Size distribution of trace organic species emitted from light-duty gasoline vehicles

Size distributions for particulate hopanes+steranes and nonvolatile polycyclic aromatic hydrocarbons (PAHs) emitted from five classes of light-duty gasoline-powered vehicles were measured using the federal test procedure (FTP), unified cycle (UC), and correction cycle (CC) driving cycles. 17alpha(H)-21beta(H)-29-norhopane, 17alpha(H)-21beta(H)-hopane, alpha beta beta-20R-stigmastane, and alpha beta beta-20S-stigmastane were highly correlated and behaved consistently across sampling methods. Coronene and benzo[ghi]perylene were the most ubiquitous heavy PAHs detected in the vehicle exhaust. The emission rates of hopanes, steranes, and PAHs contained in particles with aerodynamic diameters of less than 1.8 ,m varied by 2 orders of magnitude between the lowest- and highest-emitting vehicle classes. Hopane+sterane size distributions emitted from vehicles without an operating catalyst (including "cold-start" emissions from catalyst-equipped vehicles) were bimodal with one mode between 0.10 and 0.18 microm and the second mode >0.32 microm particle diameter. Hopane+sterane emissions released from vehicles with a catalyst at operating temperature had a single mode between 0.1 and 0.18 microm diameter. Hopane+sterane emissions from visibly smoking vehicles had a single mode between 0.18 and 0.32 microm diameter. Heavy PAH size distributions for all vehicle classes consistently had a single mode between 0.10 and 0.18 microm particle diameter (0.1-0.32 microm diameter for smoking vehicles). The geometric standard deviations for PAH size distributions were generally smaller than the corresponding hopane+sterane distributions. These trends suggest that hopanes+steranes and heavy PAHs act as tracers for separate processes of particulate organic carbon formation. PAH and hopane+sterane emissions shifted to smaller sizes during the more aggressive UC and CC driving cycles relative to the FTP. The fraction of PAH and hopane+sterane emissions in the ultrafine (Dp < 0.1 microm) range more than doubled during "warm-start" UC and CC cycles vs the FTP cycle. The enhancement of ultrafine PAHs during "cold-start" UC driving cycles was less pronounced.     

Lubricating oil and fuel contributions to particulate matter emissions from light-duty gasoline and heavy-duty diesel vehicles

Size-resolved particulate matter emissions from heavy-duty diesel vehicles (HDDVs) and light-duty gasoline vehicles (LDGVs) operated under realistic driving cycles were analyzed for elemental carbon (EC), organic carbon (OC), hopanes, steranes, and polycyclic aromatic hydrocarbons. Measured hopane and sterane size distributions did not match the total carbon size distribution in most cases, suggesting that lubricating oil was not the dominant source of particulate carbon in the vehicle exhaust. A regression analysis using 17alpha(H)-21beta(H)-29-norhopane as a tracer for lubricating oil and benzo[ghi/perylene as a tracer for gasoline showed that gasoline fuel and lubricating oil both make significant contributions to particulate EC and OC emissions from LDGVs. A similar regression analysis performed using 17alpha(H)-21beta(H)-29-norhopane as a tracer for lubricating oil and flouranthene as a tracerfor diesel fuel was able to explain the size distribution of particulate EC and OC emissions from HDDVs. The analysis showed that EC emitted from all HDDVs operated under relatively high load conditions was dominated by diesel fuel contributions with little EC attributed to lubricating oil. Particulate OC emitted from HDDVs was more evenly apportioned between fuel and oil contributions. EC emitted from LDGVs operated underfuel-rich conditions was dominated by gasoline fuel contributions. OC emitted from visibly smoking LDGVs was mostly associated with lubricating oil, but OC emitted from all other categories of LDGVs was dominated by gasoline fuel. The current study clearly illustrates that fuel and lubricating oil make separate and distinct contributions to particulate matter emissions from motor vehicles. These particles should be tracked separately during ambient source apportionment studies since the atmospheric evolution and ultimate health effects of these particles may be different. The source profiles for fuel and lubricating oil contributions to EC and OC emissions derived in this study provide a foundation for future source apportionment calculations.     

