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As metabolomics grows into a high-throughput and high demand research field, current metrics for the identification of small molecules in GC-MS still require manual verification. Though steps have been taken to improve scoring metrics by combining spectral similarity (SS) and retention index (RI), the problem persists. A large body of literature has analyzed and refined SS scores, but few studies have explicitly studied improvements to RI scores. Here, we examined whether uninvestigated assumptions of the RI score are valid and propose ways to improve them. Query RI were matched to library RI with a generous window of +/-35 to avoid unintentional removal of valid compound identifications. Each match was manually verified as a true positive, true negative or unknown. Metabolites with at least 30 true positive identifications were included in downstream analyses, resulting in a total of 87 metabolites from samples of varying complexity and type (e.g., amino acid mixtures, human urine, fungal species, etc.). Our results showed that the RI score assumptions of normality, consistent variance across metabolites, and a mean error centered at 0 are often violated. We demonstrated through a cross-validation analysis that modifying these underlying assumptions according to empirical, metabolite-specific distributions improved the true positive and negative rankings. Further, we statistically determined the minimum number of samples required to estimate distributional parameters for scoring metrics. Overall, this work proposes a robust statistical pipeline to reduce the time bottleneck of metabolite identification by improving RI scores and thus minimizes the effort to complete manual verification.

High magnetic field Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry provides the highest mass resolving power and mass measurement accuracy for detailed characterization of complex chemical mixtures. Here, we report the coupling of online liquid chromatography of complex mixtures with a 21 tesla FT-ICR mass spectrometer. The high magnetic field enables large ion populations to be analyzed for each spectrum for a high dynamic range, with 3.2 million mass resolving power at m/z 400 (6.2 s transient duration) or 1.6 million (3.1 s transient duration) while maintaining high mass accuracy for molecular formula assignment (root-mean-square assignment error < 0.150 ppm). Thousands of unique elemental compositions are assigned per mass spectrum, which can be grouped by the heteroatom class, double bond equivalents (the number of rings and double bonds to carbon), and carbon number. Figures of merit are discussed, as well as characterization of an Arabian heavy vacuum gas oil in terms of the ring number, compound class, double bond equivalents, and ion type. Consideration of elemental composition and retention order provides additional structural information.

BackgroundMicrobiomes are now recognized as main drivers of ecosystem function ranging from the oceans and soils to humans and bioreactors. However, a grand challenge in microbiome science is to characterize and quantify the chemical currencies of organic matter (i.e. metabolites) that microbes respond to and alter. Critical to this has been the development of Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), which has drastically increased molecular characterization of complex organic matter samples, but challenges users with hundreds of millions of data points where readily available, user-friendly, and customizable software tools are lacking.ResultsHere, we build on years of analytical experience with diverse sample types to develop MetaboDirect, an open-source, command-line based pipeline for the analysis, visualization, and presentation of metabolomics data by direct injection FTICR-MS after molecular formula assignment has been performed. When compared to all other available FTICR software, MetaboDirect is superior with respect to its compute time as it only requires a single line of code that launches a fully automated framework for the generation and visualization of a wide range of plots, with minimal coding experience required. Among the tools evaluated, MetaboDirect is also uniquely able to automatically generate biochemical transformation networks (ab initio) based on mass differences that provide a comprehensive experimental assessment of metabolite connectives within a given sample or a complex metabolic system, thereby providing important information about the nature of the samples and the set of the microbial reactions or pathways that gave rise to them. Finally, for more experienced users, MetaboDirect allows users to customize plots, outputs, and analyses.ConclusionApplication of MetaboDirect to FTICR-MS-based metabolomics datasets from a marine phage-bacterial infection experiment and a Sphagnum leachate microbiome incubation experiment showcase the exploration capabilities of the pipeline that will enable the FTICR-MS research community to evaluate and interpret their data in greater depth and in less time. It will further advance our knowledge of how microbial communities influence and are influenced by the chemical makeup of the surrounding system. Source code and User’s guide of MetaboDirect are freely available through (https://github.com/Coayala/MetaboDirect) and (https://metabodirect.readthedocs.io/en/latest/) respectively.

Because the rate of naphthenic acid corrosion does not correlate with the concentration of acids, it has been proposed that a subset of naphthenic acids in petroleum fractions may be more corrosive...

The remediation of oil sand process-affected water (OSPW) generated during the bitumen extraction in the oil sand region of Canada is an area of ongoing research interest. One of the primary remediation challenges is the removal of residual complex organic compounds present in the OSPW. In the present study, the molecular constitution of OSPW from aerated and nonaerated wetland treatments were characterized in constructed wetland treatment systems. Negative-ion and positive-ion atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was used to provide extensive molecular-level analysis of the samples. Multiple aerated and nonaerated treatment wetland systems were characterized in terms of naphthenic acids (NAs), oxy-NAs, heteroatom NAs class, and double bond equivalent (DBE) versus carbon number to evaluate their molecular composition and variability. A broad range of heteroatom compound classes with variable relative abundances were identified....

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is utilized for direct comparison of the chemical composition of biocrudes generated from the hydrothermal liquefaction of 100% pine, 100% algae, 75:25 pine:algae, and 50:50 pine:algae feedstocks. This analysis reveals that the composition of the 72:25 and 50:50 pine:algal HTL biocrudes is essentially a composite of the two parent feeds (i.e., pine and algae) with a lower relative abundance of Ox species and a higher relative abundance of nitrogen-containing species than the pine HTL biocrude. Alternatively, the biocrude blends have a lower relative abundance of nitrogen-containing species where N > 2 than the algal HTL biocrude. The 75:25 pine:algal HTL biocrude has more elemental formulae in common with the pine HTL biocrude than the 50:50 blend; however, both blends have more elemental formulae in common with the algal HTL biocrude. Interestingly, >20% of the elemental formulae assigned to monoisotopic peaks within the 75:25 and 50:50 biocrude blends are species not present in either the pine or algal HTL biocrudes. The highest relative abundance of these new species belong to the N2O4-6 classes, which correspond to heteroatom classes with a moderate number of nitrogen atoms and higher number of oxygen atoms per molecules than the species within the pure algal HTL biocrude. Compositionally, the novel species have the same structural motif but are of higher DBE and carbon numbers than the species within the algal HTL biocrude. These original species are most likely generated from reactions between molecules from both feeds, which results in compounds with higher oxygen content than typically seen in the algal HTL biocrude but also higher nitrogen contents than observed in the pine HTL biocrude.

