Publications (16)56.98 Total impact
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Article: Tailored Ion Radius Distribution for Increased Dynamic Range in FT-ICR Mass Analysis of Complex Mixtures.
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ABSTRACT: Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) typically utilizes m/z-independent excitation magnitude to excite all ions to the same cyclotron radius so that detected signal magnitude is directly proportional to relative ion abundance. However, deleterious space charge interaction between ion clouds is maximized for clouds of equal radius. To minimize ion cloud interactions, we induce an m/z-dependent ion radius distribution (30-45% of the maximum cell radius) that results in a three-fold increase in mass spectral dynamic range for complex mixtures, consistent with increased ion cloud lifetime for less abundant ion clouds. Further, broadband frequency-sweep (chirp) excitation that contains the 2nd and/or 3rd harmonic frequency of an excited ion cloud swept from low-to-high frequency produces systematic variations in accurate mass measurement not observed when the sweep direction is reversed. The ion cyclotron radius distribution induces an m/z-dependent frequency shift that can be corrected to provide rms mass measurement error <100 ppb on petroleum-based mixtures that contain tens of thousands of identified peaks.Analytical Chemistry 11/2012; · 5.86 Impact Factor -
Article: Selective ionization of dissolved organic nitrogen by positive ion atmospheric pressure photoionization coupled with Fourier transform ion cyclotron resonance mass spectrometry.
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ABSTRACT: Dissolved organic nitrogen (DON) comprises a heterogeneous family of organic compounds that includes both well-known biomolecules such as urea or amino acids and more complex, less characterized compounds such as humic and fulvic acids. Typically, DON represents only a small fraction of the total dissolved organic carbon pool and therefore presents inherent problems for chemical analysis and characterization. Here, we demonstrate that DON may be selectively ionized by atmospheric pressure photionization (APPI) and characterized at the molecular level by Fourier transform ion cyclotron resonance mass spectrometry. Unlike electrospray ionization (ESI), APPI ionizes polar and nonpolar compounds, and ionization efficiency is not determined by polarity. APPI is tolerant to salts, due to the thermal treatment inherent to nebulization, and thus avoids salt-adduct formation that can complicate ESI mass spectra. Here, for dissolved organic matter from various aquatic environments, we selectively ionize DON species that are not efficiently ionized by other ionization techniques and demonstrate significant signal-to-noise increase for nitrogen species by use of APPI relative to ESI.Analytical Chemistry 05/2012; 84(11):5085-90. · 5.86 Impact Factor -
Article: Characterization of pyrogenic black carbon by desorption atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry.
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ABSTRACT: We present a new method for molecular characterization of intact biochar directly, without sample preparation or pretreatment, on the basis of desorption atmospheric pressure photoionization (DAPPI) coupled to Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Conventional ionization methods (e.g., electrospray or atmospheric pressure photoionization) for characterization of natural organic matter have limited utility for the characterization of chars due to incomplete solubility in common solvents. Therefore, direct ionization techniques that do not require sample dissolution prior to analysis are ideal. Here, we apply DAPPI FTICR mass spectrometry to enable the first molecular characterization of uncharred parent oak biomass and after combustion (250 °C) or pyrolysis (400 °C). Parent oak is primarily composed of cellulose-, lignin-, and resin-like compounds. Oak combusted at 250 °C contains condensed aromatic compounds with low H/C and O/C ratios while retaining compounds with high H/C and O/C ratios. The bimodal distribution of aromatic and aliphatic compounds observed in the combusted oak sample is attributed to incomplete thermal degradation of lignin and hemicellulose. Pyrolyzed oak constituents exhibit lower H/C and O/C ratios: approximately three-quarters of the identified species are aromatic. DAPPI FTICR MS results agree with bulk elemental composition as well as functional group distributions determined by elemental analysis and solid state (13)C NMR spectroscopy. Complete molecular characterization of biomass upon thermal transformation may provide insight into the biogeochemical cycles of biochar and future renewable energy sources, particularly for samples currently limited by solubility, separation, and sample preparation.Analytical Chemistry 02/2012; 84(3):1281-7. · 5.86 Impact Factor -
Article: Electrically compensated Fourier transform ion cyclotron resonance cell for complex mixture mass analysis.
