An exact solution for R2,eff in CPMG experiments in the case of two site chemical exchange
An exact solution for R2,eff in CPMG experiments in the case of two site chemical exchange
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DOI：
10.1016/j.jmr.2014.02.023
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发表时间：
2014-07-01
影响因子：
2.2
通讯作者：
Baldwin, Andrew J.
中科院分区：
文献类型：
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作者：
Baldwin, Andrew J.
Carr-Purcell-Meiboom-Gill （CPMG）实验被广泛用于定量分析化学交换对核磁共振光谱的影响。在CPMG实验中，有效横向弛豫率R-2 R-eff通常作为脉冲频率nu（CPMG）的函数来测量。在这里，一个精确的表达式如何R-2，（eff）随nu（CMPG）的变化推导了常见的情况下，两个地点的化学交换的同相磁化。这个结果总结在附录A中，推广了Carver和Richards在1972年发表的一个经常使用的方程。该表达式通过将R-2，R-eff的计算速度提高约130倍，并产生用于数据分析的精确导数，从而能够更快速地分析CPMG数据。此外，推导提供了深入了解实验背后的物理原理。(C) 2014年作者。Elsevier Inc.出版。
The Carr-Purcell-Meiboom-Gill (CPMG) experiment is widely used to quantitatively analyse the effects of chemical exchange on NMR spectra. In a CPMG experiment, the effective transverse relaxation rate, R-2,R-eff, is typically measured as a function of the pulse frequency, nu(CPMG). Here, an exact expression for how R-2,(eff) varies with nu(CMPG) is derived for the commonly encountered scenario of two-site chemical exchange of in-phase magnetisation. This result, summarised in Appendix A, generalises a frequently used equation derived by Carver and Richards, published in 1972. The expression enables more rapid analysis of CPMG data by both speeding up calculation of R-2,R-eff over numerical methods by a factor of ca. 130, and yields exact derivatives for use in data analysis. Moreover, the derivation provides insight into the physical principles behind the experiment. (C) 2014 The Author. Published by Elsevier Inc.