Determination of Soybean Oil, Protein and Amino Acid Residues in Soybean Seeds by High Resolution Nuclear Magnetic Resonance (NMRS) and Near Infrared (NIRS)

A detailed account is presented of our high resolution nuclear magnetic resonance (HR-NMR) and near infrared (NIR) calibration models, methodologies and validation procedures, together with a large number of composition analyses for soybean seeds. NIR calibrations were developed based on both HR-NMR and analytical chemistry reference data for oil and twelve amino acid residues in mature soybeans and soybean embryos. This is our first report of HR-NMR determinations of amino acid profiles of proteins from whole soybean seeds, without protein extraction from the seed. It was found that the best results for both oil and protein calibrations were obtained with a Partial Least Squares Regression (PLS-1) analysis of our extensive NIR spectral data, acquired with either a DA7000 Dual Diode Array (Si and InGaAs detectors) instrument or with several Fourier Transform NIR (FT-NIR) spectrometers equipped with an integrating sphere/InGaAs detector accessory. In order to extend the bulk soybean samples calibration models to the analysis of single soybean seeds, we have analized in detail the component NIR spectra of all major soybean constituents through spectral deconvolutions for bulk, single and powdered soybean seeds. Baseline variations and light scattering effects in the NIR spectra were corrected, respectively, by calculating the first-order derivatives of the spectra and the Multiplicative Scattering Correction (MSC). The single soybean seed NIR spectra are broadly similar to those of bulk whole soybeans, with the exception of minor peaks in single soybean NIR spectra in the region from 950 to 1,000 nm. Based on previous experience with bulk soybean NIR calibrations, the PLS-1 calibration model was selected for protein, oil and moisture calibrations that we developed for single soybean seed analysis. In order to improve the reliability and robustness of our calibrations with the PLS-1 model we employed standard samples with a wide range of soybean constituent compositions: from 34% to 55% for protein, from 11% to 22% for oil and from 2% to 16% for moisture. Such calibrations are characterized by low standard errors and high degrees of correlation for all major soybean constituents. Morever, we obtained highly resolved NIR chemical images for selected regions of mature soybean embryos that allow for the quantitation of oil and protein components. Recent developments in high-resolution FT-NIR microspectroscopy extend the NIR sensitivity range to the picogram level, with submicron spatial resolution in the component distribution throughout intact soybean seeds and embryos. Such developments are potentially important for biotechnology applications that require rapid and ultra- sensitive analyses, such as those concerned with high-content microarrays in Genomics and Proteomics research. Other important applications of FT-NIR microspectroscopy are envisaged in biomedical research aimed at cancer prevention, the early detection of tumors by NIR-fluorescence, and identification of single cancer cells, or single virus particles in vivo by super-resolution microscopy/ microspectroscopy

Quantification of Mineral Oil Aromatic Hydrocarbons (MOAH) in Anhydrous Cosmetics Using 1 H NMR

In cosmetic products, hydrocarbons from mineral oil origin are used as ingredients in a wide variety of consistency, from liquid oil to solid wax. Refined mineral oil hydrocarbons consist of MOSH (mineral oil saturated hydrocarbons) and a low proportion of MOAH (mineral oil aromatic hydrocarbons). MOSH and MOAH comprise a variety of chemically similar single substances with straight or branched chains. In the context of precautionary consumer protection, it is crucial to determine hydrocarbons from mineral oil origin of inferior quality quickly and efficiently. This publication presents a rapid method for quantifying MOAH by proton nuclear magnetic resonance spectroscopy (¹H qNMR) in anhydrous cosmetics such as lipstick, lip gloss, and lip balm. A sample clean-up using solid-phase extraction (SPE) was developed for the complete removal of interfering aromatic substances to improve the robustness of the method for analysing compounded cosmetics. In preliminary trials using silica gel thin-layer chromatography, the retention behaviour of 21 common aromatic compounds was tested in eluents with different solvent strength including EtOAc, MeOH, cyclohexane, and dichloromethane. Based on these results, the SPE sample cleanup with silica gel and cyclohexane as an eluent was suggested as best suitable for the purpose. The SPE cleanup was successfully achieved for all tested potentially interfering aromatic cosmetic ingredients except for butylated hydroxytoluene. The recovery for lipophilic cosmetics is more than 80% based on naphthalene as calculation equivalent. Furthermore, a specific sample preparation for the examination of lipsticks was implemented. The SPE cleanup was validated, and the robustness of the method was tested on 57 samples from the retail trade. The ¹H qNMR method is a good complement to the LC-GC-FID method, which is predominantly used for the determination of MOSH and MOAH. Chromatographic problems such as migration of MOSH into the MOAH fraction during LC-GC-FID can be avoided

