A one‐shot sequence for high‐resolution diffusion‐ordered spectroscopy

Pelta, Michelle D.; Morris, Gareth A.; Stchedroff, Marc J.; Hammond, Stephen J.

doi:10.1002/mrc.1107

Cited by 242 publications

(264 citation statements)

References 28 publications

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“…At the same time, the destruction (defocusing) of the deuterium signal can be mostly reversed by using lock pre-focusing pulsed field gradients with the same area but the opposite polarity as those already present in the pulse sequence. 20 These prefocusing elements should be located before the first excitation pulse to avoid destroying signals of interest, as shown in Figure 1. This only works when pairs of positive and negative gradients are close to one another relative to T2, otherwise lock signals decay before they can be refocused.…”

Section: Signal Distortions Due To Field Disturbancesmentioning

confidence: 99%

Robust NMR water signal suppression for demanding analytical applications

Aguilar

Kenwright

2016

Analyst

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Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We describe the design and application of robust, general-purpose water signal suppression pulse sequences well suited to chemometric work. Such pulse sequences need to deal well with pulse mis-calibrations, radiation damping, chemical exchange, and the presence of sample inhomogeneities, as well as with significant variations in sample characteristics such as pH, ionic strength, relaxation characteristics and molecular weight. Of course, such pulse sequences should produce undistorted lineshapes and baselines and work well both under automation and in the hands of non-experts. As an example, one such pulse sequences, Robust-5, will be presented. This new pulse sequence meets those criteria and is able to reduce a 50 M proteo water signal down to a 0.9 mM level, without fine tuning, and under automation, and it is therefore well suited to the most demanding of analytical applications.

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Section: Signal Distortions Due To Field Disturbancesmentioning

confidence: 99%

Robust NMR water signal suppression for demanding analytical applications

Aguilar

Kenwright

2016

Analyst

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“…A 5-Hz exponential linebroadening factor was applied to the data prior to Fourier transformation, and no zero filling was used. qSpace plots were processed according to Kuchel Fast measurement of diffusion, pulse sequence as described by Pelta et al (23). Notation: RF denotes the radiofrequency time train; G z the magnetic field gradient pulse time train; ␦ is the gradient-pulse duration; g is the gradient amplitude; ⌬ is the diffusion time (time between the midpoints of the two diffusion-encoding periods); is the time between the midpoints of the antiphase field gradients within a given diffusion-encoding period; and ␣ is the "unbalancing" factor of the gradient pulses that obviates the use of EXORCYCLE phase cycling.…”

Section: Diffusion-diffraction Nmr Experimentsmentioning

confidence: 99%

“…In their work, Pelta et al (23) used a diffusion probe that delivered z-gradients of strengths up to 0.3 T m Ϫ1 . Our first challenge was to implement this pulse sequence to use gradients 30 times higher, because signal attenuation is much less when water is restricted in its motion in RBC suspensions.…”

Section: Fast Diffusion-measurement Nmr Setupmentioning

confidence: 99%

“…A few methods have been developed to decrease the experiment time (22) to record a diffusion experiment under "fast" conditions. In this context, we adapted the pulse sequence described by Pelta et al (23) to the special conditions dictated by RBC suspensions with extreme restriction of 1 H 2 O diffusion. The pulse sequence is a bipolar PFGSTE one (24), with each pair of gradient pulses unbalanced by a relative intensity factor, ␣.…”

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confidence: 99%

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Erythrocyte‐shape evolution recorded with fast‐measurement NMR diffusion–diffraction

