Method validation for determination of the 15 European-priority polycyclic aromatic hydrocarbons in primary smoke condensates by gas chromatography/mass spectrometry: interlaboratory study

A collaborative study was conducted to validate an analytical method for quantification of the 15 polycyclic aromatic hydrocarbons (PAHs) regarded in 2002 as a health concern by the former Scientific Committee on Food of the European Commission (SCF) in primary smoke condensates. The method is based on gas chromatography/mass spectrometry of a cyclohexane extract with solid-phase cleanup through silica gel. The analytes were detected in the selected-ion monitoring mode and quantified by using 3 isotopically labeled internal standard compounds. Seventeen laboratories participated in the collaborative validation study, of which 12 reported valid results. The data were subjected to Cochran, single Grubbs, and double Grubbs tests for statistical outliers. A maximum of 2 outliers was eliminated before further statistical evaluation of the method performance characteristics. Depending on the analyte, the results showed relative standard deviations for repeatability between 4.2 and 30% and for reproducibility from 9.9 to 60%. The recoveries varied between about 50 and 85%, except those for cyclopenta[cd]pyrene, dibenzo[a,l]pyrene, and dibenzo[a,h]pyrene. Nevertheless, because Commission Directive 2005/10/EC allows for a recovery range of 50-120% for (BaP) benzo[a]pyrene in various foods, it can be concluded that the method performs appropriately within the analytical range between 5 and 25 microg/kg of primary smoke condensate. For BaP the validated analytical range covered 5-20 microg/kg, and for benzo[a]anthracene (BaA) 10-25 microg/kg. The method is suitable for monitoring BaP and BaA at their respective maximum permitted levels of 10 and 20 microg/kg. Three analytes, benzo[b]-, benzo[j]-, and benzo[k]-fluoranthene could not be separated by all of the participants and were therefore treated as the sum. Nevertheless, with this method the pattern of the respective concentrations of these 15 PAHs can be monitored in primary smoke condensate as suggested by the SCF.     

Resolution of 13 polycyclic aromatic hydrocarbons by constant-wavelength synchronous spectrofluorometry.

A method capable of determining 13 PAHs (acenaphthene, anthracene, benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, dibenzo[ah]anthracene, fluoranthene, fluorene, indene[1,2,3-cd]pyrene, phenanthrene and pyrene) in a mixture of 16 EPA PAHs by second derivative synchronous spectrofluorometry in the constant wavelength mode was developed. It has not been possible to determine the following PAHs in the mixture: acenaphthylene, benzo[ghi]perylene and naphthalene. The approach studied allows the sensitive, rapid and inexpensive identification and quantitation of 13 PAHs in a solution of hexane. The detection limits are <1 microg L(-1) (except for chrysene and phenanthrene).     

Analysis of co-eluted isomers of high-molecular weight polycyclic aromatic hydrocarbons in high performance liquid chromatography fractions via solid-phase nanoextraction and time-resolved Shpol'skii spectroscopy

We present an accurate method for the determination of isomers of high-molecular weight polycyclic aromatic hydrocarbons co-eluted in HPLC fractions. The feasibility of this approach is demonstrated with two isomers of molecular weight 302 with identical mass fragmentation patterns, namely dibenzo[a,i]pyrene and naphtho[2,3-a]pyrene. Qualitative and quantitative analysis is carried out via laser-excited time-resolved Shpol'skii spectroscopy at liquid helium temperature. Unambiguous identification of co-eluted isomers is based on their characteristic 4.2 K line-narrowed spectra in n-octane as well as their fluorescence lifetimes. Pre-concentration of HPLC fractions prior to spectroscopic analysis is performed with the aid of gold nanoparticles via an environmentally friendly procedure. In addition to the two co-eluted isomers, the analytical figures of merit of the entire procedure were evaluated with dibenzo[a,l]pyrene, dibenzo[a,h]pyrene and dibenzo[a,e]pyrene. The analytical recoveries from drinking water samples varied between 98.2±5.5 (dibenzo[a,l]pyrene) and 102.7±3.2% (dibenzo[a,i]pyrene). The limits of detection ranged from 51.1 ng L(-1) (naphtho[2,3-a]pyrene) to 154 ng L(-1) (dibenzo[a,e]pyrene). The excellent analytical figures of merit associated to its HPLC compatibility makes this approach an attractive alternative for the analysis of co-eluted isomers with identical mass spectra.     

