Polycylic Aromatic Hydrocarbons Research Articles

Overexpression of antioxidant enzymes in ApoE-deficient mice suppresses Benzo(a)pyrene-accelerated atherosclerosis

The carcinogenic polycylic aromatic hydrocarbon, benzo(a)pyrene (BaP), has been shown to generate reactive oxygen species (ROS) and accelerate the development of atherosclerosis. To assess the causal role of BaP-generated ROS in this process, we evaluated atherosclerotic metrics in apolipoprotein E-deficient ( ApoE −/− ) mice with or without overexpression of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and/or catalase. Without BaP, aortic atherosclerotic lesions were smaller in ApoE −/− mice overexpressing catalase or both Cu/Zn-SOD and catalase than in those overexpressing neither or Cu/Zn-SOD only. After treating with BaP or vehicle for 24 weeks, mean lesion sizes in the aortic tree and aortic root of ApoE −/− mice were increased by approximately 60% and 40%, respectively. BaP also increased the levels of oxidized lipids in the aortic tree of ApoE −/− mice and increased the frequency of advanced lesions. In contrast, BaP did not significantly alter lipid peroxidation levels or atherosclerotic lesions in the aortas of ApoE −/− mice overexpressing Cu/Zn-SOD and/or catalase. Overexpression of Cu/Zn-SOD and/or catalase also inhibited BaP-induced expression of cell adhesion molecules in aortas and endothelial cells, and reduced BaP-induced monocyte adhesion to endothelial cells. These observations, together with the functions of catalase and Cu/Zn-SOD to scavenge hydrogen peroxide and superoxide anions, implicate a causal role of ROS in the pathogenesis of BaP-induced atherosclerosis.

PAH contaminated soil remediation by reusing an aqueous solution of cyclodextrins

We studied the possibility to re-use an aqueous solution of methyl-β-cyclodextrin (bpmCD) in order to decontaminate a soil polluted by phenanthrene and pyrene. The loss of bpmCD in the soil was insignificant. In order to eliminate polycylic aromatic hydrocarbons (PAHs) from the contaminated aqueous solution, on one hand we tested their photodegradation using TiO 2 suspensions. But it was inefficient, because of the stabilisation of PAHs within the cavity of bpmCD. On the other hand, we removed PAHs by liquid-liquid extraction with colza oil. This allowed the regeneration of cyclodextrins, by concentrating the pollutants in the organic phase with a small loss of carrier. Contaminated soils were almost completely de-polluted after 2 d of re-circulation, using a 10 mM solution of bpmCD. To reduce the amount of bpmCD loss in the oil phase, we set the fraction of colza oil low, by using a micro-emulsion or by impregnating an organic membrane with the oil. We found this last possibility more interesting.

