Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of kerogen extracts: effect of interactions between sample structure and matrix

Herod, Alan A.; Lázaro, M.J.; Rahman, Mukhlis A.; Domin, Marek; Cocksedge, M. J.; Kandiyoti, R.

doi:10.1002/(sici)1097-0231(19971015)11:15<1627::aid-rcm11>3.0.co;2-n

Cited by 36 publications

(20 citation statements)

References 17 publications

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“…Data obtained using 3‐IAA in the linear mode are characterized by a broad molecular mass distribution extending from about 200–3000 Da. Although a few features (which are due to the matrix) are superimposed on this broad distribution, this data is similar to that found by others when using polar matrices for crude oil related materials 8,17. In contrast, the data obtained in reflectron mode are much less informative.…”

Section: Resultssupporting

confidence: 88%

“…Although high‐boiling crude oil products are less amenable to mass spectrometric methods, in general,6 a variety of different crude oil related materials have been analyzed by MALDI‐MS. Herod and coworkers have used MALDI‐ or LDI‐MS for molecular mass determinations of coal‐tar pitches,7–12 coal‐derived liquids,13–16 kerogen extracts,17 petroleum residues,18 bitumens19 and other petroleum samples 20–25…”

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confidence: 99%

“…In addition to those prior studies that used MALDI‐MS for the characterization of crude oil related materials, Herod and coworkers have studied sample preparation and instrumental conditions appropriate for MALDI‐MS of crude oil related materials 7,8,13,17. Domin found that increasing the extraction voltages increases the intensity of high mass ions 8,13.…”

mentioning

confidence: 99%

“…Herod examined kerogen extracts in the absence and presence of a matrix. It was found that older kerogen extracts act as a self‐matrix while the younger kerogen extracts worked well with polar matrices 17…”

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confidence: 99%

“…A separate MALDI‐MS study of asphaltenes yielded a much lower molecular mass, in the range ∼200 to 3000 Da 27. For those prior studies that used MALDI‐MS, the most common and effective matrices employed were polar matrices such as sinapinic acid, α ‐cyano‐3‐hydroxycinnamic acid, 2,5‐dihydroxybenzoic acid, 2‐(4‐hydroxyphenylazo)benzoic acid, and 9‐anthracenecarboxylic acid 8,17…”

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confidence: 99%

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The use of nonpolar matrices for matrix‐assisted laser desorption/ionization mass spectrometric analysis of high boiling crude oil fractions

Robins

Limbach

2003

Rapid Comm Mass Spectrometry

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Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) with nonpolar matrices has been investigated for its applicability to the characterization of atmospheric resid crude oil fractions. The data obtained by use of nonpolar matrices was compared with that from polar matrices as well as from direct LDI-MS and field ionization mass spectrometry. Nonpolar matrices, such as anthracene or 9-cyanoanthracene, yield only a single radical molecular cation upon LDI. Thus, no interfering matrix-related ions are present during the MALDI-TOFMS analysis of the crude oil sample. Nonpolar matrices yield molecular mass distributions from linear mode MALDI-TOFMS that are comparable to distributions found with LDI-MS. An advantage of nonpolar matrices is the increased production of analyte ions, which allows reflectron mode MALDI-TOFMS to be performed. Nonpolar matrices are also shown to be less sensitive to solvent and sample preparation conditions than conventional polar matrices. These results suggest that nonpolar matrices may be favorable alternatives to more traditional polar or acidic matrices commonly used in the MALDI mass spectral characterization of crude oil related samples.

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confidence: 88%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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The use of nonpolar matrices for matrix‐assisted laser desorption/ionization mass spectrometric analysis of high boiling crude oil fractions

Robins

Limbach

2003

Rapid Comm Mass Spectrometry

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Determining a ‘safe’ high-mass limit in matrix-assisted laser desorption/ionisation time-of-flight mass spectra of coal derived materials with reference to instrument noise

Lázaro¹,

Herod²,

Domin³

et al. 1999

Rapid Commun. Mass Spectrom.

