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Multiple studies have focused on the effect of long-term weathering processes on oils after spill events, without considering the chemical compositional changes occurring shortly after the release of oil into the environment. Therefore, the present study provides a broad chemical characterization for understanding of the changes occurring in the chemical compositions of intermediate (°API = 27.0) and heavy (°API = 20.9) oils from the Sergipe-Alagoas basin submitted to two simulated situations, one under marine conditions and the other in a riverine environment. Samples of the oils were collected during the first 72 h of contact with the simulated environments, followed by evaluation of their chemical compositions. SARA fractionation was used to isolate the resins, which were characterized at the molecular level by UHRMS. The evaporation process was highlighted, with the GC-FID chromatographic profiles showing the disappearance of compounds from n-C10 until n-C16, as well as changes in the weathering indexes and pristane + n-C17/phytane + n-C18 ratios for the crude oils submitted to the riverine conditions. Analysis of the resins fraction showed that basic polar compounds underwent little or no alterations during the early stages of weathering. The marine environment was shown to be much less oxidative than the riverine environment. For both environments, a feature highlighted was an increase of acidic oxygenated compounds with the increase of weathering, especially for the crude oil with °API = 27.0. [ABSTRACT FROM AUTHOR]

The progress in ultrahigh-resolution mass spectrometry (UHRMS) and related technologies has significantly promoted the development of petroleomics. The study of petroleomics has greatly broadened our knowledge of the composition of petroleum at the molecular level, especially heavy fractions that cannot be analyzed by gas chromatography (GC)-based methods. To date, heteroatom-containing (O, N, S, and metal atoms) compounds in petroleum have been studied extensively by UHRMS. Nevertheless, the main components of petroleum, hydrocarbon compounds, have remained out of reach of petroleomics characterization for a long time because they are too difficult to be softly and efficiently ionized for UHRMS analysis. It is undoubtedly the case that petroleum hydrocarbons should not be the missing part of petroleomics characterization since they play important roles not only as feeding pools for various high value-added petroleum products but also as critical biomarkers for geochemistry studies. Here, the most recent breakthroughs in petroleomics characterization of hydrocarbon compounds using UHRMS rather than conventional methods have been reviewed. Innovations of soft ionization methods can transform non-polar hydrocarbon molecules into molecular ions or quasi-molecular ions that are reachable for UHRMS without fragmentation. The development of data processing methods has assisted the decoding of the complicated UHRMS data to visualize the molecular composition and structure of hydrocarbon compounds. These advances make it possible to see the whole picture of petroleum compositions, from light distillation fractions to heavy distillation fractions, and from small volatile molecules to large non-volatile ones. The applications of UHRMS-based methods for petroleomics characterization of hydrocarbon compounds in crude oils and various petroleum samples including fuel oil, slurry, and even asphaltene have made a great contribution to petrochemistry and geochemistry studies, especially in the fields of molecular refining and biomarker discovery. [ABSTRACT FROM AUTHOR]

In this work, it is reported the detailed evaluation of filtering scripts for comprehensive two-dimensional gas chromatography coupled with high-resolution mass spectrometry (GC×GC–HRMS). Automated scripts were built to perform group-type analysis of naphthenic acids (NAs) in complex mixtures, like produced water (PW) samples. The logical operations were based on high-resolution mass spectral information acquired by using electron ionization (EI) and chemical ionization in the positive mode (PCI). The most common derivatization methods were carefully evaluated for group-type analysis. The performance of the scripts was evaluated using the rank metric (RM), wherein the sum-normalized absolute difference was calculated for true positives versus false positives. The best performing approach for qualitative analysis was attained by combining the derivatization with N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) with EI due to the high intensity and characteristic pseudo-molecular ions (even-electron [M-57]+). The data obtained supported the development of selective scripts, exhibiting accuracy values above 98 % and 88 % for the reference and unknown PW samples, respectively. The retention pattern of GC×GC was also used as a discriminant parameter for ambiguous identification, highlighting the synergy between GC×GC and HRMS. The proposed scripts are an interesting alternative to profile 154 classes of MTBSTFA-derived NAs, which considerably reduced the time spent in manual data curation and annotation, while improving the reliability of the results. This is an important step to aid in the development of standard methods for the study and regulation of water-soluble compounds found in PW samples.

