We describe complex organic mixture analysis by 21 tesla (T) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Ultrahigh mass-resolving power (m/Δm 50% > 2 700 000 at m/z 400) ...and mass accuracy (80 ppb rms) enable resolution and confident identification of tens of thousands of unique elemental compositions. We demonstrate 2.2-fold higher mass-resolving power, 2.6-fold better mass measurement accuracy, and 1.3-fold more assigned molecular formulas compared to our custom-built, state-of-the-art 9.4 T FT-ICR mass spectrometer for petroleum and dissolved organic matter (DOM) analyses. Analysis of a heavy petroleum distillate exemplifies the need for ultrahigh-performance mass spectrometry (49 040 assigned molecular formulas for 21 T versus 29 012 for 9.4 T) and extends the identification of previously unresolved Oo, SsOo, and NOo classes. Mass selective ion accumulation (20 Thompson isolation) of an asphalt volcano sample yields 462 resolved mass spectral peaks at m/z 677 and reveals previously unresolved CcHhNnOoSs mass differences at high mass (m/z > 600). Similar performance gains are realized in the analysis of dissolved organic matter, where doubly charged Oo species are resolved from singly charged SOo species, which requires a mass-resolving power greater than 1 400 000 (at m/z 600). This direct comparison reveals the continued need for higher mass-resolving power and better mass accuracy for comprehensive molecular characterization of the most complex organic mixtures.
Because of increasing concern about global climate change and carbon emissions as a causal factor, many companies and organizations are pursuing “carbon footprint” projects to estimate their own ...contributions to global climate change. Protocol definitions from carbon registries help organizations analyze their footprints. The scope of these protocols varies but generally suggests estimating only direct emissions and emissions from purchased energy, with less focus on supply chain emissions. In contrast, approaches based on comprehensive environmental life-cycle assessment methods are available to track total emissions across the entire supply chain, and experience suggests that following narrowly defined estimation protocols will generally lead to large underestimates of carbon emissions for providing products and services. Direct emissions from an industry are, on average, only 14% of the total supply chain carbon emissions (often called Tier 1 emissions), and direct emissions plus industry energy inputs are, on average, only 26% of the total supply chain emissions (often called Tier 1 and 2 emissions). Without a full knowledge of their footprints, firms will be unable to pursue the most cost-effective carbon mitigation strategies. We suggest that firms use the screening-level analysis described here to set the bounds of their footprinting strategy to ensure that they do not ignore large sources of environmental effects across their supply chains. Such information can help firms pursue carbon and environmental emission mitigation projects not only within their own plants but also across their supply chain.
High Resolution Mass Spectrometry Xian, Feng; Hendrickson, Christopher L; Marshall, Alan G
Analytical chemistry (Washington),
01/2012, Letnik:
84, Številka:
2
Journal Article
We describe the design and initial performance of the first 21 tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The 21 tesla magnet is the highest field superconducting ...magnet ever used for FT-ICR and features high spatial homogeneity, high temporal stability, and negligible liquid helium consumption. The instrument includes a commercial dual linear quadrupole trap front end that features high sensitivity, precise control of trapped ion number, and collisional and electron transfer dissociation. A third linear quadrupole trap offers high ion capacity and ejection efficiency, and rf quadrupole ion injection optics deliver ions to a novel dynamically harmonized ICR cell. Mass resolving power of 150,000 (
m/Δm
50%
) is achieved for bovine serum albumin (66 kDa) for a 0.38 s detection period, and greater than 2,000,000 resolving power is achieved for a 12 s detection period. Externally calibrated broadband mass measurement accuracy is typically less than 150 ppb rms, with resolving power greater than 300,000 at
m/z
400 for a 0.76 s detection period. Combined analysis of electron transfer and collisional dissociation spectra results in 68% sequence coverage for carbonic anhydrase. The instrument is part of the NSF High-Field FT-ICR User Facility and is available free of charge to qualified users.