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ABSTRACT: Complex natural organic mixtures such as petroleum require ultrahigh mass spectral resolution to separate and identify thousands of elemental compositions. Here, we incorporate a custom-built, voltage-compensated ICR cell for Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS), based on a prior design by Tolmachev to produce optimal mass resolution. The compensated ICR cell installed in a custom-built 9.4 T FTICR mass spectrometer consists of seven cylindrical segments with axial proportions designed to generate a dc trapping potential that approaches an ideal three-dimensional axial quadrupolar potential. However, the empirically optimized compensation voltages do not correspond to the most quadrupolar trapping field. The compensation electrodes minimize variation in the reduced cyclotron frequency by balancing imperfections in the magnetic and electric field. The optimized voltages applied to compensation electrodes preserve ion cloud coherence for longer transient duration by approximately a factor of 2, enabling separation and identification of isobaric species (compounds with the same nominal mass but different exact mass) common in petroleum, such as C(3) vs SH(4) (separated by 3.4 mDa) and SH(3)(13)C vs (12)C(4) (separated by 1.1 mDa). The improved performance of the ICR cell provides more symmetric peak shape and better mass measurement accuracy. A positive ion atmospheric pressure photoionization (APPI) petroleum spectrum yields more than 26,000 assigned peaks, Fourier-limited resolving power of 800,000 at m/z 500 (6.6 s transient duration), and 124 part per billion root mean square (rms) error. The tunability of the compensation electrodes is critical for optimal performance.Analytical Chemistry 08/2011; 83(17):6907-10. · 5.86 Impact Factor -
Article: Petroleum analysis.
Analytical Chemistry 06/2011; 83(12):4665-87. · 5.86 Impact Factor -
Article: Petroleomics: advanced molecular probe for petroleum heavy ends.
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ABSTRACT: To look into complex mixtures of petroleum heavy ends at the molecular level, ultra high-resolution mass spectrometry, i.e. resolving power > 50,000, is needed to resolve overlapping components for accurate determination of molecular composition of individual components. Recent progress in Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) incorporated with soft ionization techniques adaptable to liquid chromatography enables analysis of petroleum high ends, i.e., heavy oils, residua and asphaltenes. FT-ICR MS at the Future Fuels Institute of Florida State University and the National High Magnetic Field Laboratory (NHMFL) routinely provides 1,000,000 resolving power at 400 Da, with root mean square (rms) mass measurement accuracy between 30 and 500 ppb for 5000-30,000 identified species in a single mass spectrum. Phase correction of the detected ion signal increases resolving power 40-100%, improving mass accuracy up to twofold. Overlapping ionic species that differ in mass by as little as one electron mass (548 µDa) can be resolved. A database of more than 100,000 components of different elemental composition has been generated at NHMFL.Biological Mass Spectrometry 04/2011; 46(4):337-43. · 3.41 Impact Factor -
Article: Atmospheric Pressure Laser-Induced Acoustic Desorption Chemical Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry for the Analysis of Complex Mixtures.
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ABSTRACT: We present a novel nonresonant laser-based matrix-free atmospheric pressure ionization technique, atmospheric pressure laser-induced acoustic desorption chemical ionization (AP/LIAD-CI). The technique decouples analyte desorption from subsequent ionization by reagent ions generated from a corona discharge initiated in ambient air or in the presence of vaporized toluene as a CI dopant at room temperature. Analyte desorption is initiated by a shock wave induced in a titanium foil coated with electrosprayed sample, irradiated from the rear side by high-energy laser pulses. The technique enables facile and independent optimization of the analyte desorption, ionization, and sampling events, for coupling to any mass analyzer with an AP interface. Moreover, the generated analyte ions are efficiently thermalized by collisions with atmospheric gases, thereby reducing fragmentation. We have coupled AP/LIAD-CI to ultrahigh-resolution FT-ICR MS to generate predominantly [M + H](+) or M(+•) ions to resolve and identify thousands of elemental compositions from organic mixtures as complex as petroleum crude oil distillates. Finally, we have optimized the AP/LIAD CI process and investigated ionization mechanisms by systematic variation of placement of the sample, placement of the corona discharge needle, discharge current, gas flow rate, and inclusion of toluene as a dopant.Analytical Chemistry 02/2011; · 5.86 Impact Factor -
Article: Parts-Per-Billion Fourier Transform Ion Cyclotron Resonance Mass Measurement Accuracy with a "Walking" Calibration Equation.
