Identification Of Hydrocarbons Research Articles

Detection of Radiation-Induced Hydrocarbons and 2-Alkylcyclobutanones in Irradiated Perilla Seeds

The method consists of the extraction of fat from perilla seeds, separation of hydrocarbons and 2-alkylcyclobutanones with florisil column chromatography, and identification of hydrocarbons and 2-alkylcyclobutanones by gas chromatography–mass spectroscopy (GC-MS). Concentrations of hydrocarbons and 2-alkylcyclobutanones increased with the irradiation dose. The major hydrocarbons in the irradiated perilla seeds were 8-heptadecene and 1,7-hexadecadiene from oleic acid and 6,9-heptadecadiene and 1,7,10-hexadecatriene from linoleic acid. One of the 2-alkylcyclobutanones, 2-(5′-tetradecenyl)cyclobutanone, was found in the highest concentration in the irradiated perilla seeds. Radiation-induced hydrocarbons in the perilla seeds were detected at doses of 0.5 kGy and higher, and radiation-induced 2-alkylcyclobutanones were detected at doses of 1 kGy and higher. These compounds were not detected in nonirradiated perilla seeds.

Identification of hydrocarbons and oxygen compounds in sediments from Niigata, Japan.

Identification of hydrocarbons and oxygen compounds in sediments from Niigata, Japan.

Use of Compound-Specific Stable Isotope Analysis to Source Anthropogenic Natural Gas-Derived Polycyclic Aromatic Hydrocarbons in a Lagoon Sediment

This paper reports the first identification of polycyclic aromatic hydrocarbons (PAHs) in the environment with extremely low carbon stable isotopic ratios. For sediments collected from a coastal lagoon in northern Italy, these low 13C/12C isotopic ratios for many of the PAHs together with the presence of cylcopentafused PAHs (CP-PAH) indicate that the PAHs have predominantly been derived from a high-temperature industrial process utilizing the local biogenic natural gas. The process used the biogenic gas as the feedstock for the production of acetylene. From the evidence available, the large variability in the PAH isotopic δ13C values (from −31 to −62 ‰) is ascribed mainly to biodegradation rather than to major inputs from sources of isotopically heavy PAH, such as the neighboring modern-day carbon black plants.

Identification of new steroidal hydrocarbons in refined oils and the role of hydroxy sterols as possible precursors.

The dehydration of sterols during the refining process of vegetable oils results in the formation of steroidal hydrocarbons (sterenes or steradienes) with two double bonds in the ring system. Other steroidal hydrocarbons whose structures were in agreement with the presence of three double bonds in the ring system were detected in the sterene fractions of refined vegetable oils. The 5alpha-, 7alpha-, and 7beta-hydroxy derivatives of cholesterol and phytosterols have been dehydrated in n-butanol/H(3)PO(4) to form steroidal hydrocarbons with three double bonds at the 2, 4, and 6 positions in the ring system. These hydrocarbons had the same relative retention time and mass spectra as those present in the sterene fractions of refined oils. The dehydration of the hydroxy sterols dissolved in extra virgin olive oil and in the presence of 1% bleaching earths at 80 degrees C for 1 h results in the formation of the same steroidal hydrocarbons found in the refined oils.

Identification of cuticular hydrocarbons and the alkene precursor to the pheromone in hemolymph of the female gypsy moth, Lymantria dispar.

Hydrocarbons were extracted from the surface of the cuticle and from the hemolymph of adult female gypsy moths. GC and GC/MS analysis indicated that the cuticular hydrocarbons with chain lengths >21 carbons were the same as those found in the hemolymph. These consisted of mostly saturated straight chain hydrocarbons with heptacosane the major component. Methyl branched hydrocarbons were also identified including a series of tetramethylalkanes with chain lengths of 30, 32, and 34 carbons. In addition to those found on the cuticle surface, the hemolymph contained the alkene pheromone precursor, 2-methyl-Z7-octadecene and two saturated analogues, 2-methyl-octadecane and 2-methyl-hexadecane. No evidence was obtained for the presence of the pheromone 2-methyl-7, 8-epoxy-octadecane in the hemolymph. Pheromone gland extracts indicated that small amounts (<1 ng) of the alkene precursor were also present in the gland. Relatively larger amounts of the alkene precursor were found in the hemolymph at the time when pheromone titers were higher on the gland. The presence of the hydrocarbon pheromone precursor in the hemolymph is discussed in relation to possible biosynthetic pathways for producing the gypsy moth pheromone.