World Trade Center Disaster and Asthma Type: Thomas et al. Respond

We appreciate the question raised by Ziem regarding the type of asthma reported in children exposed to the World Trade Center (WTC) disaster of 11 September 2001 (9/11) (Thomas et al. 2008). In our study we found an increase in age-specific asthma prevalence among children < 12 years of age, and a new diagnosis of asthma was strongly correlated with a report of exposure to the dust and debris cloud that occurred as buildings collapsed on 9/11. Among children < 5 years of age, we observed an increased prevalence in asthma diagnosis even among those not exposed to the dust cloud. We cannot confirm or disprove Ziem’s very reasonable suggestion that the asthma seen here was irritant rather than allergen induced. The data on asthma diagnoses were reported by parents or other guardians of the children, using a very simple standardized question. We asked whether a medical provider had ever said the child had asthma, and if yes, whether this occurred before or after 9/11. We did not collect information on severity, treatment, or duration, and did not review medical records. A follow-up survey of the children is under way and includes questions to characterize the asthma illness, but those data are not yet available. In small children, in addition to airborne irritants and atopy, respiratory viruses may also play a role in initiation or exacerbation of asthma (Schwarze and Gelfand 2000). It is difficult or impossible in a general pediatric setting to differentiate the type of asthma in children, and many pediatricians use the term “reactive airway disease” in children with recurrent wheezing whether or not there appears to be an allergic component. The airborne contaminants immediately following the 9/11 attacks included a highly alkaline mixture of gypsum, concrete, and synthetic vitreous fibers, further contaminated by metals, organochlorine compounds such as polychlorinated biphenyls and dioxins, and polycylic aromatic hydrocarbons. Later on, settled dust in indoor environments, including residences where many children lived, was found to consist of both fine, coarse, and “supercoarse” (> 10 μm in diameter) particulate matter (Lioy et al. 2006); thus, there was a clear potential for exposure to biologic or allergenic substances. Also, as the cleanup for homes, as well as public areas, was prolonged and difficult, molds could have occurred in some environments and contributed to allergic reactions. Based on earlier studies, Landrigan et al. (2004) noted that “high alkalinity of WTC dust produced bronchial hyperreactivity, persistent cough, and increased risk of asthma.” Increased asthma was subsequently reported in evaluations of 68,444 adults enrolled in the WTC Health Registry (Farfel et al. 2008). Wheeler et al. (2007) found a dose response with increased exposure to the 16-acre “pile” of debris associated with the buildings’ collapse and burning. In an overview of health effects in other adults, Farfel et al. (2008) found an association of asthma with exposure to the initial dust cloud generated by the collapse of the twin towers. We agree with Ziem that, in both children and adults, the exposures observed are more likely related to particulates and other irritants. Further work that includes more detailed histories accompanied by pulmonary function testing is needed to better characterize the pulmonary illness in these individuals.

Total concentration analysis of polycylic aromatic hydrocarbons in aqueous samples with high suspended particulate matter content

The European water framework directive (WFD) requires priority pollutants to be measured in the whole water sample and not only in the dissolved phase. However, it does not give clear definitions on how to achieve this. To overcome this limitation, a new methodology of sample preparation procedure for the analysis of polycyclic aromatic hydrocarbons on the basis of extraction disks is introduced here. The automatable procedure includes a “one-step” extraction of the analytes both dissolved in the liquid phase of the sample and sorbed to suspended particulate matter. The latter is extracted concurrently with the solid-phase extraction (SPE) material within the elution step of the procedure. Separation, identification, and quantification of the analytes is performed by GC–MS. Results from surface water samples spiked with certified sediment up to 1000 mg/l are presented in this work and compared with results derived from liquid–liquid extraction (LLE). Most measured values are within or at least near certified uncertainty limits of the sediment. The SPE disk method shows much higher recoveries and better precision (relative standard deviations between 2% and 11%) than the standard LLE method. For all substances under investigation, the limits of quantification achieved range between 0.001 and 0.005 μg/l.

Is serum γ-glutamyltransferase an exposure marker of xenobiotics? Empirical evidence with polycylic aromatic hydrocarbon

We recently hypothesized that serum gamma-glutamyltransferase (GGT), within its reference range, predicts many diseases as a biomarker for background exposure to various xenobiotics. Even though normal serum GGT was associated with xenobiotics having very long half-lives (heavy metals, dioxin, or organochlorine pesticides), it was unknown whether GGT was associated with xenobiotics with short half-lives, including polycyclic aromatic hydrocarbons (PAHs), well known carcinogens. Among 1256 adult participants in the National Health and Nutrition Examination Survey (NHANES) 2003-2004, urinary metabolites of PAH (monohydroxy-PAH), and serum GGT were measured. We selected the 10 monohydroxy-PAHs (OH-PAHs) for which at least 90% of participants had concentrations greater than the limit of detection. Among the 10 OH-PAHs, eight had significant positive correlations with serum GGT. These correlations were similarly observed in men and women, and in individuals under 60 years of age. Unlike serum GGT, alanine aminotransferase, another liver enzyme, was not associated with OH-PAHs. Taken together with the previous epidemiological evidence, the associations of serum GGT with OH-PAHs reinforce the concept that serum GGT is a marker for various environmental pollutants encountered at background levels in the general population.