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ABSTRACT: Ion cyclotron resonance frequency, f, is conventionally converted to ion mass-to-charge ratio, m/z (mass "calibration") by fitting experimental data spanning the entire detected m/z range to the relation, m/z = A/f + B/f(2), to yield rms mass error as low as ∼200 ppb for ∼10 000 resolved components of a petroleum crude oil. Analysis of residual error versus m/z and peak abundance reveals that systematic errors limit mass accuracy and thus the confidence in elemental composition assignments. Here, we present a calibration procedure in which the spectrum is divided into dozens of adjoining segments, and a separate calibration is applied to each, thereby eliminating systematic error with respect to m/z. Further, incorporation of a third term in the calibration equation that is proportional to the magnitude of each detected peak minimizes systematic error with respect to ion abundance. Finally, absorption-mode data analysis increases mass measurement accuracy only after minimization of systematic errors. We are able to increase the number of assigned peaks by as much as 25%, while reducing the rms mass error by as much as 3-fold, for significantly improved confidence in elemental composition assignment.Analytical Chemistry 01/2011; · 5.86 Impact Factor -
Article: Analysis and Identification of Biomarkers and Origin of Color in a Bright Blue Crude Oil
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ABSTRACT: We describe the detailed analysis and characterization of an unusual blue crude oil and a deposit from the monoethylene glycol (MEG) regeneration unit (MRU) on an offshore crude oil production platform. To characterize the deposit and the components in the crude oil that give it such a distinct blue hue, we investigated the samples with comprehensive two-dimensional gas chromatography (GC Â GC), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and two-dimensional (2D) fluores-cence spectroscopy. Perylene, a polycyclic aromatic hydrocarbon, known to fluoresce, was identified in the crude oil with all three of these techniques. On the basis of its photochemical properties and abundance (55 ppm), we infer perylene to be the most likely source of the blue color. In addition, we were able to conclusively identify by GC Â GC a suite of pentacyclic triterpenoids, of which the most abundant species was 17R(H),21β(H)-25-norhopane. The deposit is greatly enriched in these species. The presence of 25-norhopanes in a crude oil is considered as an indication for severe biodegradation.Energy & Fuels 12/2010; 25(1):172-182. · 2.72 Impact Factor -
Article: Heavy Petroleum Composition. 1. Exhaustive Compositional Analysis of Athabasca Bitumen HVGO Distillates by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: A Definitive Test of the Boduszynski Model
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ABSTRACT: Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) allows detailed characterization of complex petroleum samples at the level of elemental composition assignment. Ultrahigh-resolution (450 000−650 000 at m/z 500) enables identification of isobaric species that differ in mass by 3 mDa or less, and high mass accuracy (mass error of better than 300 ppb), combined with Kendrick mass sorting, allows for unambiguous molecular formula assignment to each of more than 10 000−20 000 peaks in each mass spectrum. Thus, it is possible to identify, sort, and monitor thousands of elemental compositions simultaneously, as a function of the boiling point. Here, the detailed FT-ICR MS characterization of an Athabasca bitumen heavy vacuum gas oil (HVGO) distillation series exposes the progression of heteroatom class, type (double bond equivalents (DBE), number of rings plus double bonds to carbon), and carbon number for tens of thousands of crude oil species, as a function of the boiling point. Specifically, we analyze a distillation series of Athabasca bitumen HVGO with cut temperatures from the initial boiling point (IBP) to 538 °C (in eight cuts) by atmospheric pressure photoionization (APPI), as well as positive and negative electrospray ionization (ESI) FT-ICR MS, to determine the distributions of nonpolar and polar species, as a function of the HVGO boiling point. Compositional distributions reveal definitive heteroatom class, type, and carbon number trends among distillation cuts, and provide the first detailed compositional evidence in support of the Boduszynski model that describes the progression of petroleum composition and structure as a function of the boiling point. Quantitation of the aromaticity and carbon number profiles of both polar and nonpolar species in all distillate cuts further affirms the validity of the Boduszynski model for the HVGO distillate range, and provides evidence for cycloalkane linkages, in addition to polyaromatic cores.05/2010; -