Separation and identification of hydrocarbons and other volatile compounds from cultured blue-green alga Nostoc sp. by gas chromatography–mass spectrometry using serially coupled capillary columns with consecutive nonpolar and semipolar stationary phases

The complex hydrocarbons and volatile compounds produced by cultured blue-green alga Nostoc sp. were separated by serially coupled capillary columns with consecutive nonpolar and semipolar stationary phases. More than 130 metabolites including, cyclohexane, cyclopentane, normal saturated hydrocarbons (C 7–C 30), fatty acids and benzene derivatives were identified by GC–MS. The most abundant family of hydrocarbons identified were derivatives of cyclohexane (41) and cyclopentane (11). Most of these compounds have not been reported previously in blue-green algae studies.

Identification of sesquiterpene hydrocarbons by gas phase analytical methods

Current techniques are described and demonstrated for the isolation and structural elucidation of sesquiterpene hydrocarbons, on the basis of enantioselective capillary gas chromatography, with cyclodextrin derivatives as chiral stationary phases and chemical microreactions for correlation of unknown sesquiterpenes with compounds of known constitution and absolute configuration. Copyright © 1999 John Wiley & Sons, Ltd.

Identification of Aromatic Compounds on a Single Microparticle by Laser Desorption/Ionization Ion Trap Mass Spectrometry

A laser desorption/ionization ion trap mass spectrometer was developed and used for the identification of polycyclic aromatic hydrocarbons (PAHs) and pesticides, DDT and BHC, condensed on a single microparticle. The excimer (XeCl, 308 nm) laser was adopted for the desorption and ionization of the material from the particle surface and the resulting ions were analyzed with an ion trap mass spectrometer. The mass spectra obtained from laser desorption/ionization were similar to the results from electron impact ionization. Detection sensitivity was reached to sub-nanogram/particle order when a 5 mJ/pulse of energy of the laser was used. Tandem mass spectrometry was applied to the characterization of DDT by way of collision-induced dissociation of the parent ion with ambient He buffer gas.

Identification of long chain isoprenoid hydrocarbons from pyrolytic product ofDunaliella

In the pyrolytic research onDunaliella salina cultured under natural conditions, abundant long chain regular isoprenoid hydrocarbons have been first detected and identified from algal pyrolytic product. Specially, the discovery of high abundant 2,6,10,14,18-pentamethyleicosane indicated that regular iC25 probably originated from specific holophilic algae in hypersaline environments. The result gave new referable evidence both for the distinguishment of biological origins of long chain isoprenoids found in sediments and petroleum and for the judgement of paleoenvironments.

The Identification of New Ethynyl-Substituted and Cyclopenta-Fused Polycyclic Aromatic Hydrocarbons in the Products of Anthracene Pyrolysis

The recent synthesis of new reference standards of polycyclic aromatic hydrocarbons (PAH) has enabled us to identify six new PAH species among the products of anthracene, pyrolyzed in argon at temperatures of 1300 to 1500 K. The anthracene product samples are analyzed by high performance liquid chromatography (HPLC) with diode-array ultraviolet-visible (UV) detection, and the identifications are made by matching each product component's HPLC elution time and UV absorption spectrum with those of the corresponding reference standard. The newly identified PAH products include 1-ethynylacenaphthylene (C14H8) as well as five cyclopenta-fused PAH (CP-PAH): cyclopenta[cd]fluoranthene (C18H10); dicyclopenta[cd, mn]pyrene, dicyclo-penta[cd,fg]pyrene, dicyclopenta[cd,jk]pyrene (C20H10); and benzo[ghi]cyclopenta[cd]-perylene (C24H12). Undetectable at temperatures < 1300 K, the yields of the newly identified CP-PAH rise quickly with temperature above 1350 K, levelling off somewhat at temperatures approaching 1500 K. The five new CP-PAH, along with five previously identified CP-PAH, together account for approximately a quarter, by number, of the anthracene product PAH identified and quantified to date. At the highest temperatures, the CP-PAH as a whole account for almost half of the mass of the “thermally produced” P \\H, the dominant PAH under the conditions at which soot is the major product. The results show some consistency with a CP-PAH formation mechanism involving acetylene atldition to aryl radicals, followed by cyclization of the resulting ethynyl-PAH. Further research is needed, however, to better elucidate the governing reaction mechanisms.

Identification of alkenylbenzenes in pyrolyzates using GC–MS and GC–FTIR techniques: evidence for kerogen aromatic moieties with various binding sites

Pyrolysis products obtained from heating a shale under vacuum have been analyzed for alkenylbenzenes using GC–MS and GC–FTIR. The shale pyrolysate contains a homologous series (C 11–C 23) of alkenylbenzenes with terminal unsaturations concomitant with lesser amounts of hitherto unknown trans alk-1-enylbenzenes. These latter compounds are unique constituents of kerogen pyrolyzates and are suggested to be derived from alkylbenzene moieties bound to kerogen at the benzylic position. The presence of these unsaturated compounds in pyrolyzates has been interpreted as evidence for site-specific binding of alkylbenzene moieties in kerogen. Formation of alkenylbenzene moieties is suggested to result from diagenetic cyclization/aromatization reactions of fatty acid precursors. Incorporation of structurally different lipid precursors such as saturated, mono- and polyunsaturated fatty acids is suggested to reflect the nature of the different alkenylbenzene products generated upon pyrolysis. The application of `compound specific' GC–FTIR techniques, provides a new and complementary tool to the study of geochemical samples. Compound specific IR spectra in conjunction with electron impact mass spectra are shown to facilitate the structural identification of hydrocarbons in geochemical samples.