Indoor levels of polycyclic aromatic hydrocarbons in homes with or without wood burning for heating

The aim of this study was to investigate the impact of domestic wood burning on indoor levels of polycyclic aromatic hydrocarbons (PAHs). Indoor and outdoor concentrations of 27 PAHs were measured during wintertime in homes with (n= 13) or without (n 0) wood-burning appliances and at an ambient site in a Swedish residential area where wood burning for space heating is common. Twenty-four hour indoor levels of anthracene, benzo(ghi)fluoranthene, cyclopenta(cd)pyrene, benz(a)anthracene, chrysene/triphenylene, benzo(a)pyrene (BaP), indeno(1,2,3-cd)pyrene, benzo(ghi)perylene, and coronene were significantly (about 3- to 5-fold) higher in homes with, compared with homes without, wood-burning appliances. The outdoor levels of PAHs were generally higher than the indoor levelsfor all PAHs exceptforthe methylated phenanthrenes. The total PAH cancer potency (sum of BaP equivalents) was significantly higher (about 4 times) in the wood-burning homes compared with the reference homes, with BaP being the largest contributor, while phenanthrene made the largest contribution to the total PAH concentration in indoor and outdoor air. The median indoor BaP level in the wood-burning homes (0.52 ng/m3) was 5 times higher than the Swedish health-based guideline of 0.1 ng/m3, which was also exceeded outdoors on all days (median 0.37 ng/m3).     

Polycyclic aromatic hydrocarbons in fresh and cold-smoked Atlantic salmon fillets

The occurrence of polycyclic aromatic hydrocarbons (PAHs) in smoked fish as a consequence of cold smoking was studied. Raw fillets of Salmo salar from Norway or the Irish Sea were sampled in a modern smokehouse and examined for PAH content. The same fillets, labeled with an identification number, were sampled immediately after the smoking process and analyzed. Among the investigated compounds, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, and benzo[ghi]perylene were detected in both raw and smoked fillets. No significant difference (P < 0.01) was observed between raw and smoked samples in the concentrations of six PAHs, but significant differences were found for fluorene, anthracene, fluoranthene, benz[a]anthracene, and benzo[ghi]perylene. Results confirm that PAHs concentrations in smoked fish are the product of both sea pollution and the smoking process. A modern smoking plant with an external smoke generator and a mild treatment as described here will not add significantly to the concentration of PAHs, except for some compounds.     

Characterization of polycyclic aromatic hydrocarbons (PAHs) in different size fractions in deposited road particles (DRPs) from Lake Biwa area, Japan

Deposited road particles (DRPs) collected from 13 heavily traveled roadways in an urban area of Southern Lake Biwa, Japan, were analyzed for polycyclic aromatic hydrocarbons (PAHs) in seven different particle size fractions (< or = 20 to 1000-2000 microm) and evaluated for the aryl hydrocarbon receptor (AhR) ligand activity by using a yeast bioassay. The mean compositions of individual PAHs to total PAH concentrations in different particle size fractions were 19-21% for pyrene, which was the most dominant component, 14-16% for fluoranthene, and 7-13% for benzo[g,h,i]perylene, which were the next dominant components. The total PAH distribution pattern in different particle size fractions of DRPs was different from the organic matter distribution pattern which increased with decreasing particle size of DRPs, and could be explained by the differences in their sources. Moreover, AhR ligand activities were observed in the DRP extracts of all size fractions. The activity of the DRP extracts from the smallest size fraction was approximately 5 times more potent than that of the largest size fraction in a yeast AhR ligand activity assay. The mean contribution (%) of benzo[k]-fluoranthene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene to the AhR activity of DRP extracts in all size fractions was 1.43-4.11%, 1.63-3.53%, 0.63-1.69%, and 0.31-1.42%, respectively. Although the contribution of PAHs to AhR ligand activity presented in the DRP extracts was relatively low (below 10%), it may be best to remove these DRPs before discharge to receiving water environments.     

