NEWLY IDENTIFIED PRODUCTS OF BENZENE DROPLET COMBUSTION: POLYCYCLIC AROMATIC HYDROCARBONS OF THREE TO TEN RINGS

Abstract

In order to investigate further the polycyclic aromatic hydrocarbons (PAH) produced by benzene droplet combustion, we have obtained and analyzed a highly-concentrated benzene droplet combustion sample, using high pressure liquid chromatography (HPLC) with diode-array ultraviolet-visible (UV) absorbance spectroscopy. In addition to benzo[k]fluoranthene, we have identified ten large (5- to 10-ring) PAH never before reported as products of benzene pyrolysis or combustion: dibenz[a,c]anthracene, indeno[1,2,3-cd]fluoranthene, anthanthrene, cyclopenta[cd]benzo[ghi]perylene, coronene, dibenzo[a,i]pyrene, cyclopenta[bc]coronene, benzo[a]coronene, naphtho[8,1,2-abc]coronene, and ovalene. In this sample we have also identified three smaller PAH, benz[f]indene, 2-ethynylanthracene, and benzo[c]phenanthrene, never before reported as products of benzene pyrolysis or combustion. In order to document the unequivocal identification of these compounds as benzene droplet combustion products, we present the UV absorbance spectrum of each newly identified benzene product, along with the matching UV spectrum of the respective PAH reference standard. Several of the identifications have required the acquisition of specially synthesized reference standards. Combined with our previous results, the present findings show that 50 individual PAH (and related compounds), of up to 10 rings in size, are produced during benzene droplet combustion.     

Polycyclic Aromatic Hydrocarbons in Maternal and Cord Blood Plasma

Abstract

Polycyclic aromatic hydrocarbons (PAH) come from incomplete combustion of organic materials, including tobacco smoke. Some PAH are known to be mutagenic and carcinogenic and of concern for the fetus when women smoke during pregnancy. Known consequences of smoking during pregnancy include low birth weight (LBW) and preterm (PT) delivery. This study was designed to measure concentrations of 3 PAH: anthracene (A), benzo(a)pyrene (BP) and 1-hydroxypyrene (1-HP) in paired maternal (M) and cord blood (CB) samples. Additionally, we explored relationships between the PAH concentrations and LBW or PTD. Cotinine was used as a biomarker of tobacco exposure. All 3 PAH were found in M and CB plasma. A was significantly elevated in CB plasma compared to M plasma at higher M cotinine concentrations. BP in PT infants was significantly lower than in term. There were significant correlations between M and CB concentrations of anthracene. Correlations of 1-HP with cotinine in CB and M plasma were significant but opposite in direction. Anthracene, benzo(a)pyrene and 1-hydroxypyrene are present in measurable concentrations in M and CB plasma at the time of delivery. The higher concentrations of anthracene in CB plasma may be due to differences in maternal metabolism during pregnancy, length of labor or metabolism in the fetus. Long-term effects of anthracene on the infant are unknown and merit further investigation.     

CYCLOPENT[bc]ACENAPHTHYLENE: A PUTATIVE INTERMEDIATE ON THE PATHWAY FOR THERMAL CYCLODEHYDROGENATION OF PHENANTHRENE

Phenanthrene, the archetypal “bay region” polycyclic aromatic hydrocarbon (PAH), loses two hydrogen atoms when subjected to flash vacuum pyrolysis (FVP) at 1100 °C and suffers a major skeletal rearrangement to form pyracylene (1), along with 1-, 3-, and 4-ethynylacenaphthylene (2, 3, and 4, respectively). Evidence is presented that implicates cyclopenta[bc]acenaphthylene (7) as a key intermediate on the reaction pathway from phenanthrene to these four C₁₄H₈ products.     

Association of Polycyclic Aromatic Hydrocarbons (PAHs) with Different Sizes of Atmospheric Particulate in Hisar City and its Health Aspects

