Individual Aromatic Hydrocarbons Research Articles

Trace analysis for aromatic hydrocarbons in natural waters

A method for trace analysis of volatile aromatic hydrocarbons in natural water is described. The method is based on sparging water samples with nitrogen, adsorption of hydrocarbons on activated charcoal, followed by desorption into carbon disulfide and gas chromatographic analysis. The sensitivity of the method reaches into the 0.1 to 0.2 μg/L concentration range for individual aromatic hydrocarbons. The accuracy and reliability of the method was validated. The method was used in three field studies: dispersion of aromatic hydrocarbons discharged from the Trans-Alaska Pipeline southern terminal throughout Port Valdez; survey of the Atigun River Watershed after oil spill on June 10, 1979; and chemical characterization of treated effluents from offshore oil extraction platforms in the Gulf of Mexico.

A CHEMICAL ASSESSMENT OF THE PRESENT LEVELS AND SOURCES OF HYDROCARBON POLLUTANTS IN THE GEORGES BANK REGION

ABSTRACT Analysis of five suites of samples covering 40 stations in the region of Georges Bank, Nantucket Shoals, and the lower Gulf of Maine illustrates the ubiquity of anthropogenic hydrocarbons throughout this highly productive and heavily fished area. Petroleum compounds from a recent major oil spill (Argo Merchant) and chronic inputs from ballast washings and normal shipping traffic were evident in the water column's dissolved and particulate hydrocarbon fractions. Concentrations were generally in the 0.1 parts per billion to 2.0 ppb range throughout the year, but were above 10 ppb in the four months after spills occurred in late 1976 and early 1977. Individual polynuclear aromatic hydrocarbons (which persisted in the water column during the year at levels of one to 10 nanograms/liter, also were elevated in concentration (10 to 50 ng/l) in early 1977. Surface film enrichment in petroleum hydrocarbons was 1.5 to 90 times that of subsurface waters. This illustrates the existence of a year-round reservoir (10 to 70 ppb) for petroleum-derived material in the ocean's surface microlayer. Surface sediments contained both anthropogenic and biogenic hydrocarbons. Up to 20 micrograms/gram of chromatographically unresolved complex mixture was found in siltier sediments. The unresolved complex mixture appears to have a terrigenous source. Recent tar and oil inputs to the sediments of the region also were observed, but the chemical impact on the benthos was short-lived, station revisitation showed. Sediments contained up to 50 ng/g of individual polynuclear aromatic hydrocarbons attributable to pyrolytic sources and petroleum inputs. Analyses of whole benthic invertebrates revealed sporadic but sizeable inputs of petroleum hydrocarbons to the benthic environment. These were assimilated by such edible species as sea scallops and ocean quahogs, commonly harvested in the region.

PETROLEUM SULFUR-CONTAINING COMPOUNDS AND AROMATIC HYDROCARBONS IN THE MARINE MOLLUSKS MODIOLUS DEMISSUS AND CRASSOTREA VIRGINICA1

ABSTRACT The in situ recovery of the mussel Modiolus demissus and the oyster Crassostrea virginica from successive small experimental dosings of No. 2 fuel oil was examined to determine the retention and release of petroleum hydrocarbons and petro-sulfur compounds from these marine mollusks. Extracts were obtained from the organisms over a four-month recovery period, and were analyzed by flame ionization detection (FID) and flame photometric detection (FPD) gas chromatography, and gas chromatography-mass spectrometry (GCMS). Results showed a large majority of the petroleum compounds that were present in these organisms’ after two weeks of recovery were lost by the 15th week. Both mollusks showed an enrichment of aromatic (releative to saturated) hydrocarbons during the first portion of recovery. As the recovery time lengthened, the aromatics were lost more rapidly than the saturates. Mussels showed relative increases in some individual aromatic hydrocarbons during the recovery period. The oysters, however, appeared to non-selectively depurate the aromatic hydrocarbons. The higher molecular weight petro-sulfur compounds were retained for the longest time periods. During the study period these compounds appeared to be lost from the mollusks at rates similar to those observed for the aromatic hydrocarbons.

ANALYTICAL METHODS FOR POLYNUCLEAR AROMATIC HYDROCARBONS IN CRUDE OILS, HEATING OILS, AND MARINE TISSUES*

ABSTRACT This paper primarily covers the first phase of a project to demonstrate analytical methods in their ability to measure individual polynuclear aromatic hydrocarbons in typical petroleum oils and marine animal tissues. The study of petroleum oils is complete as described herein. Work on marine tissues is in its initial stage as an analytical method is shown to be capable of measuring benz(a)-anthracene and benzo(a)pyrene when added to clams at the 5 parts per billion (ppb) level. Evaluation of results indicate a detectability of 1 ppb. Eleven to sixteen individual hydrocarbons were measured in samples of a South Louisiana crude, Kuwait crude, a No. 2 heating oil, and a Bunker C fuel. These compounds included the principal 3-to 5-ring aromatics found in petroleum and one 6-ring (benzo(ghi)-perylene). The tricyclics (phenanthrene, methylphenanthrenes) were generally present in the highest concentration and covered the range 26–7677 ppm by weight. Four- and five-ring aromatics occurred in the range <0.5–240 ppm. Concentrations of the most widely studied polynuclear aromatic hydrocarbons, benzo(a)pyrene and benz(a)anthracene, were similar to one another being present at 0.6 to 2.8 ppm in the crude oils and heating oil, whereas in Bunker C their concentrations were 44 and 90 ppm, respectively Measurements of benzo(a)pyrene by previous investigators are tabulated and compared with those of this paper. Data are also presented to show that the alkyl-substituted forms of these compounds are present at much higher concentrations than the parent compound itself.