Size-resolved polycyclic aromatic hydrocarbon emission factors from on-road gasoline and diesel vehicles: temperature effect on the nuclei-mode

Motor vehicles are a major source of polycyclic aromatic hydrocarbon (PAH) emissions in urban areas. Motor vehicle emission control strategies have included improvements in engine design, exhaust emission control, and fuel reformulation. Therefore, an updated assessment of the effects of the shifts in fuels and vehicle technologies on PAH vehicular emission factors (EFs) is needed. We have evaluated the effects of ambient temperature on the size-resolved EFs of nine US EPA Priority Pollutant PAH, down to 10 nm diameter, from on-road California gasoline light-duty vehicles with spark ignition (SI) and heavy-duty diesels with compression ignition (CI) in summer 2004 and winter 2005. During the winter, for the target PAH with the lowest subcooled equilibrium vapor pressure --benzo[a]pyrene, benzo[ghi]perylene, and indeno[1,2,3-cd]pyrene-- the mass in the nucleation mode, defined here as particles with dp <32 nm, ranged between 14 and 38% for SI vehicles and 29 and 64% for CI vehicles. Our observations of the effect of temperature on the mass of PAH in the nucleation mode are similar to the observed effect of temperature on the number concentration of diesel exhaust particles in the nucleation mode in a previous report.     

Automobile tires--a potential source of highly carcinogenic dibenzopyrenes to the environment

Eight tires were analyzed for 15 high molecular weight (HMW) polycyclic aromatic hydrocarbons (PAH), using pressurized fluid extraction. The variability of the PAH concentrations determined between different tires was large; a factor of 22.6 between the lowest and the highest. The relative abundance of the analytes was quite similar regardless of tire. Almost all (92.3%) of the total extractable PAH content was attributed to five PAHs: benzo[ghi]perylene, coronene, indeno[1,2,3-cd]pyrene, benzo[e]pyrene, and benzo[a]pyrene. The difference in the measured PAH content between summer and winter tires varied substantially across manufacturers, making estimates of total vehicle fleet emissions very uncertain. However, when comparing different types of tires from the same manufacturer they had significantly (p = 0.05) different PAH content. Previously, there have been no data available for carcinogenic dibenzopyrene isomers in automobile tires. In this study, the four dibenzopyrene isomers dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene, and dibenzo[a,h]pyrene constituted <2% of the sum of the 15 analyzed HMW PAHs. These findings show that automobile tires may be a potential previously unknown source of carcinogenic dibenzopyrenes to the environment.     

Polycyclic aromatic hydrocarbons identified in soot extracts from domestic coal-burning stoves of Henan Province, China

Using high-pressure liquid chromatography with ultraviolet-visible diode-array detection, we have analyzed polycyclic aromatic hydrocarbons (PAH) in the dichloromethane extracts of soot deposits from coal-burning stoves in several homes of Henan Province, China--including Linxian County, where esophageal cancer rates are some of the highest in the world. Thirty-two individual polycyclic aromatic compounds, ranging in size from three to eight fused aromatic rings, have been unequivocally identified among the soot extract components--including 20 benzenoid PAH, 6 fluoranthene benzologues, 1 cyclopentafused PAH, 1 indene benzologue, 3 oxygenated PAH, and 1 ring-sulfur-containing aromatic. Most of the identified compounds have been observed before among the products of laboratory coal pyrolysis experiments, but two of the components, the six-ring C24H14 napthol[1,2-b]fluoranthene and the eight-ring C30H16 tribenzo[e,ghi,k]perylene, have never before been documented as products of coal in any system. All of the Henan coal soot extracts are remarkably similar qualitatively in that they contain the same set of identified PAH, but absolute levels of individual species vary by up to 5 orders of magnitude, from sample to sample. The bulk of the identified component mass in all of these soot extracts lies in the five- and six-ring PAH--the largest single class being the family of five-ring C20H12 isomers, to which the samples' most abundant components, benzo[b]fluoranthene and benzo[e]pyrene, belong. The five- and six-ring PAH also account for the majority of the samples' known mutagens. The three strong mutagens identified in these soot samples are the C20H12 benzo[a]-pyrene and two C24H14 PAH, dibenzo[a,e]pyrene and naphtho-[2,1-a]pyrene. Seven moderate mutagens are found among the C20H12, C22H12, C22H14, and C24H14 PAH. A major class of mutagens, the cyclopenta-fused PAH, appears to be absent from these samples, but our detection of an oxidation product of the major mutagen cyclopenta[cd]- pyrene--itself mutagenic--suggests that these soot deposits may contain additional mutagenic cyclopentafused PAH oxidation products as well.     