Article: Heavy Petroleum Composition. 2. Progression of the Boduszynski Model to the Limit of Distillation by Ultrahigh-Resolution FT-ICR Mass Spectrometry
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ABSTRACT: Heavy petroleum fractions are structurally and compositionally complex mixtures that defy characterization by many traditional analytical techniques. Here, we present the detailed characterization of a Middle Eastern heavy crude oil distillation series, in further support of the Boduszynski model, which proposes that petroleum is a continuum with regard to composition, molecular weight, aromaticity, and heteroatom content as a function of the boiling point. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) provides ultrahigh resolving power and mass accuracy and thereby allows for elemental assignment for each of the tens of thousands of peaks in a single crude oil sample. Part 1 of our five-part series established the validity of the Boduszynski model for the heavy vacuum gas oil (HVGO) distillation series. Here, we extend our analysis to fractions from a Middle Eastern heavy crude with cut temperatures including and beyond the middle distillate range. Collectively, the detailed compositional results for all heteroatom classes strongly support the continuity model. Interestingly, extrapolation of distillable compositional space to a high carbon number (up to 1 MDa) cannot account for the bulk properties of nondistillable (asphaltenic) species. Thus, either the continuity model does not accurately describe nondistillable petroleum materials (they are discontinuous in compositional space) or they are not high-molecular-weight (>2000 Da) materials.05/2010; -
Article: The coupling of direct analysis in real time ionization to Fourier transform ion cyclotron resonance mass spectrometry for ultrahigh-resolution mass analysis.
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ABSTRACT: Direct Analysis in Real Time (DART) is an ambient ionization technique for mass spectrometry that provides rapid and sensitive analyses with little or no sample preparation. DART has been reported primarily for mass analyzers of low to moderate resolving power such as quadrupole ion traps and time-of-flight (TOF) mass spectrometers. In the current work, a custom-built DART source has been successfully coupled to two different Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers for the first time. Comparison of spectra of the isobaric compounds, diisopropyl methylphosphonate and theophylline, acquired by 4.7 T FT-ICR MS and TOF MS, demonstrates that the TOF resolving power can be insufficient for compositionally complex samples. 9.4 T FT-ICR MS yielded the highest mass resolving power yet reported with DART ionization for 1,2-benzanthracene and 9,10-diphenylanthracene. Polycyclic aromatic hydrocarbons exhibit a spatial dependence in ionization mechanisms between the DART source and the mass spectrometer. The feasibility of analyzing a variety of samples was established with the introduction and analysis of food products and crude oil samples. DART FT-ICR MS provides complex sample analysis that is rapid, highly selective and information-rich, but limited to relatively low-mass analytes.Rapid Communications in Mass Spectrometry 02/2010; 24(6):784-90. · 2.79 Impact Factor -
Article: Petroleomics: a test bed for ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry.
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ABSTRACT: Within a relative abundance dynamic range of approximately 10,000:1, the world's most compositionally complex organic mixture is petroleum crude oil. As such, it provides the most challenging target for mass spectral resolution and identification of molecules below m/z 2000. The mass "splits" in petroleum include most of those that also appear in proteomics, metabolomics and other complex organic mixture analysis. Therefore, petroleum provides an excellent test bed for optimizing mass spectrometer performance in general. The presence of multiple elemental compositions spanning less than 1 Da in mass facilitates mapping and correction of rf phase variation across a Fourier transform ion cyclotron resonance mass spectrum, as well as exposing otherwise inaccessible systematic mass deviations, for additional improvement in mass resolving power and mass accuracy by a factor of up to 5. Internal mass calibration, combined with systematic peak assignment for successive homologous series, enables automated elemental composition assignment of tens of thousands of peaks in a single mass spectrum.European Journal of Mass Spectrometry 01/2010; 16(3):367-71. · 1.21 Impact Factor -
Article: Petroleum crude oil characterization by IMS-MS and FTICR MS.