Abstract Biosurfactants and waterflooding have been widely reported thus far for enhancing oil production. Nevertheless, there is a lack of literature to explore enhanced oil recovered methods effects on its chemical composition. The aim of this work is to investigate the effects of a biosurfactant produced by Bacillus safensis and brine injection on the recovered petroleum composition, and their implications for geochemical interpretation. Original and oils recovered from displacement tests were analyzed by gas chromatography and ultra-high-resolution mass spectrometry, emphasizing saturated and aromatic biomarkers and basic and acidic polar compounds. Geochemical parameters based on some saturated compounds were subtly affected by the recovery methods, showing their reliable applicability in geochemical studies. Contrarily, parameters based on some aromatic compounds were more affected by biosurfactant flooding, mostly the low molecular weight compounds. Thus, these aromatic parameters should be applied with caution after such methods. The distribution of basic and acidic polar compounds can also be modified affecting the geochemical interpretation. In the case of the basic ones, the biosurfactant greatly influenced the N class species with favorable loss of lower aromaticity compounds. In addition to water solubilization, the compositional changes described in this study can be related to fractionation due to adsorption on reservoir rocks.

The progress in ultrahigh-resolution mass spectrometry (UHRMS) and related technologies has significantly promoted the development of petroleomics. The study of petroleomics has greatly broadened our knowledge of the composition of petroleum at the molecular level, especially heavy fractions that cannot be analyzed by gas chromatography (GC)-based methods. To date, heteroatom-containing (O, N, S, and metal atoms) compounds in petroleum have been studied extensively by UHRMS. Nevertheless, the main components of petroleum, hydrocarbon compounds, have remained out of reach of petroleomics characterization for a long time because they are too difficult to be softly and efficiently ionized for UHRMS analysis. It is undoubtedly the case that petroleum hydrocarbons should not be the missing part of petroleomics characterization since they play important roles not only as feeding pools for various high value-added petroleum products but also as critical biomarkers for geochemistry studies. Here, the most recent breakthroughs in petroleomics characterization of hydrocarbon compounds using UHRMS rather than conventional methods have been reviewed. Innovations of soft ionization methods can transform non-polar hydrocarbon molecules into molecular ions or quasi-molecular ions that are reachable for UHRMS without fragmentation. The development of data processing methods has assisted the decoding of the complicated UHRMS data to visualize the molecular composition and structure of hydrocarbon compounds. These advances make it possible to see the whole picture of petroleum compositions, from light distillation fractions to heavy distillation fractions, and from small volatile molecules to large non-volatile ones. The applications of UHRMS-based methods for petroleomics characterization of hydrocarbon compounds in crude oils and various petroleum samples including fuel oil, slurry, and even asphaltene have made a great contribution to petrochemistry and geochemistry studies, especially in the fields of molecular refining and biomarker discovery.

This review is devoted to the consideration of mass spectrometric platforms as applied to omics sciences. The most significant attention is paid to omics related to life sciences (genomics, proteomics, meta-bolomics, lipidomics, glycomics, plantomics, etc.). Mass spectrometric approaches to solving the problems of petroleomics, polymeromics, foodomics, humeomics, and exosomics, related to inorganic sciences, are also discussed. The review comparatively presents the advantages of various principles of separation and mass spectral techniques, complementary derivatization, used to obtain large arrays of various structural and quantitative information in the mentioned omics sciences. [ABSTRACT FROM AUTHOR]

The n-alkylcyclohexanes are poorly evaluated in biodegradation studies of Brazilian petroleum samples. In this context, this work aimed to use the homologue series of alkylcyclohexanes to assess extend of biodegradation of 26 petroleum samples from five Brazilian sedimentary basins, analyzed by gas chromatography coupled to mass spectrometry. The n-alkylcyclohexanes compounds were detected in all samples, with a distribution similar to the n-alkane profile, in which their abundance decreasing with increasing of the biodegradation extent. Based on this, it was suggested the use of the new parameter H30/DC together with the H30/AC already proposed, calculated by the ratio between C30 hopane to the dodecyl-cyclohexane, to assess biodegradation level according Peter and Moldowan scale (PM scale). In addition, it was observed an increasing in the relative abundance of DBE 2 from class O2, analyzed by ESI(-) FT-ICR MS, mainly due to the formation of monocyclic acids with biodegradation, which correlates with the decrease of n-alkylcyclohexanes, a possible precursor of these acids.

Essentially different approaches to studying oil systems (analytical, colloid-chemical, model, chemo-informational), regardless of the chronological periods of their development, are described. The analytical approach, being historically first, today, with the progress of petroleomics, becomes the source of digital data on the detailed chemical composition of oil systems, which is particularly important for the progress of the chemo-informational approach, petroinformatics. From the standpoint of systems analysis, specifically petroinformatics combines the achievements of all the other approaches, because the availability of the initial digital data on the detailed composition, obtained by petroleomics, on the parameters of the colloid-disperse structure, and on reference properties of a representative set of oil system samples gives grounds to expect that the use of chemometrics and mathematical methods of multivariate data analysis will allow reliable prediction of practically important reference properties of new oil system samples. An example of comparative processing of multivariate data for a limited sample of Russian crude oils using mathematical methods is presented. [ABSTRACT FROM AUTHOR]