Graphical Abstract
ᅟ
High-resolution mass spectrometers Marshall, Alan G; Hendrickson, Christopher L
Annual review of analytical chemistry (Palo Alto, Calif.),
01/2008, Letnik:
1
Journal Article
Recenzirano
Over the past decade, mass spectrometry has been revolutionized by access to instruments of increasingly high mass-resolving power. For small molecules up to approximately 400 Da (e.g., drugs, ...metabolites, and various natural organic mixtures ranging from foods to petroleum), it is possible to determine elemental compositions (C(c)H(h)N(n)O(o)S(s)P(p)...) of thousands of chemical components simultaneously from accurate mass measurements (the same can be done up to 1000 Da if additional information is included). At higher mass, it becomes possible to identify proteins (including posttranslational modifications) from proteolytic peptides, as well as lipids, glycoconjugates, and other biological components. At even higher mass ( approximately 100,000 Da or higher), it is possible to characterize posttranslational modifications of intact proteins and to map the binding surfaces of large biomolecule complexes. Here we review the principles and techniques of the highest-resolution analytical mass spectrometers (time-of-flight and Fourier transform ion cyclotron resonance and orbitrap mass analyzers) and describe some representative high-resolution applications.
Asphaltenes have traditionally been conceived as highly aromatic, alkyl-deficient compounds enriched in pericondensed aromatic “island” motifs. This structural definition evolved into the general ...notion that aromatic core-dominated interactions (π-stacking) drive asphaltene aggregation, and heteroatom-based intermolecular forces have no significant effect on the overall solubility and aggregation behavior. However, the exclusion of heteroatoms in asphaltene chemistry is inconsistent with the Boduszynski continuum and known asphaltene properties, such as increased heteroatom content relative to maltenes, interfacial activity, and strong adsorption to polar stationary phases. Thus, to determine whether or not heteroatoms are involved in solubility, we have separated asphaltene fractions enriched in single-core (island) or multicore motifs (archipelago) according to their partitioning in n-heptane by two fractionation methods. In the first separation procedure, the acetone fraction from Wyoming deposit n-heptane asphaltenes (island-enriched) was adsorbed on polytetrafluoroethylene powder and Soxhlet extracted with n-heptane. Subfractions were collected after one day, one week, one month, and three months of extraction, and the residue, n-heptane insoluble material, was recovered with a mixture of toluene and dichloromethane. In the second method, the acetone fraction from Athabasca bitumen n-heptane asphaltenes (archipelago-enriched) was fractionated by differential precipitation in mixtures of n-heptane and toluene. The molecular composition of the asphaltene subfractions was accessed by positive-ion atmospheric pressure photoionization coupled to 9.4 T Fourier transform ion cyclotron resonance mass spectrometry and structures were determined by infrared multiphoton dissociation. The compositional trends for heteroatom content, double bond equivalents, and alkyl substitution suggest that the Boduszynski continuum can be extended to asphaltenes. In particular, the compositional range of polyoxygenated asphaltene compounds shifts toward lower aromaticity, whereas oxygen-depleted species are more aromatic. Moreover, the results demonstrate that polyoxygenated species (e.g., O3 and S2O3 classes) are pivotal in asphaltene solubility, as they concentrate in the most polarizable and insoluble asphaltene subfractions. Therefore, the results support the existence of atypical asphaltene species with remarkably low aromaticity that reside in the most insoluble asphaltene subfractions because of their high heteroatom content. Such asphaltene compounds preferentially ionize as protonated molecules rather than radical cations and overlap the compositional range of interfacially active species, consistent with their tendency to participate in hydrogen bonding. Collectively, the results highlight the need for an asphaltene molecular model based on the existence of polyfunctional species capable of interacting with neighboring asphaltene molecules through several intermolecular forces, including London dispersion forces between aliphatic moieties, π-stacking of aromatic cores, hydrogen bonding between nitrogen and oxygen-containing functionalities, and acid/base interactions between carboxylic acids and pyridine rings.
Recent advances in instrumentation for high-field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) have enabled access to ∼70 000 unique molecular formulas in broadband mass ...spectral characterization of unfractionated/whole asphaltenes. The results accumulated over a decade highlight the need for an asphaltene molecular model that acknowledges the coexistence of (1) monofunctional and polyfunctional species; (2) island and archipelago structural motifs; and (3) heteroatom-depleted/highly aromatic compounds, as well as atypical species with low aromaticity but increased heteroatom content. Collectively, results from FT-ICR MS, preparatory-scale separations (extrography/interfacial material), gel permeation chromatography, precipitation behavior in heptane:toluene, thermal decomposition, and aggregate microstructure by atomic force microscopy (among other techniques), suggest that the strong aggregation of asphaltenes results from the synergy between several intermolecular forces: π-stacking, hydrogen bonding, London forces, and acid/base interactions. This review presents general features of asphaltene molecular composition reported over the past five decades. We focus on mass spectrometry characterization and expose the reasons why early results supported the dominance of single-core motifs. Then, the discussion shifts to recent advances in instrumentation for high-field FT-ICR MS, which have enabled the detection of thousands of species in asphaltene samples, whose molecular composition and fragmentation behavior in ultrahigh vacuum agree with the coexistence of single-core and multicore structural motifs. Furthermore, evidence that highlights the limitations of commercially available/custom-built ion sources and selective ionization effects is presented. Consequently, the limitations require separations (e.g., chromatography, extrography) to gain more-comprehensive molecular-level insights into the composition of these complex organic mixtures. The final sections present evidence for the role of aggregation in selective ionization and suggest that advanced characterization by both thermal desorption/decomposition and liquid chromatography with online FT-ICR MS detection can be employed to mitigate the effects of aggregation and provide unique insights in molecular composition/structure.