Sources, vertical fluxes, and equivalent toxicity of aromatic hydrocarbons in coastal sediments of the Río de la Plata Estuary, Argentina

Settling particles and bottom sediments collected at 1, 2.5, and 4 km off the metropolitan Buenos Aires coast in the Río de la Plata were analyzed to evaluate the sources and toxicity of resolved (PAHs) and unresolved (AROUCM) aromatic hydrocarbons. PAHs (0003-2.1 microg g(-1)) and AROUCM (0.01-78 microg g(-1)) presented the highest concentrations nearthe Buenos Aires port and sewer and decreasing values up- and downstream and along on- and offshore gradients. Sediment traps deployed in the Central area revealed large aromatic fluxes (1.3 +/- 1.5 and 31 +/- 47 mg m(-2) day(-1) for PAHs and AROUCM). The composition of sedimentary PAHs was dominated by uniformly distributed high molecular weight pyrogenic PAHs (53 +/- 11% fluoranthene, pyrene, and heavier PAHs), followed by diagenetically derived perylene more abundant in less polluted sites (29 +/- 15%) and lower molecular weight petrogenic PAHs (18 +/- 7.1% phenanthrene, anthracene, and methylated compounds), which covaried inversely with perylene. PAH diagnostic ratios indicated a stronger influence of petrogenic discharges close to the shore and the prevalence of combustion of fossil fuels and vehicle emissions over wood in offshore sediments. Sediment cores showed sustained hydrocarbon levels with decreasing proportion of petrogenic PAHs and relative enrichment of pyrogenic components and perylene down to 20-cm depth. PAH toxicity assessment by sediment quality guidelines (SQG) and dioxin-equivalent factors (PAH TEQ: 0.08-395 pg g(-1) dw) identified 1-2.5 km sediments close to the port and sewer as the most affected area. According to SQG, dibenz[a,h]anthracene and pyrene were the most critical PAHs, followed by benzo[a]pyrene, benz[a]anthracene, and chrysene. In contrast, PAH TEQs were dominated by indeno[1,2,3-cd]pyrene, benzo[k]fluoranthene, benzo[a]pyrene, perylene, and benz[a]anthracene which accounted for an average 86 +/- 5.7% of total TEQs.     

Airborne emissions from 1961 to 2004 of benzo[a]pyrene from U.S. vehicles per km of travel based on tunnel studies

We identified 13 historical measurements of polycyclic aromatic hydrocarbons (PAHs) in U.S. vehicular traffic tunnels that were either directly presented as tailpipe emission factors in microg per vehicle-kilometer or convertible to such a form. Tunnel measurements capture fleet cruise emissions. Emission factors for benzo[a]pyrene (BaP) for a tunnel fleet operating under cruise conditions were highest prior to the 1980s and fell from more than 30-microg per vehicle-km to approximately 2-microg/km in the 1990s, an approximately 15-fold decline. Total annual U.S. (cruise) emissions of BaP dropped by a lesser factor, because total annual km driven increased by a factor of 2.7 during the period. Other PAH compounds measured in tunnels over the 40-year period (e.g., benzo[ghi]perylene, coronene) showed comparable reduction factors in emissions. PAH declines were comparable to those measured in tunnels for carbon monoxide, volatile organic compounds, and particulate organic carbon. The historical PAH "source terms" determined from the data are relevant to quantifying the benefits of emissions control technology and can be used in epidemiological studies evaluating the health effects of exposure, such as those undertaken with breast cancer in New York State.     