The development of solid-surface fluorescence characterization of polycyclic aromatic hydrocarbons for potential screening tests in environmental samples

This paper presents the characterization of polycyclic aromatic hydrocarbons (PAHs) in solid-surface fluorescence as the first step for obtaining new optical sensors for PAHs screening. The fluorescence properties of the EPA-PAHs (naphthalene, acenaphthene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, benzo[k]fluoranthene, benzo[b]fluoranthene, benzo[a]pyrene, indeno [1,2,3-cd]pyrene, benzo[g,h,i]perylene and dibenzo[a,h]anthracene) on five types of solid-surfaces were evaluated. The experimental variables (pH and percentage of organic solvent in samples) were studied, obtaining different possibilities for making individual sensors for some of these PAHs and the best conditions for developing sensors for PAH screening were also studied.     

Isotope dilution determination of polycyclic aromatic hydrocarbons in olive pomace oil by gas chromatography-mass spectrometry

A gas chromatographic (GC) method with mass spectrometry detection (MS) for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in olive pomace oil has been developed. The oil was diluted with n-pentane and extracted by liquid-liquid partition with dimethyl sulphoxide (DMSO). After water addition and back-extraction with cyclohexane, a thin-layer chromatography on silica gel was performed as a further purification step. The PAHs spot was scraped off from the plate and the final extract was concentrated and analysed by GC-MS in full scan mode. The eight PAHs under investigation were determined in the presence of the corresponding labelled compounds added as internal standards to the sample at the beginning of the analytical process. The identified PAHs were then quantified by the isotope dilution methodology assuring the compensation of the concentration of each analyte for any variation in the sample preparation. The method precision was satisfactory with relative standard deviation (R.S.D.) values in the range 3.6-12.7% for all PAHs. The average recovery rates ranged from 69.0 to 97.5%. Accuracy was also calculated for benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene by analysing a certified reference material (CRM 458, coconut oil) with adequate results. All response curves exhibited a linear fit from 0.1 to 10 microg ml(-1) and the determination coefficients R2 were better than 0.9942. The limits of detection (0.1-0.4 microg kg(-1)) were acceptable when compared with the maximum permitted limit of 2 microg kg(-1) for each of the eight considered PAHs and 5 microg kg(-1) for the sum of the eight PAHs established by the Italian legislation. Measurement uncertainty was finally calculated identifying and quantifying the uncertainty components of the analytical process. The relative expanded uncertainties (Uc), expressed as percent values were in the range 8.5-11.4% thus appropriate for residues quantification in the range of concentrations considered in the present study.     

Error propagation as a factor in selection of measurement intervals for the determination of polycyclic aromatic hydrocarbons by second-derivative spectrofluorimetry

The most suitable wavelength intervals were selected for the determination of 4 polycyclic aromatic hydrocarbons (PAHs; benzo[g,h,i]perylene, dibenzo[a,h]anthracene, pyrene, and triphenylene) in very complex mixtures of 11 PAHs: anthracene, benz[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[g,h,i]perylene, benzo[k]fluoranthene, chrysene, dibenz[a,h]anthracene, phenanthrene, pyrene, and triphenylene. The multiple linear regression algorithm was applied to measurements made in several wavelength intervals previously selected on the basis of sensitivity and minimum number of interfering compounds. Of the different models obtained, those displaying minimum error propagation in the analytical result were selected. By applying the models proposed in this study, we precisely and accurately determined benzo[g,h,i]perylene, dibenz[a,h]anthracene, pyrene, and triphenylene in complex mixtures--a feat that could not be achieved by the use of constant-wavelength spectrofluorimetry in combination with second-derivative techniques.     