Abstract The presence of acidic compounds as naphthenic acids in crude oil causes several problems for the petroleum industry, including corrosion in both upstream and downstream production processes. Based on this scenario, the main objective of this work was to investigate the removal of the acidic compound from two Brazilian heavy oils by adsorption processes using six potential adsorbents: powdered shale, activated carbon, bentonite, silica gel, powdered sandstone and powdered wood. These raw materials were previously characterized by conventional and surface analysis techniques, which show that they offer a good surface area and thermal stability. To evaluate the removal efficiency at the molecular level, the crude oil samples and the filtered oils were analyzed by negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry [ESI (-) FTICR MS]. The O2 class, which is related to the relatively high acidity of the samples, was the most abundant in both crude oil samples, moreover, this class was more retained by adsorbents. Silica gel, activated carbon and bentonite were the best adsorbents of acidic compounds from the tested oils, in agreement with their markedly higher surface area and porous volume. Additionally, a chromatographic analysis was performed and showed no changes in the oil profile.

• Convenient automated analysis in 6 min using HRMS fingerprinting. • CI-HRMS-based stepwise assignment for precise composition analysis. • Single ANN model to estimate API gravity, sulfur, and nitrogen. • Unified model evaluated parameters in crude oil and distillates simultaneously. • Independent models with R2 0.86–0.97. This article proposes an alternative approach for assessing four quality parameters of petroleum and its main products, namely API gravity, total sulfur, nitrogen content, and basic nitrogen content. Such primary measures are determined experimentally using four ASTM protocols. The proposed method is based on the use of a chemical ionization Fourier transform Orbitrap® mass spectrometer (CI-HRMS) and a multivariate model that allows for the simultaneous assessment of a broad range of parameters, regardless of the volatility of the complex sample (crude oil, diesel, gas oil, naphtha, and kerosene). The composition assignment is performed stepwise based on the analysis of the monoisotopic masses and isotope patterns to generate chemically meaningful identifications. The predominant chemical composition consisted of classes of compounds containing sulfur, nitrogen, and oxygen. The analysis time was about 6 min, due to a fast automated analysis that uses fingerprinting information to predict the features of crude oil and its derivatives. The developed Artificial Neural Network (ANN) models are independent of the volatility of the sample and can be applied to both raw petroleum and its products. The ANN models afford acceptable predictions. The values of the global coefficient of determination (R2) ranged from 0.86 to 0.97, which were calculated between predicted and reference values – obtained from ASTM methods. The four quality parameters are estimated by convenient CI-HRMS method and such measurements are demonstrated to be a viable alternative to the classic ASTM methods otherwise only available by laborious and low sample throughput experimental techniques. [ABSTRACT FROM AUTHOR]

Produced water (PW) is a type of wastewater that arises during oil and gas production. Due to its potential environmental impact, PW is one of the most closely monitored forms of wastewater in the petroleum industry. The total oil and grease (TOG) content in the water is a crucial parameter for assessing the environmental impact of PW. Traditional methods for analyzing TOG in PW can be time-consuming and may not be compatible with green chemistry principles. In this study, an alternative method for classifying PW samples is proposed using a one-class classifier (OCC) model, which has proven useful for classification problems. To achieve this goal, headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography (GC×GC) were employed to obtain TOG profiles from PW. A series of simulated PW samples containing TOG were generated using a mixture design comprising four petrochemicals at concentrations ranging from 10 mg L-1 to 50 mg L-1. The polydimethylsiloxane (PDMS) fiber showed the most representative extraction of analytes. The optimization of the HS-SPME method was performed using a Doehlert design with two variables, and the final conditions were set at 80 °C and 70 min for extraction temperature and time, respectively. A pixel-based data approach was used to implement data-driven soft independent modeling by class analogy (DD-SIMCA). Although DD-SIMCA is a developing area in GC×GC studies, the proposed model produced outstanding results with a sensitivity of 94.3 %, specificity of 95.0 %, and accuracy of 94.5 %, considering the complex and broad compositional range of the modeled mixtures. These findings demonstrated the effectiveness of the OCC model approach in classifying PW samples according to environmental regulations. [Display omitted] • Total oil and grease profiles can be utilized for the classification of produced water samples according to local resolution. • A Doehlert design with two variables is suitable for optimizing the HS-SPME method. • A pixel-based data approach, utilizing two-dimensional chromatograms for multivariate data processing. • One-class classifier models are appropriate for solving classification problems using chromatographic profiles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Plackett-Burman and full designs of experiments are used to obtain optimized spectral acquisition for petroleomics by ESI(±)FT-ICR MS; • Spectral profiles of FT-ICR MS are analyzed using a global desirability based on 12 responses; • Optimizing ESI(±) parameters reduced assays from 2,048 to 27; • Concentration and flow rate are the experimental parameters; • Collision voltage and time of flight are the most significant for ESI(-). The Fourier Transform Ion Cyclotron Resonance mass spectrometer (FT-ICR MS) is an efficient and widely used analytical instrument for characterizing complex organic mixtures at the molecular level. The Electrospray ionization (ESI) source is commonly used for identifying heteroatomic compounds (N, O, S) in crude oil. The high complexity of the sample provides a wealth of information, and therefore, processing and visualization programs are used to facilitate data interpretation. Several experimental configurations of parameters exist for the acquisition of ESI(+)FT-ICR MS and ESI(-)FT-ICR MS of crude oils. In this context, the design of experiments can help obtain optimal test conditions. The objective of this work was to identify the most significant experimental parameters among the 11 available (concentration, skimmer, time of flight (TOF), flow rate, ion accumulation time (IAT), accumulated scans (scans), dry temperature, capillary, dry gas, nebulizer, and collision voltage (CV)) for the acquisition of ESI(±)FT-ICR MS in Petroleomics using design of experiments by Plackett Burman and full design. Global desirability was used as a response parameter obtained from MS data (resolution, signal-to-noise ratio, signal-to-charge ratio signal with highest absolute intensity, total signals, low mass error, and high mass error). Additionally, responses from the mass spectra processing program were also used (the number of molecular formulas, molecular formulas of the majority class, average error, assignment percentage, amount of DBE in the plot of DBE versus carbon number (CN), and the relationship between the number of zero intensities and the number of DBE values in the plot of DBE versus CN). The study found that concentration and flow rate were the most significant experimental parameters for ESI(+), while for ESI(-), TOF and CV were the most significant experimental parameters. Lower concentration (0.1–0.5 mg/mL) and higher flowrate (5–6 µL/min) improved the desirability by ESI(+), higher values of CV (50 V) improved the desirability by ESI(-) for crude oil analysis. [ABSTRACT FROM AUTHOR]