Identification of steroidal hydrocarbons in refined confectionery fats by gas chromatography–mass spectrometry

Steroidal hydrocarbon degradation products (steradienes) of sterols formed during the bleaching of confectionery fats were isolated by a new rapid silica column technique. The steradienes were separated by gas chromatography with mass spectrometric detection. Refined mango butter contained predominantly a sterene which was unrelated to the major desmethyl sterols. Dehydration products of triterpene alcohols were isolated from stearin fractions of refined shea butter which is used in the manufacture of chocolate.

99/00266 Identification of isomeric polycyclic aromatic hydrocarbons (PAH) in pyrolysates from ethynylated PAH by gas chromatography-Fourier infrared spectroscopy. Their relevance for the understanding of PAH rearrangement and interconversion processes during combustion

99/00266 Identification of isomeric polycyclic aromatic hydrocarbons (PAH) in pyrolysates from ethynylated PAH by gas chromatography-Fourier infrared spectroscopy. Their relevance for the understanding of PAH rearrangement and interconversion processes during combustion

99/00168 Isomeric identification and quantification of polycyclic aromatic hydrocarbons in environmental samples by liquid chromatography tandem mass spectrometry using a high pressure quadrupole collision cell

This study is part of a comprehensive research program on the generation and migration of petroleum from the organic-rich Posidonia Shale (Lower Toarcian, Jurassic) of the Hils syncline, northern Germany. Four cores of the complete Posidonia Shale (with varying amounts of underlying Pliensbachian and overlying Aalenian mudstones) provided the sample base. Depending upon their distance from a presumed subjacent heat source, the Vlotho Massif, the cores display progressive levels of increasing thermal maturation with R0-values (0.48, 0.68, 0.88 and 1.45%) which span the limits of the oil-generation window. Primary stratigraphic, lithologic and petrographic attributes of the four sections are all very similar. Each includes a lower marlstone member (about 5 m thick) overlain by 11–31 m of calcareous clay-shale. Clay minerals, calcite, pyrite, kerogen, and quartz are the principal constituents. Thus, there is no evidence that depositional conditions of the Posidonia Shale varied significantly over the sampled area. The omnipresence of framboidal pyrite, clearly formed from the activity of sulphate-reducing bacteria at or near the depositional interface, is strong evidence that uniform reducing (anoxic) conditions were persistent at all localities. This conclusion supports the assumption that initially each section was identical in overall properties and that significant differences observed in geochemistry, organic macerals, and other properties are directly related to the variable levels of thermal maturation.Kerogen from the least mature section (Ro = 0.48%) is Type II and composed of alginite A, alginite B, liptodetrinite, bituminite and some terrestrial (sporinite, vitrinite and inertinite) macerals. With increasing maturation the alginite macerals exhibit a progressive change in morphology and fluorescence properties. Alginite of the least mature section displays a strong green fluorescence. At 0.68% Ro, alginite macerals exhibit yellow-orange fluorescence and are structurally well preserved, although geochemical data indicate generation and loss of large amounts of oil. At 0.88% Ro, hydrocarbon generation is almost complete and few primary alginites remain. They have been transformed into secondary liptinites, designated as metaalginite, which have similar fluorescence colours. At the highest maturation level (1.45% Ro), metaalginites are only weakly fluorescent with a shift toward red colours.Calcite- and/or bitumen-filled bedding-plane micro- and macrofractures occur exclusively in the organic-rich Posidonia Shale at maturity levels of 0.68% Ro and above. Such features are totally absent in the immature Posidonia section and in the adjacent organic-poor mudstones. This observation indicates that the fractures developed in direct response to overpressuring (i.e. pore pressure exceeding lithologic load) related to oil and gas generation in the source rock. The fractures undoubtedly provided important expulsion conduits for generated products.

Chromatography, Absorption, and Fluorescence: A New Instrumental Analysis Experiment on the Measurement of Polycyclic Aromatic Hydrocarbons in Cigarette Smoke

The recent approval by the American Chemical Society of an undergraduate chemistry degree with an option in environmental chemistry requires the development of new experiments that teach fundamental chemistry in the context of environmental issues. We present an experiment suitable for an undergraduate junior/senior-level instrumental analysis laboratory which illustrates the principles of high-performance liquid chromatography (HPLC) and its application to the identification and measurement of polycyclic aromatic hydrocarbons (PAH) in tobacco smoke. Absorption and fluorescence detection methods for PAH, especially the differences in sensitivity and selectivity of these methods, are clearly demonstrated along with the basic principles of HPLC.