Improved efficiency of extraction of polycyclic aromatic hydrocarbons (PAHs) from the National Institute of Standards and Technology (NIST) Standard Reference Material Diesel Particulate Matter (SRM 2975) using accelerated solvent extraction

The efficiency of extraction of polycyclic aromatic hydrocarbons (PAHs) with molecular masses of 252, 276, 278, 300, and 302 Da from standard reference material diesel particulate matter (SRM 2975) has been investigated using accelerated solvent extraction (ASE) with dichloromethane, toluene, methanol, and mixtures of toluene and methanol. Extraction of SRM 2975 using toluene/methanol (9:1, v/v) at maximum instrumental settings (200 °C, 20.7 MPa, and five extraction cycles) with 30-min extraction times resulted in the following elevations of the measured concentration when compared with the certified and reference concentrations reported by the National Institute of Standards and Technology (NIST): benzo[b]fluoranthene, 46%; benzo[k]fluoranthene, 137%; benzo[e]pyrene, 103%; benzo[a]pyrene, 1,570%; perylene, 37%; indeno[1,2,3-cd]pyrene, 41%; benzo[ghi]perylene, 163%; and coronene, 361%. The concentrations of the following PAHs were comparable to the reference values assigned by NIST: indeno[1,2,3-cd]fluoranthene, dibenz[a,h]anthracene, and picene. The measured concentration of dibenzo[a,e]-pyrene was lower than the information value reported by the NIST. The measured concentrations of other highly carcinogenic PAHs (dibenzo[a,l]pyrene, dibenzo[a,i]pyrene, and dibenzo[a,h]pyrene) in SRM 2975 are also reported. Comparison of measurements using the optimized ASE method and using similar conditions to those applied by the NIST for the assignment of PAH concentrations in SRM 2975 indicated that the higher values obtained in the present study were associated with more complete extraction of PAHs from the diesel particulate material. Re-extraction of the particulate samples demonstrated that the deuterated internal standards were more readily recovered than the native PAHs, which may explain the lower values reported by the NIST. The analytical results obtained in the study demonstrated that the efficient extraction of PAHs from SRM 2975 is a critical requirement for the accurate determination of PAHs with high molecular masses in this standard reference material and that the optimization of extraction conditions is essential to avoid underestimation of the PAH concentrations. The requirement is especially relevant to the human carcinogen benzo[a]pyrene, which is commonly used as an indicator of the carcinogenic risk presented by PAH mixtures.     

Collection and analytical characterisation of the atmospheric particulate in the city of Bari

In this paper an application of new procedures for atmospheric particulate analysis is illustrated. PM10, PAHs (benzo[a]anthracene (BaA), benzo[b]fluoranthene (BbF), benzo[j]fluoranthene (BjF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), indeno[1, 2, 3-cd]pyrene (Ip), dibenzo[a, h]anthracene (DbA)) and heavy metals (Cu, Ni, Zn, Co, Mn, Cd, Fe and Pb) were investigated. PM10 determination was performed by gravimetric method, PAHs were measured by GC-MS, and heavy metals by HPIC. An air quality monitoring campaign on the territory of Bari municipality has been organised, and its results are shown.     

Determination of polycyclic aromatic hydrocarbons with molecular weight 302 in water samples by solid-phase nano-extraction and laser excited time-resolved Shpol'skii spectroscopy

Monitoring of high-molecular weight polycyclic aromatic hydrocarbons (HMW-PAH) via simple and cost effective methods still remains a challenge. In this article, we combine solid-phase nano-extraction (SPNE) and 4.2 K laser-excited time resolved Shpol'skii spectroscopy (LETRSS) into a valuable alternative for the water analysis of dibenzo[a,l]pyrene, dibenzo[a,h]pyrene, dibenzo[a,i]pyrene and naphtho[2,3-a]pyrene. In comparison to the original SPNE procedure, the present method improves PAH recoveries and reduces extraction time from 30 to 20 min per sample. Quantitative release of HMW-PAH into the Shpol'skii matrix (n-octane) is best accomplished with a mixture of 48 μL of methanol and 2 μL of 1-pentanethiol. Their migration into the 50 μL layer of n-octane provides highly resolved spectra with distinct fluorescence lifetimes for unambiguous isomer determination. Complete analysis takes less than 30 min per sample and consumes only 100 micro-liters of organic solvents. 500 μL of water are sufficient to obtain limits of detection ranging from 16 ng L(-1) (dibenzo[a,l]pyrene) to 55 ng L(-1) (dibenzo[a,i]pyrene), relative standard deviations better than 3% and analytical recoveries above 90%. Although a straightforward comparison to chromatographic methods is not possible because of the lack of analytical figures of merit on HMW-PAH, the excellent precision of measurements, limits of detection and overall recoveries makes SPNE-LETRSS an attractive approach to water analysis of HMW-PAH.     

