Nuclear magnetic resonance isotope-enhanced

Example Isotopic enrichment is a standard means to enhance the response of an analyte in nuclear magnetic resonance (NMR). Such measures gain importance if extremely low solubility is combined with a large number of carbons, as is often the case with [60]fullerene compounds. [19] The molecular ion signals, IVT, of Qo with natural isotopic abundance and of C-enriched Cgo are shown below (Fig. 3.11 for EI-MS of [60]fullerenes cf. Refs. [20-22]). From these mass spectra, the enrichment can be determined by use of Eq. 3.1. For Qo of natural isotopic abundance we obtain Mrceo = 60 x 12.0108 u = 720.65 u. Applying Eq. 

In more recent years, it has become less essential to use radioactivity, which, though very useful, is also hazardous. As we have mentioned, there are also stable, rare isotopes. In the case of hydrogen we have deuterium in the case of carbon we have carbon 13 (seven neutrons). It is also possible to label a biochemical compound with a stable isotope. Some of these isotopes ( C being one) can be monitored by nuclear magnetic resonance (NMR) all of them can be detected by mass spectrometry, which, as the name implies, relies on measuring the differences in mass of different molecules or fragments of molecules. The improved sensitivity of these two techniques in recent years has enhanced the usefulness of stable isotopes. 

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. 

Nuclear magnetic resonance spectroscopy of metal 7c-complexes is widely used currently for identification and characterization of metal n-complexes. Both and NMR spectra are commonly reported in contemporary literature. With the increasing availability of instruments capable of studying several different isotopes as well as the enhanced resolution of spectra with the development of commercial 100 and 220 Me instruments,... 

---