Stradivari's Varnish Revisited: Feature Improvements Using Chemical Modification

The most widespread varnish formulations used by master violin-makers of the "Italian Golden Age", including Antonio Stradivari, were based on mixtures of siccative oils (e.g., linseed oil) and natural resins (e.g., colophony). Similar formulations are still used for the finish of contemporary instruments. Although most precious violins made by Stradivari and other Cremonese Masters are kept in museums, several instruments are still played and their finish may undergo deterioration due to contact with the players. Moreover, the decay of the traditional varnish may occur due to mechanical stress and natural aging caused by environmental agents (e.g., exposure to uncontrolled light, humidity, and temperature changes). The main aim of this research work is to investigate the possible improvement of varnish resistance to the decay induced by different aging processes. For this purpose, the traditional varnish (linseed oil/colophony 3:1 w/w) was recreated in the laboratory following an ancient recipe and then it was functionalized with a cross-linking agent (3-Glycidyloxypropyltrimethoxysilane, GLYMO). Plain and functionalized varnishes underwent artificial aging (UV light, temperature, and humidity variations), and their properties were comparatively studied using different techniques. All the results suggest that the functionalized varnish displays improved resistance to the aging process and particularly enhanced photostability and increased hardness (resistance to scratches)

Beyond the noise : high fidelity MR signal processing

This thesis describes a variety of methods developed to increase the sensitivity and resolution of liquid state nuclear magnetic resonance (NMR) experiments. NMR is known as one of the most versatile non-invasive analytical techniques yet often suffers from low sensitivity. The main contribution to this low sensitivity issue is a presence of noise and level of noise in the spectrum is expressed numerically as “signal-to-noise ratio”. NMR signal processing involves sensitivity and resolution enhancement achieved by noise reduction using mathematical algorithms. A singular value decomposition based reduced rank matrix method, composite property mapping, in particular is studied extensively in this thesis to present its advantages, limitations, and applications. In theory, when the sum of k noiseless sinusoidal decays is formatted into a specific matrix form (i.e., Toeplitz), the matrix is known to possess k linearly independent columns. This information becomes apparent only after a singular value decomposition of the matrix. Singular value decomposition factorises the large matrix into three smaller submatrices: right and left singular vector matrices, and one diagonal matrix containing singular values. Were k noiseless sinusoidal decays involved, there would be only k nonzero singular values appearing in the diagonal matrix in descending order providing the information of the amplitude of each sinusoidal decay. The number of non-zero singular values or the number of linearly independent columns is known as the rank of the matrix. With real NMR data none of the singular values equals zero and the matrix has full rank. The reduction of the rank of the matrix and thus the noise in the reconstructed NMR data can be achieved by replacing all the singular values except the first k values with zeroes. This noise reduction process becomes difficult when biomolecular NMR data is to be processed due to the number of resonances being unknown and the presence of a large solvent peak