• An unexpected wide range of alkanes from source rocks was first reported. • n-alkanes and monocyclic alkanes showed extraordinary carbon-numbered predominance. • The fresh discoveries were based on the development of HPLC-HRMS method. Carbon number predominance of n-alkanes and monocyclic alkanes reveals essential geological information such as biological source, sediment maturity, and paleoenvironmental conditions. The carbon number range of the special distribution pattern is reported to lower than C 40 , prominantly in the range of C 24 -C 34. Generally, this special distribution pattern fades away with the increase of maturity. However, these well-accepted beliefs are challenged by our investigations. In this work, C 10 -C 125 n-alkanes and monocyclic alkanes were identified for the first time in the highly mature source rock of Well Luntan-1 in Tarim Basin (China). Both series exhibited significant even carbon number predominance observed in C 50 and C 110 , but there was no carbon - number predominance observed before C 50. The similar distribution patterns of n-alkanes and monocyclic alkanes indicated that they might have the same biological precursors. The discovery of higher alkanes with ultra-long carbon chains and their extraordinary display of carbon number predominance provided us with a new perspective, which may open up the era of macromolecular biomarkers exploration. [ABSTRACT FROM AUTHOR]

Comprehensive chemical investigation of non-volatile complex mixtures, without extensive sample pretreatment, remains challenging due to the high number of constituents with different chemical properties. In past years, direct high-resolution mass spectrometry established itself as powerful technique for the detailed molecular description of ultra-complex mixtures, but was mainly used with atmospheric pressure ionization. In this study, we present a direct inlet approach with vacuum ionization and high-resolution time-of-flight mass spectrometry. Exemplary, the non-volatile fractions of crude oil were directly inserted into the ion source and volatilized under reduced pressure conditions. An applied temperature gradient enabled thermal pre-separation, according to volatility, prior to electron ionization and mass spectrometric detection. With exact mass information, peaks were assigned to elemental compositions and grouped into component classes. Moreover, the application of supervised and unsupervised statistical tools allowed differentiation of the samples on a molecular level and the identification and attribution of significant chemical features. Image 1 • Direct analysis of petroleum vacuum residues. • Thermal preseparation of non-volatile substances before mass spectrometric detection. • Discrimination of six bitumen samples according to their molecular fingerprint. • Unsupervised classification to material type and origin. • Identification of molecular markers. [ABSTRACT FROM AUTHOR]

