Extraction Refining of Heavy Vacuum Gas Oil

Selective refining of heavy vacuum gas oil and a combined fraction of light and heavy vacuum gas oils to remove aromatic and organoelement compounds and heavy metals by five-step countercurrent extraction with N-methylpyrrolidone or dimethylacetamide in the presence of heptane containing 1 wt % toluene was studied.     

Application of solid‐phase microextraction to the determination of polycyclic aromatic sulfur heterocycles in Bohai Sea crude oils

A simple and rapid solid‐phase microextraction approach for the isolation of polycyclic aromatic sulfur heterocycles from the aromatic fraction of crude oil is described. 8‐Hydroxyquinoline silica gel impregnated with palladium chloride was used as a sorbent material for extraction. Operational parameters of the extraction solvents have been evaluated and optimized. Benzothiophene, dibenzothiophene, and benzo[b]naphtho[1,2‐d]thiophene and their C₁–C₄ alkyl derivatives were identified and quantified by GC–MS. Under optimum conditions, the limits of detection for benzothiophene, dibenzothiophene, and benzo[b]naphtho[1,2‐d]thiophene were 0.277, 0.193, and 0.597 μg/g oil, respectively. The recoveries for the polycyclic aromatic sulfur heterocycles ranged from 81.5 to 92.1%, and the linear dynamic range was from 10 to 1000 ng/mL. The developed methodology was tested in the characterization of crude oil samples collected at the DY, SZ, ZH, and HC petroleum oil fields of the Bohai Sea. The results proved that SPE coupled with GC–MS is a promising tool for the quantitative analysis of polycyclic aromatic sulfur heterocycles in crude oils, especially for oil samples with low concentrations of polycyclic aromatic sulfur heterocycles.     

Determination of organic acids and ketones in contaminated soils

Hydrocarbons and metabolites from biodegradation in soil have been isolated and separated using Soxhlet extraction, with n-heptane and dichloromethane, combined with solid-phase extraction on silica gel and basic aluminum oxide using n-pentane, dichloromethane, methanol, and sulfuric acid – methanol as eluents. This procedure can be used for determination of metabolites both in laboratory-prepared soil samples containing mineral oils and in actual contaminated soil. After microbiological degradation, organic acids and ketones which were not original components of the diesel fuel and lubricating oil contaminating the soil samples were identified using capillary gas chromatography – mass spectrometry in batch-soil experiments. Predominantly alicyclic and branched-chain aliphatic organic acids and diacids, and aromatic ketones, were found to be formed after a few weeks degradation.     

Extraction Refining of Light Vacuum Gas Oil

Highly selective refining of light vacuum gas oil by five-step countercurrent extraction of aromatic and heteroatomic compounds with N-methylpyrrolidone or dimethylacetamide in the presence of low-boiling nonpolar solvents was studied. The resulting refined oil can be used as high-quality raw material in hydrocracking and catalytic cracking.     

Structural determination by atmospheric pressure photoionization tandem mass spectrometry of some compounds isolated from the SARA fractions obtained from bitumen

We have identified compounds obtained from the SARA fractions of bitumen by using atmospheric pressure photoionization mass spectrometry and low‐energy collision tandem mass spectrometric analyses with a QqToF‐MS/MS hybrid instrument. The identified compounds were isolated from the maltene saturated oil and the aromatic fractions of the SARA components of a bitumen. The QqToF instrument had sufficient mass resolution to provide accurate molecular weight information and to enhance the tandem mass spectrometry results. The APPI‐QqToF‐MS analysis of the separated compounds showed a series of protonated molecules [M + H]⁺ and molecular ions [M]^+? of the same mass but having different chemical structures, in the maltene saturated oil and the aromatic SARA fractions. These isobaric ions were a molecular ion [M₂]^+? at m/z 418.2787 and a protonated molecule [M₅ + H]⁺ at m/z 287.1625 in the saturated oil fraction, and molecular ions [M₆]^+? at m/z 418.1584 and [M₇]^+? at m/z 287.1285 in the aromatic fraction. The identification of this series of chemical compounds was achieved by performing CID‐MS/MS analyses of the molecular ions [M]^+? ([M₁]^+? at m/z 446. 2980, [M₂]^+? at m/z 418.2787, [M₃]^+? at m/z 360.3350 and [M₄]^+? at m/z 346.2095) in the saturated oil fraction and of the [M₅ + H]⁺ ion at m/z 287.1625 also in the saturated oil fraction. The observed CID‐MS/MS fragmentation differences were explained by proposed different breakdown processes of the precursor ions. The presented tandem mass spectrometric study shows the capability of MS/MS experiments to differentiate between different classes of chemical compounds of the SARA components of bitumen and to explain the reasons for the observed mass spectrometric differences. However, greater mass resolution than that provided by the QqToF‐MS/MS instrument would be required for the analysis of the asphaltene fraction of bitumen. Copyright © 2011 John Wiley & Sons, Ltd.     