Thermosetting Polymers via Azide Alkyne Cycloaddition

This dissertation exploits properties inherent to azide-alkyne cycloaddition and applies practical solutions to difficult problems. Chapter II addresses structure-property relationships in glassy azido-alkyne matrices by varying the identity of the central linkage within tetrapropargyl bis-aniline-type crosslinkers, and by the addition or omission of Cu(I) catalyst. This systematic study showed that an ether or methylene linkage yielded lower melting tetrapropargyl crosslinkers that were soluble in, and produced homogeneous, networks when cured with, a standard azido resin, di(3-azido-2-hydroxypropyl) ether of bisphenol-A; in contrast, a sulfone linkage yielded a relatively insoluble crosslinker and poorly dispersed, heterogeneous networks when reacted with the same resin. The study also showed that the presence of Cu(I) and the concomitant network regularity afforded by a single triazole regioisomer increased compression modulus and Tg. However, due to increased kinetics of reaction the catalyzed system was much harder to process. Chapter III introduces the use of azide-alkyne cycloaddition as an alternative curing mechanism in non-isocyanate polyurethanes (NIPU). Several commercial polyisocyanate resins derived from hexamethylene diisocyanate were converted to propargyl carbamates by reaction with propargyl alcohol; azidated co-reactants were synthesized from several different commercial polyols including polyether, polyester, and polyacrylic types. Each resin/coreactant combination was rendered into a two-component coating system and cured in the presence and absence of Cu(I) catalyst. Coating properties were compared to the precursor polyisocyanate/polyol coating systems, and the best-performing NIPU coating was found to result from a propargylated allophanate resin, XP2580, and an azidated polyacrylic resin, Setalux DA870. The latter coatings met or exceeded the properties of the precursor polyurethane coatings except for uncatalyzed rate of cure at ambient temperature. Chapter IV focused on increasing the sluggish curing kinetics observed for the azide-propargyl systems. In Chapter III, this was overcome by the addition of Cu(I). However, this also caused discoloration to the coating. This chapter focused on making an aesthetically pleasing coating that cured similarly to the as received material. This was achieved by the synthesis of 2-hydroxyethyl propiolate (2-HEP) and its subsequent reaction with XP2580 to form a propiolate modified polyurethane resin. Incorporation of the propiolate functionality increased the rate of reaction with the azidated Setalux DA870, such that the observed curing kinetics were approximately the same as that of the as-received resin pairs. Chapter V, the final chapter, addressed problem that plagued the carbamates synthesized in the previous two chapters. Upon propargylation, the viscosity increased dramatically, making the resins difficult to work with unless diluted by an appreciable amount of organic solvents. This was overcome by sacrificing a fraction of the isocyanate functionality to attach internal plasticizing moieties consisting of a monoalkyl ether of either ethylene glycol (EG) or diethylene glycol (DEG). This approach was successful in reducing coating system viscosity, and created a softer and more flexible coating with a lower glass transition. This study showed that the length of alkyl chain, rather than the choice of EG or DEG, produced the larger effect on viscosity and coating properties, i.e., butyl provided a much greater plasticizing effect than ethyl