Distribution and sources of solvent extractable organic compounds in PM2.5 during 2007 Chinese Spring Festival in Beijing

The solvent extractable organic compounds (SEOC), including n-alkanes, polycylic aromatic hydrocarbons, fatty acids, and dicarboxylic acids in PM2.5 during the 2007 Chinese Spring Festival in Beijing, were measured via gas chromatography-mass spectrometry for determining the characteristics and sources of these organic pollutants. The concentrations of total n-alkanes, PAHs, and organic acids before Chinese Spring Festival Eve (1025.5, 95.9, and 543.3 ng/m3, respectively) were higher than those after (536.6, 58.9, and 331.8 ng/m3, respectively). n-Aalkanes and PAHs had much higher concentration in nighttime than those in daytime because of high relative humidity and low wind speed during the night. Combustion of coal and exhaust emission were major sources of n-alkanes. It could be concluded by the characteristic ratios that the primary source of PAHs in fine particles was the combustion of coal, but the combustion of gasoline was in the next place. The ratios of C18:0/C16 indicated the contribution of vehicular emissions to the fatty acids. Dicarboxylic and aromatic acids were abundant in daytime than in nighttime because these acids were secondary organic acid and the photochemical degradation of aromatic hydrocarbons was the main source.

Interstellar polycylic aromatic hydrocarbons: from space to the laboratory

Polycyclic Aromatic Hydrocarbons (PAHs) are the most likely carriers proposed to account for the Aromatic Infrared Bands observed in emission between 3.3 and 12.7 μm, fulfilling both the chemical (presence of CC and CH aromatic bonds) and excitation constraints. We explain here how the emission spectrum of such species in astronomical environments can be modelled, to obtain for each infrared band both its intensity and its detailed profile. The PAH model suffers from the lack of identification of individual species. Two strategies are described here that are currently being used to progress in this identification process. The first idea is that features in the far IR are much more specific to the exact molecular identity. Therefore their search with the coming Herschel Space Observatory will provide an unambiguous way to identify these molecules through their IR emission. Second, a reflection on where interstellar PAHs come from and how they evolve due to environmental conditions (UV irradiation, gas and dust interactions) is also necessary to get more insights into the nature of interstellar PAH candidates. In particular, recent studies have emphasized a chemical link between PAHs and very small grains in photodissociation regions. Finally, we illustrate in this paper how progress in this field can only be attained by a synergy between astronomical observations, fundamental studies, both theoretical and experimental, and models.

Characteristics, toxicity, and source apportionment of polycylic aromatic hydrocarbons (PAHs) in road dust of Ulsan, Korea

This study identified concentrations, molecular distributions, toxicities, and sources of polycylic aromatic hydrocarbons (PAHs) in road dust from different areas of Ulsan, the largest industrial city in Korea. The total PAH concentrations in industrial areas were dependent on industrial emissions and vehicular exhaust, while those in urban areas were mainly dependent on traffic density, sampling site location, and accumulation of pollutants or road dust. The PAH concentration of each particle size group increased with decreasing particle size. This may be because of the higher surface area available for deposition or coating of PAHs in road dust with smaller particle sizes. The molecular distributions of PAHs among the sites in the petrochemical area and heavy traffic area were similar because of the similarities in their emission sources. The toxic equivalent concentrations (TEQs) of PAHs in the road dust ranged from 0.93 μg/g to 16.74 μg/g in industrial areas and from 4.37 μg/g to 68.84 μg/g in urban areas. The correlation coefficient of total PAH concentration and TEQ in urban areas was 0.98, which was much higher than that in industrial areas where it was 0.75. Principal component analysis showed that PAHs in road dust from Ulsan originate from four main sources: diesel vehicular emissions, oil combustion, gasoline vehicular emissions, and coal combustion.

