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|Type:||Artigo de periódico|
|Title:||FT-ICR MS analysis of asphaltenes: Asphaltenes go in, fullerenes come out|
|Abstract:||Asphaltenes analysis still remains a challenge due to their unknown molecular structure and self-associative behavior. FT-ICR MS analyses using five different ionization methods, ESI, APCI, APPI, LDI and MALDI, in both positive and negative mode were performed. A characteristic and typical behavior was observed for the experiments using LDI(+/-) and MALDI(+/-) FT-ICR analyses: a broadband mass spectrum ranging from m/z 500 to 3000 was observed with a 24 Da interval. This phenomenon was attributed to fullerene cluster formation. The most abundant allotropic form of fullerene, C-60, was observed at m/z 719.99914. These species were not observed in APCI(+)/APPI(+) analyses. This last analysis of asphaltene samples doped with the C-60 solution promptly reveals the typical fullerene ions. LDI(+) analyses of pure C-60 showed condensation products. These results indicate a clusterization of asphaltenes in the LDI/MALDI plume, which showed a highly dependency on the laser power density. The dispersion of LDI results on carbonaceus samples in the literature is associated with the lack of control of these parameters. However, to access the sample composition, APPI and APCI should be more suitable. (C) 2014 Elsevier Ltd. All rights reserved.|
|Editor:||Elsevier Sci Ltd|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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