Investigation of Novel Thiol Click Reactions

The thio-Michael addition reaction is traditionally considered a base catalyzed reaction which involves high catalyst concentrations and long reaction times. This reaction utilizes potent, simple nucleophiles to catalyze the reaction, decreases the catalyst concentration and greatly increases the reaction times. The free radical mediated thiol-ene click reaction uses light or heat and an initiator to catalyze the rapid and quantitative addition of thiols to most electron rich enes without the formation of side products and in the absence of solvent. Recently, the thiol-ene click reaction has been exploited for these reasons in materials science and organic synthesis. The research herein describes the nucleophile catalyzed thio-Michael addition to electron poor enes as a integral reaction in the canon of thiol-ene click reactions. This dissertation includes chapters of the kinetics and spectroscopic evaluation of the nucleophile catalyzed thio- Michael addition reaction and resulting products; the use of nucleophile catalyzed thio- Michael addition for the rapid synthesis of star polymers; and the physical and mechanical properties of networks prepared with a combination of the photo-cured and nucleophile cured reactions of multi-acrylates with multi-functional thiols. This dissertation also discusses the less researched thiol-yne reaction, which provides the addition of two thiol groups to one alkyne group. Mechanistically, a thiyl radical adds to an alkyne group creating a very reactive thio vinyl radical, which, in turn, abstracts a hydrogen from another thiol creating a new thiyl radical. The resulting thio vinyl group, which shows higher reactivity than the initial alkyne, reacts rapidly with a second thiyl group. Additional chapters in this dissertation will discuss the formation of multi-functional materials (16 \u3e functionality \u3e 8) in a sequential nucleophile catalyzed thio-Michael addition followed by the thiol-yne reaction; the mechanical and physical properties of films prepared with multi-functional alkynes and multi-functional thiols; and the linear relationship of refractive index and sulfur content in polysulfide networks made possible by the thiol-yne reaction. The first fundamental study discusses a proposed anionic chain mechanism for the nucleophile catalyzed thio-Michael addition to electron poor alkenes. Traditional base catalyzed mechanisms show the deprotonation of the thiol by a weak base such as triethyl amine. Results show that nucleophilic amines, such as hexyl amine, with similar pKa values as the weak bases have faster rates of reaction, indicating that base strength alone is not responsible for the apparent increase in rates. Results demonstrate that the effect of nucleophilicity has a greater role than basicity (pKa) in the rates of reaction. An anionic chain mechanism is proposed involving the initiation of the thio-Michael reaction by an initial attack of a nucleophile onto an electron poor double bond creating a super-strong enolate anion which carries out the subsequent base catalyzed thio-Michael addition. The second study reports the facile formation of star polymers using the nucleophile catalyzed thio-Michael addition reaction of polymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization and a tri-acrylate monomer. The nucleophilic catalyst employed for the thio-Michael addition reaction has shown to have a dual purpose: to catalyze the Michael addition and to prevent the disulfide formation commonly seen in the reduction step of the RAFT end group. Acrylates are commonly used for the preparation of polymer networks due to their wide commercial availability, tunable mechanical properties, and sensitivity to photopolymerization. Photo-cured multi-acrylate systems produce films with inhomogeneous micro-structures leading to broad glass transition temperatures (Tg). Incorporation of thiols into these systems narrows the Tgs but quantitative addition (1 to 1) of thiol to acrylate does not occur due to the competitive acrylate homopolymerization. The nucleophile catalyzed thio-Michael addition reaction promotes the quantitative addition of thiols to acrylates resulting in very narrow Tgs. The third study discusses the use of sequential thio-Michael reaction followed by the photo-cured reaction. This process allows tunability of mechanical and physical properties of resulting films. In the fourth study, the nucleophile catalyzed thio-Michael addition reaction is used for preparation of multi-functional alkynes. Alkynes, like alkenes, react rapidly and quantitatively with thiols in a photocured system in a 1:2 ratio. A series of polyfunctional branched materials was prepared by clicking two thiol groups to one terminal alkyne proceeded quantitatively, in the absence of solvent, rapidly and with no evidence of side products. The fifth study demonstrates the preparation of a series of multi-functional alkyne monomers (f=4,6,8) that were subsequently photopolymerized with a series of multifunctional thiols (f=2,3,4). Mechanical and physical properties showed an increasing correlation between gel point and functionality. Additionally, this study demonstrated the utility of tailoring the Tg values by increasing the functionality of starting monomers. High sulfur content materials have shown to have high refractive index values. In the final study, networks were prepared from commercially available dialkyne and dithiols, consisting only of sulfur and hydrocarbon. Sulfur content in some films reached nearly 50% and, as a result, refractive index values were determined to be greater than 1.65. Data from this study shows a linear relationship between the weight% sulfur and the refractive index in sulfur containing crosslinked hydrocarbon networks

Photopolymerization and Characterization of Crosslinked Thiol-ene Networks and POSS/Thiol-ene Nanocomposites

Interests in the area of thiol-ene photopolymerization are rapidly expanding due to the numerous advantages over the polymers produced by traditional solvent based polymerizations. Although current research of photoinitiated thiol-ene polymerization is diverse, numerous opportunities are available for investigating structure/property and structure/reactivity relationships and novel material applications. This research in this dissertation includes a fundamental study of the effect of monomelic thiol functionality on thiol-ene polymerization kinetics and formation of the thiol-ene network structure, and an investigation of the development of novel silicate based thiol-ene nanocomposites. The first fundamental study investigates the effect of thiol functionality on the kinetics and ensuing network structure. More specifically, the influence of thiol functionality on the polymerization rate and the thermal and mechanical behavior is described. Novel multifunctional thiol monomers having functionalities, f = 2, 5.6, 8.1, and 11, were synthesized via an amine-catalyzed thiol Michael addition reaction. High conversions of functional groups and marginal changes in thermal and mechanical properties for highly functional thiol monomers (f \u3e 6) suggest that delayed gelation occurs, resulting in a polymer network with reduced effective crosslinked density. Also, thiol functionality has a marginal effect on polymerization rates. The development of a novel silicate based thiol-ene nanocomposite involves an investigation of the changes in the network structure that occurs upon the inclusion of organically modified silicate nanoparticles. As for all nanocomposite materials, the prevention of aggregation is a challenge and is addressed by improving compatibility and optimizing concentration of the silicate particle within the polymer matrix. A fundamental study examines the effect of compatibility and method of incorporation (physical or chemical) of the silicate particle on the morphology and subsequent thermal, mechanical, and physical behavior by varying the type of organic substituents on the caged silicate particle and the molar concentration of silicate particle within the thiol-ene matrix. In all cases, POSS whether incorporated chemically or physically in the network reduces flame spread. Results show that compatibilization of the silicate particles has a great influence on the thermal and physical properties of the network. The influence of silicate particle inclusion is examined by analyzing thermal, mechanical, and physical properties, including enthalpic relaxation. When incorporated chemically into the network with no aggregation, POSS does not alter the thermal transitions, physical properties or mechanical transitions significantly. If hydrogen bonding chemical groups are attached to POSS, an increase in thermal and mechanical transitions as well as modulus in the rubbery region occurs. The interaction of incorporated POSS within the crosslinked thiol-ene polymer was also characterized by the changes in free volume within the network structure. This investigation includes direct analysis of free volume by positron annihilation lifetime spectroscopy (PALS) and oxygen flux measurements. Results indicate that if POSS can be connected chemically into the polymer matrix with little or no aggregation the free volume is unaffected. In addition, the oxygen permeability is unaffected by the presence of POSS whether or not it is incorporated into the thiol-ene network

