origin characterization.

    PubMed

    Spiteri, Marc; Dubin, Elodie; Cotton, Jérôme; Poirel, Marion; Corman, Bruno; Jamin, Eric; Lees, Michèle; Rutledge, Douglas

    2016-06-01

    A data fusion approach was applied to a commercial honey data set analysed by (1)H-nuclear magnetic resonance (NMR) 400 MHz and liquid chromatography-high resolution mass spectrometry (LC-HRMS). The latter was performed using two types of mass spectrometers: an Orbitrap-MS and a time of flight (TOF)-MS. Fifty-six honey samples from four monofloral origins (acacia, orange blossom, lavender and eucalyptus) and multifloral sources from various geographical origins were analysed using the three instruments. The discriminating power of the results was examined by PCA first considering each technique separately, and then combining NMR and LC-HRMS together with or without variable selection. It was shown that the discriminating potential is increased through the data fusion, allowing for a better separation of eucalyptus, orange blossom and lavender. The NMR-Orbitrap-MS and NMR-TOF-MS mid-level fusion models with variable selection were preferred as a good discrimination was obtained with no misclassification observed for the latter. This study opens the path to new comprehensive food profiling approaches combining more than one technique in order to benefit from the advantages of several technologies. Graphical Abstract Data fusion between high resolution 1H-NMR and mass spectrometry. PMID:27086012

  1. Study of inclusion complex between 2,6-dinitrobenzoic acid and β-cyclodextrin by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD, SEM and photophysical methods.

    PubMed

    Srinivasan, Krishnan; Stalin, Thambusamy

    2014-09-15

    The formation of host-guest inclusion complex of 2,6-dinitrobenzoic acid (2,6-DNB) with nano-hydrophobic cavity of β-cyclodextrin (β-CD) in solution phase has been studied by UV-visible spectroscopy and electrochemical analysis (cyclic voltammetry, CV). The effect of acid-base concentrations of 2,6-DNB has been studied in presence and absence of β-CD to determination for the ground state acidity constant (pKa). The binding constant of inclusion complex at 303 K was calculated using Benesi-Hildebrand plot and thermodynamic parameter (ΔG) was also calculated. The solid inclusion complex formation between β-CD and 2,6-DNB was confirmed by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD and SEM analysis. A schematic representation of this inclusion process was proposed by molecular docking studies using patch dock server. PMID:24769381

  2. Study of inclusion complex between 2,6-dinitrobenzoic acid and β-cyclodextrin by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD, SEM and photophysical methods

    NASA Astrophysics Data System (ADS)

    Srinivasan, Krishnan; Stalin, Thambusamy

    2014-09-01

    The formation of host-guest inclusion complex of 2,6-dinitrobenzoic acid (2,6-DNB) with nano-hydrophobic cavity of β-cyclodextrin (β-CD) in solution phase has been studied by UV-visible spectroscopy and electrochemical analysis (cyclic voltammetry, CV). The effect of acid-base concentrations of 2,6-DNB has been studied in presence and absence of β-CD to determination for the ground state acidity constant (pKa). The binding constant of inclusion complex at 303 K was calculated using Benesi-Hildebrand plot and thermodynamic parameter (ΔG) was also calculated. The solid inclusion complex formation between β-CD and 2,6-DNB was confirmed by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD and SEM analysis. A schematic representation of this inclusion process was proposed by molecular docking studies using patch dock server.

  3. UV-vis, IR and 1H NMR spectroscopic studies and characterization of ionic-pair crystal violet-oxytetracycline

    NASA Astrophysics Data System (ADS)

    Orellana, Sandra; Soto, César; Toral, M. Inés

    2010-01-01

    The present study shows the formation and characterization of the ionic-pair between the antibiotic oxytetracycline and the dye crystal violet in ammonia solution pH 9.0 ± 0.2 extracted into chloroform. The characterization was demonstrated using UV-vis spectrophotometry, 1H NMR, measurement of relaxation times T1 and IR spectroscopy, using a comparison between the signals of individual pure compounds with the signals with the mixture CV-OTC in different alkaline media. The formation of ionic-pair was also corroborated by new signals and chemical shifts. (2D) NMR spectroscopy experiments show that the interaction is electrostatic.

  4. 1H-detected solid-state NMR of proteins entrapped in bioinspired silica: a new tool for biomaterials characterization

    PubMed Central

    Ravera, Enrico; Cerofolini, Linda; Martelli, Tommaso; Louka, Alexandra; Fragai, Marco; Luchinat, Claudio

    2016-01-01

    Proton-detection in solid-state NMR, enabled by high magnetic fields (>18 T) and fast magic angle spinning (>50 kHz), allows for the acquisition of traditional 1H-15N experiments on systems that are too big to be observed in solution. Among those, proteins entrapped in a bioinspired silica matrix are an attractive target that is receiving a large share of attention. We demonstrate that 1H-detected SSNMR provides a novel approach to the rapid assessment of structural integrity in proteins entrapped in bioinspired silica. PMID:27279168

  5. (1)H-detected solid-state NMR of proteins entrapped in bioinspired silica: a new tool for biomaterials characterization.