Preparation of Transformer Oil Body by Extraction Refining of 300-500°C Fraction of Low-Paraffinicity Oil

A raffinate meeting the requirements for the transformer oil body was obtained from the 300-350°C fraction of low-paraffinicity oil by five-step countercurrent extraction of aromatic hydrocarbons and organoelement compounds with aqueous methyl Cellosolve in the presence of pentane.     

Computerized GC/MS detection of monoaromatic and triaromatic steroid hydrocarbons in Alamein crude oil

Series of C-ring monoaromatic steroid hydrocarbons (C₂₁, C₂₂, C₂₇ ? C₂₉) and triaromatic steroid hydrocarbons (C₂₀, C₂₁, C₂₆ ? C₂₈) have been recognized in the aromatic hydrocarbon fraction of Alamein crude oil from the western desert, Egypt. Detection of these compounds were based on mass fragmentography of the key ions m/z 253 and m/z 231 and comparison of the mass spectra and relative retention times with literature data. The predominance of the C₂₉ monoaromatic steroids and C₂₈ triaromatic steroids provide further evidence for a land plant origin of Alamein oil. The results substantiate previous evidence of the occurrence of an aromatization process with increasing maturation and indicate a moderate maturity level for Alamein oil.     

Determination of wear metals in lubricating oils by flame atomic absorption spectrophotometry

A simple, rapid and reliable method was developed for the determination of copper, nickel, iron and lead in fresh and used lubricating oil samples by flame atomic absorption spectrophotometry (FAAS). In the present study, a mixture of organic solvents containing propionic acid and iso-butylmethyl ketone (1: 1) was used to extract the metals from lubricating oil samples followed by FAAS analysis. Aqueous standard solutions can be easily employed with the proposed mixed solvent system instead of organometallic standards. The analytical results obtained by employing the proposed solvent extraction system were found to be in good agreement with the results for aqueous media obtained after the destruction of oil samples matrix. Percentage recovery studies showed 88–98% for Cu, 92–95% for Fe, 96–106% for Ni and 84–100% for Pb with relative standard deviation of 2–6%. The developed method was effectively applied to routine determination of Cu, Ni, Fe, and Pb in lubricating oil samples.     

The development of a method for the qualitative and quantitative determination of petroleum hydrocarbon components using thin-layer chromatography with flame ionization detection

An analytical scheme to determine groups of petroleum hydrocarbon compounds in crude oil was developed and used for the qualitative and quantitative characterization of crude oil samples from the Shengli oilfield, the second largest oilfield in China. Crude oil samples were fractionated and analyzed by thin-layer chromatography with flame ionization detection (TLC-FID). Relative standard deviation (RSD) values for retention time, peak height and half peak width were less than 5.2% for all classes of compounds, based on nine independent replicates. The crude oil light fraction was further analyzed by GC–MS and the majority of identified compounds were methyl- or hydro-derivatives of long-chain hydrocarbons and aromatic compounds. The external standard method used in the present study can lower detection limits of petroleum hydrocarbon compound classes to 20.0 mg L⁻¹, and the crude oil concentration in the range of 30 and 35,000 mg L⁻¹ has a high linear correlation (r² > 0.97, P < 0.05) with peak area. A comparison between elution chromatography (EC) and TLC-FID regarding the recovery of petroleum hydrocarbon compounds was carried out with aged crude oil contaminated soils of 50, 80, 200 and 300 mg g⁻¹. The tested TLC-FID method showed a 10% higher recovery for total extractable materials than the reference EC method. The calibration factor was fraction-dependent and varied with the recovery rate of TLC/EC. Regarding the tested extraction procedures, accelerated solvent extraction (ASE) had a higher extraction efficiency for crude oil contaminated soils than Soxhlet and ultrasonic extractions.     