The acidic components of Athabasca bitumen interfacial material (IM) were isolated and subsequently fractionated based on hydrophobicity by a modified aminopropyl silica (MAPS) method to determine whether low-molecular-weight IM acids are preferentially ionized in negative-ion electrospray ionization (ESI (−)) and, thus, bias the compositional information obtained by direct infusion (dilute and shoot) mass spectral analysis. Characterization by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) revealed that MAPS fractionation of IM acids extends the detection of high-m/z (>600-Da) IM compounds by 2-fold, yields an approximate 10-fold increase in the number of assigned formulas, and exposes a continuum of acidic species that includes the first definitive identification of doubly charged acids in interfacial material. Comparison of the heteroatom contents of singly and doubly charged Ox species, combined with the acid-targeted extraction procedure, ...

Naphthenic acid fraction compounds (NAFCs) are naturally present in the oil sand. These compounds become integrated into the oil sands process-affected water (OSPW) during the bitumen extraction process. NAFCs have been identified as causing toxicity in the OSPW to aquatic organisms. Water treatment technologies that are largely passive, such as constructed treatment wetlands, are a sought-after technology for the degradation of NAFCs in aquatic environments, partly because of their low energy intensity. However, it can be challenging to accurately assess the performance regarding decreased NAFC concentration and biodegradation characteristics in water samples that have been exposed to such systems. This is due to interferences of biological products such as fatty acids and humic-like materials, which may give false-positive information on NAFCs estimation with conventional analytical sample cleanup methods such as liquid–liquid extraction (LLE). It is recognized that this same issue exists when attemptin...

Adsorption of dissolved organic matter (DOM) to mineral surfaces is an important process determining DOM bioavailability and carbon sequestration in soils. However, little is known about preferential adsorption of DOM at the molecular level. In this study, DOM originating from composted biosolids was analyzed in order to elucidate DOM adsorptive fractionation by clay soil. Structural changes in DOM due to adsorption to soil were studied using two complementary approaches: (i) macroscale analysis including resin separation and (ii) molecular characterization using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Both approaches demonstrated consistency regarding the DOM adsorptive fractionation. Resin separation showed preferential adsorption of the hydrophobic acid (HoA) fraction by soil surfaces, with up to 70% of total adsorbed carbon; this fraction was apparently responsible for low DOM desorption. FT-ICR MS data demonstrated preferential adsorption of polyphenols, which are components of the HoA fraction. Adsorption of highly oxidized, saturated “carbohydrate-like” molecules was also observed, which might be a result of adsorption of the hydrophilic neutral (HiN) fraction. DOM exhibited concentration-dependent fractionation: enhanced adsorption of highly oxidized compounds at low DOM concentrations, and selective adsorption of less oxidized components at higher DOM concentrations, suggesting that adsorptive fractionation of DOM depended on the extent of its loading. Our findings suggest that a significant amount of carbon originating from the applied DOM was irreversibly stabilized by mineral surfaces. The study demonstrates that both DOM chemical heterogeneity and DOM concentration need to be considered in order to predict DOM reactivity and carbon stabilization in soils.

To harness the potential of microbiome science across the broad range of relevant disciplines, new approaches to data infrastructure and transdisciplinary collaboration are necessary. The National Microbiome Data Collaborative (NMDC) is a new initiative to support microbiome data exploration and discovery through a collaborative, integrative data science ecosystem. To harness the potential of microbiome science across the broad range of relevant disciplines, new approaches to data infrastructure and transdisciplinary collaboration are necessary. The National Microbiome Data Collaborative is a new initiative to support microbiome data exploration and discovery through a collaborative, integrative data science ecosystem.

Herein, a method to calculate the total sulfur concentration in petroleum samples from the chemometric modeling of data obtained by positive-ion atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry [(+) APPI FT-ICR MS] is described. Analysis by FT-ICR MS provides both a measurement of the total sulfur concentration and detailed molecular-level speciation of sulfur-containing compounds. A total of 30 crude oil samples ranging from 0.2 to 4.6 wt % sulfur were employed to train the sulfur prediction model. The ratios of the percent relative abundance (%RA) between the sulfur classes (Sx) and the hydrocarbon (HC) class were employed as variables for principal component analysis (PCA). The PCA results reveal a highly linear trend along the principal component with the highest explained variance (PC1). Analysis of the loadings plot reveals that the S1/HC ratio governs the trend in PC1. Values for PC2 are governed by S1/HC, S2/HC, and S3/HC ratios and provide the abili...

The role of the water content adsorbed to silica gel for the selective isolation of petroleum interfacially active material was examined. Systematic variation of the amount of water adsorbed on the silica surface and its effect on retained petroleum species (interfacially active) revealed that gravimetric yields of isolated interfacial material (IM) were inversely proportional to the amount of water loaded onto the silica gel. However, with the exception of the water-saturated silica gel (66.6% water g–1 silica gel), all silica gels investigated (11.1–53.8% water g–1 silica gel) were stained after IM isolation, indicating that >53.8% water g–1 silica gel is required to prevent irreversible, oil–silica interactions. Moreover, emulsion stability tests reveal that IM isolated from the water-saturated silica gel (66.6% water g–1 silica gel) forms the most stable emulsion relative to IM isolated from the unsaturated silica gels. Molecular-level analysis of isolated IM fractions as a function of the silica wate...

Isolation of crude oil components that concentrate at the oil/water interface [i.e., interfacial material (IM)] facilitates their molecular identification and quantitation, which is critical for advances in optimal petroleum production and processing. For a given crude oil, the molecular composition of IM determines its emulsion stability and identifies those chemistries that disproportionately contribute to the interfacial layer. Here, we describe a scalable, simple, quick, and efficient procedure to isolate IM from petroleum crude oils and/or other organic matrices. Hydrated silica (∼26 monolayers of water on a silica surface) enables separation of interfacially active species through their interaction with the immobilized water. Species with little or no interaction with the hydrated silica (water-laden) surface are eluted with a 1:1 (vol) mixture of heptane/toluene (heptol). The interfacially active species are subsequently isolated through the addition of methanol to the eluting solvent mixture, whic...