Polycyclic aromatic hydrocarbons in mussels (Mytilus galloprovincialis) from the Ionian Sea, Italy

Concentrations of eight polycyclic aromatic hydrocarbons (PAHs) (phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[ghi]perylene) were determined in mussels (Mytilus galloprovincialis) collected between June and September 1995 from 10 locations along a sound of sea formed by two inlets (Mar Piccolo) close to the Gulf of Taranto (Ionian Sea, Italy). In mussels the concentrations of total PAHs were between 14.8 and 645.3 microg/kg wet weight. Among the single identified compounds, the predominance of phenanthrene (29.5 microg/kg wet weight) and anthracene (64.7 microg/kg wet weight) was evident. Another relevant pollutant was pyrene (18.4 microg/kg wet weight) followed by fluoranthene (7.2 microg/kg wet weight), whereas the other compounds showed low levels. The mussels that showed the highest total concentrations of PAHs were collected from stations affected by stronger human activities (industrial fallout, urban wastewaters, and contaminants transported via riverine discharge). Our results were similar to those found in areas classified as moderately polluted. This observation suggests the need for an increased effort in controlling sources of pollution in this area recognized as one of the most productive mussel-farming areas in the Italy.     

Exposure to polycyclic aromatic hydrocarbons through consumption of edible marine species in Catalonia, Spain

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs; naphthalene, acenaphtylene, acenaphtene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-c,d]pyrene, dibenzo[a,h]anthracene, and benzo[g,h,i]perylene) were determined by gas chromatography-mass spectrometry in samples of 14 edible marine species (sardine, tuna, anchovy, mackerel, swordfish, salmon, hake, red mullet, sole, cuttlefish, squid, clam, mussel, and shrimp) collected in March and April 2005. These species are widely consumed by the population of Catalonia, Spain. PAH intake was also estimated for eight age and sex groups of this population. Mussel, clam, and shrimp had the highest PAH concentrations (22.4, 21.5, and 15.9 ng/g of fresh weight, respectively). In contrast, sole (2.5 ng/g of fresh weight) and cuttlefish and squid (both 3.0 ng/g of fresh weight) had the lowest mean concentrations. The highest PAH intake was found in women and girls (5.3 and 5.2 ng/kg/day, respectively), but female adolescents and female seniors had the lowest PAH intakes (3.3 ng/kg/day in both groups). The intake of benzo[a]pyrene and six other PAHs that are probably human carcinogens through consumption of these marine species would be associated with 0.27/10(6) increase in the risk of development of cancer over a 70-year life span.     

Polycyclic aromatic hydrocarbons (PAH) in chocolate on the German market

Benzo[a]anthracene (BaA), chrysene (CHR), cyclopenta[c,d]pyrene (CPP), 5-methylchrysene (5MC), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[j]fluGoranthene (BjF), benzo[a]pyrene (BaP), dibenzo[a,h]anthracene (DhA), indeno[1,2,3-cd]pyrene (IcP), benzo[g,h,i]perylene (BgP), dibenzo[a,l]pyrene (DlP), dibenzo[a,e]pyrene (DeP), dibenzo[a,i]pyrene (DiP) and dibenzo[a,h]pyrene (DhP), the 15 SCFPAH, assessed to be relevant as well as benzo[c]fluorene (BcL) recommended by the European Food Safety Authority (EFSA), were analysed in different types of chocolate. The sample preparation included accelerated solvent extraction (ASE), size exclusion chromatography (SEC) and solid phase chromatography using small silica gel columns. The individual PAH were separated by gas chromatography using a VF-17ms GC column and detected by high resolution mass spectrometry (HRMS). The investigation of 40 samples of various types of chocolate with different cocoa contents resulted in a median benzo[a]pyrene (BaP) content of 0.22 μg/kg. Furthermore, the results showed a linear correlation between the content of BaP and the sum content of the 16 priority PAH. Therefore, the analysis of BaP as a leading substance seems to be suitable to estimate the PAH contamination in chocolate.     

Trophic dilution of polycyclic aromatic hydrocarbons (PAHs) in a marine food web from Bohai Bay, north China