The concentration of polycyclic aromatic hydrocarbons (PAHs) associated with different particulate sizes of suspended particulate matter (SPM) was studied in Hisar city with the help of a MOUDI-NR 10-stage (18 μm to 0.056 μm) cascade impactor. The vehicular-cum-commercial, vehicular, commercial, and institutional/residential locations had the average concentration (ng/g) of 11.39, 10.39/10.22 (NH 10/Bus Terminus), 8.89, and 8.93, respectively. Vehicular emission was the chief source and diesel-vehicle dominated areas represented higher concentration of PAHs associated with coarse fraction. An increase in PAH associated with fine fraction was observed with an increase in vehicular density. Maximum average concentration (11.26 ng/g) was found to be associated in particle range of <0.56–0.32 μm. It was followed by particle range (μm) of <18–10, <1.8–1, <0.18–0.1, <1–0.56, <5.6–3.2, <0.32–0.18, <3.2–1.8 <0.1–0.056, and <10–5.6 with average values (ng/g) of 10.75, 10.35, 10.22, 10.16, 10.06, 9.50, 9.18, 9.18, and 9.00, respectively. Among the PAHs studied, maximum levels were observed for pyrene, followed by Benzo(b)fluoranthene, Benzo(e)pyrene, benzo(k)fluoranthene, fluoranthene, phenanthrene, benzo(ghi)perylene, anthracene, and naphthalene. With respect to the percent fraction of PAHs studied, the vehicular-cum-commercial area represented maximum fraction (22%) followed by vehicular area (21% each for NH-10 and Bus Terminus), institutional/residential area (18%), and commercial area (18%). The isomeric ratios revealed that most of the PAHs originate from combustion of diesel, gasoline, used engine oil, and coal/wood. The association of PAHs with fine fraction of health concern since it can penetrate and get accumulated in deep respiratory regions.     

Monitoring of Polycyclic Aromatic Hydrocarbons in Water during Preparation Processes

This article presents results on investigation of quantitative changes of polycyclic aromatic hydrocarbons (PAHs) during water treatment processes. PAHs constitute one of several classes of organic pollutants consisting of three or more fused benzene rings. Many of them are quite persistent and some are known to be carcinogens. That is why presentation of quantitative PAHs changes in water during preparation processes is very important. In Polish legislation and European Union law there are recommendations for PAHs concentration in drinking water. The limit value of the sum of 4 PAHs (benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[g,h,i]perylene, indeno[1,2,3-cd]pyrene) is 100 ng/L. Limit concentration of benzo[a]pyrene defined in regulations (Polish and UE) is 10 ng/L. The purpose of the present study was to determine changes of concentrations of PAHs in various stages of water treatment process and comparison the values of this index with the limits specified in valid Minister of Health Regulation and Council Directive 98/83/EC. A total concentration of 16 PAHs in the investigated water treatment processes was in the range of 39–204 ng/L. The maximum level was recorded for water after intermediate ozonation. In different water treatment processes were observed fluctuations in PAHs concentrations. Decreased values were recorded among others after pre-ozonation and coagulation and after sedimentation process. Increase of PAHs level occurred after filtration through sand filters. Concentrations of 4 PAHs in drinking water is much below the limit value defined in Polish and UE legislation. Concentration of 16 PAHs in water after final chlorine-disinfection also meets the requirements of the regulation for 4 PAHs.     

Polycyclic Aromatic Hydrocarbons,Heavy Metals,and Genotoxicity of the Suburban Soils from Guangzhou,China

During the past few decades, urban and suburban developments have grown at unprecedented rates and extents with unknown consequences for ecosystem function. The problem of soil pollution as a result of the accelerating development of Guangzhou in China is becoming great concerns. In the present study, gas chromatograph coupled mass spectrometry (GC-MS), inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) were employed to determine the 16 US Environmental Protection Agency (EPA) priority polycyclic aromatic hydrocarbons (PAHs) and the heavy metals (As, Cr, Cu, Pb, Cd, Hg, and Se) of soils collected from suburban areas of Guangzhou. The genotoxicity of these soils was screened with micronucleus (MN) assay in Vicia faba root cells. The concentrations of the pollutants in the soils were (dried weight): ΣPAHs (230.6–1263 ng·g^?1), As (2282.6–36064 μg·kg^?1), Cr (7109–64699 μg·kg^?1), Cu (7047–56388 μg·kg^?1), Pb (9675.9–93739 μg·kg^?1), Cd (68.5–847.3 μg·kg^?1), Hg (85.4–549.2 μg·kg^?1), and Se (219.2–968 μg·kg^?1), which fell in the moderately polluted range. However, six out of nine soil-exposed groups had a significant increases of MN frequencies observed in the V. faba root cells compared with the negative group (P < 0.05, P < 0.01), indicating that they had potential genotoxic risks. Bringing together the chemical analyses with the biological effects observed in this study, the genotoxic response could at a certain degree be explained by both the soil PAHs and heavy metals. Our results suggested that apart from chemical analysis, bioassays like the MN assay of V. faba root cells should also be included in a battery of tests to assess the eco-environmental risks of urban and/or urbanization in the developing areas on the soils.     