分子印迹聚合物选择性降低烟气中稠环芳烃类物质

以芘(PYR)为模板,由热引发本体聚合合成了芘分子印迹聚合物(MIP),考察了印迹聚合物的选择性吸附性能,采用Scatchard模型分析了印迹聚合物的结合特性,用离线固相萃取实验考察了印迹聚合物对同类底物的吸附能力,并将芘分子印迹聚合物应用到卷烟滤嘴中,用GC/MS法考察了卷烟主流烟气中稠环芳烃类物质释放量的变化。 结果表明,芘分子印迹聚合物具有选择性降低卷烟烟气中稠环芳烃类物质的功能,当MIP添加量为1.5 mg时,能将卷烟烟气中的苯并[a]芘(B[a]P)、苯并(a)蒽(B[a]A)和苣(CHR)的释放量分别降低31.08%、25.69%和27.33%。     

Interpretative optimization and artificial neural network modeling of the gas chromatographic separation of polycyclic aromatic hydrocarbons

An interpretative strategy (factorial design experimentation+total resolution analysis+chromatogram simulation) was employed to optimize the separation of 16 polycyclic aromatic hydrocarbons (PAHs) (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo(a)anthracene, benzo(k)fluoranthene, benzo(b)fluoranthene, benzo(a)pyrene, indeno(1,2,3-c,d)pyrene, dibenzo(a,h)anthracene, benzo(g,h,i)perylene) in temperature-programmed gas chromatography (GC). Also, the retention behavior of PAHs in the same GC system was studied by a feed-forward artificial neural network (ANN). GC separation was investigated as a function of one (linear temperature ramp) or two (linear temperature ramp+the final hold temperature) variables. The applied interpretative approach resulted in rather good agreement between the measured and the predicted retention times for PAHs in both one and two variable modeling. The ANN model, strongly affected by the number of input experiments, was shown to be less effective for one variable used, but quite successful when two input variables were used. All PAHs, including difficult to separate peak pairs (benzo(k)fluoranthene/benzo(b)fluoranthene and indeno(1,2,3-c,d)pyrene/dibenzo(a,h)anthracene), were separated in a standard (5% phenyl-95% dimethylpolysiloxane) capillary column at an optimum temperature ramp of 8.0 degrees C/min and final hold temperature in the range of 260-320 degrees C.     

Determination of polycyclic aromatic hydrocarbons by high-performance liquid chromatography-particle beam-mass spectrometry

In this article, we report a high-performance liquid chromatography-particle beam-mass spectrometric (HPLC-PB-MS) method for the determination of polycyclic aromatic hydrocarbons (PAHs). The PB interface consists of a concentric ultrasonic nebulizer with temperature-controlled desolvation chamber and a three-stage momentum separator. The HPLCPB-MS method showed greater sensitivity for PAHs with molecular weights above 178 than for those PAHs with molecular weights below 178. The percent relative standard deviations for the determination of 0.5 ng chrysene, 1.0 ng dibenzo[a,h]anthracene, 1.0 ng benzo[g,h,i]perylene, and 2.5 ng coronene were 20%, 2.5%, 13.7%, and 6%, respectively. The detection limits at signal/noise = 3 were 0.2 ng for chrysene, 1.0 ng for dibenzo[a,h]anthracene, 0.5 ng for benzo[g,h,i]perylene, and 1.5 ng for coronene.     

Optimization of the matrix solid-phase dispersion sample preparation procedure for analysis of polycyclic aromatic hydrocarbons in soils: comparison with microwave-assisted extraction

A fast and simple preparation procedure based on the matrix solid-phase dispersion (MSPD) technique is proposed for the first time for the isolation of 16 polycyclic aromatic hydrocarbons (PAHs) from soil samples. Naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[e]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-c,d]pyrene were considered in the study. Extraction and clean-up of samples were carried out in a single step. The main parameters that affect extraction yield, such as dispersant, type and amount of additives, clean-up co-sorbent and extractive solvent were evaluated and optimized. The addition of an alkali solution in MSPD was required to provide quantitative recoveries. Analytical determinations were carried out by high performance liquid chromatography (HPLC) with fluorescence detection. Quantification limits (between 0.01 and 0.6 ng g(-1) dry mass) were well below the regulatory limits for all the compounds considered. The extraction yields for the different compounds obtained by MSPD were compared with the yields obtained by microwave-assisted extraction (MAE). To test the accuracy of the MSPD technique, the optimized methodology was applied to the analysis of standard reference material BCR-524 (contaminated industrial soil), with excellent results.     

