Hydrogen isotope type-curves of very hot crude oils

Several crude oil accumulations in the Pannonian Basin are trapped in uncommonly hot (>170°C) reservoirs. Their maturities range from mature to very mature on the basis of cracking parameters of their biological marker homologous series (ratio of products to reactants). A stable carbon isotopic study of these oils, poor in biological markers commonly used for correlation purposes, did not provide a reliable oil-to-oil correlation. As an alternative tool, the hydrogen isotope compositions of oil fractions separated on the basis of different polarities were measured, and hydrogen isotope type-curves were generated for a set of mature to very mature crude oil samples. This method of presenting hydrogen isotope composition of fractions as type-curves is novel. Nineteen samples (17 crude oils from SE-Hungary, 1 oil condensate and 1 artificial oil) were chosen for the present study. The aim was to examine the applicability of hydrogen isotope type-curves in oil-to-oil correlation and to test the simultaneous application of carbon and hydrogen isotope type-curves in the field of petroleum geochemistry. We have shown that, although the conventionally used co-variation plots proved to be inadequate for the correlation of these hot and mature oils, the simultaneous use of carbon and the newly introduced hydrogen isotope type-curves allows us to group and distinguish oils of different origins.     

Advances in Asymmetric Wettable Janus Materials for Oil–Water Separation

The frequent occurrence of crude oil spills and the indiscriminate discharge of oily wastewater have caused serious environmental pollution. The existing separation methods have some defects and are not suitable for complex oil–water emulsions. Therefore, the efficient separation of complex oil–water emulsions has been of great interest to researchers. Asymmetric wettable Janus materials, which can efficiently separate complex oil–water emulsions, have attracted widespread attention. This comprehensive review systematically summarizes the research progress of asymmetric wettable Janus materials for oil–water separation in the last decade, and introduces, in detail, the preparation methods of them. Specifically, the latest research results of two-dimensional Janus materials, three-dimensional Janus materials, smart responsive Janus materials, and environmentally friendly Janus materials for oil–water separation are elaborated. Finally, ongoing challenges and outlook for the future research of asymmetric wettable Janus materials are presented.     

Boron chemistry in a new light

Photocatalysis has recently opened up new avenues for the generation of radical species under visible light irradiation conditions. A particularly fascinating class of photocatalyzed transformations relies on the activation of stable boron species with visible-light since it allows the creation of boryl and/or carbon radicals through single electron transfer or energy transfer without the need for specific and costly equipment. This new paradigm has found numerous applications in synthetic organic chemistry, catalysis, and macromolecular chemistry. In this minireview, the concepts underlying photoactivation of boron-species as well as applications to the creation of C–H, C–C, C–O, B–C and B–S bond are discussed.     

Olive Oil Traceability Studies Using Inorganic and Isotopic Signatures: A Review

The olive oil industry is subject to significant fraudulent practices that can lead to serious economic implications and even affect consumer health. Therefore, many analytical strategies have been developed for olive oil’s geographic authentication, including multi-elemental and isotopic analyses. In the first part of this review, the range of multi-elemental concentrations recorded in olive oil from the main olive oil-producing countries is discussed. The compiled data from the literature indicates that the concentrations of elements are in comparable ranges overall. They can be classified into three categories, with (1) Rb and Pb well below 1 µg kg⁻¹; (2) elements such as As, B, Mn, Ni, and Sr ranging on average between 10 and 100 µg kg⁻¹; and (3) elements including Cr, Fe, and Ca ranging between 100 to 10,000 µg kg⁻¹. Various sample preparations, detection techniques, and statistical data treatments were reviewed and discussed. Results obtained through the selected analytical approaches have demonstrated a strong correlation between the multi-elemental composition of the oil and that of the soil in which the plant grew. The review next focused on the limits of olive oil authentication using the multi-elemental composition method. Finally, different methods based on isotopic signatures were compiled and critically assessed. Stable isotopes of light elements have provided acceptable segregation of oils from different origins for years already. More recently, the determination of stable isotopes of strontium has proven to be a reliable tool in determining the geographical origin of food products. The ratio ⁸⁷Sr/⁸⁶Sr is stable over time and directly related to soil geology; it merits further study and is likely to become part of the standard tool kit for olive oil origin determination, along with a combination of different isotopic approaches and multi-elemental composition.     

