Characterization of Petroleum Asphaltenes by Size Exclusion Chromatography, UV-fluorescence and Mass Spectrometry

Al-Muhareb, Eiman M.; Morgan, Trevor; Herod, Alan A.; Kandiyoti, R.

doi:10.1080/10916460601054222

Cited by 42 publications

(68 citation statements)

References 15 publications

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“…The spectrum appears to be similar to the PB-MS (Figure 2b) and in agreement with a part of literature (Acevedo et al, 2005;Al-Muhareb et al, 2007;Hortal et al, 2006;Tanaka et al, 2004), with no ion peaks detected at masses higher than 700-800 u, even if the nominal mass range detection of the technique is much higher (up to tens of thousands of units). Different energy pulses and concentration have been used, without any dramatic effect on the spectrum.…”

Section: Mass Spectrometry Of Large Aromatic Molecules 643supporting

confidence: 84%

“…The controversy has not been resolved by studies employing mass spectrometry with a soft ionization source like laser desorption-ionization (LDI). Indeed, different groups have reported mean MWs spanning 2 orders of magnitude for similar LDI setups and asphaltene samples (Acevedo et al, 2005;Al-Muhareb et al, 2007;Hortal et al 2006;Tanaka et al, 2004).…”

Section: Mass Spectrometry Of Large Aromatic Molecules 643mentioning

confidence: 98%

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Mass Spectrometric Advances in the Analysis of Large Aromatic Fractions of Heavy Fuel Oils and Carbon Particulates

Apicella

Alfè

Ciajolo

2010

Combustion Science and Technology

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Advanced mass spectrometric systems have been tested for the analysis of heavy fractions of fuel oils and combustion-formed particulate in terms of mass range detection and resolution. The analysis of these complex aromatic samples is not amenable to conventional chromatographic-mass spectrometric techniques due to their low volatility and degradability. In this paper, the advantages and the shortcomings of different ionization methods (electron impact, photoionization, laser ionization) and different mass analyzers (quadrupole, ion trap, time of flight) have been carefully investigated. The optimization of operative parameters has shown to be crucial for the extension of mass detection range. The Atmospheric Pressure Photoionization-Mass Spectrometry techniques showed the best performances in terms of low fragmentation of the parent ion and sensitivity for the analysis of asphaltenes. Laser Desorption Ionization-Mass Spectrometry showed to be more suitable for the analysis of aromatic tarry combustion-formed species.

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Section: Mass Spectrometry Of Large Aromatic Molecules 643supporting

confidence: 84%

Section: Mass Spectrometry Of Large Aromatic Molecules 643mentioning

confidence: 98%

Mass Spectrometric Advances in the Analysis of Large Aromatic Fractions of Heavy Fuel Oils and Carbon Particulates

Apicella

Alfè

Ciajolo

2010

Combustion Science and Technology

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“…The presence of components excluded from the porosity of the SEC column, eluting between 9-13 min may be interpreted as showing the presence of large molecules, and/or possibly indicating the presence of three-dimensional structures or conformations (eluting earlier than would be warranted by their molecular masses alone) rather than of aggregates of the small polar components [1,24,25] of coal tars, identified by GC-MS analysis. The first pentane fraction chromatograms showed some low intensity excluded material in the coal derived liquids.…”

Section: Resultsmentioning

confidence: 99%

The Pentane- and Toluene-Soluble Fractions of a Petroleum Residue and three Coal Tars by Size Exclusion Chromatography and UV-Fluorescence Spectroscopy