Surface IR applied to rapid and direct immunosensing of environmental pollutants

This paper describes the elaboration of a model immunosensor monitored by polarization modulation reflection absorption infrared spectroscopy (PM-RAIRS) and quartz crystal microbalance (QCM-D), as well as its reactivity using PM-RAIRS as transduction technique. To prove its relevance, this immunosensor was applied to the detection of benzo[a]pyrene (BaP), a carcinogenic polycylic aromatic hydrocarbon. Very few immunoassays, and even fewer immunosensors, have been described for the assay of BaP, making it an interesting target for analytical device development. The PM-RAIRS immunosensor was constructed on planar gold-coated sensors functionalized with cystamine then glutaraldehyde. Antibodies were immobilized through their affinity to protein G, covalently coupled to the aldehyde layer. In a first stage, a model mouse IgG was utilized to optimize the elaboration parameters; then, a monoclonal anti-PAH antibody was used and detection tests were performed, monitored by PM-RAIRS. The successive functionalization steps were monitored by PM-RAIRS and QCM-D. The binding of the proteins to gold surface, their saturation coverages and association constants, as well as their capture efficiencies were discussed. BaP capture by the antibody layer was evidenced by the appearance of a new ν(C–H) band at 3039 cm −1 typical of aromatic C–H bonds. The integrated area of this band varied linearly with the BAP concentration within the range of tested concentrations, with a limit of detection close to 3 μM. This represents the first example of direct, label-free immunodetection of a low molecular weight molecule by PM-RAIRS transduction. The simplicity and the rapid response of this IR sensor make it already very worthwhile to preliminary on-site measurements.

Phenanthrene stimulates the degradation of pyrene and fluoranthene by Burkholderia sp. VUN10013

Pyrene and fluoranthene, when supplied as the sole carbon source, were not degraded by Burkholderia sp. VUN10013. However, when added in a mixture with phenanthrene, both pyrene and fluoranthene were degraded in liquid broth and soil. The amounts of pyrene and fluoranthene in liquid media (initial concentrations of 50 mg l−1 each) decreased to 42.1% and 41.1%, respectively, after 21 days. The amounts of pyrene and fluoranthene in soil (initial concentrations of 75 mg kg−1 dry soil each) decreased to 25.8% and 12.1%, respectively, after 60 days. None of the high molecular weight (HMW) polycylic aromatic hydrocarbons (PAHs) tested adversely affected phenanthrene degradation by this bacterial strain and the amount of phenanthrene decreased rapidly within 3 and 15 days of incubation in liquid broth and soil, respectively. Anthracene also stimulated the degradation of pyrene or fluoranthene by Burkholderia sp. VUN10013, but to a lesser extent than phenanthrene. The extent of anthracene degradation decreased in the presence of these HMW PAHs.

Facile Synthesis of Monodisperse Magnesium Oxide Microspheres via Seed‐Induced Precipitation and Their Applications in High‐ Performance Liquid Chromatography

AbstractLow‐cost, uniform, and monodisperse spherical particles are desirable for a variety of applications. We report the realization of uniform spherical magnesium oxide with a diameter of 10.5 μm and specific surface area of 140.9 m2 g–1 resulting from a facile seed‐induced precipitation in the presence of a trace amount of phosphate species. By optimizing the experimental parameters, the results demonstrate that the morphologies of magnesium oxide precursors are very sensitive to the amount and the sequence of addition of Mg5(CO3)4(OH)2 · 4H2O seeds, as well as the amount and type of phosphate species. These particles have also been used as a packing material for high performance liquid chromatography. In comparison with the commercial spherical silica, as‐synthesized spherical magnesium oxide exhibits excellent efficiency in the separation of polycyclic aromatic hydrocarbons, and has a larger retention to planar compounds in contrast to non‐planar ones. It is believed that this method will provide a simple and versatile approach to large‐scale production of spherical magnesium oxide via a facile seed‐induced mechanism. The spherical magnesium oxide may find widespread use as a packing material in the group separation of polycylic aromatic hydrocarbons from target samples.

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in sediments from the Mersey Estuary, U.K.

Sediments from the Mersey Estuary were analysed for polycylic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Total PAH concentrations ranged from 626 to 3766 microg/kg and total PCB concentrations ranged from 36 to 1409 microg/kg. These concentrations are intermediate in comparison to other U.K estuaries with similar histories of industrialisation and urbanisation. The distribution of individual PAHs were consistent throughout the Mersey Estuary, this together with molecular indices suggests mainly pyrolitic inputs, augmented by a variety of industrial petrogenic sources. Comparison of tri-to-hepta PCB congeners revealed multiple sources and inputs throughout the estuary. A sediment core collected in close proximity to Garston Docks revealed the take-off, peak pollutant input and recent decline of PCB pollution. However, a second depth profile of sediments at Ellesmere Port showed little change in total or individual PCB concentrations due to extensive sediment reworking and mixing.

