Estudo da ionização de hidrocarbonetos do petróleo por APCI(+)FT-ICR MS.
Nenhuma Miniatura disponível
Data
2018-08-28
Autores
Souza, Lindamara Maria de
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal do Espírito Santo
Resumo
Analyzing paraffins/fractions of saturates, is a difficult task because they are apolar compounds, characterizing a challenge to the mass spectrometry. However, Atmospheric Pressure Chemical Ionization (APCI) source has provided higher applicability. In order to understand and apply APCI(+) MS to analyze paraffins with the best performance and correlate the MS results with other techniques, this work was divided into three sections: i) associate the results of paraffin analysis by analytical techniques to the Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) results. In addition, studying the ionization of paraffins in the presence of polyaromatic. ii) Comparing the ionization efficiency of saturated hydrocarbons (HCs), polyaromatic hydrocarbons (PAHs), and fractions of n-paraffins, as a function of different types of nebulizing gases (synthetic air, nitrogen (N2) and helium (He)) at the APCI source; iii) Study the interaction of petroleum paraffin deposition inhibitors by establishing a correlation between rheology and oil-finger cold tests with gas chromatography results and mass spectrometry of the saturated fraction of the same oils. These studies showed good agreement between APCI(+)FT-ICR MS and High-Temperature Gas Chromatography (HTGC) data through the distribution of carbon numbers plots for paraffin samples. Mwvalues could be compared to Nuclear Magnetic Resonance spectroscopy (RMN) results. Comprehensive Two-dimensional Gas Chromatography (GCxGC) and APCI(+)FT-ICR MS indicated the presence of cyclic paraffin in saturated fractions obtained from the SAP (Saturate, Aromatic and Polar) method. It was noted that PAHs at concentrations greater than or equal to 25 ppm suppressed the ionization of paraffins, but at low concentrations of PAHs (up to 15 ppm) it is possible to ionize paraffins. The evaluation of different ion gas source (nebulizer gas) showed, surprisingly, that the synthetic air presented an excellent signal-to-noise ratio and a lower matrix suppression. For the samples of n-paraffin, synthetic air and He presented similar ionization performance by hydride abstraction ([M-H]+). However, He showed lower mass errors and lower number of molecules with heteroatoms when HCS and PAH standards were analyzed. The correlation between cold-finger and rheology results with MS showed that inhibitors that caused viscosity reduction and deposit mass acted on oils with similar paraffin fractions for the composition of cyclic HCs
Descrição
Palavras-chave
Ressonância ciclotrônica de íons , Parafinas , Hidrocarbonetos , Ionização , Espectrometria de massa