Validation of a method for extraction of polycyclic aromatic hydrocarbons from sewage sludge and analysis by GC-MS

In the present study, the solid–liquid extraction with low temperature purification was validated for the determination of 16 polycyclic aromatic hydrocarbons from sewage sludge by gas chromatography-mass spectrometry. Recoveries ranged 70–114% for naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene and chrysene, while the compounds benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, dibenzo[a,h]anthracene and benzo[g,h,i]perylene showed recoveries of between 40 and 70%. The relative standard deviation was less than 13% for all of the compounds. Negative matrix effect was observed on the 10 compounds with less retention time in the chromatographic analysis and positive matrix effect noticed on the others. The limits of quantification were from 2 to 20 μg kg^?1, about 30 times less than the maximum residue limit allowed in sludge by the European Union. The validated method produced quantification of 11 PAHs in one sludge sample at concentrations ranging 20–2000 μg kg^?1.     

Determination of nanogram/kilogram levels of polycyclic aromatic hydrocarbons in foods by HPLC with fluorescence detection

Methodology was developed for the determination of eight polycyclic aromatic hydrocarbons (PAH) in five food categories including meat/fish, dried dairy products, cereals, leafy vegetables and vegetable/marine oils. The eight PAH were fluoranthene, benzo[a]anthracene, benzo[k]fluoranthene, benzo[b]fluoranthene, benzo[a]pyrene, 7,12-dimethylbenzo[a]anthracene, dibenzo[ah]anthracene and dibenzo[ai]pyrene. Samples were digested with alcoholic KOH followed by partitioning into solvents such as cyclohexane or isooctane. Lipids and other interferences were removed by solvent partitioning with dimethylformamide or dimethylsulfoxide/water. Additional cleanup involving column chromatography on silica gel, Florisil or Sephadex LH-20 was employed as required. Reversed-phase chromatography with gradient elution and fluorescence detection was employed for the determinations. Confirmation was carried out by GC-MS/SIM. Detection limits ranged from 2-90 ng/kg depending on the PAH and food analyzed. Results of a small survey indicated that the meat/fish category had the highest levels (low microgram/kg, on average) of the foods studied.     

Evaluation of Polycyclic Aromatic Hydrocarbons in Smoked Cheeses Made in Poland by HPLC Method

Smoked cheeses are particularly popular among consumers for their flavor and aroma. Of interest, therefore, is the health aspect related to the likelihood of polycyclic aromatic hydrocarbons (PAHs), which are known carcinogens found in smoked products. Thus, the purpose of this study was to evaluate the occurrence of 15 polycyclic aromatic hydrocarbons (PAHs) in smoked and non-smoked cheeses purchased in Poland to monitor their safety. The level of selected PAHs in cheese samples was determined using the HPLC-DAD-FLD method. Most of the cheeses tested met the maximum level of benzo[a]pyrene (2 μg/kg) and the sum of benz[a]anthracene, chrysene, benzo[b]fluoranthene and benzo[a]pyrene (12 μg/kg) established for these products. However, all the cheeses studied in this work had relatively low amounts of the sum of these compounds compared to the information available in the cheese literature, ranging from <LOD to 24.5 μg/kg. This amount does not pose a health risk to consumers. The predominant PAHs found were naphthalene, phenanthrene, fluorene and acenaphthene. Benzo[a]pyrene, the marker compound representing carcinogenic PAHs, was found in 100% and 0% of Polish smoked and non-smoked cheeses, respectively. Although there are currently no regulations for smoked cheeses and maximum concentrations of PAHs in this type of food product, control of PAHs content in cheeses is important due to the mutagenic and carcinogenic potential of these chemicals.     