Pagès

Szekely

Kuchel

2008

Magnetic Resonance Imaging

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Purpose:To monitor red blood cell (RBC) shape evolution by 1 H 2 O diffusion-diffraction NMR in time steps comparable to those required for the acquisition of a 31 P NMR spectrum; thus, to correlate RBC mean diameter with ATP concentration after poisoning with NaF. Materials and Methods:Pulsed-field gradient-stimulated echo (PFGSTE) diffusion experiments were recorded on 1 H 2 O in RBC suspensions. Under conditions of restricted diffusion, q-space experiments report on mean RBC diameter. To decrease experiment time, the phase cycling of radiofrequency (RF) pulses was cut to two transients by using unbalanced pairs of gradient pulses. Data processing used a recent digital filter. Differential interference contrast (DIC) light microscopy also recorded shape changes. 31 P NMR spectroscopy gave estimates of mean ATP concentration.Results: NaF caused RBC-shape evolution from discocytes, through various forms of echinocytes, to spherocytes, over ϳ6 h and ϳ10 h at 37°C and 25°C, respectively. ATP declined to ϳ0.5 its normal concentration before the first stage of discocyte transformation; the concentration was 0.0 after ϳ1.5 h and 3.0 h, respectively, at the two temperatures. Conclusion:RBC shape was readily monitored by NMR with a temporal resolution that was useful for correlations with both DIC microscopy and 31 P NMR spectra.

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“…The original HR-DOSY pulse sequence requires multiple steps of phase cycling, which may be reduced to one with the Oneshot approach. 4 The number of gradient increments can be reduced, using a non-uniform sampling of the diffusion dimension. 5 For 3D DOSY, the diffusion information may also be encoded in the width of the NMR peaks, with the accordion approach.…”

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Spatially encoded 2D and 3D diffusion-ordered NMR spectroscopy

et al. 2017

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We show that the acquisition of 3D diffusion-ordered NMR spectroscopy (DOSY) experiments can be accelerated significantly with the use of spatial encoding (SPEN). The SPEN DOSY approach is discussed, analysed with numerical simulation, and illustrated on a mixture of small molecules.The analysis of complex mixtures of small molecules is a major challenge in chemistry, with applications in metabolomics, natural-product research and chemical synthesis. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool to address this challenge; arrays of NMR spectra are commonly used for identification and structure elucidation. A variety of schemes have been reported to recover the "pure" spectra of components in mixtures. 1 Diffusion-ordered spectroscopy (DOSY) is the most widely used approach for such spectral separation. 2 In DOSY, signal amplitudes are attenuated by a pair of gradient pulses (each of area K) separated by a diffusion delay; a fit of the diffusion-induced decay returns the diffusion coefficient D for each resonance, so that sub-spectra can be separated according to the value of D.The DOSY approach is applicable to a range of Ndimensional (ND, with N typically 1 or 2) NMR experiments. 2a, 3 The use of an incremented gradient area, however, results in a pseudo-(N+1)D experiment and increases the total experimental time by a factor of about 10. Several strategies have been described for the acceleration of DOSY experiments. The original HR-DOSY pulse sequence requires multiple steps of phase cycling, which may be reduced to one with the Oneshot approach. 4 The number of gradient increments can be reduced, using a non-uniform sampling of the diffusion dimension. 5 For 3D DOSY, the diffusion information may also be encoded in the width of the NMR peaks, with the accordion approach. 6 Single-scan DOSY implementations include the Difftrain approach, 7 which has found applications for the analysis of heterogeneous media. Alternatively, the acquisition of the DOSY data may be parallelised, with a spatial encoding of the K dimension. 8 This concept, introduced by Keeler and co-workers, makes it possible to acquired 2D DOSY data in a single scan. It is particularly useful for the analysis of transient processes and hyperpolarised samples. 9 In this communication, we show that spatially encoded diffusion-ordered spectroscopy (SPEN DOSY) can be used for fast separation of 2D correlation spectra of components in mixtures. In order to gain insight into the SPEN DOSY mechanism, we first introduce a numerical simulation framework that can simultaneously account for the complex spin and spatial dynamics. We then describe a generalised implementation of SPEN DOSY. As an example of SPEN 3D DOSY, the acquisition of a 3D DOSY COSY spectrum is accelerated by over an order of magnitude. Figure 1a shows a schematic pulse sequence for spatially encoded multidimensional DOSY experiments. The gradient pulses of the classic STE-based DOSY pulse sequence are replaced with the concurrent application of linearly swept chirp ...

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A one‐shot sequence for high‐resolution diffusion‐ordered spectroscopy

Cited by 242 publications

References 28 publications

Robust NMR water signal suppression for demanding analytical applications

Robust NMR water signal suppression for demanding analytical applications

Erythrocyte‐shape evolution recorded with fast‐measurement NMR diffusion–diffraction

Spatially encoded 2D and 3D diffusion-ordered NMR spectroscopy

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