Isotope resolution

SIMS—The detection limits are by far the best of the five techniques and is the only one that offers isotopic resolution for all elements. Quantification is difficult because of the wide variation in sputtering yields produced by different ion beams. 

Application of FT-ICR-MS for on-hne capillary electrophoresis-MS (CE-MS), e.g., in the analysis of single cells [78]. A erythrocyte cell was lysed in a CE colunm. The a- and P-chaitrs of hemoglobin, ca. 450 amol present in the cell, were detected with isotopic resolution. 

Figure 4 ESI-FT-ICR mass spectrum of freestanding T domain Pks4 from bikaverin biosynthetic pathway, (a) Multiple charge states of apo ( ) and holo ( ) Pks4. (b) Single charge state (11 +) of Pks4 shows isotopic resolution obtained by FT-ICFt-MS analysis.

As in the stellar case, information on the isotopic composition of the GCRs would be of prime interest in helping to evaluate the fractional contribution of freshly synthesised r-process material to this quite recent sample of galactic material. In fact, GCR composition measurements with isotopic resolution up to at least Z 40 are within the reach of present detector technology, as exemplified by the R-process Isotope Observer RIO project currently under study [57]. 

Fig. 20.13. Contour plot from the HPLC/FT-ICR-MS coupling of a pyrrole amide compound collection (R2 = C6Hs, R3 = H) This method allows to prove the identity of isomers. The isotope resolution of the molecule ion peaks is recognizable.

Fig. 10.12 ESI-FT-ICR mass spectra of (a) the fluoroacetic acid, pH 3. The inserts show native intact hem-protein complex of horse isotopic resolutions for the 9- and 1 7-fold heart myoglobin (b) spectrum ofthe denatured protonated molecular ions [145]. apoprotein upon dissociation of hem in tri-...

Much like X-rays, the interactions of neutrons with matter are atomic in nature. The difference is that neutrons are sensitive to nuclei directly, whereas X-rays interact with electrons. Hence, while X-rays are unsuitable to detect light elements because of the low atomic electron count, neutron scattering factors depend on the properties of the nucleus [206]. The most relevant consequence in the context of this discussion is that neutron-based tools are better suited for the detection of H and Li than X-rays, as H and Li are among the most highly neutron-absorbing atoms, and that they offer isotope resolution capability. In principle, they are also nondestructive. 

Fig. 11.25. MALDI-TOF spectrum of polystyrene 12500 doped with Ag ions. The isotopic pattern of silver does not affect the spectrum as isotopic resolution here is not achieved anyway. Adapted from Ref [ 119] by permission. John Wiley Sons, 2001.

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