Stable isotope variation as a tool to trace the authenticity of beef

Organic beef coming principally from Germany was analysed for the hydrogen, carbon, oxygen, nitrogen and sulfur stable isotopic composition to test the possibility of tracing back the geographical origin. Since there is a well-known pattern of D/H and ¹⁸O/¹⁶O in meteoric water and in ground water, there is an existing link to tissue water in the beef. By including the stable isotope ratios of the other elements of life further information is available: soils show different isotope ratios of ¹⁵N/¹⁴N and ³⁴S/³²S depending on the geological composition, cultivation and atmospheric sulfur deposition. As organic farming is mainly obliged to use only their produced fodder, that ratio is reflected in the beef as well.Different organic beef samples from various German farms have been collected and analysed over nearly two years. To check the differentiation of foreign beef, samples from Argentina and Chile were also included in the study. The analyses of meat samples indicate that it is possible to trace back the region (e.g. Argentina and Germany) by using isotopes of oxygen and hydrogen. A local geographical differentiation can be done by using the stable isotopes of nitrogen and sulfur, as was demonstrated for three farms in Colonia Bay. An optimal differentiation also depends on the quality of further information (e.g. the season, kind of cattle breeding or the declaration of the local geographical origin). Certainly authenticity of beef is not only linked with the geographical origin but can also reflect the differentiation of organic and conventional farming. The fodder of organic cattle farming consists mainly of C₃ plants and the use of C₄ plants is more usual in conventional cattle farming. A ¹³C/¹²C ratio above –20 appears as a limit for organic farming. Increased values have to be controlled based on their authenticity.     

原油与沉积物中的二苯并噻吩系列化合物的GC-MS分析及其在有机地球化学中的应用

近年来,人们对原油和沉积物中二苯并噻吩类化合物进行了广泛研究,认识到该类化合物蕴藏着丰富的地质-地球化学信息,尤其在油/源和油/油对比、烃源岩和原油成熟度确定以及烃源岩沉积环境特征探讨等方面展示了广阔的应用前景。色谱-质谱技术为二苯并噻吩类化合物研究提供了良好的     

Determination of mercury in SRM crude oils and refined products by isotope dilution cold vapor ICP-MS using closed-system combustion

Mercury was determined by isotope dilution cold-vapor inductively coupled plasma mass spectrometry (ID-CV-ICP-MS) in four different liquid petroleum SRMs. Samples of approximately 0.3 g were spiked with stable (201)Hg and wet ashed in a closed system (Carius tube) using 6 g of high-purity nitric acid. Three different types of commercial oils were measured: two Texas crude oils, SRM 2721 (41.7+/-5.7 pg g(-1)) and SRM 2722 (129+/-13 pg g(-1)), a low-sulfur diesel fuel, SRM 2724b (34+/-26 pg g(-1)), and a low-sulfur residual fuel oil, SRM 1619b (3.5+/-0.74 ng g(-1)) (mean value and 95% CI). The Hg values for the crude oils and the diesel fuel are the lowest values ever reported for these matrices. The method detection limit, which is ultimately limited by method blank uncertainty, is approximately 10 pg g(-1) for a 0.3 g sample. Accurate Hg measurements in petroleum products are needed to assess the contribution to the global Hg cycle and may be needed in the near future to comply with reporting regulations for toxic elements.     

