Estendendo a caracterização dos compostos nitrogenados em resíduo de vácuo por FT-ICR MS

• Autor(a) principal: Vasconcelos, Géssica Adriana
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/00130000053br
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/5952
• topic: Petroleômica; ESI FT-ICR MS; Compostos nitrogenados; Extração em fase sólida; Extração em líquido-líquido; Extração em coluna cromatográfica; Petroleomics; ESI FT-ICR MS; Nitrogen compounds; Solid-phase extraction; Liquid-liquid extraction; Chromatographic columm extraction; QUIMICA::QUIMICA ANALITICA

Petroleomics by FT-ICR MS was able to characterize petroleum and its derivatives at molecular level. The most used ionization source on the analysis of these compounds is electrospray. However, species that are more basic or more acidic suppress the ionization of other compounds with less strength. This disadvantage consists of, especially in positive mode, only detecting compounds with higher pKa values preventing the mass spectrometer from reading less basic species that is also present in the sample. In view of this, the development of new methods whose purpose is to minimize these effects is essential. An alternative is to use fast techniques of extraction and separation followed by analysis by FT-ICR MS. This study pursued two goals: first, to perform an extraction of vacuum residue into basic and neutral nitrogen compounds using different methods, and second, to fractionate the basic nitrogen compounds present in RV according to their mass/ratio. Three methods were tested to achieve the first objective: solvent extraction (LLE), column chromatography (LC), and solid phase extraction (SPE). The results showed that LLE was the less selective technique among all three studied procedures. SPE and LC showed similar results, and they allowed to partially separate the basic nitrogen compounds from neutral species. To accomplish the second goal, a fractionation using SPE was applied to the vacuum residue sample. This procedure permitted to detect compounds that apparently were not present in the untreated sample as a consequence of a reduction on ion suppression effect. Electrospray ionization and high resolution mass spectrometry (FT-ICR MS) were employed on the analysis of each sample.