Although naphthenic acids are minor constituents in petroleum, their characterization is crucial because they are geochemically important tracers and play a key role in corrosion processes in refineries. Moreover, different isomers may exhibit different reactivity and may serve as potential biomarkers. However, determination of acid isomers in petroleum/hydrocarbon matrixes remains analytically challenging. Here, we achieve the separation and structural characterization of isomeric homologue series of naphthenic acids in petroleum samples by ion mobility time-of-flight mass spectrometry (IM-TOF MS). IM-TOF MS data processing and molecular formula assignments (for most abundant heteroatom classes), integrated with ion mobility data by PetroOrg software, expose structural differences and patterns among petroleum compounds and facilitate the identification of series of isomers. For example, a family of isomeric acids (CcHhO2) of double bond equivalents (DBE) = 5 and carbon number ranging from C28–C34 appear ...

We report a novel chromatographic method to enrich and separate nickel and vanadyl porphyrins from a natural seep sample and combine molecular level characterization by positive-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Vanadyl and nickel porphyrin model compound elution from primary secondary amine (PSA) stationary phase combined with UV-vis spectroscopy confirms enrichment and subsequent fractionation of nickel and vanadyl porphyrins into polarity-based subfractions. A more than 100-fold increase in signal-to-noise ratio for nickel porphyrins enables unequivocal elemental composition assignment confirmed by isotopic fine structure for all isotopes1% relative abundance, and the first mass spectral identification of (61)Ni porphyrin isotopologues derived from natural seeps. Oxygen-containing vanadyl porphyrins and sulfur-containing vanadyl porphyrins are isolated in the same fraction simultaneously from the same sample. We provide the first chromatographic evidence of carboxylic acid functionalities peripheral to the porphyrin core, in agreement with previous studies.

Woody biomass has the potential to be utilized at an alternative fuel source through its pyrolytic conversion. Here, fast pyrolysis bio-oils derived from several western USA woody species are characterized by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to determine molecular-level composition. The composition and properties (pH, electrical conductivity, and elemental analyses) of the biochar byproduct were also determined. The bio-oils are comprised mainly of Ox species. Oak (Quercus garryana Douglas ex Hook), mixed conifer (Pseudotsuga menziesii Mirb. Franco, Tsuga heterophylla (Raf.) Sarg, Abies concolor (Gord. & Glend.) Lindl. ex Hildebr.), and scotch broom (Cytisus scoparius (L.) Link) bio-oils contain lower Ox (O1-O7) species that exhibit bimodal distributions whereas mixed conifer feedstock from a fire salvage harvest contains a larger range of Ox species (O2-O13) that exhibit a mainly monomodal distribution. Boron-containing species in the pyrolysis oils were also identified for the first time by FT-ICR MS. Biochar analysis revealed that all biochars had similar pH values (~7-8); however, the electrical conductivity and elemental analyses varied across the samples. Understanding the composition of pyrolysis byproducts will help direct their uses to the most appropriate locations.

We present an analytical method for direct analysis of thin-layer chromatography (TLC) separations of petroleum samples by laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) imaging. LDI of TLC plates selectively ionizes condensed aromatic hydrocarbons and facilitates two-dimensional imaging of TLC-separated petroleum compounds. Molecular-level characterization available only with ultrahigh-resolution FT-ICR MS provides elemental composition assignment and surpasses conventional TLC readout-based flame ionization detection. Resolution and assignment of migrated molecules targeted by LDI combined with FT-ICR MS provides elemental composition assignment and, therefore, chemical information, i.e., heteroatom class, aromaticity (double bond equivalents), and carbon number. Here, three petroleum samples (a field deposit, a crude oil, and a tar ball) were TLC-separated by their solubility in n-heptane and imaged by LDI FT-ICR MS.

Naphthenic (NAP) acids have been previously characterized by negative electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), both directly and from acid extracts. Here, we show that collective characterization of NAP acids with negative-ion ESI, both with and without prior extraction, results in a loss of signal from high mass acids because of ion suppression by low mass acids. We have developed an extraction to simultaneously isolate and fractionate NAP acids into distinct molecular weight ranges, thereby grouping acids into fractions with similar ionization efficiency. A NAP acid fraction was isolated (all acids isolated collectively in one fraction) and compared to NAP acid isolation by molecular weight. Characterization of acid molecular weight fractions extended the observed upper mass limit from ∼850 Da for the collectively isolated acids to ∼1450 Da for the acids isolated by molecular weight range, thereby approximately doubling the observed mass rang...

The technique of choice for petroleomics has been ultra-high-resolution and high-accuracy Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), but other techniques such as ion mobility have been shown to provide additional or alternative information about crude oil composition. Using the traveling wave ion mobility (TWIM) cell of a hybrid Q-TWIM-TOF first-generation Synapt instrument and electrospray ionization in both the positive and negative ion modes, different crude oil samples with different polar compound profiles and petro fuels (diesel and gasoline) with or without additives were analyzed using either CO2 or N2 as the drift gas. Parameters such as gas pressure, velocity, and wave height were optimized for each type of crude oil or fuel sample. The ability of TWIM–MS to separate crude oil components according to their classes was verified by comparison with FT-ICR data. Results showed separation of several classes of polar compounds (NO, O2, and N), and their separation was imp...