Impact of gas chromatography and mass spectrometry combined with gas chromatography and olfactometry for the sex differentiation of Baccharis articulata by the analysis of volatile compounds

The Baccharis genus has more than 400 species of aromatic plants. However, only approximately 50 species have been studied in oil composition to date. From these studies, very few take into consideration differences between male and female plants, which is a significant and distinctive factor in Baccharis in the Asteraceae family. Baccharis articulata is a common shrub that grows wild in south Brazil, northern and central Argentina, Bolivia, Paraguay and Uruguay. It is considered to be a medicinal plant and is employed in traditional medicine. We report B. articulata male and female volatile composition obtained by simultaneous distillation–extraction technique and analyzed by gas chromatography with mass spectrometry. Also, an assessment of aromatic differences between volatile extracts was evaluated by gas chromatography with olfactometry. The results show a very similar chemical composition between male and female extracts, with a high proportion of terpene compounds of which β‐pinene, limonene and germacrene D are the main components. Despite the chemical similarity, great differences in aromatic profile were found: male plant samples exhibited the strongest odorants in number and intensity of aromatic attributes. These differences explain field observations which indicate differences between male and female flower aroma, and might be of ecological significance in the attraction of pollinating insects.     

Methodology for Bioassay-Directed Fractionation Studies of Air Particulate Material and Other Complex Environmental Matrices

Abstract

A normal phase HPLC methodology using a semi-preparative polyaminocyano column in conjunction with a selection of short-term genotoxicity assays has been developed for bioassay-directed fractionation studies of complex environmental mixtures. To illustrate the effectiveness of this methodology, an organic extract prepared from respirable air particulate samples collected in Hamilton, Canada was separated into a non-polar aromatic fraction and a polar aromatic fraction using a combination of alumina and Sephadex LH20 chromatography. These fractions were evaluated for their genotoxic potential using the Salmonella/microsome (Ames) assay with six different strains of Salmonella.

The non-polar aromatic fraction was analyzed by normal phase HPLC and the eluent was collected in one-minute subfractions; these subtractions were bioassayed in three different Salmonella strains (YG1021 -S9, YG1024 -S9 and YG1029 +S9) to afford three different mutation profiles of this sample. Some subfractions which exhibited high mutagenic responses were subjected to further chemical analyses using GC/MS in order to identify those compounds responsible for the genotoxic responses. The nitroarene compounds 2-nitrofluoranthene, 1-nitropyrene and 2-nitropyrene and higher molecular weight polycyclic aromatic hydrocarbons such as benzo[a]pyrene and indeno[l,2,3-cd]pyrene were identified and quantified in some of the biologically active subfractions. The normal phase gradient conditions afforded very reproducible retention times for a series of polycyclic aromatic standards with a broad range of compound polarities. In addition, polycyclic aromatic hydrocarbons (PAH) were observed to elute from the normal phase HPLC column in a series of peaks; successive peaks contained PAH of increasing molecular weight while any individual peak was shown to contain PAH of the same molecular weight.     

Viscosity modification of lubricating oil based on high-concentration silica nanoparticle colloidal system

In this study, colloidal systems with SiO₂ nanoparticle as viscosity modifier additive were synthesized in the lubricating oil via an in situ Stober sol-gel method. The fluid characters of lubricating oil and viscosity variation were carefully investigated via rheological methods. The results showed that the lubricating oil transformed from Newtonian fluid to non-Newtonian fluid with increasing the concentration of nanoparticles, and smaller particles displayed better thickening effect toward lubricating oil. For the system with highly concentrated nanoparticle (20?wt%), the rheological behavior mainly depends on the size of nano-SiO₂. The lubricating oil with smaller nano-SiO₂ particles displayed higher structural strength and response rate, resulting in good recoverability after high-speed shear. The viscosity changed with temperature and also displayed a thermo-responsive behavior, which significantly alleviated the effect of shear thinning on the viscosity under high temperature. This study presented a new strategy for effectively tuning the fluid characters and modifying the viscosity of lubricating oils by adding highly concentrated inorganic nanoparticles.     