Identification, characterization and quantitation of pyrogenic polycylic aromatic hydrocarbons and other organic compounds in tire fire products

On 15 August 2001, a tire fire took place at the Pneu Lavoie Facility in Gatineau, Quebec, in which 4000 to 6000 new and recycled tires were stored along with other potentially hazardous materials. Comprehensive gas chromatography–mass spectrometry (GC–MS) analyses were performed on the tire fire samples to facilitate detailed chemical composition characterization of toxic polycyclic aromatic hydrocarbons (PAHs) and other organic compounds in samples. It is found that significant amounts of PAHs, particularly the high-ring-number PAHs, were generated during the fire. In total, 165 PAH compounds including 13 isomers of molecular weight (MW) 302, 10 isomers of MW 278, 10 isomers of MW 276, 7 isomers of MW 252, 7 isomers of MW 228, and 8 isomers of MW 216 PAHs were positively identified in the tire fire wipe samples for the first time. Numerous S-, O-, and N-containing PAH compounds were also detected. The identification and characterization of the PAH isomers was mainly based on: (1) a positive match of mass spectral data of the PAH isomers with the NIST authentic mass spectra database; (2) a positive match of the GC retention indices ( I) of PAHs with authentic standards and with those reported in the literature; (3) agreement of the PAH elution order with the NIST (US National Institute of Standards and Technology) Standard Reference Material 1597 for complex mixture of PAHs from coal tar; (4) a positive match of the distribution patterns of PAH isomers in the SIM mode between the tire fire samples and the NIST Standard Reference Materials and well-characterized reference oils. Quantitation of target PAHs was done on the GC–MS in the selected ion monitoring (SIM) mode using the internal standard method. The relative response factors (RRF) for target PAHs were obtained from analyses of authentic PAH standard compounds. Alkylated PAH homologues were quantitated using straight baseline integration of each level of alkylation.

Contaminant exposure in outmigrant juvenile salmon from Pacific Northwest estuaries of the United States

To better understand the dynamics of contaminant uptake in outmigrant juvenile salmon in the Pacific Northwest, concentrations of polychlorinated biphenyls (PCBs), DDTs, polycylic aromatic hydrocarbons (PAHs) and organochlorine pesticides were measured in tissues and prey of juvenile chinook and coho salmon from several estuaries and hatcheries in the US Pacific Northwest. PCBs, DDTs, and PAHs were found in tissues (whole bodies or bile) and stomach contents of chinook and coho salmon sampled from all estuaries, as well as in chinook salmon from hatcheries. Organochlorine pesticides were detected less frequently. Of the two species sampled, chinook salmon had the highest whole body contaminant concentrations, typically 2--5 times higher than coho salmon from the same sites. In comparison to estuarine chinook salmon, body burdens of PCBs and DDTs in hatchery chinook were relatively high, in part because of the high lipid content of the hatchery fish. Concentrations of PCBs were highest in chinook salmon from the Duwamish Estuary, the Columbia River and Yaquina Bay, exceeding the NOAA Fisheries' estimated threshold for adverse health effects of 2400 ng/g lipid. Concentrations of DDTs were especially high in juvenile chinook salmon from the Columbia River and Nisqually Estuary; concentrations of PAH metabolites in bile were highest in chinook salmon from the Duwamish Estuary and Grays Harbor. Juvenile chinook salmon are likely absorbing some contaminants during estuarine residence through their prey, as PCBs, PAHs, and DDTs were consistently present in stomach contents, at concentrations significantly correlated with contaminant body burdens in fish from the same sites.