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ABSTRACT: Here, complementary ion mobility/mass spectrometry (IM/MS) and ultrahigh-resolution Fourier transform ion cyclotron resonance (FTICR) MS analyses of light, medium, and heavy petroleum crude oils yielded distributions of the heteroatom-containing hydrocarbons, as well as multiple conformational classes. The IM/MS technique provides unique fingerprints for fast identification of signature conformational/compositional patterns, whereas FTICR MS analysis provides comprehensive heteroatom class distributions. IM/MS and FTICR MS results reveal an increase in compositional complexity in proceeding from light to medium to heavy crude oils. Inspection of the mobility results shows a high structural diversity for the C(n)H(h)XY (XY = N(1), S(1), N(1), O(1), NS, SO(1-2), NO(1-2), etc.) series, as well as a shift from planar to more compact three-dimensional structures with increasing mass.Analytical Chemistry 11/2009; 81(24):9941-7. · 5.86 Impact Factor -
Article: Identification of Vanadyl Porphyrins in a Heavy Crude Oil and Raw Asphaltene by Atmospheric Pressure Photoionization Fourier Transform Ion Cyclotron Resonance (FT-ICR) Mass Spectrometry
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ABSTRACT: Vanadyl porphyrins are detected and characterized by their double-bond equivalents (DBE = number of rings plus double bonds) and carbon number in an unfractionated (raw) asphaltene and unaltered South American crude oil. Atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) provides the high mass-resolving power (450 000−650 000 at m/z 500) and accurate mass (<300 ppb) to unambiguously assign elemental compositions to each of more than 10 000 peaks in each mass spectrum. Kendrick mass sorting revealed unusually high mass errors for peaks assigned to high DBE O2 species as well as a suspicious bimodal distribution in plots of DBE versus carbon number for all O2 species. Inclusion of vanadium in the chemical formula assignment resolved the bimodal distribution into lower DBE O2 species and vanadyl porphyrins, with a subsequent decrease in mass assignment errors to the same level as those for the thousands of other identified species. Vanadyl porphyrins are detected as both M+ • and [M + H]+ molecular and quasimolecular ions. Trends in the relative abundance of specific DBE values reveal the structural diversity of the vanadyl porphyrins in the asphaltene and heavy crude oil. To our knowledge, the current results are the first to directly identify and catalog the structural diversity of vanadyl porphyrins directly in raw (unfractionated) asphaltene and unaltered heavy crude oil.04/2009; -
Article: Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity
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ABSTRACT: Author Posting. © Elsevier B.V., 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Organic Geochemistry 41 (2010): 812-821, doi:10.1016/j.orggeochem.2010.05.003. Hydraulic connectivity of petroleum reservoirs represents one of the biggest uncertainties for both oil production and petroleum system studies. Here, a geochemical analysis involving bulk and detailed measures of crude oil composition is shown to constrain connectivity more tightly than is possible with conventional methods. Three crude oils collected from different depths in a single well exhibit large gradients in viscosity, density, and asphaltene content. Crude oil samples are collected with a wireline sampling tool providing samples from well‐defined locations and relatively free of contamination by drilling fluids; the known provenance of these samples minimizes uncertainties in the subsequent analysis. The detailed chemical composition of almost the entire crude oil is determined by use of comprehensive two‐dimensional gas chromatography (GC×GC) to interrogate the nonpolar fraction and negative ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT‐ICR MS) to interrogate the polar fraction. The simultaneous presence of 25‐ norhopanes and mildly altered normal and isoprenoid alkanes is detected, suggesting that the reservoir has experienced multiple charges and contains a mixture of oils biodegraded to different extents. The gradient in asphaltene concentration is explained by an equilibrium model considering only gravitational segregation of asphaltene nanoaggregates; this grading can be responsible for the observed variation in viscosity. Combining these analyses yields a consistent picture of a connected reservoir in which the observed viscosity variation originates from gravitational segregation of asphaltene nanoaggregates in a crude oil with high asphaltene concentration resulting from multiple charges, including one charge that suffered severe biodegradation. Observation of these gradients having appropriate magnitudes suggests good reservoir connectivity with greater confidence than is possible with traditional techniques alone. The mass spectrometry work was supported by the NSF Division of Materials Research through DMR‐06‐54118, and the State of Florida.
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2011
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Florida State University
- Department of Chemistry and Biochemistry
Tallahassee, FL, USA
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