Inductively coupled plasma-mass spectrometry: Capabilities and applications

Researchers in the field of trace elements analysis are continuously in search of new instrumental solutions for obtaining better results in terms of analysis speed, precision, accuracy, detection power, and applicability to a wider range of analytical problems. One of the more recent innovations in this field is the inductively coupled plasma (ICP) source coupled with a mass spectrometry (MS). An ICP-MS system consists of an ICP torch which ionizes the species present and a mass spectrometer for the separation under vacuum of the different species. The main advantages of this technique with respect to graphite furnace atomic absorption spectrometry (GFAAS) and to ICP atomic emission spectrometry (ICP-AES) are: (a) detection limits better than those obtained with graphite furnace, i.e., down to the ng g⁻¹ level, due to the high sensitivity of the channel electron multiplier, which transforms the mass of each ion into an electric signal; (b) the possibility of detecting refractory elements, lanthanides, and all the other elements including halogens, C, and S; (c) high analysis speed (up to 90 elements in 5 min) due to the velocity of the quadrupole mass spectrometer in selecting different masses with respect to the speed necessary to scan different wavelengths; (d) spectral simplicity, because spectra have peaks only at the mass of each isotope and all elements have at least one isotope free from spectral overlap of other analytes; (e) capability of determining individual isotopes of each element. The instrument, therefore, allows not only quantitative elemental analyses to be carried out, but also semiquantitative assays of all the elements present and isotopic ratio analyses to determine quantitatively two or more isotopes of the same element. The most interesting application fields of this technique are in environmental chemistry, geochemistry, oil chemistry, technology of semiconductors, and biochemistry.     

Essential Oil Composition and Stable Isotope Profile of Cultivated Ocimum campechianum Mill. (Lamiaceae) from Peru

Ocimum campechianum Mill. (Peruvian basil) is an essential oil-bearing plant of the Lamiaceae family. Volatile oil produced through steam distillation of Peruvian basil was examined to establish the aromatic and stable isotope profiles of samples (n = 9) from three different cultivated plots in Peru. The resulting essential oils were analyzed by GC/FID, GC/MS, and GC/IRMS. In accordance with findings from other researchers, multiple chemotypes, defined by the most abundant aromatic compounds, exist within these populations. Overall, 55% of samples are the eugenol chemotype (values ranging 15.4–30.2%), 33% are the methyl eugenol chemotype (values ranging 68.1–68.7%), and a single sample is a mixture of both chemotypes, containing high levels of both eugenol (38.1%) and methyl eugenol (8.6%). Stable isotope ratios, δ²H and δ¹³C, performed on prominent compounds provide supporting data for distinguishing chemotypes. Complete aromatic profiles, stable isotope ratios, and essential oil yield are established for each sample. This study confirms the existence of multiple chemotypes and, for the first time, to the author’s best knowledge, establishes stable isotope ratios for O. campechianum essential oil, which proves a useful tool in further investigating plant metabolism and determining essential oil authenticity.     

Ceramic boron carbonitrides for unlocking organic halides with visible light

Photochemistry provides a sustainable pathway for organic transformations by inducing radical intermediates from substrates through electron transfer process. However, progress is limited by heterogeneous photocatalysts that are required to be efficient, stable, and inexpensive for long-term operation with easy recyclability and product separation. Here, we report that boron carbonitride (BCN) ceramics are such a system and can reduce organic halides, including (het)aryl and alkyl halides, with visible light irradiation. Cross-coupling of halides to afford new C–H, C–C, and C–S bonds can proceed at ambient reaction conditions. Hydrogen, (het)aryl, and sulfonyl groups were introduced into the arenes and heteroarenes at the designed positions by means of mesolytic C–X (carbon–halogen) bond cleavage in the absence of any metal-based catalysts or ligands. BCN can be used not only for half reactions, like reduction reactions with a sacrificial agent, but also redox reactions through oxidative and reductive interfacial electron transfer. The BCN photocatalyst shows tolerance to different substituents and conserved activity after five recycles. The apparent metal-free system opens new opportunities for a wide range of organic catalysts using light energy and sustainable materials, which are metal-free, inexpensive and stable.

A metal-free photoredox system was introduced for the transformation of organic halides to afford C–H, C–C, and C–S bonds without the addition of any metals, ligands, extra reductants or additives.     

