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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Rapid and simple determination of T-1 relaxation times in time-domain NMR by Continuous Wave Free Precession sequence

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Author(s):
Moraes, Tiago Bueno ; Monaretto, Tatiana ; Colnago, Luiz Alberto
Total Authors: 3
Document type: Journal article
Source: JOURNAL OF MAGNETIC RESONANCE; v. 270, p. 1-6, SEP 2016.
Web of Science Citations: 7
Abstract

Longitudinal (T-1) and transverse (T-2) relaxation times have been widely used in time-domain NMR (TD-NMR) to determine several physicochemical properties of petroleum, polymers, and food products. The measurement of T-2 through the CPMG pulse sequence has been used in most of these applications because it denotes a rapid, robust method. On the other hand, T-1 has been occasionally used in TD-NMR due to the long measurement time required to collect multiple points along the T-1 relaxation curve. Recently, several rapid methods to measure T-1 have been proposed. Those methods based upon single shot, known as Continuous Wave Free Precession (CWFP) pulse sequences, have been employed in the simultaneous measurement of T-1 and T-2 in a rapid fashion. However, these sequences can be used exclusively in instrument featuring short dead time because the magnitude of the signal at thermal equilibrium is required. In this paper, we demonstrate that a special CWFP sequence with a low flip angle can be a simple and rapid method to measure T-1 regardless of instruments dead time. Experimental results confirmed that the method called CWFP-T-1 may be used to measure both single T-1 value and T-1 distribution in heterogeneous samples. Therefore, CWFP-T-1 sequence can be a feasible alternative to CPMG in the determination of physicochemical properties, particularly in processes where fast protocols are requested such as industrial applications. (C) 2016 Elsevier Inc. All rights reserved. (AU)

FAPESP's process: 13/03770-1 - Development and applications of pulses sequences with alternating phases in the time domain NMR
Grantee:Tatiana Monaretto
Support type: Scholarships in Brazil - Master
FAPESP's process: 11/11160-3 - Development of steady state free precession (SSFP) sequences with phase alternation for rapid acquisition of high resolution NMR spectra
Grantee:Tiago Bueno de Moraes
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 14/22126-9 - Development of time domain NMR spectrometers and methods for chemical analyses in field
Grantee:Luiz Alberto Colnago
Support type: Regular Research Grants