We have studied the behavior of isomers and analogues by traveling wave ion mobility mass spectrometry (TWIM-MS) using drift-gases with varying masses and polarizabilities. Despite the reduced length of the cell (18 cm), a pair of constitutional isomers, N-butylaniline and para-butylaniline, with theoretical collision cross-section values in helium (ΩHe) differing by as little as 1.2 A2 (1.5%) but possessing contrasting charge distribution, showed baseline peak-to-peak resolution (Rp-p) for their protonated molecules, using carbon dioxide (CO2), nitrous oxide (N2O) and ethene (C2H4) as the TWIM drift-gas. Near baseline Rp-p was also obtained in CO2 for a group of protonated haloanilines (para-chloroaniline, para-bromoaniline and para-iodoaniline) which display contrasting masses and theoretical ΩHe, which differ by as much as 15.7 A2 (19.5%) but similar charge distributions. The deprotonated isomeric pair of trans-oleic acid and cis-oleic acid possessing nearly identical theoretical ΩHe and ΩN2 as well as similar charge distributions, remained unresolved. Interestingly, an inversion of drift-times were observed for the 1,3-dialkylimidazolium ions when comparing He, N2 and N2O. Using density functional theory as a means of examining the ions electronic structure, and He and N2-based trajectory method algorithm, we discuss the effect of the long-range charge induced dipole attractive and short-range Van der Waals forces involved in the TWIM separation in drift-gases of differing polarizabilities. We therefore propose that examining the electronic structure of the ions under investigation may potentially indicate whether the use of more polarizable drift-gases could improve separation and the overall success of TWIM-MS analysis. Copyright © 2013 John Wiley & Sons, Ltd.

Electrospray ionization (ESI) coupled to ultra-high resolution and accuracy Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was employed for the direct analysis of whisky samples. No pre-separation or extraction steps were employed and, owing to the gentleness of ESI, characteristic profiles of polar constituents of authentic whiskies from five different brands were obtained, which greatly contrast to those of counterfeit samples. Owing to the accuracy of FT-ICR MS mass measurements, elemental composition of the main ions detected were also securely determined, and related to a series of carboxylic acids, phenols, saccharides, fat acids and sulfur or nitrogen constituents of whisky. The accurate mass measurements and the number of detected ions, together with the direct, no sample preparation procedure employed, make FT-ICR MS a highly reliable approach to fingerprint whisky and to control its quality, and to screen for aging, counterfeiting and adulteration at the molecular level.

Ion mobility spectrometry (IMS) separates ions while they travel through a buffer gas under the influence of an electrical field. The separation is affected by mass and charge but most particularly by shape (collision cross section). When coupled to MS, IMS-MS offers therefore a powerful tool for structural elucidation and isomer separation. Systematic studies aimed to compare and quantitate the effects of structural changes on drift time such as length and ramification of carbon chain, unsaturation, geometrical isomerism (cis/trans isomers for instance), cyclization and ring size are, however, scarce. Herein we used traveling wave ion mobility mass spectrometry (TWIM-MS) to systematically evaluate the relationship between structure and drift time. For that, a series of deprotonated carboxylic acids were used as model ions with a carboxylate “charge tag” for gas phase MS manipulation. Carboxylic acids showed a near linear correlation between the increase of carbon number and the increase of collision cross section (CCS). The number of double bonds changes slightly the CCS of unsaturated acids. No differences in drift time and no significant differences in CCS of cis- and trans-double bond of oleic and elaidic acids were observed. Cyclization considerably reduces the CCS. In cyclic carboxylic acids, the increase of double bonds and aromatization significantly reduces the CCS and the drift times. The use of a more polarizable drift gas, CO2, improved in some cases the separation, as for biomarker isomers of steranoic acids. The β-isomer (cis-decaline) has smaller CCS and therefore displayed lower drift time compared to the α-isomer (trans-decaline). Structural changes revealed by calculations were correlated with trends in drift times.

Twenty-five years ago, Boduszynski et al. conducted a comprehensive study of heavy oil composition and concluded that crude oil composition increases gradually and continuously with regard to aromaticity, molecular weight, and heteroatom content from the light distillates to non-distillables (the Boduszynski continuum model). Previous exhaustive characterization of heavy vacuum gas oil by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) provided compositional data that strongly supports the continuum model. However, when the molecular formulas obtained by FT-ICR MS for the distillates and asphaltenes from the same parent crude oil are plotted as double bond equivalents (DBE) versus carbon number, a gap appears between the compositional space of “asphaltenes” and “maltenes”, in contradiction to the Boduszynski–Altgelt model. Here, a heavy distillate cut (atmospheric equivalent boiling point of 523–593 °C) is fractionated according to the number of aromatic rings by HPLC-2. The C7-dea...

International audience; Because of its high molecular complexity, ultra high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is used to characterize heavy petroleum distillates. However, high peak capacity can also be obtained with ion mobility-mass spectrometry (IM-MS). In this case, the additional separation dimension allows for the compensation of the lower resolving power of the time-of-flight mass analyzer. The processing and elemental composition assignments from such bidimensional IM-MS data cannot be achieved with conventional software packages. PetroOrg, a new software package, was used to compare IM-MS data sets recorded with atmospheric solid analysis probe (ASAP) and three other atmospheric pressure ionization sources. The choice of the ionization source is indeed very critical as it defines the type of compounds that can be detected from mixtures. Electrospray ionization (ESI) is very specific to polar compounds and yields relatively simple data sets that can be readily attributed to nitrogen containing compounds allowing their speciation. On the other hand, gas phase ionization methods such as APCI, APPI, and ASAP yielded valuable information concerning thiophenic species. However, in this case the IM-MS peak capacity is not sufficient to separate all isobaric species. It is worth noting that ASAP and APPI yielded similar mass spectra although the ASAP ionization mechanism is believed to be closer to that of APCI. Most likely this is due to the absence of solvent with ASAP that reinforces charge exchange processes and therefore affords low ionization discrimination such as with APPI.