Successful high-throughput characterization of intact proteins from complex biological samples by mass spectrometry requires instrumentation capable of high mass resolving power, mass accuracy, ...sensitivity, and spectral acquisition rate. These limitations often necessitate the performance of hundreds of LC–MS/MS experiments to obtain reasonable coverage of the targeted proteome, which is still typically limited to molecular weights below 30 kDa. The National High Magnetic Field Laboratory (NHMFL) recently installed a 21 T FT-ICR mass spectrometer, which is part of the NHMFL FT-ICR User Facility and available to all qualified users. Here we demonstrate top-down LC-21 T FT-ICR MS/MS of intact proteins derived from human colorectal cancer cell lysate. We identified a combined total of 684 unique protein entries observed as 3238 unique proteoforms at a 1% false discovery rate, based on rapid, data-dependent acquisition of collision-induced and electron-transfer dissociation tandem mass spectra from just 40 LC–MS/MS experiments. Our identifications included 372 proteoforms with molecular weights over 30 kDa detected at isotopic resolution, which substantially extends the accessible mass range for high-throughput top-down LC–MS/MS.
With the rapid growth of therapeutic monoclonal antibodies (mAbs), stringent quality control is needed to ensure clinical safety and efficacy. Monoclonal antibody primary sequence and ...post-translational modifications (PTM) are conventionally analyzed with labor-intensive, bottom-up tandem mass spectrometry (MS/MS), which is limited by incomplete peptide sequence coverage and introduction of artifacts during the lengthy analysis procedure. Here, we describe top-down and middle-down approaches with the advantages of fast sample preparation with minimal artifacts, ultrahigh mass accuracy, and extensive residue cleavages by use of 21 tesla FT-ICR MS/MS. The ultrahigh mass accuracy yields an RMS error of 0.2–0.4 ppm for antibody light chain, heavy chain, heavy chain Fc/2, and Fd subunits. The corresponding sequence coverages are 81%, 38%, 72%, and 65% with MS/MS RMS error ~4 ppm. Extension to a monoclonal antibody in human serum as a monoclonal gammopathy model yielded 53% sequence coverage from two nano-LC MS/MS runs. A blind analysis of five therapeutic monoclonal antibodies at clinically relevant concentrations in human serum resulted in correct identification of all five antibodies. Nano-LC 21 T FT-ICR MS/MS provides nonpareil mass resolution, mass accuracy, and sequence coverage for mAbs, and sets a benchmark for MS/MS analysis of multiple mAbs in serum. This is the first time that extensive cleavages for both variable and constant regions have been achieved for mAbs in a human serum background.
Graphical Abstract
ᅟ
Detailed characterization of complex biological surfaces by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) requires instrumentation that is capable of high mass ...resolving power, mass accuracy, and dynamic range. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) offers the highest mass spectral performance for MALDI MSI experiments, and often reveals molecular features that are unresolved on lower performance instrumentation. Higher magnetic field strength improves all performance characteristics of FT-ICR; mass resolving power improves linearly, while mass accuracy and dynamic range improve quadratically with magnetic field strength. Here, MALDI MSI at 21T is demonstrated for the first time: mass resolving power in excess of 1 600 000 (at m/z 400), root-mean-square mass measurement accuracy below 100 ppb, and dynamic range per pixel over 500:1 were obtained from the direct analysis of biological tissue sections. Molecular features with m/z differences as small as 1.79 mDa were resolved and identified with high mass accuracy. These features allow for the separation and identification of lipids to the underlying structures of tissues. The unique molecular detail, accuracy, sensitivity, and dynamic range combined in a 21T MALDI FT-ICR MSI experiment enable researchers to visualize molecular structures in complex tissues that have remained hidden until now. The instrument described allows for future innovative, such as high-end studies to unravel the complexity of biological, geological, and engineered organic material surfaces with an unsurpassed detail.
PDF