Photopolymerization and Characterization of Thiol-enes and Thiourethanes

Compared to conventional acrylic monomer systems, thiol-ene photopolymerization, an efficient click process leading to the formation of dense and uniform molecular networks, has several distinct advantages including relative insensitivity to oxygen inhibition, high monomer conversion and low shrinkage. Although there has been a revival of interest in thiol-enes in the past 6 years, the structure-property relationship of these networks has not been explored in detail. For future applications, thiol-enes with higher shelf-life stability and glass transition temperatures need to be used. Sulfur containing urethanes, thiourethanes and dithiourethanes are a class of widely used materials due to their distinct properties such as high refractive index. However, the structure-property relationships of thiourethanes and dithiourethanes have not been explored in detail. This research provides a fundamental study of the photopolymerization and properties of thiol-enes and the structure-property relationships of sulfur containing urethanes. The effect of chemical structure of thiol-ene monomers on physical and mechanical properties, the photopolymerization of thiol-ene free-radical/ene cationic hybrid systems, the development and characterization of thiourethane thiol-ene networks, the effect of hydrogen bonding on the physical aging of thiourethane thiol-ene networks, the investigation of hydrogen bonding behavior of thiourethanes and dithiourethanes and the structure-property relationships are all presented. The first study deals with the photopolymerization and characterization of four different types of ene monomers with both primary and secondary multifunctional thiols. The results indicate that ene structures can significantly affect the rigidity and the physical and mechanical properties of the thiol-ene networks. Network density controlled by the functionality of ene monomers was found also to be a major factor in defining network properties. Networks formed from the secondary thiol-ene systems are basically equivalent to those made from primary thiol-enes with respect to physical mechanical and optical properties. The secondary thiol monomer samples evaluated were found to have excellent storage stability and relatively low odor. The second study reports the photopolymerization kinetics of mixtures containing a trithiol and a trivinyl ether (in different molar ratios) with a cationic photoinitiator. Using the combination of real-time FTIR and rheology to follow both chemical conversion and Theological property development, a clear picture of physical property development during the complete polymerization process is obtained. This represents the first example of a thiol-ene radical/ene cationic two-step hybrid photopolymerization process in which thiol copolymerizes with vinyl ether functional groups in a rapid radical step growth process followed by vinyl ether cationic homopolymerization. The sequential thiol-vinyl ether copolymerization and the vinyl ether cationic polymerization result in crosslinked networks with thermal and mechanical properties that are combinations of each system. The third study concentrates on the development of novel thiourethane based thiol-ene (TUTE) films prepared from diisocyanates, tetrafunctional thiols and trienes. The incorporation of thiourethane linkages into the thiol-ene networks results in TUTE films with high glass transition temperatures. Increase of Tg was achieved by aging at room temperature and annealing the UV cured films at 85 °C. The aged/annealed film with thiol prepared from isophorone diisocyanate and cured with a 10,080 mJ/cm radiant exposure had the highest DMA based glass transition temperature (108 °C) and a tan 8 peak with a full width at half maximum (FWHM) of 22 °C, indicating a very uniform matrix structure. All of the initially prepared TUTE films exhibited good physical and mechanical properties based on pencil hardness, pendulum hardness, impact and bending tests. The physical aging behavior of a class of photopolymerized thiourethane thiol-ene networks were characterized by thermal and spectroscopic analysis, the results of which are directly related to changes in macroscopic physical and mechanical properties. The hydrogen bonding associated with the thiourethane chemical structure exerts at most a slight retarding effect on the enthalpy relaxation, but there is a significant increase in the glass transition temperature of the thiourethane thiol-ene networks, an important implication for application of these materials and the stabilization of their physical, mechanical and thermal transition properties. To define the difference between ordinary urethanes and thiourethanes, the hydrogen bonding behavior of a homologous family of model urethane, thiourethane and dithiourethane compounds prepared from primary isocyanates/isothiocyanates were investigated in solution, melt and solid states. The relative strengths of hydrogen bonds in these systems were evaluated, and the results compared to theoretical calculations of hydrogen bonding strength. The polyurethane and polythiourethane were found to have approximately equivalent physical and mechanical properties as a result of a similar extent of hydrogen bonding, whereas the polydithiourethane model compound, due to a lower degree of hydrogen bonding, has reduced thermal and mechanical transition temperatures as well as lower hardness values. The polythiourethane and polydithiourethane networks exhibit narrower glass transitions compared to polyurethane networks apparently the result of an efficient isocyanate/isothiocyanate-thiol reaction with little or no side products. Due to weakness of the C-S bond compared to the C-0 bond, thiourethanes and dithiourethanes have lower thermal stability than corresponding urethanes. Finally the thiourethanes and dithiourethane have higher refractive index values than their urethane counterparts. To complete the comparison study on urethane type materials, another homologous family of model urethane, thiourethane and dithiourethane prepared from both aliphatic and aromatic secondary isocyanates were comprehensively characterized by a series of spectroscopic, thermal, physical and mechanical analysis measurements to define the relative hydrogen bond strength and its correlation with properties. The polyurethane and polythiourethane systems have similar physical and mechanical properties as a result of their similar structures and hydrogen bonding behavior, whereas the polydithiourethane, due to relatively weaker hydrogen bonding has reduced physical properties. The NMR, FTIR and XRD measurements of small molecule models in solution, melt and solid states indicate the relative hydrogen bonding strength as: urethane ~ thiourethane \u3e dithiourethane. The aromatic urethane is more stable under UV irradiation than the corresponding thiourethane analogues. Due to the weaker C-S bond compared to C-0 bond, thiourethane and dithiourethane have reduced thermal stability compared to their urethane counterpart. Similar Tg values observed for polyurethane and polythiourethane systems are higher than those for the polydithiourethane, consistent with the lower hydrogen bonding in the latter