    PubMed

    Ravera, Enrico; Cerofolini, Linda; Martelli, Tommaso; Louka, Alexandra; Fragai, Marco; Luchinat, Claudio

    2016-01-01

    Proton-detection in solid-state NMR, enabled by high magnetic fields (>18 T) and fast magic angle spinning (>50 kHz), allows for the acquisition of traditional (1)H-(15)N experiments on systems that are too big to be observed in solution. Among those, proteins entrapped in a bioinspired silica matrix are an attractive target that is receiving a large share of attention. We demonstrate that (1)H-detected SSNMR provides a novel approach to the rapid assessment of structural integrity in proteins entrapped in bioinspired silica. PMID:27279168

  6. 1H-detected solid-state NMR of proteins entrapped in bioinspired silica: a new tool for biomaterials characterization

    NASA Astrophysics Data System (ADS)

    Ravera, Enrico; Cerofolini, Linda; Martelli, Tommaso; Louka, Alexandra; Fragai, Marco; Luchinat, Claudio

    2016-06-01

    Proton-detection in solid-state NMR, enabled by high magnetic fields (>18 T) and fast magic angle spinning (>50 kHz), allows for the acquisition of traditional 1H-15N experiments on systems that are too big to be observed in solution. Among those, proteins entrapped in a bioinspired silica matrix are an attractive target that is receiving a large share of attention. We demonstrate that 1H-detected SSNMR provides a novel approach to the rapid assessment of structural integrity in proteins entrapped in bioinspired silica.

  7. Segmental dynamic heterogeneity of short-chain grafted-poly(dimethylsiloxane) by 1H spin-diffusion NMR

    NASA Astrophysics Data System (ADS)

    Bertmer, Marko; Demco, Dan E.; Wang, Mingfei; Melian, Claudiu; Marcean-Chelcea, Ramona I.; Fechete, Radu; Baias, Maria; Blümich, Bernhard

    2006-11-01

    Segmental dynamic heterogeneity of short-chain grafted poly(dimethylsiloxane) (PDMS) on pyrogenic silica was investigated using 1H NMR spin-diffusion. A double-quantum dipolar filter was employed for selection of the interface (rigid) region. One-dimensional spin-diffusion equations were solved numerically for a space distribution of spin diffusivity D( x) of the mobile PDMS chains. The degree of heterogeneity can be quantified by the parameters of Gaussian and exponential diffusivity distribution functions which yield similar diffusivities. The rigid and mobile domain sizes and spin diffusivities were correlated with the PDMS chain length, the temperature, and 1H residual dipolar couplings.

  8. Selective detection and complete identification of triglycerides in cortical bone by high-resolution (1)H MAS NMR spectroscopy.

    PubMed

    Mroue, Kamal H; Xu, Jiadi; Zhu, Peizhi; Morris, Michael D; Ramamoorthy, Ayyalusamy

    2016-07-28

    Using (1)H-based magic angle spinning solid-state NMR spectroscopy, we report an atomistic-level characterization of triglycerides in compact cortical bone. By suppressing contributions from immobile molecules present in bone, we show that a (1)H-based constant-time uniform-sign cross-peak (CTUC) two-dimensional COSY-type experiment that correlates the chemical shifts of protons can selectively detect a mobile triglyceride layer as the main component of small lipid droplets embedded on the surface of collagen fibrils. High sensitivity and resolution afforded by this NMR approach could be potentially utilized to investigate the origin of triglycerides and their pathological roles associated with bone fractures, diseases, and aging. PMID:27374353

  9. The origin of molecular mobility during biomass pyrolysis as revealed by in situ (1)H NMR spectroscopy.

    PubMed

    Dufour, Anthony; Castro-Diaz, Miguel; Brosse, Nicolas; Bouroukba, Mohamed; Snape, Colin

    2012-07-01

    The thermochemical conversion of lignocellulosic biomass feedstocks offers an important potential route for the production of biofuels and value-added green chemicals. Pyrolysis is the first phenomenon involved in all biomass thermochemical processes and it controls to a major extent the product composition. The composition of pyrolysis products can be affected markedly by the extent of softening that occurs. In spite of extensive work on biomass pyrolysis, the development of fluidity during the pyrolysis of biomass has not been quantified. This paper provides the first experimental investigation of proton mobility during biomass pyrolysis by in situ (1)H NMR spectroscopy. The origin of mobility is discussed for cellulose, lignin and xylan. The effect of minerals on cellulose mobility is also investigated. Interactions between polymers in the native biomass network are revealed by in situ (1)H NMR analysis. PMID:22573541

  10. FT-IR and {sup 1}H NMR characterization of the products of an ethylene inverse diffusion flame

    SciTech Connect

    Santamaria, Alexander; Mondragon, Fanor; Molina, Alejandro; Marsh, Nathan D.; Eddings, Eric G.; Sarofim, Adel F.

    2006-07-15

    Knowledge of the chemical structure of young soot and its precursors is very useful in the understanding of the paths leading to soot particle inception. This paper presents analyses of the chemical functional groups, based on FT-IR and {sup 1}H NMR spectroscopy of the products obtained in an ethylene inverse diffusion flame. The trends in the data indicate that the soluble fraction of the soot becomes progressively more aromatic and less aliphatic as the height above the burner increases. Results from {sup 1}H NMR spectra of the chloroform-soluble soot samples taken at different heights above the burner corroborate the infrared results based on proton chemical shifts (Ha, H{alpha}, H{beta}, and H{gamma}). The results indicate that the aliphatic {beta} and {gamma} hydrogens suffered the most drastic reduction, while the aromatic character increased considerably with height, particularly in the first half of the flame. (author)