Factors affecting the collection and fitting of nuclear magnetic cross-relaxation spectroscopy data with application to waxy corn starch.
Factors affecting the collection and fitting of nuclear magnetic cross-relaxation spectroscopy data with application to waxy corn starch.
复制标题
影响核磁交叉弛豫光谱数据收集和拟合的因素及其在糯玉米淀粉中的应用。
DOI：
10.1021/jf000353h
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发表时间：
2000
影响因子：
6.1
通讯作者：
Eads,TM
中科院分区：
文献类型：
--
作者：
Lewen,KS;McCormick,IH;Molitor,P;Schmidt,SJ;Eads,TM
使用水和含水蜡质玉米淀粉悬浮液进行核磁交叉弛豫光谱（CRS）数据收集和分析的方法的检查，以更好地执行和解释使用CRS获得的结果。CRS数据收集性能评估的时间达到稳态饱和，液体质子的直接饱和，产生横向磁化，并依赖于偏移频率和射频（RF）的磁场强度的纵向弛豫在RF饱和的存在。RF饱和场强，表观交叉弛豫速率和固体纵向弛豫速率的输入值的变化对固体含量和固体内部流动性从拟合NMR数据修改的理论表达式的结果进行了评估的影响。研究了固液质子比的拟合值和化学计量值之间的差异。拟合过程使用高斯线形用于类固体自旋系统的RF饱和，并且使用洛伦兹线形用于液体自旋系统的RF饱和。讨论了在有限的数据集下可以获得可接受结果的条件。关键词：糯玉米淀粉;核磁共振谱;核磁共振;交叉弛豫
An examination of the methods for nuclear magnetic cross-relaxation spectroscopy (CRS) data collection and analysis was conducted using water and an aqueous waxy corn starch suspension to better perform and interpret the results obtained using CRS. The CRS data collection properties evaluated were the time to achieve steady state saturation, the direct saturation of liquid protons, generation of transverse magnetization, and dependence of the offset frequency and radio frequency (RF) field strength of longitudinal relaxation in the presence of RF saturation. Effects were evaluated for variations of input values of RF saturation field strength, apparent cross-relaxation rate, and solid longitudinal relaxation rate on the results for solid content and solid internal mobility from fitting NMR data to modified theoretical expressions. Discrepancies between fitted and stoichiometric values for the solid to liquid proton ratio were investigated. The fitting procedure used a Gaussian line shape for RF saturation of the solid-like spin system and a Lorentzian line shape for RF saturation of the liquid-spin system. Conditions under which acceptable results can be obtained with limited data sets are discussed.Keywords: Waxy corn starch; nuclear magnetic resonance spectroscopy; NMR; cross-relaxation