Robust NMR water signal suppression for demanding analytical applications

Aguilar, J. A.; Kenwright, Simon. J.

doi:10.1039/c5an02121a

Cited by 21 publications

(20 citation statements)

References 29 publications

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“…This issue has also been mentioned in at least one other paper. 44 However, a recent study 48 showed that pulse sequences sensitive to gradient imperfections could still give good line shape by alternating gradient signs between scans. In that case, the WATERGATE water suppression scheme was used, but as we show here the scheme seems to be useful for other pulse sequences, including PURGE.…”

Section: Alternate Water Suppression Techniques and Avoiding Some Of mentioning

confidence: 99%

“…Our results confirm the utility of the PURGE pulse sequence, especially with the rather simple solution to compensate for gradient imperfections. 48 It should be noted that it is possible to adjust the pre-emphasis on most gradients. However, this is time-consuming and also specific for each probe.…”

Section: Alternate Water Suppression Techniques and Avoiding Some Of mentioning

confidence: 99%

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Alternatives to Nuclear Overhauser Enhancement Spectroscopy Presat and Carr–Purcell–Meiboom–Gill Presat for NMR-Based Metabolomics

2017

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NMR metabolomics are primarily conducted with 1D nuclear Overhauser enhancement spectroscopy (NOESY) presat for water suppression and Carr–Purcell–Meiboom–Gill (CPMG) presat as a T2 filter to remove macromolecule signals. Others pulse sequences exist for these two objectives but are not often used in metabolomics studies, because they are less robust or unknown to the NMR metabolomics community. However, recent improvements on alternative pulse sequences provide attractive alternatives to 1D NOESY presat and CPMG presat. We focus this perspective on PURGE, a water suppression technique, and PROJECT presat, a T2 filter. These two pulse sequences, when optimized, performed at least on par with 1D NOESY presat and CPMG presat, if not better. These pulse sequences were tested on common samples for metabolomics, human plasma, and urine.

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Section: Alternate Water Suppression Techniques and Avoiding Some Of mentioning

confidence: 99%

Section: Alternate Water Suppression Techniques and Avoiding Some Of mentioning

confidence: 99%

Alternatives to Nuclear Overhauser Enhancement Spectroscopy Presat and Carr–Purcell–Meiboom–Gill Presat for NMR-Based Metabolomics

2017

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“…Therefore, it was necessary to suppress the water signal very efficiently to allow for unambiguous identification of the methanol produced. This was achieved with the recently reported Robust-5 pulse sequence 23 (see experimental section for details). The results, presented in Figure 2, compare three sets of measurements: (i) ultrapure water placed for 5 seconds in contact with the surface of HOPG, (ii) ultrapure water placed for 2 hours in contact with the surface of HOPG, and (iii) ultrapure water placed for 2 hours in contact with the surface of HOPG while applying a DC potential of +1 V to the HOPG surface with respect to a platinum electrode placed directly in the water.…”

Section: Resultsmentioning

confidence: 99%

In Situ Molecular-Level Observation of Methanol Catalysis at the Water–Graphite Interface

Foster

Aguilar

Kusumaatmaja

et al. 2018

ACS Appl. Mater. Interfaces

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Methanol occupies a central role in chemical synthesis and is considered an ideal candidate for cleaner fuel storage and transportation. It can be catalyzed from water and volatile organic compounds, such as carbon dioxide, thereby offering an attractive solution for reducing carbon emissions. However, molecular-level experimental observations of the catalytic process are scarce, and most existing catalysts tend to rely on empirically optimized, expensive, and complex nanocomposite materials. This lack of molecular-level insights has precluded the development of simpler, more cost-effective alternatives. Here, we show that graphite immersed in ultrapure water is able to spontaneously catalyze methanol from volatile organic compounds in ambient conditions. Using single-molecule resolution atomic force microscopy (AFM) in liquid, we directly observe the formation and evolution of methanol-water nanostructures at the surface of graphite. These molecularly ordered structures nucleate near catalytically active surface features, such as atomic step edges, and grow progressively as further methanol is being catalyzed. Complementary nuclear magnetic resonance analysis of the liquid confirms the formation of methanol and quantifies its concentration. We also show that electric fields significantly enhance the catalysis rate, even when as small as that induced by the natural surface potential of the silicon AFM tip. These findings could have a significant impact on the development of organic catalysts and on the function of nanoscale carbon devices.

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“…EDTA was tested in parallel to facilitate comparisons. To ensure the accuracy of stock ligand concentrations, we employed quantitative 1 H NMR spectroscopy with the ROBUST5 pulse sequence for solvent suppression, in the presence of an internal standard (t‐butanol), to determine the precise concentrations of the EDTA , AmGly 2 and AmPy 2 stock solutions. Such an approach is preferable to relying on inferred stock concentrations from the mass of ligand dissolved in a given volume of water, owing to the hygroscopicity of the ligands.…”

Section: Resultsmentioning

confidence: 99%

On the Antibacterial Activity of Azacarboxylate Ligands: Lowered Metal Ion Affinities for Bis‐amide Derivatives of EDTA do not mean Reduced Activity

Mulla

Beecroft

Pál

et al. 2018

Chemistry A European J

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EDTA is widely used as an inhibitor of bacterial growth, affecting the uptake and control of metal ions by microorganisms. We describe the synthesis and characterisation of two symmetrical bis-amide derivatives of EDTA, featuring glycyl or pyridyl substituents: AmGly and AmPy . Metal ion affinities (logK) have been evaluated for a range of metals (Mg , Ca , Fe , Mn , Zn ), revealing less avid binding compared to EDTA. The solid-state structures of AmGly and of its Mg complex have been determined crystallographically. The latter shows an unusual 7-coordinate, capped octahedral Mg centre. The antibacterial activities of the two ligands and of EDTA have been evaluated against a range of health-relevant bacterial species, three Gram negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) and a Gram positive (Staphylococcus aureus). The AmPy ligand is the only one that displays a significant inhibitory effect against K. pneumoniae, but is less effective against the other organisms. AmGly exhibits a more powerful inhibitory effect against E. coli at lower concentrations than EDTA (<3 mm) or AmPy , but loses its efficacy at higher concentrations. The growth inhibition of EDTA and AmGly on mutant E. coli strains with defects in outer-membrane lipopolysaccharide (LPS) structures has been assessed to provide insight into the unexpected behaviour. Taken together, the results contradict the assumption of a simple link between metal ion affinity and antimicrobial efficacy.

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Robust NMR water signal suppression for demanding analytical applications

Cited by 21 publications

References 29 publications

Alternatives to Nuclear Overhauser Enhancement Spectroscopy Presat and Carr–Purcell–Meiboom–Gill Presat for NMR-Based Metabolomics

Alternatives to Nuclear Overhauser Enhancement Spectroscopy Presat and Carr–Purcell–Meiboom–Gill Presat for NMR-Based Metabolomics

In Situ Molecular-Level Observation of Methanol Catalysis at the Water–Graphite Interface

On the Antibacterial Activity of Azacarboxylate Ligands: Lowered Metal Ion Affinities for Bis‐amide Derivatives of EDTA do not mean Reduced Activity

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