NMR continued

The use of NMR continues to improve existing methods, and to develop new concepts. By cleverly combining existing pulse-sequences, new sequences are formed with improved properties. An example is the combination of the COSY and DOSY sequence to a new 3D-NMR COSY-IDOSY sequence with improved sensitivity, a 32-fold decrease in experiment time, and an improved resolution resulting in better data analysis [34]. 

In the past, HPLC-NMR was limited by its sensitivity, but with advancements in NMR magnets and probes, carotenoids can be detected in the upper nanogram range using this technique (Albert, 1999 Dachtler et ah, 2001). As chromatography and NMR continue to develop, it is likely that HPLC-NMR will be used more routinely for the structural elucidation of carotenoid stereoisomers in foods. 

Proton ID NMR continues to be extremely useful for lignin structural studies, as reviewed more recently [164]. Its role is being augmented by 2D methods. 

It is an understatement to say that the manipulation of nuclear magnetization in physical and spin space described in the three chapters of this section on NMR constitute one of the most powerful spectroscopic approaches to the study of matter in solution and solid phases. NMR continues to evolve in delightful ways that keeps this spectroscopy fresh and applicable in solving structure and dynamics problems in complex materials. 

In NMR spectroscopy, the sensitivity has been the issue of general interest. The technological/methodological advances in sensitivity enhancement made so far had enabled one to reveal hitherto inaccessible structural information, strengthening NMR spectroscopy as a means for chemical analysis. Further progress in future is anticipated to push NMR spectroscopy, and thereby science, forward. That is why the sensitivity enhanced NMR continues and will continue to be an active research subject matter in the community. 

The utility of solid state NMR continues to grow. Many new applications, particularly those based on motional differences of the phases, are developing, as experiments are easier to do with better spinners and decoupling methods. 

Nuclear magnetic resonance (NMR) continues to be the method of choice to study tautomerism in solution with low temperature studies becoming more common due to the use of dipolar aprotic solvents of low melting point, such as DMY-dj [16] and HMPA-iij g [17]. The main limitation of the use of NMR is due to it being a slow method that often needs the use of model compounds, whereas, UV-Vis spectroscopy is very fast and tautomers are seen... 

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