Simplified Hydrocarbon Compound Type Analysis Using a Dynamic Batch Inlet System Coupled to a Mass Spectrometer

Roussis, Stilianos G.; Cameron, Andrew S.

doi:10.1021/ef960221j

Cited by 19 publications

(19 citation statements)

References 38 publications

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“…[11][12][13][14][15][16] The methods provide quantitative information (i.e., relative amounts normalized to a total of 100%) about groups of chemical compounds summarized according to the degree of hydrogen deficiency, as reflected by the Z number (Z = 2, 0, À2, ,…) in the general formula for hydrocarbons C n H 2nZ . [17][18][19] The relative amounts of compound types such as paraffins (Z = 2), one-ring cycloparaffins (Z = 0), alkylbenzenes (Z = À6), etc, are used for quality control and monitoring of the effects of the different processing parameters. The LRMS hydrocarbon compound type methods, however, provide no information about the molecular weight distribution of compounds due to the interfering patterns of molecular and fragment ions produced under the highenergy ionization regime (70 eV electron ionization) used in the experiments.…”

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confidence: 99%

Exhaustive determination of hydrocarbon compound type distributions by high resolution mass spectrometry

Roussis

1999

Rapid Commun. Mass Spectrom.

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The need to obtain detailed chemical information about heavy petroleum fractions, where the usefulness of chromatographic separation techniques is limited, has been addressed by using high resolution mass spectrometry (HRMS). A magnetic sector mass spectrometer was used for the experiments. The instrument meets the mass and dynamic range criteria for the analysis of compounds in complex hydrocarbon fractions, but not the resolving power needs for the separation of overlapping mass doublets. A simple and fast method has been developed that permits the calculation of the relative amounts of the ion species in overlapping mass doublets by consideration of the unresolved peak abundance and the difference between the theoretical and measured masses. The exhaustive determination of hydrocarbon compound type distributions is achieved by the sequential comparison of the theoretical masses of compounds with a given formula against those measured in the mass spectrum.

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confidence: 99%

Exhaustive determination of hydrocarbon compound type distributions by high resolution mass spectrometry

Roussis

1999

Rapid Commun. Mass Spectrom.

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“…6͒ during excitation/detection plays an important role in obtaining both high resolving power and accurate relative peak magnitudes. At trapping potential above 1.5 V, the C 6 H 4 35 Cl 79 Br + signal dropped in relative magnitude or even disappeared. At trapping potential above 1.5 V, the C 6 H 4 35 Cl 79 Br + signal dropped in relative magnitude or even disappeared.…”

Section: Mass Resolving Power Mass Resolution and Mass Accuracymentioning

confidence: 99%

“…1-bromo-2chlorobenzene is particularly challenging because its isotopic doublet, C 6 H 4 37 Cl 79 Br + and C 6 H 4 35 Cl 81 Br + , is separated by only 0.9 mDa. 1-bromo-2chlorobenzene is particularly challenging because its isotopic doublet, C 6 H 4 37 Cl 79 Br + and C 6 H 4 35 Cl 81 Br + , is separated by only 0.9 mDa.…”

Section: Mass Resolving Power Mass Resolution and Mass Accuracymentioning

confidence: 99%

“…If the trapping potential was increased from 0.5 to 1.5 V, resolving power was maintained, but the peak height ratio for C 6 H 4 37 Cl 79 Br + and C 6 H 4 35 Cl 81 Br + was incorrect. The C 6 H 4 35 Cl 79 Br + signal decayed faster than that for C 6 H 4 35 Cl 81 Br + , in accord with prior observations 46 that ions of lower number density decay faster due to a loss of phase coherence during the detection period. To monitor the time evolution of the ICR signal, we divided the 3.2 s time-domain signal acquired at 1.5 V trapping potential into eight equal segments and processed each segment ͑0.4 s du-ration͒ separately.…”

Section: Mass Resolving Power Mass Resolution and Mass Accuracymentioning

confidence: 99%

“…Use of an external EI source facilitates sample introduction for reduced sample consumption. 35 The compatibility of the new sample introduction system with high vacuum makes it a robust, simple, low-maintenance sample inlet. 33 Higher magnetic-field strength B ͑7 T͒ for the present instrument versus 5.6 T for its predecessor 32 benefits complex mixture analysis in several respects: mass resolving power ͑and therefore mass resolution and mass accuracy͒ increase linearly with B, whereas tendency for peak coalescence varies inversely with B, for improved resolution and identification of closely spaced mass peaks, and upper mass limit and the maximum number of trapped ions increase as B 2 , for improved detection of low-abundance ions.…”

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External electron ionization 7T Fourier transform ion cyclotron resonance mass spectrometer for resolution and identification of volatile organic mixtures