A River-wide Survey of Polychlorinated Biphenyls (PCBs), Polycylic Aromatic Hydrocarbons (PAHs), and Selected Organochlorine Pesticide Residues in Sediments of the Detroit River—1999

The spatial distribution of hydrophobic organic contaminants, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and octachlorostyrene (OCS) in sediments of the Detroit River was established using data from a 1999 river-wide survey. The survey employed a stratified random sampling design that divided the river into six geostatistical zones consisting of upper, middle, and lower U.S. and equivalent Canadian river reaches. Organic carbon normalized OCS sediment concentrations demonstrated no significant differences between U.S. or Canadian sediments or upstream/downstream gradients suggesting that OCS is derived primarily from sources upstream of the Detroit River. In contrast, sum PCBs and sum PAHs were significantly elevated at U.S. as compared to Canadian stations and demonstrated significant increasing upstream/downstream gradients in organic carbon normalized sediment contamination. The upper and middle U.S. river reaches contained a number of near-shore stations with high localized PCB and PAH sediment concentrations suggesting multiple inputs along the upper U.S. portion of the river. Consistent with past surveys, wide-spread sediment contamination of PCBs and PAHs continues to be observed in the highly industrialized Trenton Channel and downstream of Grosse Isle. Threshold effect level (TEL) sediment quality guidelines for PAHs and PCBs were exceeded in 92.6 and 77.8%, respectively, of stations in Trenton Channel and downstream of Grosse Isle. This large reservoir of degraded sediments in the lower U.S. river reach has the potential to enter Lake Erie during sediment disturbance events and likely contributes to gentoxic stress and increased bioaccumulation of PCBs in resident benthos, fish, and wildlife.

Flow dynamics of a pulsed planar expansion

Plasma expansion sources are popular in molecular spectroscopy and in astrochemistry because they generate cold radicals and ions in detectable amounts. The dynamics of a planar flow generated by a pulsed discharge slit nozzle (PDN) have been numerically investigated for a variety of carrier gases seeded with various molecular species. The determination of the bulk flow characteristics is key to a comprehensive modeling of the plasma that is produced in PDN sources. It is found that the flow is established and stabilized within 75 and 25 μs when Ar and He are used as carrier gases, respectively. The residence time in the inter-electrode active region is found to be considerably shorter with He than with Ar gas carrier. The detection signal observed upon injection of astrochemical species such as polycylic aromatic hydrocarbons (PAHs) in moderate amounts in the carrier gas exhibits a non linear relation with the initial PAH concentration in the reservoir which is governed by the temperature. The local temperature along the flow axis can be predicted from the initial conditions using the isentropic equation. However, the local pressure and density behavior diverge significantly from an isentropic flow. Finally, implications for the characteristics of the plasma expansion are discussed to help design future laboratory simulations.

Emission of particulate matter and polycyclic aromatic hydrocarbons from select cookstove–fuel systems in Asia

Abstract Emission of particulate matter (PM) and polycylic aromatic hydrocarbons (PAH) from 12 selected cookstoves in Asia burning wood fuel, rice husk briquettes and anthracite coal was investigated. Monitoring was conducted using a hood and a semi-VOC sampling train. 17 PAH (16 US EPA priority plus B e P ) were analyzed by HPLC-UV to yield PAH in the PM and gas phase samples separately. PM emission factor for wood fuel, rice husk briquettes and anthracite coal, is around 2– 5 g kg - 1 , 5 g kg - 1 and 7 g kg - 1 , respectively. Emission factor of 17 PAH for the two biomass fuels is 24– 114 mg kg - 1 and 140 mg kg - 1 , respectively. The majority of PAH in the biomass fuel smoke is of light and more volatile PAH with above 86% of the total 17 PAH found in the vapor phase. For the anthracite coal emission factor of 17 PAH was low ( 2 mg kg - 1 ) and found only in the PM phase. PAH content of PM varies with cookstoves and is 0.08– 1.64 mg g - 1 (of PM) for total 17 PAH, 0.06– 0.98 mg g - 1 for genotoxic PAH, and 0.001– 0.147 mg g - 1 for B a P alone. Emission data from this study was collated with those previously presented, which provides a broader emission database for domestic combustion.