Application of mesoporous carbon as a solid‐phase microextraction fiber coating for the extraction of volatile aromatic compounds

A mesoporous carbon was fabricated using MCM‐41 as a template and sucrose as a carbon source. The carbon material was coated on stainless‐steel wires by using the sol–gel technique. The prepared solid‐phase microextraction fiber was used for the extraction of five volatile aromatic compounds (chlorobenzene, ethylbenzene, o‐xylene, bromobenzene, and 4‐chlorotoluene) from tea beverage samples (red tea and green tea) prior to gas chromatography with mass spectrometric detection. The main experimental parameters affecting the extraction of the volatile aromatic compounds by the fiber, including the extraction time, sample volume, extraction temperature, salt addition, and desorption conditions, were investigated. The linearity was observed in the range from 0.1 to 10.0 μg/L with the correlation coefficients (r) ranging from 0.9923 to 0.9982 and the limits of detection were less than 10.0 ng/L. The recoveries of the volatile aromatic compounds by the method from tea beverage samples at spiking levels of 1.0 and 10.0 μg/L ranged from 73.1 to 99.1%.     

Combination of ultrasonic extraction and stripping analysis: an effective and reliable way for the determination of Cu and Pb in lubricating oils

The determination of metals in lubricating oil has been used as an important way to prevent components failures, to provide environmental information and in some cases, to identify adulteration. In this work, an effective and simple procedure is proposed for Cu and Pb determination in lubricating oils. An ultrasonic bath was employed for extraction of these elements from oil samples in a mixture 1:1 (v/v) of concentrated HCl and H₂O₂. A very efficient extraction of Cu and Pb (∼100%) was attained after 30 min of ultrasound, allowing the simultaneous determination of both metals using square-wave anodic stripping voltammetry at thin-film gold electrodes. The extraction procedure was performed in 4 mL polypropylene closed vessels and dozens of samples could be treated simultaneously in the same ultrasonic bath. The regions of the ultrasonic bath, where the maximum efficiency of extraction was attained were evaluated. Over the optimized region, 30 samples can be treated simultaneously. Used lubricating oils from automotive engines were analyzed by using the optimized extraction procedure.     

Efficient Extractive Desulfurization of Fuel Oils Using N‐Pyrrolidone/Alkylphosphate‐Based Ionic Liquids

Four BrØsted acid ionic liquids (ILS) [MMP][DMP], [MEP][DEP], [HMP][DMP] and [HEP][DEP] were synthesized and used as extractants for desulfurization of aromatic sulfur compounds in model oil. The mutual solubility of four ILs were investigated. The extraction equilibrium of four ILs could be reached in as soon as 5 min and the extraction capability followed the order [MMP][DMP]>[MEP][DEP]>[HEP][DEP]>[HMP][DMP]. The S extraction showed the highest efficiency under the conditions of 30°C, 30 min and 1:1 (V/V) IL:oil. Under the optimal condition, 70.9% of thiophene (TS), 76.9% of benzothiophene (BT) and 87.5% of dibenzothiophene (DBT) in n‐octane could be efficiently removed by [MMP][DMP]. The multiple extraction and regeneration performance of [MMP][DMP] for TS was also investigated and the results were satisfying. These results suggest that [MMP][DMP] has the best extraction capability and can serve as a promising solvent for extractive desulfurization of fuel oils.     

Molecular characterization of organically-bound sulfur in crude oils. A feasibility study for the application of Raney Ni desulfurization as a new method to characterize crude oils

Five crude oils with varying sulfur contents (0.1 – 4.7%) were characterized on a molecular level for organically-bound sulfur. Aromatic fractions were analyzed by GC-(MS) and asphaltene and polar fractions were analyzed by flash pyrolysis-GC-(MS). The polar fractions were also desulfurized with Raney Ni and the hydrocarbons formed were analyzed by GC-MS. Major sulfur compounds in the aromatic fractions were identified as alkylbenzo- and alkyldiben-zothiophenes. The flash pyrolyzates of the asphaltene contained alkylthiophenes and alkylbenzothiophenes as major compounds, depending on the thermal maturity of the oil. Generally, the sulfur-rich crude oils contained relatively more sulfur compounds. The flash pyrolyzates of polar fractions contained a variety of sulfur compounds (alkylthiolanes, alkylthianes, terpenoid sulfides, alkylbenzothiophenes) with substantial differences between different crude oils. Raney Ni desulfurization of the polar fraction yielded hydrocarbons dominated by n-alkanes, but isoprenoid alkanes, n-alkylcyclohexanes, mid-chain methylalkanes, tricyclic terpanes, hopanes and steranes were also present. These hydrocarbons show a potential to fingerprint crude oils since their distribution patterns are more characteristic than those of the hydrocarbons present in the saturated hydrocarbon fraction.     

