Practical guide for accurate quantitative solution state NMR analysis

Abstract

A practical guide to experimental conditions such as statistical variation of signal intensity on quantitative solution state nuclear magnetic resonanace (NMR) analysis is discussed and presented. Statistical analysis showed that there is a relationship between a targeted precision and practical pulse intervals. The bandwidth of the audio filter needs to be set so that all the signals of interest fall into 80% of the centre part of the filter. When fulfilling these conditions, the relative standard deviation (RSD) of a signal area in repeated experiments can be estimated by determining the signal-to-noise ratio (SN) of a single spectrum. When the SN reached 1000, the RSD became constant with increasing SN. With such a condition, accuracy better than 1% should be obtained with quantitative NMR.

Metabolic profiling strategy for discovery of nutritional biomarkers: proline betaine as a marker of citrus consumption

“…Fruit spectra were acquired by using a standard onedimensional pulse sequence [RD-90°-t1-90°-tm-90°-acquire FID] with water suppression that irradiated during a RD of 2 s with tm set to 100 ms and a 90°pulse set to 10 ls. The proline betaine and TSP resonances were fully relaxed after a delay time tau of 1.25 and 3 s, respectively, resulting in a spin-lattice relaxation time T1 (=tau/ln2) of 4.33 s. The interpulse delay time d1 (=5 · T1) was therefore set to 21.64 s (24). For spectral processing, FIDs were multiplied by an exponential function that corresponded to line broadening of 0.3 Hz before Fourier transformation.…”

A new approach for accurate quantitative determination using fluorine nuclear magnetic resonance spectroscopy

“…All the parameters for quantitative 19 F NMR analysis were optimized with reference to those for quantitative 1 H NMR analysis [5,11,12].…”

“…As it can be used not only for the purity determination of a pure material [5][6][7] but also for the concentration evaluation [8][9][10], this technique is a high-utility analytical method. Discussions of the accuracy of quantitative 1 H NMR spectroscopy in purity determination have also emerged [5,11,12]. 19 F NMR spectroscopy has similar properties to 1 H NMR spectroscopy; the two techniques have identical nuclear spin and similar resonance frequency and sensitivity.…”

Determination of Water Content in THF Based on Chemical Shift Differences in Solution NMR

“…However, this method has some limitations and maybe subject to inaccuracy. 24,25 Specifically, welldesigned experimental conditions depending on samples (e.g., deuterium locking and shimming, recycle delay, acquisition time, signal gain) are required to obtain proper spectra for precise and accurate quantification. In particular, if the ratio of components to be compared is too big or small, the error could become significant since the integration of NMR signal has some intrinsic error.…”

“…In particular, if the ratio of components to be compared is too big or small, the error could become significant since the integration of NMR signal has some intrinsic error. 24,25 Therefore, other sensitive and convenient techniques such as optical signaling methods have been studied to detect trace levels of water. In that regard, chemical shift differences may be an alternative if highly sensitive sensor molecules applicable for a wide range of water contents are designed.…”