Purcell

Quinn

et al. 2006

Review of Scientific Instruments

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A 193 nm laser photofragmentation time-of-flight mass spectrometric study of chloroiodomethane J. Chem. Phys. 123, 174316 (2005); 10.1063/1.2074507 5.6 tesla Fourier transform ion cyclotron resonance mass spectrometer for analysis of volatile complex mixtures Rev.An external electron ionization ͑EI͒ source has been interfaced to a 7 T Fourier transform ion cyclotron resonance mass spectrometer and tested for volatile complex mixture analysis. A new Sulfinert ® -deactivated inlet system provides continuous stable sample flow to the EI source, leading to stable ion signal ͑±10% deviation͒ for 2 h from a 200 nL mixture of 15 n-alkylbenzenes. Ultrahigh-mass resolving power, m / ⌬m 50% Ϸ 735 000, was obtained for 1-bromo-2-chlorobenzene with accurate isotopic ratio measurement. Base line resolution was observed for two of the closest commonly encountered mass doublets, C 3 /SH 4 ͑m 2 − m 1 = 3.4 mDa at m / z = 190͒ and SH 3 13 C/C 4 ͑m 2 − m 1 = 1.1 mDa at m / z = 190͒. Although hydrocarbons dominate the positive-ion 18 eV EI Fourier transform ion cyclotron resonance mass spectrum from diesel fuels, many sulfur-, nitrogen-, and oxygen-containing compounds were readily observed without prior fractionation. By comparing 18 eV EI Fourier transform ion cyclotron resonance mass spectra of unprocessed and processed diesel fuels, we were able to identify which heteroatom-containing species were removed by processing.

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Low-energy ionization of hydrocarbons in the quadrupole ion trap mass spectrometer

Roussis

Fitzgerald

Cameron

1998

Rapid Commun. Mass Spectrom.

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The capabilities of a commercial ion trap mass spectrometer to readily perform chemical ionization experiments have been exploited to account for the restrictions of the instrument to perform low-energy ($10 eV) electron ionization (EI) experiments. CS 2 and benzene have been used as representative reagent compounds for low-energy ionization by charge exchange in the ion trap with the main objective being the production of mass spectra of hydrocarbon compounds with intense peaks in the molecular ion region. nPentane was used as a representative small alkane reagent compound to investigate its capability to form intense peaks of molecular ion species in the spectra of saturated hydrocarbons. No intense peaks were produced in the molecular ion region, by any of the three reagents, for the mass spectra of model linear saturated hydrocarbons. The relatively weak stability of these compounds and the excess amounts of internal energy supplied by the various dynamic processes in the ion trap may partly account for the increased fragmentation. Intense molecular ion species and fragment ion peaks were observed in the mass spectra of cyclic saturated hydrocarbons. Charge exchange of aromatic compounds with CS 2 and benzene produced mass spectra with intense molecular ion peaks and limited fragmentation, similar to the mass spectra obtained in conventional mass spectrometers. The methods developed in this study were used for the analysis of typical middle distillate and heavy petroleum samples. # 1998 John Wiley & Sons, Ltd. Received 8 January 1998; Revised 2 February 1998; Accepted 3 February 1998 Rapid Commun. Mass Spectrom. 12, 373-381 (1998 The quadrupole ion trap mass spectrometer combines several important analytical features. These are: (i) excellent sensitivity for quantitative analysis, [1][2][3][4] (ii) capabilities for chemical ionization and tandem mass spectrometry (MS/MS), 4-7 and (iii) reduced size, weight and cost compared to other instruments with similar capabilities (i.e. sector, quadrupole filter analyzers). Chemical ionization (CI) and tandem mass spectrometry greatly enhance the selectivity of analysis. Different reagent compounds can be used in chemical ionization experiments to selectively ionize compounds based on thermochemical criteria. 8 Typically, exothermic ion-molecule reactions between chemical ionization reagent ions and analyte molecules are associated with large rate constants and can lead to the formation of abundant reaction products. Endothermic reagent ion-analyte molecule reactions are generally associated with small rate constants and do not lead to the formation of abundant product ions. The choice of appropriate reagent compounds can thus selectively permit the analysis of certain classes of compounds. For example, the use of ammonia as chemical ionization reagent gas is typically used for the selective ionization of very basic compounds 8,9 and has been successfully used in ion trap CI experiments for the characterization of nitrogen and sulfur heterocycles in petroleum fractions...

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Simplified Hydrocarbon Compound Type Analysis Using a Dynamic Batch Inlet System Coupled to a Mass Spectrometer

Cited by 19 publications

References 38 publications

Exhaustive determination of hydrocarbon compound type distributions by high resolution mass spectrometry

Exhaustive determination of hydrocarbon compound type distributions by high resolution mass spectrometry

External electron ionization 7T Fourier transform ion cyclotron resonance mass spectrometer for resolution and identification of volatile organic mixtures

Low-energy ionization of hydrocarbons in the quadrupole ion trap mass spectrometer

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