Solvent Suppression in High-Resolution 1H NMR Spectroscopy Using Conventional and Phase Alternated Continuous Wave Free Precession

Duarte, Claudimar J.; Colnago, Luiz Alberto; Azeredo, Rodrigo Bagueira de Vasconcellos; Venâncio, Tiago

doi:10.1007/s00723-013-0482-6

Cited by 9 publications

(7 citation statements)

References 27 publications

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“…The experiments used a CWFP train with a few hundred pulses, producing a null signal for the solvent line on resonance before the acquisition. The method has been used in one-dimensional (1D) and two-dimensional (2D) high-resolution NMR experiments [36].…”

Section: Fast and Simultaneous T1 And T2 Measurementsmentioning

confidence: 99%

Applications of Continuous Wave Free Precession Sequences in Low-Field, Time-Domain NMR

2019

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This review discusses the theory and applications of the Continuous Wave Free Precession (CWFP) sequence in low-field, time-domain nuclear magnetic resonance (TD-NMR). CWFP is a special case of the Steady State Free Precession (SSFP) regime that is obtained when a train of radiofrequency pulses, separated by a time interval T p shorter than the effective transverse relaxation time (T 2 *), is applied to a sample. Unlike regular pulsed experiments, in the CWFP regime, the amplitude is not dependent on T 1 . Therefore, T p should be as short as possible (limited by hardware). For T p < 0.5 ms, thousands of scans can be performed per second, and the signal to noise ratio can be enhanced by more than one order of magnitude. The amplitude of the CWFP signal is dependent on T 1 /T 2 ; therefore, it can be used in quantitative analyses for samples with a similar relaxation ratio. The time constant to reach the CWFP regime (T*) is also dependent on relaxation times and flip angle (θ). Therefore, T* has been used as a single shot experiment to measure T 1 using a low flip angle (5 • ) or T 2 , using θ = 180 • . For measuring T 1 and T 2 simultaneously in a single experiment, it is necessary to use θ = 90 • , the values of T* and M 0 , and the magnitude of CWFP signal |M ss |. Therefore, CWFP is an important sequence for TD-NMR, being an alternative to the Carr-Purcell-Meiboom-Gill sequence, which depends only on T 2 . The use of CWFP for the improvement of the signal to noise ratio in quantitative and qualitative analyses and in relaxation measurements are presented and discussed.to suppress these anomalies using a small variation of T p that cancels the echo component. In the same year, Schwenk [4] proposed the Quadriga Fourier Transform (QFT) to suppress these anomalies. The QFT method was based on a small variation in frequency offset. Although these procedures minimize these anomalies, SSFP sequences were not routinely used in high resolution NMR.We revised these methods and suggested some modifications to increase the applications of SSFP in high-resolution NMR using the Traff apodization function [5] to minimize the truncation problem, or processing the SSFP time domain signal with a parametric method based on Krylov Basis Diagonalization Method (KBDM) [6]. KBDM solves the truncation and phase anomalies but not the amplitude problem. Therefore, SSFP sequences cannot be used to efficiently enhance signal to noise ratio (SNR) in high-resolution NMR. SSFP sequences have been successfully used in magnetic resonance imaging [7,8] and in low-field, time-domain NMR [9][10][11]. The use of a SSFP sequence in low field time domain (TD-NMR) started in year 2000 [12,13]. The applications of SSFP sequences in TD-NMR can be performed under the drastic condition where T p < 1 ms. Under this condition, a truly continuous wave free precession (CWFP) regime is obtained [13]. Normally, CWFP sequences use T p < 0.5 ms, as T p has to be shorter than T 2 *, which is in the order of 1 ms in most TD-NMR spectrometers.In the CWFP regime, F...