Trophic transfer of polycyclic aromatic hydrocarbons (PAHs) in aquatic ecosystems is an important criterion for assessing their ecological risk. This study analyzed 18 PAHs in phytoplankton/seston, zooplankton, five invertebrate species, five fish species, and one seabird species collected from Bohai Bay, and trophic transfer of the PAHs was determined in the food web, of which the length was approximately 4 on the basis of stable nitrogen isotope values. The concentrations of PAHs (2-64.5 ng/g wet weight) in the marine ecosystem were moderate compared with other marine organisms worldwide, and the PAH compositions exhibited species-specific profiles that were related to trophic levels in some organisms. Significant negative relationships were also found between trophic levels and lipid-normalized concentrations for 10 PAH compounds (acenaphthylene, anthracene, fluoranthene, pyrene, chrysene, benz[a]anthracene, benzo[b]fluoranthene + benzo[k]fluoranthene, benzo[e]pyrene, benzo[a]pyrene, and perylene), and their trophic magnification factors (TMFs) ranged from 0.11 for fluoranthene to 0.45 for acenaphthylene. These results confirm that PAHs undergo trophic dilution in the marine food web, which is likely to be the combined results of low assimilation efficiencies and efficient metabolic transformation at higher trophic levels.     

Polycyclic aromatic hydrocarbon levels and risk assessment for food from service facilities in Korea

ABSTRACT

In this study, levels of benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene (BaP), dibenzo[a,h]anthracene, benzo[g,h,i]perylene and indeno[1,2,3-c,d]pyrene in 412 food items collected from food service facilities in Korea were analysed. The concentrations of the eight polycyclic aromatic hydrocarbons (PAHs) ranged 0.13–0.48 μg/kg. The concentrations of benzo[a]pyrene in all food samples were <1 μg/kg, which is the lowest maximum limit in foods regulated by European Union legislation. PAH contents were employed to conduct exposure and risk assessment. The chronic daily intake of PAHs from 412 food samples was 5.48 × 10^–6-4.70 ×x 10^–4 µg-TEQ_BaP/kg/day with margins of exposure of 1.04 × 10⁹-1.16 × 10¹¹.     

Distribution of aged 14C-PCB and 14C-PAH residues in particle-size and humic fractions of an agricultural soil

Organic matter is considered to be the single most importantfactor limiting availability and mobility of persistent organic pollutants (POPs) in soil. This study aimed to characterize the distribution of 14C-PCB (congeners 28 and 52) and 14C-PAH (fluoranthene and benzo[a]pyrene) residues in an Orthic Luvisol soil obtained from two lysimeter studies initiated in 1990 at the Agrosphere Institute (Forschungszentrum Jülich GmbH, Germany). The lysimeter soils contained a low-density OM fraction, isolated during soil washing, which contained a significant fraction (3-12%) of the total 14C-activity. Soils were also fractionated according to three particle sizes: >20, 20-2, and <2 microm. Relative affinity values of 14C-activity for the different particle sizes varied in the order 20-2 microm > (<2 microm) approximately (>20 microm) for the PCBs. Relative affinity values of 14C-activity for the different particle sizes varied in the order 20-2 microm > (<2 microm) > (>20 microm) for the PAHs. The distribution of 14C-PCB or 14C-PAH residues in the organic and inorganic matrixes of the particle-size fractions was determined using methyl isobutyl ketone (MIBK). 14C-PCB and 14C-PAH-associated activities were primarily located in the humin fraction of the 20-2 and <2 microm particle-size fractions of the soil. A small fraction was associated with the fulvic and humic acid fractions; these were quantitatively more important for the PAHs than the PCBs. There appeared to be a high degree of association of 14C-activity with the mineral fraction following MIBK separation of the humic fractions, ranging between 8 and 52% for 14C-PCBs and 57-80% for 14C-PAHs. The mineral (inorganic) component of the soils apparently played a significant (previously unreported) role in the sequestration of both PCBs 28 and 52 and the PAHs fluoranthene and benzo[a]pyrene.     