"-Omics" is a powerful screening method with applications in molecular biology, toxicology, wildlife biology, natural product discovery, and many other fields. Genomics, proteomics, metabolomics, and lipidomics are common examples included under the "-omics" umbrella. This screening method uses combinations of untargeted, semi-targeted, and targeted analyses paired with data mining to facilitate researchers' understanding of the genome, proteins, and small organic molecules in biological systems. Recently, however, the use of "-omics" has expanded into the fields of geology, specifically petrology, and paleolimnology. Specifically, untargeted analyses stand to transform these fields as petroleomics, and sediment-"omics" become more prevalent. "-Omics" facilitates the visualization of small molecule profiles from environmental matrices (i.e. oil and sediment). Small molecule profiles can provide improved understanding of small molecules distributions throughout the environment, and how those compositions can change depending on conditions (i.e. climate change, weathering, etc.). "-Omics" also facilities discovery of next-generation biomarkers that can be used for oil source identification and as proxies for reconstructing past environmental changes. Untargeted analyses paired with data mining and multivariate statistical analyses represents a powerful suite of tools for hypothesis generation, and new method development for environmental reconstructions. Here we present an introduction to "-omics" methodology, technical terms, and examples of applications to paleolimnology and petrology. The purpose of this review is to highlight the important considerations at each step in the "-omics" workflow to produce high quality and statistically powerful data for petrological and paleolimnological applications. Unlabelled Image • "-Omics" workflow with examples relevant to sediment, soil and oil samples. • Highlight practical considerations for each step in the "-omics" workflow. • Establish quality control and standard practices for environmental "-omics". • Focus on production of reliable and statistically powerful "-omics" data. • Overview of common univariate and multivariate statistical analyses. [ABSTRACT FROM AUTHOR]

Highlights • Petroleomics of crude oils recovered from the Mero Field, Santos Basin, Brazil. • The samples were generated under a thermal condition related to the peak of the oil window (0.7–0.9%Ro). • The samples were generated by a source-rock deposited in a lacustrine environment. • ESI FT-ICR MS is a trustworthy way to achieve a geochemical assessment. Abstract Three crude oils recovered from three different wells of the Mero Field in the pre-salt of the Santos Basin were selected for detailed geochemical analysis. The samples were analyzed using a 7.2 T LTQ FT-ICR MS instrument by negative electrospray ionization (–ESI), focusing on the polar compounds, i.e., nitrogen-, sulfur-, and oxygen-containing compounds (NSO). Additionally, a combination of traditional geochemical methods including GC-FID, GC-MS, and carbon isotopic composition (whole oil and n -alkanes) were used to assess the samples. Through this work, it was demonstrated that –ESI FT-ICR MS is a reliable method for assessing crude oil composition and providing information about the origin and thermal maturity of the samples. Results showed that the dominant heteroatom classes are N 1 , O 2 , N 1 O 1 , and O 1. Due to the similarity of double bound equivalent (DBE), which means number of unsaturation present in an organic molecule, and carbon number distributions for the N 1 class species it is possible to suggest that Mero's filling history had an oil charge representing the peak of the oil window (0.7–0.9 %Ro) and that the oils were generated by a source rock deposited in a lacustrine environment. [ABSTRACT FROM AUTHOR]

Highlights • Petroleomic was applied to 69 off-shore Brazilian crude oils samples. • Kerogen type plays an important control on NSO compounds. • Clear separation based on polar species found in marine and lacustrine oils. • Negative ESI FTICR-MS can be used to perform geochemical assessment in crude oils. Abstract Lacustrine and marine crude oils from different off-shore Brazilian basins were analyzed using a 7.2 Tesla LTQ FTICR-MS instrument. The samples were analyzed via electrospray ionization in the negative ion mode focusing on the polar compounds, i.e., nitrogen-, sulfur-, and oxygen-containing (NSO) compounds. We also employed a combination of other geochemical methods, such as GC-FID and GC-MS analyses, to characterize and assess the depositional environments of the different oil families. The results indicate that lacustrine oils tend to be enriched in Nx compounds, while marine oils show preference for Ox compounds. The dominant heteroatomic classes in crude oils are N1, followed by O1, O2, and N1O1 with remarkable differences in their distributions between marine and lacustrine, strongly suggesting the control by the kerogen type of the heteroatomic compounds found in these crude oils. Considerable differences in the DBE distribution of the main classes analyzed between the crude oils allowed an efficient geochemical characterization regarding their origin. The use of negative ESI FTICR-MS as a geochemistry tool can provide additional information beyond that obtained with currently employed geochemical methods, resulting in the full comprehension of crude oil composition. [ABSTRACT FROM AUTHOR]