Gas-phase reactions of model carbosulfonium ions (CH3-S+ = CH2; CH3CH2-S+ = CH2 and Ph-S+ = CH2) and an O-analogue carboxonium ion (CH3-O+ = CH2) with acyclic (isoprene, 1,3-butadiene, methyl vinyl ketone) and cyclic (1,3-cyclohexadiene, thiophene, furan) conjugated dienes were systematically investigated by pentaquadrupole mass spectrometry. As corroborated by B3LYP/6-311 G(d,p) calculations, the carbosulfonium ions first react at large extents with the dienes forming adducts via simple addition. The nascent adducts, depending on their stability and internal energy, react further via two competitive channels: (1) in reactions with acyclic dienes via cyclization that yields formally [4 + 2+] cycloadducts, or (2) in reactions with the cyclic dienes via dissociation by HSR loss that yields methylenation (net CH+ transfer) products. In great contrast to its S-analogues, CH3-O+ = CH2 (as well as C2H5-O+ = CH2 and Ph-O+ = CH2 in reactions with isoprene) forms little or no adduct and proton transfer is the dominant reaction channel. Isomerization to more acidic protonated aldehydes in the course of reaction seems to be the most plausible cause of the contrasting reactivity of carboxonium ions. The CH2 = CH-O+ = CH2 ion forms an abundant [4 + 2+] cycloadduct with isoprene, but similar to the behavior of such α,β-unsaturated carboxonium ions in solution, seems to occur across the C = C bond. Copyright © 2012 John Wiley & Sons, Ltd.

The ability of time-of-flight (TOF) mass spectrometry using an ultrahigh resolving power (Rp of 100 000 at m/z 400)analyzer (HRT) to provide a proper platform for comprehensive petroleomic studies has been evaluated. The innovative HRT design for ultrahigh resolution using a “zig-zag” multi-reflecting analyzer with a folded flight path, efficient ion refocusing, and no substantial loss of ion transmission was tested. For comparison, samples were also analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) using variable Rp (from 100 000 at m/z 400 to 400 000 at m/z 400). Both HRT and FT-ICR MS data were processed and compared using software specifically designed to process either TOF or FT-ICR data for petroleomic studies. Owing to the increase in Rp with m/z, the 100 000 at m/z 400 Rp of the HRT is found to be, overall, comparable to that of a 200 000 at m/z 400 FT-ICR. This Rp is sufficient to allow for proper resolution, correctly resolve most isobaric interferences, and acc...

Seven gas oil (GO) cuts from the same atmospheric petroleum residuum were obtained by molecular distillation at final temperatures of 490.0 and 503.2 °C (medium GO), 522.5 and 549.5 °C (heavy GO), and 583.7, 622.4, and 662.2 °C (extra heavy GO). The detailed chemical composition of these samples was investigated using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC–TOFMS) and electrospray ionization ultrahigh-resolution and -accuracy Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). Many compound classes were identified by GC × GC–TOFMS, such as tri-, tetra-, and pentacyclic terpanes, steranes, and secohopanes; several polycyclic aromatic hydrocarbons (PAHs), such as fluorene, phenanthrene, pyrene, and benzo[g,h,i]perylene; sulfur compounds, e.g., alkylbenzothiophenes, alkyldibenzothiophenes, and alkylbenzonaphthothiophenes; and alkylphenols. With ESI FT-ICR MS in both the positive- and negative-ion modes, many polar components tha...

An absorption-mode Fourier transform ion cyclotron resonance (FT-ICR) mass spectrum exhibits two types of baseline distortion: a slow periodic oscillation even where no signal peaks are present, and additional distortion near signal peaks and proportional to signal magnitude. These distortions interfere with automated peak-picking, unless the baseline systematic variation is much less than baseline rms random noise. We previously showed that the slow oscillation is removed by low-pass filtering. Here, we present a fast, robust, and automated algorithm that flattens the absorption-mode spectral baseline, even in the vicinity of signal peaks. The method begins by defining baseline data values, followed by linear interpolation to generate baseline data values between the defined values, then boxcar smoothing to generate a final baseline spectrum, and final subtraction of that baseline from the original spectrum to yield a baseline-flattened absorption-mode spectrum. We apply the algorithm to a crude oil spectrum (with 8000 peaks) and to a ribonuclease A protein spectrum (with multiply-charged ion isotopic distributions). We identify many more peaks (crude oil) without loss of mass accuracy, and obtain more accurate isotopic distributions (RNase A).

The six possible isomers of di- N -acetylchitotetraoses [ AADD , ADDA , ADAD , DADA , DAAD , and DDAA , where D stands for 2-amino-2-deoxy-β- d -glucose (GlcN) and A for 2-acetamido-2-deoxy-β- d -glucose (GlcNAc)] were analyzed by ESI(+)-MS n . Collision induced dissociation via MS n experiments were performed for the sodiated molecules of m / z 769 [M+Na] + for each isomer, and fragments were generated mainly by glycosidic bond and cross-ring cleavages. Rules of fragmentation were then established. A reducing end D residue yields the O,2 A 4 cross-ring [M−59+Na] + fragment of m / z 710 as the most abundant, whereas isomers containing a reducing end A prefer to lose water to form the [M−18+Na] + ion of m / z 751, as well as abundant O,2 A 4 cross-ring [M−101+Na] + fragments of m / z 668 and B 3 [M−221+Na] + ions of m / z 548. MS 3 of C- and Y-type ions shows analogous fragmentation behaviour that allows identification of the reducing end next-neighbour residue. Due to gas-phase anchimeric assistance, B-type cleavage between the glycosidic oxygen and the anomeric carbon atom is favoured when the glycon is an A residue. Relative ion abundances are generally in the order B ≫ C > Y, but may vary depending on the next neighbour towards the non-reducing end. These fragmentation rules were used for partial sequence analysis of hetero-chitooligosaccharides of the composition D 2 A 3 , D 3 A 3 , D 2 A 4 , D 4 A 3 , and D 3 A 4 .

Direct-infusion electrospray ionization-mass spectrometry [ESI(+)-MS] of several milk powder samples, confiscated by the Brazilian Federal Police, showed ions accounting for sodiated and potassiated molecules of disaccharides (m/z 365 and 381) as well as trisaccharides (m/z 527 and 543), whereas monosaccharide ions were not detected. The trisaccharide ions were not detected in samples of genuine milk powder, raising the suspicion that their presence indicates adulteration by the addition of maltodextrin. In control samples, maltose and maltotriose were hydrolyzed by alpha-glucosidase and not beta-galactosidase, whereas lactose was resistant to alpha-glucosidase but was hydrolyzed with beta-galactosidase. Samples suspected of being adulterated behaved in the same fashion, confirming the presence of maltose and maltotriose or maltodextrin. Direct-infusion ESI-MS is shown therefore to provide rapid screening of milk powder for adulteration with maltodextrin, whereas its combination with selective enzymatic hydrolysis provides highly reliable confirmation for unambiguous results.

