Nuclear magnetic resonance combination with other analytical

DSC is increasingly being applied to the study of epoxy resin cure in combination with other analytical methods such as nuclear magnetic resonance and Fourier transform infra-red spectroscopy, chromatographic methods, and dynamic mechanical or dielectric studies. It is probably as part of such combined investigations that DSC can be used most effectively in basic research, and in quality control and assessment. 

The newer MS experiments in a data-dependent acquisition mode provide the MS and MS" data from a single injection. Accurate mass measurements, software-assisted data acquisition, and processing methods have been very useful for metabolite detection and identification. In addition, when MS is combined with other analytical techniques such as derivatization, H/D exchange, and stable isotope labeling have been proven very useful for structural characterization of unusual, uncommon, and difficult metabolites. Further, the flexibility and broad applications of mass spectrometry have allowed for the creation of hybrid instruments and coupling to other powerful analytical techniques, most notably nuclear magnetic resonance (NMR), to further enhance the utility in the field of drug metabolism. 

Perhaps the most revolutionary development has been the application of on-line mass spectroscopic detection for compositional analysis. Polymer composition can be inferred from column retention time or from viscometric and other indirect detection methods, but mass spectroscopy has reduced much of the ambiguity associated with that process. Quantitation of end groups and of co-polymer composition can now be accomplished directly through mass spectroscopy. Mass spectroscopy is particularly well suited as an on-line GPC technique, since common GPC solvents interfere with other on-line detectors, including UV-VIS absorbance, nuclear magnetic resonance and infrared spectroscopic detectors. By contrast, common GPC solvents are readily adaptable to mass spectroscopic interfaces. No detection technique offers a combination of universality of analyte detection, specificity of information, and ease of use comparable to that of mass spectroscopy. 

The analytical technologies used In metabolomic investigations are nuclear magnetic resonance and mass spectrometry alone or in combination with liquid or gas chromatographic separation of metabolites (243). Other techniques include thin-layer chromatography, Fourier-transform infrared spectrometry, metabolite arrays, and Raman spectroscopy. 

Capillary column gas chromatography (GC)/mass spectrometry (MS) has also been used to achieve more difficult separations and to perform the structural analysis of molecules, and laboratory automation technologies, including robotics, have become a powerful trend in both analytical chemistry and small molecule synthesis. On the other hand, liquid chromatography (LC)/MS is more suitable for biomedical applications than GC/MS because of the heat sensitivity exhibited by almost all biomolecules. More recent advances in protein studies have resulted from combining various mass spectrometers with a variety of LC methods, and improvements in the sensitivity of nuclear magnetic resonance spectroscopy (NMR) now allow direct connection of this powerful methodology with LC. Finally, the online purification of biomolecules by LC has been achieved with the development of chip electrophoresis (microfluidics). 

It must be emphasised that infrared and Raman spectroscopy should not be used to the exclusion of other techniques such as H and C nuclear magnetic resonance, which are particularly useful characterisation techniques. Other useful techniques are mass spectroscopy, ultraviolet-visible spectroscopy, chromatography, thermo-analytical techniques (such as differential scanning calorimetry (DSC), thermal gravimetry (TG) etc.), or combined techniques such as GC-MS (gas chromatography combined with mass spectrometry)... 

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