Influence of γ-irradiation and microwaves on the linear unsaturated hydrocarbon fraction in spices

Linear, unsaturated hydrocarbons were detected in spice samples treated with γ-rays or microwaves. The analyses were performed on aniseed, basil, cinnamon, entire and ground chilli, origano, paprika, black pepper, rosemary and sage. These samples were submitted to different treatments: γ-irradiation at 5 kGy, γ-irradiation at 10 kGy, microwaves (frequency of 2450 Mhz for 20 min), and not treated. The identification of linear, saturated, monoenic and dienic hydrocarbons was performed by using off-line liquid chromatography/gas chromatography (LC/GC) mass spectrometry. Unsaturated hydrocarbons were found only in the samples subjected to γ-irradiation, and 8-heptadecene was found to be a marker for γ-irradiation; in fact this compound was absent in the untreated and the microwaved samples. On-line, coupled LC-GC was used for the determination of dienic hydrocarbons.

Use of Fluorescence Emission Spectra for the Routine Identification of Polycyclic Aromatic Hydrocarbons in Liquid Chromatography

Fluorescence detection provides a highly sensitive and selective method of detection for polycyclic aromatic hydrocarbons (PAHs). However, the acquisition of fluorescence spectral data for purposes of peak identification has hitherto only been reported using techniques which interrupt chromatographic runs or rely on complex additional instrumentation. The application and limitations of acquiring fluorescence spectra using a commercially available detector during routine chromatography are discussed.

Identification of isomeric polycyclic aromatic hydrocarbons (PAH) in pyrolysates from ethynylated PAH by gas chromatography-Fourier infrared spectroscopy. Their relevance for the understanding of PAH rearrangement and interconversion processes during combustion

The utility of gas chromatography with infrared spectrometric detection (GC-IR) for the structural elucidation of pyrolysate constituents obtained by Flash Vacuum Pyrolysis (FVP; 900–1100°C, 10 −2 Torr) of ethynylated Polycyclic Aromatic Hydrocarbons (E-PAH) is demonstrated. E-PAH are efficient precursors for ubiquitous and genotoxic C 14H 8, C 16H 10 and C 20H 12 cyclopenta-fused PAH (CP-PAH) combustion effluents. The formation of CP-PAH from E-PAH as well as CP-PAH rearrangements and/or interconversions are readily recognized. GC-IR being complementary to GC-MS enables the identification and structural assignment of previously undetected isomeric PAH, which are only present in trace-level amounts. The results are of interest for the elucidation of PAH build up processes and for the rationalization of the ubiquitous formation of a distinct set of PAH during combustion.

Isomeric identification and quantification of polycyclic aromatic hydrocarbons in environmental samples by liquid chromatography tandem mass spectrometry using a high pressure quadrupole collision cell

Isomeric identification and quantification of polycyclic aromatic hydrocarbons in environmental samples by liquid chromatography tandem mass spectrometry using a high pressure quadrupole collision cell

Application of toxicity‐based fractionation techniques and structure‐activity relationship models for the identification of phototoxic polycyclic aromatic hydrocarbons in sediment pore water

AbstractRecent studies conducted at our laboratory have shown that sediments contaminated with complex mixtures of polycyclic aromatic hydrocarbons (PAHs) can exhibit enhanced toxicity (lethality) to a variety of aquatic species when the samples are tested under ultraviolet (UV) light designed to mimic the wavelengths present in sunlight. However, because these contaminated sediments can contain literally thousands of chemicals, it is difficult to use conventional analytical techniques to identify those compounds responsible for photo‐induced toxicity. The purpose of this study was to adapt existing toxicity identification evaluation methods to attempt to identify those compounds contributing to the phototoxicity observed in our sediment samples. Pore water obtained from sediments collected near an oil refinery discharge was toxic to Lumbriculus variegatus following exposure to UV light, while organisms exposed to the same pore water, but without subsequent UV treatment, showed no toxic effect. Solid‐phase extraction disks and high‐performance liquid chromatography were used, in conjunction with toxicity tests with L. variegatus, to extract and fractionate phototoxic chemicals from the pore water. Phototoxic fractions analyzed by gas chromatography–mass spectrometry revealed the presence of a number of aliphatic hydrocarbons, substituted PAHs, and PAHs containing heteroatoms. Chemicals were screened for their phototoxic potential based on empirical data and predictive models. A refined list of PAHs was then evaluated on the basis of their phototoxic potency as defined by a recently developed quantitative structure–activity relationship model and estimates of their bioaccumulation potential. Based on the model predictions of potency and bioaccumulation, nine likely phototoxic chemicals were identified.