Sulfur-containing compounds (SCCs) are the most abundant heteroatom compounds in petroleum. The characterization of SCCs in crude oils and petroleum products has great importance not only for the downstream refining process control/optimization and environmental compliance but also for upstream geochemical studies for exploration and production. In recent years, a variety of methods to analyze SCCs have been developed and practiced where chromatography and mass spectrometry have played major roles. This review summarizes the analytical strategy and some of the most important and promising technologies, from sample pretreatment to molecular level characterization. For the convenience of discussions and practical applications, we divide the petroleum mixtures containing sulfur components into gas chromatography (GC)-amenable and nonvolatile fractions. For the former, gas chromatography (GC) and comprehensive two-dimensional gas chromatography (GC × GC) utilizing sulfur-selective detectors or mass spectrometry (GC–MS) are predominant analytical techniques. For the latter, molecular characterization is much more difficult and challenging. High performance liquid chromatography (HPLC) or direct liquid infusion and its combination with mass spectrometry (LC–MS), especially ultra-high resolution mass spectrometry, such as Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and Orbitrap MS, associated with various atmospheric ionization techniques are the most practical approaches. Some ionization techniques are underutilized, such as atmospheric pressure chemical ionization (APCI). The use of surface desorption ionization techniques, direct electrospray ionization (DSEI) and desorption atmospheric chemical ionization (DAPCI), for the molecular characterization of insoluble kerogens that has been characterized by X-ray near edge structure spectroscopy (XANES) and X-ray photoelectron spectroscopy (XPS) remain to be explored. [ABSTRACT FROM AUTHOR]

The thermal maturity level impact on polar compounds was analyzed for a suite of hydrous pyrolysis (HP) products using a 7.2 Tesla LTQ FTICR-MS instrument. The sample suite was analyzed via electrospray ionization in the negative ion mode focusing on the polar compounds, i.e., nitrogen-, sulfur-, and oxygen-containing (NSO) compounds. The HP experiments were performed under isothermal conditions for 2 h at eleven different temperatures (300, 310, 320, 325, 330, 340, 345, 350, 355, 360 and 365 °C) to simulate the full range of thermal levels starting at early bitumen generation to maximum oil generation. The maturity suite samples consist of one immature bitumen (original sample), eleven expelled oil samples and eight residual bitumen samples. In general, O x compounds are destroyed by decarboxylation and dehydration with increasing maturity; sulfur compounds decrease; the aromaticity and degree of condensation increase; and steranoic and hopanoic acids decrease. Additionally, we investigated fluid retention properties comparing the carbon number distribution between the expelled oil and residual bitumen samples from each experiment. The maturity related changes of the acidic O 2 compounds in the expelled oil samples led us to create several regressions that we propose as new maturity parameters covering the full range of oil generation. [ABSTRACT FROM AUTHOR]

Two methods of asphaltenes fractionation have been employed to facilitate the characterization of their respective subfractions. The methods are based on step-wise precipitation with different n -hexane/crude oil ratios, and on adsorption onto CaCO 3 . Three subfractions were produced for each method, being named of 3.5 V, 3.5–6 V, and 6–40 V (for the first method); and non-adsorbed (bulk), adsorbed, and irreversibly adsorbed (for the second method). The fractions were characterized by elementary analysis, nuclear magnetic resonance of proton ( 1 H NMR) and by positive ion-mode electrospray Fourier transform ion cyclotron resonance mass spectrometry (ESI(+)FT-ICR MS). The elemental analysis, described in previous work, revealed that the C/H ratio for whole asphaltene and its sub-fractions varied between a narrow range (0.83–0.88) which means they present similar aromaticity or unsaturation. Furthermore, the elemental analysis corroborates with the 1 H NMR analysis suggesting that subfraction 6–40 V presented a more aromatic profile than of remaining subfractions, while for the fractionation using CaCO 3 , this behavior was observed for the adsorbed subfraction. However, a more detailed molecular information was obtained from ESI(+)-FT-ICR MS data, showing that polar compounds species with lower carbon numbers were mainly found for the irreversibly adsorbed subfraction. Besides, the double bond equivalent (DBE) distribution is an important tool to associate the chemical information with solubility parameters, in which, a narrower DBE distribution was observed for irreversibly adsorbed (for fractionation onto CaCO 3 ) and subfraction 3.5 V (fractionation in n -hexane) samples, indicating that they are less soluble in hydrocarbons. Also, solubility parameters ( δ) were calculated from ESI(+)FT-ICR MS data, where the results indicate that subfractions produced in n -hexane have a lower tendency to precipitate in hydrocarbons in relation to subfractions produced onto CaCO 3 . [ABSTRACT FROM AUTHOR]

Heavy oil fractions studies are of great importance for the oil industry, receiving particular attention in recent decades due to interest in obtaining compounds with higher added value derived from heavy oil fractions. Moreover, these studies also aim to offer solutions to problems caused by these fractions during all oil processing steps. Asphaltenes placed in n-methylpyrrolidone (NMP) produce two fractions with distinct characteristics, soluble and insoluble in NMP (called NS and NI, respectively). In previously studies it was suggested that the NI fraction presents low content of aromatic compounds, opening a new debate on the composition of asphaltene as is widely discussed in the literature. Here, we show the deep characterization of three set of asphaltenes fractions obtained in NMP using Fourier transform ion cyclotron resonance mass spectrometry coupled to positive and negative-ions mode electrospray ionization (ESI(±)-FT-ICR MS), Fourier transform infrared spectroscopy (FTIR), molecular fluorescence and p roton nuclear magnetic resonance ( 1 H NMR) spectroscopy. FTIR, 1 H NMR and molecular fluorescence demonstrated differences among asphaltene fractions studied, in which, NS fractions exhibited a more polar and aromatic character. On the other hand, NI fractions showed nonpolar profile, being proved by the presence of high amounts of alkyl and naphthenic hydrocarbons showing high abundance of alkyl and naphthenic hydrocarbon related compounds. ESI(±)FT-ICR MS data corroborate the FTIR, 1 H NMR and molecular fluorescence data, which show NS fractions with a high proportion of heteroatomic species and higher aromaticity (higher DBE values) compared with NI fractions. [ABSTRACT FROM AUTHOR]

