Compositional characterization, mass spectrometric

Before that time, experimental evidence for the existence of heterofullerenes was very rare. In 1991 Smalley and co-workers [4,5] reported on the mass spectrometric detection of borafullerenes C5q B (n = 1-6) generated by laser vaporization of graphite-boron nitride composites. Later, in the same year, the preparation of several clusters was reported [6-8]. However, none of these species has been isolated or structurally characterized. In 1994 Clemmer et al. presented evidence for heterofullerenes containing a metal as part of the framework [9]. Muhr etal. reported on the preparation of monoborafullerenes however, presumably due to the instability of these systems, no pure material could be isolated and completely characterized [10]. Real preparative heterofullerene chemistry began in 1995. The... 

Concentration and distillation provide the pure silane 5, which was characterized by NMR- and mass spectrometric investi tions (GC/MS). Because of the exo/endo-composition of 3, it is assumed that dinorbomyldichlorosilane is a mixture of isomers also. However, we did not succeed in achieving a suitable gas-chromatographic separation. The general properties of both norbomylsilanes are summarized in Table 1. 

Figures 16.2 and 16.3 show the mass- spectrometric patterns [90] characterizing the composition of the primary decomposition products on heating of microgram amounts of AgN03 and Cd(N03)2 at a rate of about IK s on tantalum (Fig. 16.2) and graphite (Fig. 16.3) platforms. The quadrupole mass spectrometer described in Sect. 2.3 (Fig. 2.1) was used. Detailed quantitative analysis of the data obtained led to the following conclusions [90].

Mass spectrometric analysis of glycoproteins has three objectives identify the protein substrate, determine the site of glycosylation, and characterize the structure (i.e composition, sequence, and linkage) of the glycans. 

Gil, A.M. Duarte, I.F. Godejohann, M. Braumann, U. Maraschin, M. Spraul, M. Characterization of the aromatic composition of some hquid foods by nuclear magnetic resonance spectrometry and liquid chromatography with nuclear magnetic resonance and mass spectrometric detection. Anal. Chim. Acta 2003, 488, 35-51. 

Mass Spectrometric Approaches to Sequencing and Compositional Characterization... 

Catania (Italy) Author of more than 50 publications and of 18 international invited lectures. He is currently working in the field of characterization of polymers and copolymers. He is an editorial board member of Rapid Communications in Mass Spectrometry. Research interests Structural characterization of polymers by mass-spectrometric techniques MALDI for the analysis of polymers and copolymers chain statistics applied to copolymer sequence analysis MonteCarlo simulations Bivariate distributions of chain size, and composition in high conversion copolymers. 

For powdered samples, mass-spectrometric (MS) analysis of the gas phase composition during isotope exchange is used for the estimation of parameters characterizing both the smface reaction and oxygen diffusion in the bulk. 

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