Photodegradation of Anthracene and Benzo[a]anthracene in Polar and Apolar Media: New Pathways of Photodegradation

The photochemical reactions of anthracene and benzo[a]anthracene polycyclic aromatic hydrocarbons (PAHs) in polar and apolar solvents (cyclohexane and water/acetonitrile) were studied using spectroscopic and chromatographic techniques. These homogenous photolysis experiments are used as simplified models to compare PAHs photochemistry in water and oil (or oil films). Moreover, these processes were to some extent used as model in literature in order to study those occurring on particulate matter and aerosol surfaces. In both media, new photochemical reaction products were found. Generally, the reaction rate in the polar medium is faster than that in the apolar medium, and the photodegradation quantum yields increase with increasing polarity of the medium. HPLC-absorption/emission analysis confirmed the literature reports that mainly oxygenated photoproducts, such as PAH-hydroxides, were formed. The novelty of this article is that GC-MS data revealed the presence of new photoproducts that have not yet been described. This simplified model system allowed us to characterize the product distribution, thus simplifying the interpretation of the photodegradation mechanism. The identification of new photofragmentation paths, originating by irradiation of primary PAH photoproducts, may suggest an innovative way of remediation triggered by light.     

Preparation of Deoxynucleosides,Deoxynucleotides and Oligodeoxynucleotides Bearing Adducts of PAH Diol Epoxides at the N6 Position of Adenine

Abstract

Oligonucleotides bearing adducts of the diol epoxides of benzo[a]pyrene and other polycyclic aromatic hydrocarbons on the exocyclic amino group of adenine have been prepared in a regio and stereospecific manner. The strategy involves reversal of the electrophile-nucleophile relationship; the PAH is linked to the adenine nucleus via condensation of an aminotriol (derived from the diol epoxide) with 6?fluoropurine deoxyribonucleoside. This condensation is carried out after the fluoro nucleoside has been incorporated into the oligonucleotide, but while the oligomer is still immobilized on the solid matrix. The diastereomeric oligomers derived from (±)?anti?BPDE are readily separable by HPLC, thus circumventing the need for individual enantiomers of the diol epoxide.     

Production and Immunochemical Characterization of a High-Affinity Monoclonal Antibody Specific for 7-(Benzo[a]pyren-6-yl)guanine (Bp-6-N7GUA), a Depurinating DNA Adduct of Benzo[a]pyrene

Molecular dosimetry of depurinating DNA adducts of benzo[a]pyrene (BP) offers a promising new approach to determining risk of PAH-induced cancer. Depurinating adducts are the predominant form of BP-induced DNA damage, are excreted in urine and, importantly, are linked to cancer initiation. We have produced a monoclonal antibody (MAb) with high specific affinity for BP-6-N7Gua, a major depurinating DNA adduct of BP, and have developed a sensitive and specific competitive enzyme-linked immunosorbent assay (ELISA). The I_50S (quantity producing 50% inhibition of MAb binding in the ELISA) of selected BP adducts and metabolites were determined. The results indicated 1) a high degree of discrimination between BP-6-N7Gua (I₅₀=750 fmol) and BP (I₅₀=900,000 fmol), 2) high affinity of the MAb for BP-6-N7Ade (I₅₀=1,500 fmol), another major depurinating DNA adduct, and 3) specific structural requirements for MAb-adduct binding. In addition, the competitive ELISA provided an accurate determination of BP-6-N7Gua added to normal human urine, at a sensitivity of 200 fmol.     

The impact of soy-based biodiesel on PAH, nitro-PAH and oxy-PAH emissions from a passenger car operated over regulated and nonregulated driving cycles

This study explores the impact of neat soy-based methyl ester and its 50% v/v blend with low sulphur automotive diesel on PAH, nitro-PAH and oxy-PAH emissions of a Euro 2 compliant diesel passenger car tested on a chassis dynamometer. Emission measurements were evaluated for the certification NEDC, a hot-start UDC (urban part of NEDC) and the non-legislated Artemis driving cycles which simulate urban, rural and highway driving conditions in Europe. Overall, 16 PAHs, 4 nitro-PAHs and 6 oxy-PAHs were determined in the exhaust. The results obtained, showed that PAH emissions decreased with the addition of biodiesel during all driving modes. However, their nitrated and oxygenated products were found to increase with biodiesel compared to diesel fuel. The use of pure biodiesel led in some increases in PAH emissions when compared to its 50% blend. PAH emissions were also found to be adversely influenced by cold-start conditions and certain fuel properties.