Stable isotopes and the international system of units

It is now over 60 years since Nier built the first isotope ratio mass spectrometer. The introduction of continuous-flow techniques heralded a huge expansion in the use of stable isotopes in biomedical and environmental sciences, yet there is no consensus on the appropriate units, especially in the biomedical field. Most isotope ratio mass spectrometry (IRMS) instruments calculate isotopic abundance in terms of delta notation (delta, per thousand, per mil), which is a convention determined by geochemistry, because most of the original IRMS instruments were developed in isotope geochemistry laboratories to measure natural abundance variations. Delta units are not SI units. This paper considers the appropriate units for studies using stable isotopes based on the International System of Units (SI). The SI base unit for concentration is the mol, from which atom fraction and mol fraction are derived. The units of stable isotope abundance, atom % and mol %, are the atom and mol fractions expressed as percentages. Atom % excess and mol % excess are the SI units of enrichment and are to be recommended for use in tracer studies.     

碳稳定同位素比质谱法对中东原油的鉴别

采用气相色谱/稳定同位素比质谱法(GC/IRMS)对具有相似化学特征的科威特、阿联酋、沙特以及伊拉克产的原油中正构烷烃(n-C10～n-C24)的碳稳定同位素比δ(13C/12C)进行了分析,通过原油单体烃分布趋势对比、主成分归类、同位素比值与诊断比例(Diagnostic ratio,DR)联用等方法对4种原油进行了鉴别。结果表明,沙特与伊拉克所产原油、科威特与阿联酋所产原油的单体烃分布趋势相似,且主成分相近,采用同位素比值与诊断比例联用法成功地对它们进行溯源。结果表明,沙特与伊拉克所产原油的δ(13C/12C)值以及DR(n-C17/pristane(Pr)、n-C18/phytane(Ph)、Pr/Ph)相近,说明它们具有相同的母质类型及沉积环境,属于同一种原油;科威特与阿联酋所产原油的δ(13C/12C)值相似,而DR明显不同,表明其母质类型及成熟度不同,属于不同种原油。本研究所采用的分析技术也适用于其它原油的溯源研究。     

Determination of the uncertainties in the theoretical mass isotopomer distribution of molecules

A procedure for the determination of the uncertainties in the theoretical mass isotopomer distribution of molecules due to natural variations in the isotope composition of their constituting elements is described here for the first time. For this purpose, a Visual Basic macro for Microsoft Excel was written by adapting the direct stepwise calculation algorithm published by Kubinyi (Anal. Chim. Acta 1991, 247, 107-119, [11] Fig. 1). In our procedure no pruning threshold factors were used to eliminate round up errors for large molecules. Then, the Kragten [13] procedure of uncertainty propagation (Analyst 1994, 119, 2161-2165) was applied taking into account the correlation coefficients between the isotope abundances of the corresponding atoms. For bi-isotopic elements (C, H, N, Cl, Br) the correlation coefficients were given the value of −1. For tri- and tetra-isotopic elements the correlation coefficients were calculated using the mass dependent fractionation law used in stable isotope geochemistry and values of +1 or −1 were obtained depending on the isotope system considered. It was observed that for small organic molecules of natural isotope abundances, such as phenol or polybrominated diphenylethers, the method provided relatively small propagated uncertainties similar in magnitude to those measured experimentally. For ¹³C-labelled molecules the calculated uncertainties were mainly due to the uncertainties in the isotope enrichment of ¹³C and were much larger than the experimental uncertainties. For large molecules of natural isotope abundances, such as peptide C₆₈H₁₀₇N₁₇O₂₅ (NIST 8327 RM), the uncertainties in their mass isotopomer distributions were much larger and their source could be assigned mainly to the uncertainty of the natural isotope composition of carbon. When the size of the molecule was even larger, such as bovine insulin (C₂₅₄H₃₇₇N₆₅O₇₅S₆), Kragten procedure provided a good estimate for the uncertainty when the most probable isotope composition of carbon in mammals was used in the calculations.     