Preliminary work on Passiflora alata leaves failed to detect harmane alkaloids using LC. The aim of this work was to investigate the production of harmane alkaloids through the cell culture of P. alata, inducing its precursor (L-tryptophan). The leaf explants presented satisfactory results after disinfection, and the callus formation was initiated in MS media with adequate quantities of phytohormones. Sixty days after inoculation, calli were inoculated in the optimized semi-solid MS media, with and without the addition of L-tryptophan (50, 100, 200 mg/L) and kept in standard conditions for 90 days. Calli were collected on days 6, 16, 26, 36, and 90, followed by acid-base extraction, and analysed by LC. The results showed an absence of harmane, harmin, harmol, harmalol, and harmaline. With L-tryptophan feeding, two peaks were detected, collected and analysed through positive mode electrospray [ESI(+)-MS] and sequential analysis in tandem ESI(+)-MS/MS. The spectra obtained were very similar, with a repetition of the more intense ions, and consecutive loss of 68 Da units, attributed to the heterocycle pyrazole. It appeared that this transformation was not related to any enzymatic pathway previously described for the plant from L-tryptophan, and the biosynthesis of β-carboline alkaloids in callus culture of P. alata were not observed in this work.As folhas de varias espécies de Passiflora são utilizadas como ansioliticas e sedativas. Passiflora alata Curtis, Passifloraceae consta em três edições da farmacopéia brasileira, porem não há muitos estudos sobre sua composição química. No passado, enfatizava-se a ação conjunta de alcalóides e flavonóides. Em trabalho anterior, não foi detectada a presença de alcalóides harmanicos através de CLAE. Assim, decidiu-se investigar a produção dos mesmos através de cultivo celular, introduzindo seu precursor metabólico L-triptofano. Os explantes foliares apresentaram resultados satisfatorios para germinação apos assepsia, e a formação de calo foi iniciada em meio MS com quantidades adequadas de fitohormonios, previamente determinadas. Sessenta dias após a inoculação os calos foram repicados para meio semi-solido com e sem L-triptofano (50, 100, 200 mg/L), mantidos por 90 dias em condições padrão. Amostras foram coletadas com 6, 16, 26, 36, e 90 dias, realizada extração acido-base e o extrato analisado por CLAE. Os resultados mostraram a ausência de harmana, harmina, harmol, harmalol e harmalina. Dois picos presentes nas amostras com L-triptofano foram coletados e analisados através de espectrometria de massas, electrospray modo positiva [ESI(+)-MS] e analise em tandem ESI(+)-MS/MS. Os espectros correspondentes foram similares, mostrando a perda consecutiva de 68 Da, atribuídos ao pirazol. Este fato aponta para uma transformação não enzimática, não relacionada a uma biossintese previamente descrita para alcalóides β-carbolínicos.

1 H NMR and MALDI-TOF MS measurements were used to study the thermo-mechanical and thermo-oxidative degradation mechanisms of bottle-grade PET (btg-PET). In the thermo-oxidative degradation, the concentration of low molar mass compounds increased with time and the main products were cyclic and linear di-acid oligomers. In the thermo-mechanical degradation, the main-chain scission reactions affect the stability of the cyclic oligomers. One of the most important bottle-grade PET co-monomers is diethylene glycol (DEG), which is a “reactive site” in the thermal degradation of btg-PET. The DEG co-monomer was shown to be the precursor to colour changes in btg-PET, owing to the attack by molecular oxygen on the methylenic protons adjacent to the ether oxygen atoms of DEG. This behaviour was observed in the thermo-oxidative degradation process in which the degradation of DEG causes the release of hydroxyl radicals in the polymeric matrix, thereby producing mono- and di-hydroxyl substituted species. This was also observed in the thermo-mechanical degradation process.

A novel ion/molecule reaction was observed to occur under electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo ionization (APPI) conditions, leading to dimerization of ionized 4-(methyl mercapto)-phenol followed by fast H(*) loss. The reaction is particularly favored during ESI, which suggests that this ion/molecule reaction can occur both in the solution inside the ESI-charged droplets and in the gas-phase environment of most other atmospheric pressure ionization techniques. The dimerization reaction is inherent to the electrolytic process during ESI, whereas it is more by ion/molecule chemistry in nature during APCI and APPI. From the tandem mass spectrometry (MS/MS) data, accurate mass measurements, hydrogen/deuterium (H/D) exchange experiments and density functional theory (DFT) calculations, two methyl sulfonium ions appear to be the most likely products of this electrophilic aromatic substitution reaction. The possible occurrence of this unexpected reaction complicates mass spectral data interpretation and can be misleading in terms of structural assignment as reported herein for 4-(methyl mercapto)-phenol.

A general mass spectrometric method able to recognize the site of substitution of monosubstituted pyridines is described. The method requires that the molecule under investigation forms, upon ionization and dissociation, the respective alpha-, beta- or gamma- pyridinium ion of m/z 78. Pyridinium ions are stable and common fragments of ionized and protonated pyridines and are found to function as appropriate structurally diagnostic fragment ions. They can be identified by their characteristic and nearly identical collision-induced dissociation behavior and distinguished by the combined use of two structurally diagnostic ion/molecule reactions with acetonitrile and 2-methyl-1,3-dioxolane. alpha-, beta- or gamma-substitution in pyridines can, therefore, be securely recognized via an MS-only method based on structurally diagnostic ions and by the inspection of a single molecule (no need for intracomparisons within the whole set of isomers).