Gold Nanoparticle-Modified Etched Capillaries for Open-Tubular Capillary Electrochromatography

The use of gold nanoparticles in conjunction with etched capillary-based open-tubular capillary electrochromatography (OTCEC) to improve the efficiency of separation and the selectivity between selected solutes is described. The fused-silica capillaries (50-microm i.d.) were etched with ammonium hydrogen difluoride, followed by prederivatization of the new surface with (3-mercaptopropyl)trimethoxysilane (MPTMS) for the immobilization of dodecanethiol gold nanoparticles, for OTCEC. The electrochromatography of a "reversed-phase" test mixture and of selected polycylic aromatic hydrocarbons was investigated, and efficient separations and high theoretical plate numbers per meter were obtained. The electroosmotic flow characteristics of the etched gold nanoparticle capillary, unetched gold nanoparticle capillary, bare capillary, and etched bare capillary were studied by varying the percentage of organic modifier in buffer, buffer pH, and separation voltage. Optical microscopy and scanning electron microscopy were used to examine the process of etching and modification and the surface features of the etched gold nanoparticle capillary. The results confirm that dodecanethiol gold nanoparticles bonded on the etched inner wall of the fused-silica capillary can provide sufficient solute-bonded phase interactions to obtain OTCEC separations with reproducible retention, as well as characteristic reversed-phase behavior, even with the inner diameter of the capillary of 50 microm.

Catalytic oxidation of naphthalene using a Pt/Al2O3 catalyst

Polycylic aromatic hydrocarbons (PAHs) are listed as carcinogenic and mutagenic priority pollutants, belonging to the environmental endocrine disrupters. Most PAHs in the environment stem from the atmospheric deposition and diesel emission. Consequently, the elimination of PAHs in the off-gases is one of the priority and emerging challenges. Catalytic oxidation has been widely used in the destruction of organic compounds due to its high efficiency (or conversion of reactants), its economic benefits and good applicability.This study investigates the application of the catalytic oxidation using Pt/γ-Al2O3 catalysts to decompose PAHs and taking naphthalene (the simplest and least toxic PAH) as a target compound. It studies the relationships between conversion, operating parameters and relevant factors such as treatment temperatures, catalyst sizes and space velocities. Also, a related reaction kinetic expression is proposed to provide a simplified expression of the relevant kinetic parameters.The results indicate that the Pt/γ-Al2O3 catalyst used accelerates the reaction rate of the decomposition of naphthalene and decreases the reaction temperature. A high conversion (over 95%) can be achieved at a moderate reaction temperature of 480K and space velocity below 35,000h−1. Non-catalytic (thermal) oxidation achieves the same conversion at a temperature beyond 1000K. The results also indicate that Rideal–Eley mechanism and Arrhenius equation can be reasonably applied to describe the data by using the pseudo-first-order reaction kinetic equation with activation energy of 149.97kJ/mol and frequency factor equal to 3.26×1017s−1.

The mutagenic effects of 7,12-dimethylbenz[ a]anthacene, 3-methylcholanthrene and benzo[ a]pyrene to the developing Syrian hamster fetus measured by an in vivo/in vitro mutation assay

The transplacental mutagenicity of three polycylic aromatic hydrocarbons, 7,12-dimethylbenz[ a]anthacene (DMBA), 3-methylcholanthrene (MC) and benzo[ a]pyrene (BP), was measured by an in vivo/in vitro mutation assay. Fetal sensitivity and dose-response characteristics with regard to transplacental mutagenesis by these compounds have never been quantified. In the current experiment, pregnant Syrian hamsters were exposed to these compounds at day 12 of gestation. Twenty-four hours later the fetuses were removed and their cells were allowed a 5-day expression time in culture. They were then seeded for colony formation and also for mutation selection by diphtheria toxin. DMBA at 0.2 mmol/kg (51.3 mg/kg) had an induced mutant frequency of 1.56×10 −4 mutants per surviving cell. This was 598 times the historical control. DMBA at 0.2 mmol/kg was 3.6 times more potent than the highly mutagenic positive control, ethylnitrosourea, at 1 mmol/kg. DMBA also caused a dose-dependent increase in cloning efficiency, which was highly correlated with mutation rate. BP and MC were less effective than DMBA, causing increased mutations that were 31.6 and 17.7 times the historical control, respectively, and for neither was there any correlation of mutation rate with cloning efficiency. The special effectiveness of DMBA as a transplacental mutagen may relate to its ability to cause increased cell division and fixation of DNA lesions as mutations.