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Section: Fast and Simultaneous T1 And T2 Measurementsmentioning

confidence: 99%

Applications of Continuous Wave Free Precession Sequences in Low-Field, Time-Domain NMR

2019

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“…Therefore, in the SSFP regime, each pulse produces FID and echo signals that are 180 out of phase. SSFP sequences have been widely used in fast magnetic resonance imaging protocols as well as to enhance the signal-to-noise (SNR) ratio in high-resolution NMR spectroscopy [15][16][17][18][19]. Figure 1c shows the SSFP signal observed in a very fast pulse rate in which T p < T 2 * .…”

Section: Steady-state Free Precession Sequencesmentioning

confidence: 99%

Food Analysis Using Fast Steady-State Free Precession TD-NMR Relaxometric Methods

Colnago

Moraes

Monaretto

2016

Modern Magnetic Resonance

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The importance of NMR relaxometry in food analysis has been growing at a fast pace in recent years. Most food-related applications rely upon the transverse relaxation time (T 2) that can be measured with a single-shot method using the Carr-Purcell-Meiboom-Gill pulse sequence. On the other hand, the longitudinal relaxation time (T 1) has been seldom used due to the long measurement time of classical methods (e.g., inversion recovery, saturation recovery, and other pulse sequences). To bypass the long acquisition time, several single-shot, steady-state methods have been proposed to measure T 1 , T 2 , and T 1 /T 2 ratio. This chapter presents and discusses the advantages and disadvantages of rapid, single-shot continuous wave free precession (CWFP) pulse sequences in the measurement of

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“…Liquid state NMR of proteins strongly relies on the observation of the amide NH proton resonances and is therefore carried out in a solvent mainly composed of light water. The concentration of hydrogen in protein NMR samples (110 mol L −1 ) compared to the one of the protein itself (1 mmol L −1 or less, (Zheng and Price, 2010)) forced NMR spectroscopists to create efficient water signal suppression techniques (Lee et al, 2017;Chen et al, 2017;Duarte et al, 2013;Gouilleux et al, 2017). Without them, the water signal would cover a wide band of signals of high structural importance and would also hamper the accurate operation of analog to digital signal conversion devices (Mo and Raftery, 2008) resulting in detection sensitivity reduction.…”

Section: Introductionmentioning

confidence: 99%

Multiple solvent signal presaturation in <sup>13</sup>C NMR

Canton¹,

Roe²,

Poigny³

et al. 2020

Preprint

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Abstract. The analysis by proton-decoupled carbon-13 nuclear magnetic resonance spectroscopy of samples dissolved in solvents presenting strong multiple resonances can be facilitated by the suppression of these resonances by multi–site presaturation. The advantage drawn from this operation is the elimination of the possible artifacts that arise from the solvent signals in non–optimized decoupling conditions. Solvent presaturation was implemented on glycerol, 1,2–propanediol, 1,3–propanediol, 1,2–butanediol, 1,3–butanediol with at least 94 % on–resonance efficiency and a bandwidth of less 5 than 50 Hz measured at 50 % signal intensity decrease. The experimental measurement of the signal suppression bandwidth leads to unexpected selectivity profiles for frequency close resonances. Computer resolution of the Bloch equations during multi–site presaturation provide an insight into the origin of the observed profile perturbations.

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Solvent Suppression in High-Resolution 1H NMR Spectroscopy Using Conventional and Phase Alternated Continuous Wave Free Precession

Cited by 9 publications

References 27 publications

Applications of Continuous Wave Free Precession Sequences in Low-Field, Time-Domain NMR

Applications of Continuous Wave Free Precession Sequences in Low-Field, Time-Domain NMR

Food Analysis Using Fast Steady-State Free Precession TD-NMR Relaxometric Methods

Multiple solvent signal presaturation in <sup>13</sup>C NMR

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Solvent Suppression in High-Resolution 1H NMR Spectroscopy Using Conventional and Phase Alternated Continuous Wave Free Precession

Cited by 9 publications

References 27 publications

Applications of Continuous Wave Free Precession Sequences in Low-Field, Time-Domain NMR

Applications of Continuous Wave Free Precession Sequences in Low-Field, Time-Domain NMR

Food Analysis Using Fast Steady-State Free Precession TD-NMR Relaxometric Methods

Multiple solvent signal presaturation in &lt;sup&gt;13&lt;/sup&gt;C NMR

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Multiple solvent signal presaturation in <sup>13</sup>C NMR