冷冻除脂-气相色谱-串联质谱法检测食用植物油中30 种多环芳烃

建立冷冻除脂--气相色谱-串联质谱检测食用植物油中30?种多环芳烃（polycyclic aromatic hydrocarbons,PAH）的方法。选用6?种氘标记PAH为内标,样品经乙腈--丙酮溶液（4∶1,V/V）于离心管中涡旋提取,10?000?r/min离心5?min,－80?℃对油脂冷冻固化,倾出提取液,再经减压浓缩和氮气吹干,以二氯甲烷复溶,气相色谱--串联质谱多反应监测方式进行检测。结果表明,在相应质量浓度范围内30?种PAH均有良好线性（R2＞0.998）,检出限为0.10～1.83?μg/kg,定量限为0.35～6.11?μg/kg,在5、20?μg/kg和50?μg/kg添加水平下的回收率为67.77%～119.28%,相对标准偏差为1.18%～12.47%。采用本方法对市售11?类38?个食用植物油样品的检测显示,萘、1-甲基萘、2--甲基萘、联苯、2,6--二甲基萘、苊烯、苊、2,3,6--三甲基萘、芴、二苯并噻吩、菲、蒽、1-甲基菲、荧蒽、芘、环戊烯[c,d]芘、苯并[a]蒽、屈、苯并[b]荧蒽、苯并[k]荧蒽、苯并[e]芘和苯并[a]芘的检出率均为100%;5--甲基屈、苝、茚并[1,2,3--c,d]芘、二苯并[a,h]蒽、苯并[g,h,i]苝和二苯并[a,l]芘的检出率分别为86.84%、63.16%、81.58%、21.05%、81.58%和26.32%;二苯并[a,e]芘和二苯并[a,h]芘未检出;PAH总量为92.56～905.16?μg/kg,其中苯并[a]芘含量为1.94～7.40?μg/kg,依据食品安全标准限量,PAH处于较安全水平。     

Molecular simulations of benzene and PAH interactions with soot

Molecular mechanics simulations and ab initio calculations were performed to investigate the mechanism of PAH-soot adsorption. Partitioning of benzene, naphthalene, fluorene, phenanthrene, anthracene, pyrene, fluoranthene, benzo[a]anthracene, benzo[k]fluoranthene, benzo[a]pyrene, and benzo[g,h,i]perylene between water and soot was modeled with classical and quantum mechanical calculations in order to determine a method for predicting log(K(d)) values. In both cases, the predicted mechanism of adsorption is interaction of the pi-electrons in the PAH and soot (i.e., pi-pi van der Waals forces). Solvation energies, the energy difference between the solute in the gas phase and in the model aqueous phase, calculated with molecular mechanics did not follow the observed solubilities of the PAHs. Molecular dynamics simulations overestimate the favorability of PAHs in the aqueous phase. Hence, the partitioning between the aqueous phase and soot does not accurately correlate with observed log(K(d)) values. Models of PAH adsorption using structures from molecular mechanics and energies from ab initio calculations do produce water-soot partitioning energies that correlate well with observed log(K(d)) values. The log(K(d)) values for benzene, anthracene, fluorene, and benzo[a]pyrene were predicted based on the correlation between calculated partitioning energies and observed log(K(d)) values. Results presented here suggest that partitioning of PAHs onto soot should depend on the size of the PAH, the planarity of PAH molecule, and the aromaticity of the compound. The methodology developed bythis research can be used to predict PAH K(d) values that have not yet been measured.     

Polycyclic aromatic hydrocarbons in food samples collected in Barcelona, Spain

This study reports on the concentrations of eight polycyclic aromatic hydrocarbons (PAHs) in food samples collected in the city of Barcelona (Catalonia, Spain) from 2003 to 2004. Food samples included meat products, fish (fresh and smoked), other seafood (cephalopods, crustaceans, and bivalves), vegetable oil, and tea. Concentrations of benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[g,h,i]perylene, benzo[alpha]pyrene, benzo[e]pyrene, dibenz[a,h]anthracene, and indeno[1,2,3-c,d]pyrene were determined by reversed-phase high-performance liquid chromatography with fluorescence detection. PAHs were detected in most tea samples (94%), which had the highest concentration of total PAHs (mean concentration of 59 microg/kg). Other food groups with a high presence of PAHs were bivalves (present in 34% of the samples; mean value of 2.7 microg/kg) and meat products (present in 13% of the samples; mean value of 1.7 microg/kg). The PAHs detected most frequently were benzo[e]pyrene and benzo[b]fluoranthene. No sample had levels above current regulation standards. Nevertheless, the frequent presence of PAHs in bivalves, tea samples, and meat products, together with the fact that dietary sources are the main exposure to these carcinogenic compounds, suggests the need for some monitoring scheme to follow up on these trends.