Identification of individual aromatic hydrocarbons in kerosene fraction (b.p. 150–250°)

Identification of individual aromatic hydrocarbons in kerosene fraction (b.p. 150–250°)

Low-temperature regeneration of solvent in extraction of aromatic hydrocarbons with propylene carbonate

1. A study has been made of phase equilibria in ternary systems of pentadecane-aromatic hydrocarbons — propylene carbonate, at 20°C. Distribution coefficients of the aromatic hydrocarbons between phases have been calculated, and these have been used to calculate the approximate pentadecane/feedstock ratio required for complete extraction of an individual aromatic hydrocarbon. 2. The results of experiments conducted with a countercurrent column on the reextraction of aromatic hydrocarbons from a real extract solution by means of pentadecane have shown that, with a 1/1 ratio of pentadecane to feedstock and a reextraction zone height corresponding to 3–4 theoretical extraction stages, extraction of the aromatic hydrocarbons is essentially complete. 3. The pentadecane-aromatic hydrocarbon mixture can be separated in low-efficiency fractionating columns, owing to the large difference in boiling points.

Chromatographic determination of content of individual aromatic hydrocarbons in naphtha fractions

Chromatographic determination of content of individual aromatic hydrocarbons in naphtha fractions

Application of a two-stage scheme of gas chromatographic analysis of unstable reforming catalysate

1. A method was worked out for the determination of the composition of unstable reforming catalyzate in a two-stage Chromatograph. The method permits us to determine the content of individual aromatic hydrocarbons and of light paraffinic hydrocarbons up to C6 inclusive. Duration of the analysis is one hour. 2. For higher precision of the quantitative analysis a method of evaluating the peak areas is proposed, using an integrator. The method eliminates the influence of drift of the zero line of the Chromatograph on the evaluation.

Catalytic reforming of the 85?140� C fraction of Lelyakov petroleum

1. We have studied the material balance and composition of the products of catalytic reforming of the 85140°C fraction of Lelyakov petroleum. 2. It has been shown that in the temperature range 470–500°C, at a volumetric flow rate of the feedstock of 1.5 h−1, and at a pressure of 35 atm the yields of the liquid reforming products and the 62–150°C target fraction change by only 3–5 wt. %. Whereas the yield of the liquid products falls with increasing temperature, that of the 62–150°C target fraction increases. 3. It has been established that under the investigated conditions an increase in the process temperature from 470 to 500°C is accompanied by an increase in the overall yield of aromatic hydrocarbons (benzene, toluene, ethylbenzene, and xylenes), but the ratio of the individual aromatic hydrocarbons in the catalysates remains virtually constant.

Interaction of polynucleotides with aromatic hydrocarbons

AbstractDNA in its native and denatured form and yeast RNA complex individual aromatic hydrocarbon molecules but single‐stranded poly A does not. The degree of complexing appears to depend on molecular dimensions; it is appreciable for phenanthrene, pyrene, and benzpyrene but very small or undetectible for coronene, tetracene, pentacene, and 20‐methylcholanthrene.

Hydrogen concentration during low-pressure hydrocracking

1. Experiments on the hydrocracking of mixtures of individual aromatic hydrocarbons and some fractions of coal tar at 20–50 kg/cm2 and using hydrogen-containing coke oven gas showed that, for the same molar ratios of hydrogen to the raw material, the degree of conversion of the starting raw material and the yield of the desired products is attained by increasing the space velocity (or circulation) of the coke oven gas, calculated per unit of raw material and by selection of the optimum conditions, is almost identical. 2. In the industrial process for the hydrocracking of coal tar and its fractions under low pressure, coke oven gas can be used. In this case, the pressure for the process will not differ from the pressure used when pure hydrogen is used if the same molar ratio of hydrogen to the raw material is used.

Aromatic hydrocarbons in nuclear submarine atmospheres.

Abstract An analytical study has been directed to the identification and determination of individual aromatic hydrocarbons present in nuclear submarine atmospheres in concentrations of parts per million or less. Hydrocarbon oil samples were desorbed from activated carbon which had been exposed in submarine atmospheres. The aromatic hydrocarbon content of these oils was approximately 25 to 30% of the total. The quantitative distributions of individual aromatic hydrocarbons found in submarines were strikingly similar to those of typical petroleum distillates in the same boiling range. Several commercial petroleum products were studied as possible sources of hydrocarbons in submarine atmospheres.