One fundamental challenge with either acute or chronic oil spills is to identify the source, especially in highly polluted areas, near natural oil seeps, when the source contains more than one petroleum product or when extensive weathering has occurred. Here we focus on heavy fuel oil that spilled (~200,000 L) from two suspected fuel tanks that were ruptured on the motor vessel (M/V) Cosco Busan when it struck the San Francisco-Oakland Bay Bridge in November 2007. We highlight the utility of principal component analysis (PCA) of elemental composition data obtained by high resolution FT-ICR mass spectrometry to correctly identify the source of environmental contamination caused by the unintended release of heavy fuel oil (HFO). Using ultrahigh resolution electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry, we uniquely assigned thousands of elemental compositions of heteroatom-containing species in neat samples from both tanks and then applied principal component analysis. The components were based on double bond equivalents for constituents of elemental composition, CcHhN1S1. To determine if the fidelity of our source identification was affected by weathering, field samples were collected at various intervals up to two years after the spill. We are able to identify a suite of polar petroleum markers that are environmentally persistent, enabling us to confidently identify that only one tank was the source of the spilled oil: in fact, a single principal component could account for 98% of the variance. Although identification is unaffected by the presence of higher polarity, petrogenic oxidation (weathering) products, future studies may require removal of such species by anion exchange chromatography prior to mass spectral analysis due to their preferential ionization by ESI.

We have studied the behavior of isomers and analogues by traveling wave ion mobility mass spectrometry (TWIM-MS) using drift-gases with varying masses and polarizabilities. Despite the reduced length of the cell (18 cm), a pair of constitutional isomers, N-butylaniline and para-butylaniline, with theoretical collision cross-section values in helium (ΩHe ) differing by as little as 1.2 Å(2) (1.5%) but possessing contrasting charge distribution, showed baseline peak-to-peak resolution (Rp-p ) for their protonated molecules, using carbon dioxide (CO2), nitrous oxide (N2O) and ethene (C2H4 ) as the TWIM drift-gas. Near baseline Rp-p was also obtained in CO2 for a group of protonated haloanilines (para-chloroaniline, para-bromoaniline and para-iodoaniline) which display contrasting masses and theoretical ΩHe , which differ by as much as 15.7 Å(2) (19.5%) but similar charge distributions. The deprotonated isomeric pair of trans-oleic acid and cis-oleic acid possessing nearly identical theoretical ΩHe and ΩN2 as well as similar charge distributions, remained unresolved. Interestingly, an inversion of drift-times were observed for the 1,3-dialkylimidazolium ions when comparing He, N2 and N2O. Using density functional theory as a means of examining the ions electronic structure, and He and N2-based trajectory method algorithm, we discuss the effect of the long-range charge induced dipole attractive and short-range Van der Waals forces involved in the TWIM separation in drift-gases of differing polarizabilities. We therefore propose that examining the electronic structure of the ions under investigation may potentially indicate whether the use of more polarizable drift-gases could improve separation and the overall success of TWIM-MS analysis.

Gas-phase reactions of model carbosulfonium ions (CH(3)-S(+)=CH(2;) CH(3)CH(2)-S(+)=CH(2) and Ph-S(+)=CH(2)) and an O-analogue carboxonium ion (CH(3)-O(+)=CH(2)) with acyclic (isoprene, 1,3-butadiene, methyl vinyl ketone) and cyclic (1,3-cyclohexadiene, thiophene, furan) conjugated dienes were systematically investigated by pentaquadrupole mass spectrometry. As corroborated by B3LYP/6-311 G(d,p) calculations, the carbosulfonium ions first react at large extents with the dienes forming adducts via simple addition. The nascent adducts, depending on their stability and internal energy, react further via two competitive channels: (1) in reactions with acyclic dienes via cyclization that yields formally [4+2(+)] cycloadducts, or (2) in reactions with the cyclic dienes via dissociation by HSR loss that yields methylenation (net CH(+) transfer) products. In great contrast to its S-analogues, CH(3)-O(+)=CH(2) (as well as C(2)H(5)-O(+)=CH(2) and Ph-O(+)=CH(2) in reactions with isoprene) forms little or no adduct and proton transfer is the dominant reaction channel. Isomerization to more acidic protonated aldehydes in the course of reaction seems to be the most plausible cause of the contrasting reactivity of carboxonium ions. The CH(2)=CH-O(+)=CH(2) ion forms an abundant [4+2(+)] cycloadduct with isoprene, but similar to the behavior of such α,β-unsaturated carboxonium ions in solution, seems to occur across the C=C bond.

Travelling-wave ion mobility mass spectrometry was used to measure the intrinsic mobility of a series of gaseous supra-cation and supra-anion aggregates of several ionic liquids. Close mobilities were observed in a T-wave cell filled with helium at ca. 0.8 mbar for [(DAI) n+1 (X) n ] + (DAI is the 1,3-dialkylimidazolium cation and X is the anion) as compared to the respective anions [(DAI) n (X) n+1 ] - for n=0 to 9. The anomalous behavior reported before in the condensed phase seems therefore to be related to the unique structural organization of pure ionic liquids that provides both polar and non-polar regions with directionality in which the anionic species are more retained than the cationic species in the salt network.

An ambient ionization/desorption technique, namely, easy ambient sonic-spray ionization mass spectrometry (EASI), has been applied to crude oil samples. From a single droplet of the sample placed on an inert surface, EASI(+/-) is shown to promote efficient desorption and ionization of a myriad of polar components via the action of its cloud of very minute supersonic bipolar charged droplets. The gaseous [M + H](+) and [M - H](-) ions concurrently formed by EASI(+/-) were analyzed by Fourier transform mass spectrometry (FT-ICR MS), and a total of approximately 6000 acidic and basic components have been attributed. EASI(+/-) FT-ICR MS of crude oils is show to be almost as fast as ESI(+)/ESI(-) FT-ICR MS, providing similar compositional information of polar components and spectral quality comparable to that of a commercial nonochip-based robotic ESI device. EASI(+/-) requires no sample workup thus eliminating risks of contamination during sample manipulation and memory effects because of carry over in pumping ESI lines. More importantly, EASI(+/-) is a voltage-free ionization technique therefore eliminating risks of redox processes or duality of ionization mechanisms that can be observed in voltage-assisted processes. Data visualization via typical petroleomic plots confirms the similarity of the compositional information provided by EASI(+/-) compared to ESI(+)/ESI(-). The ambient EASI(+/-) FT-ICR MS method requires no voltage switching in changing the ion polarity mode, offering a workup, heating and voltage-free protocol for petroleomic studies performed at open atmosphere directly on the undisturbed crude oil sample.