A method to fractionate and separate nitrogen compounds according to their carbon number is presented here. Typical Brazilian vacuum residue was submitted to solid-phase extraction using a strong cation exchanger to fractionate the basic nitrogen compounds according to their molecular weight. The method described in this paper extended vacuum residue characterization by gradually removing the most basic species that suppress the ionization of compounds with higher mass (and thus less efficiently ionized). Approximately 1393 peaks were assigned when untreated vacuum residue was directly infused into a positive-ion electrospray ionization (ESI(+)) mass spectrometer coupled to Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). In contrast, more than 3500 different nitrogenous elemental compositions were attributed after fractionation. Nitrogen compounds with carbon numbers up to C 100 were detected. Also, new classes (NO, N 2 O, and NOS) of nitrogen compounds were detected after the fractionation. [ABSTRACT FROM AUTHOR]

This study describes the development of an analytical methodology for the separation of quaternary amines using non-aqueous microchip electrophoresis (NAME) coupled with capacitively coupled contactless conductivity detection (C 4 D). All experiments were performed using a commercial microchip electrophoresis system consisting of a C 4 D detector, a high-voltage sequencer and a microfluidic platform to assemble a glass microchip with integrated sensing electrodes. The detection parameters were optimized and the best response was reached applying a 700-kHz sinusoidal wave with 14 V pp excitation voltage. The running electrolyte composition was optimized aiming to achieve the best analytical performance. The mixture containing methanol and acetonitrile at the proportion of 90:10 (v:v) as well as sodium deoxycholate provided separations of ten quaternary amines with high efficiency and baseline resolution. The separation efficiencies ranged from 8.7 × 10 4 to 3.0 × 10 5 plates/m. The proposed methodology provided linear response in the concentration range between 50 and 1000 μmol/L and limits of detection between 2 and 27 μmol/L. The analytical feasibility of the proposed methodology was tested in the determination of quaternary amines in corrosion inhibitor samples often used for coating oil pipelines. Five quaternary amines (dodecyltrimethylammonium chloride, tetradecyltrimetylammonium bromide, cetyltrimethylammonium bromide, tetraoctylammonium bromide and tetradodecylammonium bromide) were successfully detected at concentration levels from 0.07 to 6.45 mol/L. The accuracy of the developed methodology was investigated and the achieved recovery values varied from 85 to 122%. Based on the reported data, NAME-C 4 D devices exhibited great potential to provide high performance separations of hydrophobic compounds. The developed methodology can be useful for the analysis of species that usually present strong adsorption on the channel inner walls. [ABSTRACT FROM AUTHOR]

The application of atmospheric pressure ionization (API) sources in gas chromatography-mass spectrometry (GC-MS) determinations is becoming more popular since they have shown great capabilities to sort out the main drawbacks of vacuum ionization techniques like electron ionization (EI) and chemical ionization (CI). The development of new API techniques and set-ups have grown in the last decades, opening the field of GC-MS to new applications and facing some of the major issues in current analytical methodologies such as the requirement of a compromise between sensitivity and selectivity. Thus, this review is mainly focused on the use of GC-API-MS in different application fields such as food analysis (food safety and food metabolomics), environmental analysis, clinical analysis, drug and pharmaceutical analysis, and petroleomics, among others. The methodologies have been critically reviewed to compare the performance of different API sources and approaches, highlighting the main contributions to overcoming some of the major limitations of the current methodologies as well as the new perspectives that GC-API-MS might open in the different fields. [Display omitted] • GC-API-MS couplings have increased in many analytical fields. • GC-APCI is the most used coupling, especially in food safety and environmental analysis. • GC-APLI shows a great impact in petroleomics to detect aromatic compounds. • GC-API has overcome many analytical issues in clinical and drug analysis. • API and EI data combination is preferred in GC-MS non-targeted applications. [ABSTRACT FROM AUTHOR]