The role of analytical chemistry in Niger Delta petroleum exploration: A review

Petroleum and organic matter from which the petroleum is derived are composed of organic compounds with some trace elements. These compounds give an insight into the origin, thermal maturity and paleoenvironmental history of petroleum, which are essential elements in petroleum exploration. The main tool to acquire the geochemical data is analytical techniques. Due to progress in the development of new analytical techniques, many hitherto petroleum exploration problems have been resolved. Analytical chemistry has played a significant role in the development of petroleum resources of Niger Delta. Various analytical techniques that have aided the success of petroleum exploration in the Niger Delta are discussed. The analytical techniques that have helped to understand the petroleum system of the basin are also described. Recent and emerging analytical methodologies including green analytical methods as applicable to petroleum exploration particularly Niger Delta petroleum province are discussed in this paper. Analytical chemistry is an invaluable tool in finding the Niger Delta oils.     

Stable Carbon Isotope Analysis of Hexachlorocyclohexanes by Liquid–Liquid Extraction Gas Chromatography Isotope Ratio Mass Spectrometry: Method Evaluation and Applications

Compound specific isotope analysis (CSIA) and enantiomer specific isotope analysis (ESIA) are powerful tools for assessing the fate of hexachlorocyclohexanes (HCHs) in the environment. However, there is no systematic study on the CSIA and ESIA analysis test methods of the carbon isotopes of HCHs in water and soil environments, in particular the isotope fractionation in the pre-concentration process. We endeavored to test the compatibility of CSIA and ESIA with the liquid–liquid extraction method of HCHs in water. The results showed that there were negligible changes in the δ¹³C of HCHs after extraction, indicating that liquid–liquid extraction can be used as a pre-concentration method for the determination of δ¹³C of HCHs in water. The optimized method was validated and then applied to differentiate three HCHs from different manufacturers, to identify in situ degradation of HCHs of groundwater from a contaminated site and to resolve the carbon isotope fractionation occurring in the α-HCH oxidation by CaO₂/Fe(II) Fenton system. The results showed that the same reagents from different manufacturers have different carbon isotope compositions, and different isomers from the same manufacturer also have different isotope compositions, showing useful evidence in identifying the source of HCHs. The more enriched δ¹³C in the down-gradient wells indicated that HCHs have undergone biodegradation or/and chemical reactions in the groundwater system of the site. Carbon isotopic enrichment factors (ε_C) of −1.90 ± 0.10‰ were obtained in the oxidation process. Hence, the method validated in this study has great potential as a method for identifying the degradation of HCHs in a water environment.     

A novel online approach to the determination of isotopic ratios for organically bound chlorine, bromine and sulphur

A novel approach for the measurement of (37)Cl, (81)Br and (34)S in organic compounds containing chlorine, bromine, and sulphur is presented to overcome some of the major drawbacks of existing methods. Contemporary methods either require reference materials with the exact molecular compositions of the substances to be tested, or necessitate several laborious offline procedures prior to isotope analysis. In our online setup, organic compounds are separated by gas chromatography (GC) coupled to a high-temperature reactor. Using hydrogen as a makeup gas, the reactor achieves quantitative conversion of chlorinated, brominated and sulphurated organic compounds into gaseous hydrogen chloride (HCl), hydrogen bromide (HBr), and hydrogen sulphide (H(2)S), respectively. In this study, the GC interface was coupled to a quadrupole mass spectrometer operated in single-ion mode. The ion traces of either H(35)Cl (m/z 36) and H(37)Cl (m/z 38), H(79)Br (m/z 80) and H(81)Br (m/z 82), or H(2)(32)S (m/z 34) and H(2)(34)S (m/z 36), were recorded to determine the isotopic ratios of chlorine, bromine, and sulphur isotopes. The conversion interface presented here provides a basis for a novel method for compound-specific isotope analysis of halogenated and sulphur-containing compounds. Rapid online measurements of organic chlorine-, bromine- and sulphur-containing mixtures will facilitate the isotopic analysis of compounds containing these elements, and broaden their usage in fields of environmental forensics employing isotopic concepts.     