Correlation chemical shift imaging with low-power adiabatic pulses and constant-density spiral trajectories

In this work we introduce the concept of correlation chemical shift imaging (CCSI). Novel CCSI pulse sequences are demonstrated on clinical scanners for two-dimensional Correlation Spectroscopy (COSY) and Total Correlation Spectroscopy (TOCSY) imaging experiments. To date there has been limited progress reported towards a feasible and robust multivoxel 2D COSY. Localized 2D TOCSY imaging is shown for the first time in this work. Excitation with adiabatic GOIA-W(16,4) pulses (Gradient Offset Independent Adiabaticity Wurst modulation) provides minimal chemical shift displacement error, reduced lipid contamination from subcutaneous fat, uniform optimal flip angles, and efficient mixing for coupled spins, while enabling short repetition times due to low power requirements. Constant-density spiral readout trajectories are used to acquire simultaneously two spatial dimensions and f2 frequency dimension in (kx,ky,t2) space in order to speed up data collection, while f1 frequency dimension is encoded by consecutive time increments of t1 in (kx,ky,t1,t2) space. The efficient spiral sampling of the k-space enables the acquisition of a single-slice 2D COSY dataset with an 8 × 8 matrix in 8:32 min on 3 T clinical scanners, which makes it feasible for in vivo studies on human subjects. Here we present the first results obtained on phantoms, human volunteers and patients with brain tumors. The patient data obtained by us represent the first clinical demonstration of a feasible and robust multivoxel 2D COSY. Compared to the 2D J-resolved method, 2D COSY and TOCSY provide increased spectral dispersion which scales up with increasing main magnetic field strength and may have improved ability to unambiguously identify overlapping metabolites. It is expected that the new developments presented in this work will facilitate in vivo application of 2D chemical shift correlation MRS in basic science and clinical studies.National Institutes of Health (U.S.) (NIH grant R01 1200-206456)National Institutes of Health (U.S.) (NIH grant R01 EB007942)Siemens Aktiengesellschaft (Siemens-MIT Alliance