Photooxidation can alter the environmental fate and effects of spilled oil. To better understand this process, oil slicks were generated on seawater mesocosms and exposed to sunlight for 8 days. The molecular composition of seawater under irradiated and non-irradiated oil slicks was characterized using ion mobility spectrometry-mass spectrometry and polyaromatic hydrocarbons analyses. Biomimetic extraction was performed to quantify neutral and ionized constituents. Results show that seawater underneath irradiated oil showed significantly higher amounts of hydrocarbons with oxygen- and sulfur-containing by-products peaking by day 4–6; however, concentrations of dissolved organic carbon were similar. Biomimetic extraction indicated toxic units in irradiated mesocosms increased, mainly due to ionized components, but remained <1, suggesting limited potential for ecotoxicity. Because the experimental design mimicked important aspects of natural conditions (freshly collected seawater, natural sunlight, and relevant oil thickness and concentrations), this study improves our understanding of the effects of photooxidation during a marine oil spill. • The composition of water beneath photooxidized oil slick is not well understood. • Untargeted analysis characterized the composition of photooxidized by-products. • Sunlight increased aqueous exposures to hydrocarbons and degradation-products. • Biomimetic extraction indicated toxic units of constituents in water increased. • Even so, toxic units remained <1 indicating low potential for acute aquatic toxicity. [ABSTRACT FROM AUTHOR]

The geochemical characterization of petroleum is an essential task to develop new strategies and technologies when analyzing the commercial potential of crude oils for exploitation. Due to the chemical complexity of these samples, the use of modern analytical techniques along with multivariate exploratory data analysis approaches is an interesting strategy to extract relevant geochemical characteristics about the oils. In this work, important geochemical information obtained from crude oils from different production basins were obtained analyzing the maltene fraction of the oils by comprehensive two-dimensional gas chromatography coupled to quadrupole mass spectrometry (GC × GC–QMS), and performing multiway principal component analysis (MPCA) of the chromatographic data. The results showed that four MPC explained 93.57% of the data variance, expressing mainly the differences on the profiles of the saturated hydrocarbon fraction of the oils (C 13 -C 18 and C 19 -C 30 n -alkanes and the pristane/phytane ratio). The MPC1 grouped the samples severely biodegraded oils, while the type of the depositional paleoenvironments of the oils and its oxidation conditions (as well as their thermal maturity) could be inferred analysing others relevant MPC. Additionally, considerations about the source of the oil samples was also possible based on the overall distribution of relevant biomarkers such as the phenanthrene derivatives, tri-, tetra- and pentacyclic terpanes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Vacuum assisted extraction was used to extract naphthenic acids from produced water. • Microwave assisted methylation of acids was performed in-sample. • Group-type analysis was performed by using the accurate mass and isotope patterns. In this article, we describe the preliminary findings obtained with headspace vacuum-assisted sorbent extraction (VASE) as an alternative for sample preparation in the analysis of organic acids in produced water (PW). VASE is a headspace technique that combines the use of high-capacity sorbent traps and low-pressure conditions. Method development included extraction parameters and thermal desorption conditions. Multivariate optimization using design of experiments (DOE) was performed for variable screening and method optimization. A microwave-assisted derivatization protocol was proposed to convert the organic acids into its corresponding methyl esters (ME). The reaction was conducted in-sample prior to VASE extraction, and had the advantage of dismissing the use of organic solvents. The isolated fraction was analyzed by gas chromatography coupled to high resolution mass spectrometry (GC-HRMS). Quantitative analysis exhibited a linear range from 1 to 100 µg L-1. The reported detection limits ranged from 0.001 to 0.070 µg L-1 using the model acids. The method was successfully applied for qualitative analysis of PW samples. It was possible to detect important classes, such as hydrocarbons, oxygen- and nitrogen- containing compounds. Several NAs species with different double-bond equivalent (DBE) values and carbon numbers could be found in both samples. The greenness of the analytical method was also evaluated, exhibiting better environmental metrics when compared with traditional liquid–liquid extraction. [ABSTRACT FROM AUTHOR]

High-resolution mass spectrometry (MS) is indispensable for the molecular-level analysis of biological and environmental samples with great intra- and inter-molecular complexity. Here, we summarize developments in Fourier transform mass spectrometry (FTMS), the flagship of high-resolution MS techniques, accomplished in our laboratory. Particularly, we describe the recent and envisioned progress in structural analysis of: i) isolated large proteins and their simple mixtures, with a focus on monoclonal antibodies, via top–down, middle–down, and extended bottom–up mass spectrometry; ii) complex protein mixtures and proteomes via extended bottom–up proteomics; and iii) crude oil fractions and similar complex molecular mixtures. Despite the unequivocal success in molecular structural analysis, the demonstrated results clearly indicate that the compromise between MS acquisition speed (throughput) and achievable resolution level inhibits further advances of MS applications in the areas related to life, environmental, and material sciences. To further advance beyond state-of-the-art FTMS capabilities in these areas, we present the technique of super-resolution mass spectrometry that has been pioneered by our laboratory.