Heavy element stable isotope ratios : analytical approaches and applications

Continuous developments in inorganic mass spectrometry techniques, including a combination of an inductively coupled plasma ion source and a magnetic sector-based mass spectrometer equipped with a multiple-collector array, have revolutionized the precision of isotope ratio measurements, and applications of inorganic mass spectrometry for biochemistry, geochemistry, and marine chemistry are beginning to appear on the horizon. Series of pioneering studies have revealed that natural stable isotope fractionations of many elements heavier than S (e.g., Fe, Cu, Zn, Sr, Ce, Nd, Mo, Cd, W, Tl, and U) are common on Earth, and it had been widely recognized that most physicochemical reactions or biochemical processes induce mass-dependent isotope fractionation. The variations in isotope ratios of the heavy elements can provide new insights into past and present biochemical and geochemical processes. To achieve this, the analytical community is actively solving problems such as spectral interference, mass discrimination drift, chemical separation and purification, and reduction of the contamination of analytes. This article describes data calibration and standardization protocols to allow interlaboratory comparisons or to maintain traceability of data, and basic principles of isotope fractionation in nature, together with high-selectivity and high-yield chemical separation and purification techniques for stable isotope studies.

Nuclear-physical methods of analysis in oil geology and industry of Kazakstan

Methods and results of elemental analysis of hydrocarbons performed by nuclear-physical methods are presented. It is shown that activation analysis (AA), X-ray fluorescent (XRF) analysis and atomic-emission spectroscopy with inductively-coupled plasma (AES-ISP) allow determination of up to 30 elements in oils and bitumens and up to 40 elements in petroleum cokes, in oil-bitumen rocks, in oil and coal shales. Presented are the results of scientific and practical applications of the developed techniques.     

SPORES AND POLLEN IN CRUDE OILS AND PETROLEUM SOURCE OF TARIM BASIN

One hundred and forty-seven species of spores and pollen referred to 77 genera found in the crudeoil samples taken from four petroliferous provinces of the Tarim Basin of Xinjiang Provincehave been studied in this paper. By means of these spore and pollen fossils, the geological ages anddistribution of the petroleum source rocks of the basin are judged. Also, the principles and methodsto judge the petroleum source of a petroleum province by spore/pollen and other microfossils in crudeoils are explained.     

Screening and Demulsification Mechanism of Fluorinated Demulsifier Based on Molecular Dynamics Simulation

In order to solve the problem of demulsification difficulties in Liaohe Oilfield, 24 kinds of demulsifiers were screened by using the interface generation energy (IFE) module in the molecular dynamics simulation software Materials Studio to determine the ability of demulsifier molecules to reduce the total energy of the oil–water interface after entering the oil–water interface. Neural network analysis (NNA) and genetic function approximation (GFA) were used as technical means to predict the demulsification effect of the Liaohe crude oil demulsifier. The simulation results show that the SDJ9927 demulsifier with ethylene oxide (EO) and propylene oxide (PO) values of 21 (EO) and 44 (PO) reduced the total energy and interfacial tension of the oil–water interface to the greatest extent, and the interfacial formation energy reached −640.48 Kcal/mol. NNA predicted that the water removal amount of the SDJ9927 demulsifier was 7.21 mL, with an overall error of less than 1.83. GFA predicted that the water removal amount of the SDJ9927 demulsifier was 7.41mL, with an overall error of less than 0.9. The predicted results are consistent with the experimental screening results. SDJ9927 had the highest water removal rate and the best demulsification effect. NNA and GFA had high correlation coefficients, and their R²s were 0.802 and 0.861, respectively. The higher R² was, the more accurate the prediction accuracy was. Finally, the demulsification mechanism of the interfacial film breaking due to the collision of fluorinated polyether demulsifiers was studied. It was found that the carbon–fluorine chain had high surface activity and high stability, which could protect the carbon–carbon bond in the demulsifier molecules to ensure that there was no re-emulsion due to the stirring external force.