Optimal flip angle for robust practical quantitative NMR measurement using a fixed pulse length

• Published in: Magnetic resonance in chemistry Vol. 57; no. 7; pp. 390 - 394
• Main Authors: Gao, Jinhai, Tsao, Jeffrey, Rajan, Srinivasan, Wang, Bing
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.07.2019
• Subjects: Calibration; NMR; Nuclear magnetic resonance; optimal flip angle; Organic chemistry; Pulse duration; quantitative NMR; Spectrometers; optimal flip angle; quantitative NMR
• ISSN: 0749-1581; 1097-458X
• DOI: 10.1002/mrc.4859

NMR quantification has been traditionally performed by using internal standards. Although methods using external reference in NMR quantification have been developed, the major obstacles in using external referencing method are the measurement deviations associated with changing sample conditions and the requirement of pulse width calibration for every sample in order to compensate these errors. The calibration process is time consuming and in some cases impossible. We developed a quantitative NMR method fixed pulse length (FIXPUL) for all measurements without sample‐by‐sample calibration. The method is based on the use of an optimal flip angle calibrated for an external standard so that the quantitative errors associated with the pulse width variations are minimized. FIXPUL can be implemented on most basic NMR spectrometers and is robust and easily automated. The method is applicable to a wide range of solution NMR samples in chemistry, biology, and drug research and discovery. A quantitative NMR method using a fixed pulse length (FIXPUL) for all samples is developed, based on the use of an optimal flip angle of 116° calibrated for an external standard so that the quantitative errors associated with the pulse width variations are minimized. The method is robust and can be easily automated, applicable to a wide range of solution NMR samples.