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Three methods for determining a 'safe' estimate for high-mass limits of MALDI spectra of coal derived liquids were explored, using a sample of coal-tar pitch and its pyridine-insoluble fraction. Co-addition of increasing numbers of single-shot spectra (10, 30, 50 and 100 pulses) showed visually observable reductions in noise levels, consistent with robust and statistically meaningful signals. Three separate types of post-acquisition calculation were used to identify high-mass limits of the spectra. (i) A literature method indicated high-mass limits similar to those observed visually-as a shift from baseline at the highest masses, nearly 350 000 u for the coal tar pitch and about 390 000 u for its pyridine insoluble fraction. (ii) Comparing instrument signal with pre-selected multiples of the standard deviation, upper mass estimates of between 40-60 000 u for the coal-tar pitch and about 95 000 u for its pyridine-insoluble fraction were found. (iii) Calculation of the slope was used to identify 'lift-off' of the spectrum from baseline. The angle between the smoothed spectrum and the baseline was matched to a pre-selected value (e.g. 0.5 degrees and 1 degrees ). However, the arbitrary specification of the key parameter did not establish this last method on a firm basis. The choice of a criterion for estimating high-mass limits of MALDI spectra remains a semi-quantitative procedure; a reasonably conservative high-mass limit may be estimated by comparison of signal with five times the standard deviation. However, evaluation of size exclusion chromatograms of the present samples using polystyrene standards suggests that molecular mass distributions of pitch samples arrived at by MALDI mass spectrometry are, at least partly, determined by the limitations of available instruments. Copyright 1999 John Wiley & Sons, Ltd.

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Identification of organically associated trace elements in wood and coal by inductively coupled plasma mass spectrometry

Richaud

Lázaro

Lachas

et al. 2000

Rapid Commun. Mass Spectrom.

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1-Methyl-2-pyrrolidinone (NMP) was used to extract samples of wood (forest residue) and coal; the extracts were analysed by inductively coupled plasma mass spectrometry (ICP-MS) using two different sample preparation methods, in order to identify trace elements associated with the organic part of the samples. A sample of fly ash was similarly extracted and analysed in order to assess the behaviour of the mineral matter contained within the wood and coal samples. 32% of the biomass was extracted at the higher temperature and 12% at room temperature while only 12% of the coal was extracted at the higher temperature and 3% at room temperature. Less than 2% of the ash dissolved at the higher temperature. Size exclusion chromatograms of the extracts indicated the presence of significant amounts of large molecular mass materials (>1000 mu) in the biomass and coal extracts but not in the ash extract. Trace element analyses were carried out using ICP-MS on the acid digests prepared by 'wet ashing' and microwave extraction. Sixteen elements (As, Ba, Be, Cd, Co, Cr, Cu, Ga, Mn, Mo, Ni, Pb, Sb, Se, V and Zn) were quantified, in the samples before extraction, in the extracts and in the residues. Concentrations of trace elements in the original biomass sample were lower than in the coal sample while the concentrations in the ash sample were the highest. The major trace elements in the NMP extracts were Ba, Cu, Mn and Zn from the forest residue; Ba, Cu, Mn, Pb and Zn from the coal; Cu and Zn from the ash. These elements are believed to be associated with the organic extracts from the forest residue and coal, and also from the ash. Be and Sb were not quantified in the extracts because they were present at too low concentrations; up to 40% of Mn was extracted from the biomass sample at 202 degrees C, while Se was totally extracted from the ash sample. For the forest residue, approximately 7% (at room temperature) and 45% (at 202 degrees C) of the total trace elements studied were in the extract; for the coal, approximately 8% (at room temperature) and 23% (at 202 degrees C) were in the extract. For the ash, only 1.4% of the trace elements were extracted at 202 degrees C, comprising 25% of Cd but less than 1% of Pb.

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Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of kerogen extracts: effect of interactions between sample structure and matrix

Cited by 36 publications

References 17 publications

The use of nonpolar matrices for matrix‐assisted laser desorption/ionization mass spectrometric analysis of high boiling crude oil fractions

The use of nonpolar matrices for matrix‐assisted laser desorption/ionization mass spectrometric analysis of high boiling crude oil fractions

Determining a ‘safe’ high-mass limit in matrix-assisted laser desorption/ionisation time-of-flight mass spectra of coal derived materials with reference to instrument noise

Identification of organically associated trace elements in wood and coal by inductively coupled plasma mass spectrometry

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