Karaca

Millán

Morgan

et al. 2007

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Les fractions solubles dans le pentane et le toluène d'un résidu pétrolier et de trois échantillons de goudron de charbons par chromatographie d'exclusion stérique et par spectroscopie de fluorescence -Un résidu pétrolier de distillation atmosphérique ainsi que trois échantillons de goudron issus des pyrolyses de différents charbons sont séparés en sept fractions par chromatographie liquide sur gel de silice. Les solvants utilisés successivement sont : le pentane, le toluène, l'acétonitrile, la pyridine, la 1-methyl-2-pyrrolidinone (NMP) et l'eau permettant l'obtention de 7 fractions. Les fractions obtenues pour chacun des quatre échantillons sont ensuite comparées par chromatographie d'exclusion stérique (SEC) au moyen d'NMP comme éluant, puis par spectroscopie de fluorescence. Cet article traite uniquement le cas des fractions solubles dans le pentane et le toluène, car étant les moins polaires. D'après les analyses SEC, la taille des molécules aromatiques entre les premières fractions solubles dans le pentane et celles solubles dans le toluène augmente. Ainsi, les fractions du résidu pétrolier possèdent des molécules de plus grande taille que celles extraites, par le même solvant, pour les différents goudrons. Les trois échantillons de goudrons montrent des différences significatives, indiquant que la température de pyrolyse joue un rôle important sur la taille des molécules. Les résultats de spectroscopie, en solution NMP, montrent également de grandes différences entre le résidu pétrolier et les trois goudrons, de même que ces trois derniers sont différents entre eux. En général, les fractions du résidu pétrolier contiennent de plus petits groupes aromatiques que les fractions liquides issues du charbon. Ces fractions de faible polarité, contenant des éléments exclus par la colonne chromatographique, ont peu de chance d'être des agrégats de molécules polaires. Abstract

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“…First, Acevedo et al 7 and Tanaka et al 8 report heavy molecular weights (average ∼2000 Da), arguing that relatively low laser pulse energy is insufficient to volatilize/ionize the heaviest components of this complex mixture. On similar grounds, Al-Muhareb et al 9 measured an asphaltene mass spectrum with a maximum >50 000 Da and signal extending beyond 200 000 Da. Second, Martínez-Haya and co-workers 10,11 suggest that lighter masses (peak ∼500 Da and average ∼900 Da) more accurately represent asphaltene molecular weights, arguing that high pulse energy and sample concentration promote aggregation of asphaltenes in the plasma plume produced in LDI.…”

mentioning

confidence: 95%

Two-Step Laser Mass Spectrometry of Asphaltenes

et al. 2008

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Defined by their solubility in toluene and insolubility in n-heptane, asphaltenes are a highly aromatic, polydisperse mixture consisting of the heaviest and most polar fraction of crude oil. Although asphaltenes are critically important to the exploitation of conventional oil and are poised to rise in significance along with the exploitation of heavy oil, even as fundamental a quantity as their molecular weight distribution is unknown to within an order of magnitude. Laser desorption/ionization (LDI) mass spectra vary greatly with experimental parameters so are difficult to interpret: some groups favor high laser pulse energy measurements (yielding heavy molecular weights), arguing that high pulse energy is required to detect the heaviest components of this mixture; other groups favor low pulse energy measurements (yielding light molecular weights), arguing that low pulse energy is required to avoid aggregation in the plasma plume. Here we report asphaltene mass spectra recorded with two-step laser mass spectrometry (L2MS), in which desorption and ionization are decoupled and no plasma is produced. L2MS mass spectra of asphaltenes are insensitive to laser pulse energy and other parameters, demonstrating that the asphaltene molecular weight distribution can be measured without limitation from insufficient laser pulse energy or plasma-phase aggregation. These data resolve the controversy from LDI, showing that the asphaltene molecular weight distribution peaks near 600 Da and previous measurements reporting much heavier species suffered from aggregation effects.

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Characterization of Petroleum Asphaltenes by Size Exclusion Chromatography, UV-fluorescence and Mass Spectrometry

Cited by 42 publications

References 15 publications

Mass Spectrometric Advances in the Analysis of Large Aromatic Fractions of Heavy Fuel Oils and Carbon Particulates

Mass Spectrometric Advances in the Analysis of Large Aromatic Fractions of Heavy Fuel Oils and Carbon Particulates

The Pentane- and Toluene-Soluble Fractions of a Petroleum Residue and three Coal Tars by Size Exclusion Chromatography and UV-Fluorescence Spectroscopy

Two-Step Laser Mass Spectrometry of Asphaltenes

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