Determination of Sterically Hindered Phenols and α-Tocopherol by Cyclic Voltammetry

Sterically hindered phenols (2,6-di-tert-butyl-4-methylphenol (BHT) and its derivatives) are irreversibly oxidized at +0.96–1.30 V on glassy carbon electrode (GCE) in 0.1 M LiCIO₄ in acetonitrile in accordance to cyclic voltammetry data. α-Tocopherol gives oxidation step at +0.4 V on voltammograms under the same conditions. Oxidation process leads to formation of corresponding quinoid derivatives. Calibration graphs linearity is 1.5–2 order for all compounds under investigation. Limits of detection are in the range 9.6–44.3 µM. The approach has been applied for determination of BHT and α-tocopherol in vegetable and lubricating oils as well as pharmaceuticals and cosmetics using preliminary single extraction of analytes with acetonitrile for 15 min at oil/extractant ratio of 1:2.5.     

Characterization of military fog oil by comprehensive two-dimensional gas chromatography

The most commonly used military fog oil is characterized by comprehensive two-dimensional gas chromatography (GC×GC) coupled to either Flame Ionization Detection (FID) or Time-of-Flight Mass Spectrometric Detection (TOFMS) to advance the knowledge regarding the complete chemical makeup of this complex matrix. Two different GC×GC column sets were investigated, one employing a non-polar column combined with a shape selective column and the other an inverse column set (medium-polar/non-polar). The inverse set maximizes the use of the two-dimensional separation space and segregates aliphatic from aromatic fractions. The shape selective column best separates individual polycyclic aromatic hydrocarbons (PAHs) from the bulk oil. The results reveal that fog oil (FO) is composed mainly of aliphatic compounds ranging from C₁₀ to C₃₀, where naphthenes comprise the major fraction. Although many different species of aromatics are present, they constitute only a minor fraction in this oil, and no conjugated PAHs are found. The composition of chemically similar aliphatic constituents limits the analytical power of silica gel fractionation and GC–MS analysis to characterize FO. Among the aliphatic compounds identified are alkanes, cyclohexanes, hexahydroindanes, decalins, adamantanes, and bicyclohexane. The aromatic fraction is composed of alkylbenzene compounds, indanes, tetrahydronaphthalenes, partially hydrogenated PAHs, biphenyls, dibenzofurans and dibenzothiophenes. This work represents the best characterization of military fog oil to date. As the characterization process shows, information on such complex samples can only be parsed using a combination of sample preprocessing steps, multiple detection schemes, and an intelligent selection of column chemistries.     

Composition and Antimicrobial Activity of <Emphasis Type="Italic">Helichrysum italicum</Emphasis> Essential Oil and Its Terpene and Terpenoid Fractions

The essential oil of Helichrysum italicum (Roth) G. Don from Croatia has been fractionated into terpene and terpenoid fractions and analyzed using GC/MS. Fifty-two compounds were identified. The main hydrocarbons of the oil were α-pinene (10.2%), α-cedrene (9.6%) aromadendrene (4.4%), β-caryophyllene (4.2%), and limonene (3.8%), while the main oxygen-containing compounds were neryl acetate (11.5%), 2-methylcyclohexyl pentanoate (8.3%), 2-methylcyclohexyl octanoate (4.8%), and geranyl acetate (4.7%). The essential oil and its terpene and terpenoid fractions were evaluated for antibacterial and antifungal activities. The screening of antimicrobial activity was conducted by a disc diffusion test and the minimum inhibitory concentration was determined against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. The essential oil and its terpenoid fraction exhibited higher antimicrobial activity with respect to the terpene fraction. The antimicrobial activities of the oil and its terpenoid fraction were more pronounced against Staphylococcus aureus and Candida albicans.__________Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 29–32, January–February, 2005.