Determination of polycyclic aromatic hydrocarbons (PAHs) in particulate matter collected with low volume samplers

The determination of polycyclic aromatic hydrocarbons (PAHs) contained in samples of particulate matter (PM), collected with low volume pumps, were carried out with an high sensitivity method that comes from several revisions of a previous method. The present work describes how, by using programmable temperature vaporization (PTV) and a mass selective detector with inert ionic source for the GC-MS analysis and the modifications of microwave-assisted extraction (MAE), the sensitivity of the method can be increased.The PAHs chosen for testing the method are: benzo[a]anthracene (BaA), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), indeno[1,2,3-cd]pyrene (Ip) and dibenzo[a,h]anthracene (DbA). They, in fact, belong to that group of substances that are the most harmful for human health for their carcinogenicity.PAHs recoveries for spiked standard solutions at different concentrations were between 95 and 100% with relative standard deviation ranging from 1 to 3%. The revised method was validated using a 1649a urban dust standard reference material (SRM). The results obtained were in good agreement with certified values. The high sensitivity of the method allows to carry out analyses using only a half of the sampled filter (usually 47 mm diameter membranes). In this way, the other half can be used for the characterization of the other components of PM (heavy metals, organic carbon, ions, etc). The last step has been constituted by application of the optimized method on real samples collected in two cities located in Southern Italy (Bari and Taranto).     

Efficient syntheses of C(8)-aryl adducts of adenine and guanine formed by reaction of radical cation metabolites of carcinogenic polycyclic aromatic hydrocarbons with DNA

The synthesis of the C(8)-aryl adducts of adenine and guanine formed by reaction of the radical cation metabolites of carcinogenic polycyclic aromatic hydrocarbons (PAHs), such as benzo[a]pyrene (BP) and dibenzo[def,p]chrysene (DBC), with DNA is reported. The synthetic approach involves in the key step direct reaction of a PAH aldehyde with a di- or triamine precursor of a purine. The method is operationally simple, affords good yields of adducts, and is broad in its scope. The C(8)-aryl adducts of adenine and guanine derived from BP (6-BP-8-Ade and 6-BP-8-Gua) and DBC (10-DBC-8-Ade and 10-DBC-8-Gua) were synthesized in good yields by this method. Analogous C(8)-aryl adenine and guanine derivatives of other PAHs (anthracene, benz[a]anthracene, and chrysene) were also readily prepared via this approach. This method of synthesis is superior to the only method that is currently available. It entails direct reaction of short-lived PAH radical cations (generated electrochemically or chemically) with 2'-deoxyribonucleosides or the corresponding purine bases. It provides the adducts in low yields accompanied by complex mixtures of secondary products. An alternative synthesis that involves Pd-catalyzed Suzuki-Miyaura coupling of arylboronic acids with 8-bromopurine nucleosides was also investigated. Although the C(8)-purine adducts of PAHs, such as naphthalene, phenanthrene, pyrene, and chrysene, could be prepared by this method, analogous adducts of carcinogenic PAHs and other structurally related PAHs, e.g., anthracene, benz[a]anthracene, benzo[a]pyrene, and dibenzo[def,p]chrysene, could not be obtained. This difference was shown to be a consequence of the facility of competing hydrolytic deboronation of the corresponding arylboronic acids.     

Supercritical fluid extraction of polycyclic aromatic hydrocarbons from liver samples and determination by HPLC-FL

An extraction/clean-up procedure by SFE was developed for isolating PAHs from liver samples for subsequent HPLC-FL determination of ten PAHs in the enriched extract. Recoveries (90-115%) and RSD % (< or =7.7) were satisfactory. When applied to 11 samples of bird of prey (Tyto alba) protected species and classified of special interest, from the Galicia (Northwest to Spain), benzo[ghi]perylene and indeno[1,2,3-cd]pyrene were undetectable; chrysene and benzo[a]pyrene are only detected in one sample; benzo[a]anthracene and benzo[k]fluoranthene are only quantified in one sample and benzo[b]fluoranthene in two samples. The other PAHs, anthracene, fluoranthene and pyrene are present in almost all the samples.     

The Electronic Structure of Carcinogenic Dibenzopyrenes: Linear Dichroism, Fluorescence Polarization Spectroscopy and Quantum Mechanical Calculations

Abstract— In studies of polycyclic aromatic hydrocarbon carcinogenicity three dibenzopyrenes have been named as the strongest mutagens together with the frequently studied benzo[a]pyrene. A detailed study of the electronic structure of one of the three compounds, dibenzo [ a, i ] pyrene, was performed several years ago. Here we present a similar study of the two remaining compounds, dibenzo [ a, h ] pyrene and dibenzo [ a, e ] pyrene. The studies include electronic linear dichroism spectra, fluorescence polarization spectra and quantum mechanical calculations for both molecules, as well as vibrational linear dichroism spectra for the former of the two.