We report on the synthesis and properties of a family of linear cyanide bridged mixed-valence heptanuclear complexes with the formula: trans-[L 4RuII{(μ-NC)FeIII(NC)4(μ-CN) RuIIL′4(μ-NC)FeIII(CN) 5}2]6- (with L and L′ a para substituted pyridine). We also report on the properties of a related pentanuclear complex. These oligomers were purified by size exclusion chromatography, characterized by electrospray ionization (ESI) mass spectrometry and elemental analysis, and their linear shape was confirmed by scanning tunneling microscopy (STM). These complexes present a rich electrochemistry associated with the seven redox active centers. The redox potential split of identical fragments indicates that there is considerable communication along the cyanide bridged backbone of the compounds, even for centers more than 3 nm apart. This small attenuation of the interaction at long distances make these cyanide bridged compounds good candidates for molecular wires. Interestingly, the extent of the communication depends on the relative energy of the fragments, as evaluated by their redox potentials, providing a guide for improvement of this interesting property. Fil: Alborés, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina Fil: Slep, Leonardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina Fil: Eberlin, Livia S.. Universidade Estadual de Campinas; Brasil Fil: Corilo, Yuri E.. Universidade Estadual de Campinas; Brasil Fil: Eberlin, Marcos N.. Universidade Estadual de Campinas; Brasil Fil: Benitez, Guillermo Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina Fil: Vela, Maria E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina Fil: Salvarezza, Roberto Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina Fil: Baraldo Victorica, Luis Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina

Fresh leaves of Vernonia scorpioides are widely used in Brazil to treat a variety of skin disorders. Previous in vivo studies with extracts of this species had also demonstrated a high antitumor potential. This paper reports isolation of four sesquiterpene lactones (hirsutinolides and glaucolides), together with diacetylpiptocarphol, 8-acetyl-13-etoxypiptocarphol, luteolin, apigenin, and ethyl caffeate from fresh leaves and flowers of Vernonia scorpioides. The hypothesis that hirsutinolide 3 is formed during extraction was verified theoretically using Density Functional Theory. The effects of isolated compounds on in vitro tumor cells were investigated, as well as their genotoxicity by means of an in vitro comet assay. The results indicate that glaucolide 2 and hirsutinolide 4 are toxic to HeLa cells. These compounds were genotoxic in vitro, a property that appears to be related to the presence of their epoxy groups, which has been a more reliable indication of toxicity than substitution on C-13 or the presence of alpha,beta-unsaturated keto-groups. These results need to be replicated in vivo in order to ascertain their toxicity.

A general mass spectrometric method able to recognize the site of substitution of monosubstituted pyridines is described. The method requires that the molecule under investigation forms, upon ionization and dissociation, the respective alpha-, beta- or gamma- pyridinium ion of m/z 78. Pyridinium ions are stable and common fragments of ionized and protonated pyridines and are found to function as appropriate structurally diagnostic fragment ions. They can be identified by their characteristic and nearly identical collision-induced dissociation behavior and distinguished by the combined use of two structurally diagnostic ion/molecule reactions with acetonitrile and 2-methyl-1,3-dioxolane. alpha-, beta- or gamma-substitution in pyridines can, therefore, be securely recognized via an MS-only method based on structurally diagnostic ions and by the inspection of a single molecule (no need for intracomparisons within the whole set of isomers).

The interception, formation and characterization of the first stable, long lived charge-tagged N-heterocyclic carbenes of the general type 4x+ (x = 1–3) and analogues is reported. Via ESI(+)-MS of solutions of bromine salts of doubly, triply and quadruply charged imidazolium ion IL (3.Brn, n = 2–4), the isolated 4x+ as well as charged aggregates [3.Br(n−x)]x+ likely to be participating in the [3.Br(n−x)]x+ ⇌ 4x+ + HBr solution equilibrium could be transferred and characterized in the gas phase. Mimicking the solution equilibrium, the gaseous [3.Br(n−x)]x+ were found to dissociate nearly exclusively viaHBr loss during thermal activationvia collisions to form gaseous 4x+, which were found to add to acrolein and acetone.

The ion/molecule chemistry of four representative propagyl/allenyl cations 1-4 of the general formula R(1)CH(+)-C[triple bond]C-R (a)--R(1)CH=C=C(+)-R (b), that is, the reactive C(3)H(3)(+) ions of m/z 39 from EI of propargyl chloride (H(2)C(+)-C[triple bond]C-H, 1a), isomeric C(4)H(5)(+) ions of m/z 53 from EI of 3-butyne-2-ol (2a, H(2)C(+)-C[triple bond]C-CH(3)) and 2-butyne-1-ol (CH(3)-CH(+)-C[triple bond]C-H, 3a), and Ph-C(3)H(2)(+) ions of m/z 115 from 3-phenyl-2-propyn-1-ol (H(2)C(+)-C[triple bond]C-Ph, 4a) was studied via pentaquadrupole mass spectrometry. With pyridine, proton transfer was observed as the predominant process for 1 and the sole reaction channel for the isomeric 2 and 3, whereas 4 reacted preferentially by adduct formation. These outcomes were rationalized using DFT calculations from isodesmic proton transfer reactions. Similar reaction tendencies were observed with acetonitrile and acrylonitrile, with adduct formation appearing again as a minor pathway for 1, 2 and 4, and as a major reaction channel for 4. With 1,3-dioxolane, hydride abstraction was a dominant reaction, with proton transfer and adduct formation competing as side reactions. With 2,2-dimethyl-1,3-dioxolane, an interplay of reactions including methyl anion abstraction, proton transfer, hydride abstraction and adduct formation were observed depending on the ion structure, with 4 reacting again mainly by adduct formation. Proton transfer was also observed as a dominant process in reactions with ethanol for 1, 2 and 3, with 4 being nearly unreactive whereas no adduct formation was observed for any of the carbocations studied. Limited reactivity was exhibited by these ions in cycloaddition reaction with isoprene.