Oxidized metabolites from cyclopenta‐fused polycyclic aromatic hydrocarbons (CP‐PAHs). A DFT model study of their carbocations formed by epoxide ring opening

A density functional theory (DFT) study aimed at understanding structure–reactivity relationships in the oxidized metabolites of cyclopenta‐fused polycyclic aromatic hydrocarbons (CP‐PAHs) is reported. Epoxidation at various positions was examined in order to identify the most stable epoxide in each class of CP‐PAHs. Relative energies of the carbocations resulting from O‐protonation and epoxide ring opening were analyzed and compared, taking into account the available biological activity data on these compounds. Geometrical, electronic, and conformational issues were considered. Charge delocalization modes in the resulting carbocations were deduced via the natural population analysis (NPA)‐derived changes in charges. Computational results pointed to the importance of the unsaturated cyclopenta ring on the reactivity of these compounds. The reported bioactivity of this highly mutagenic/carcinogenic family of PAHs was observed to parallel their relative carbocation stabilities. A different behavior was observed in crowded non‐planar structures possessing a distorted aromatic system. A covalent adduct formed between a CP‐PAH epoxide and a purine base was computed inside a DNA fragment employing the ONIOM method. Copyright © 2010 John Wiley & Sons, Ltd.     

Analysis of polycyclic aromatic hydrocarbons extracted from air particulate matter using a temperature programmable injector coupled to GC–C–IRMS†

Compound specific isotopic analysis (CSIA) can provide information about the origin of analysed compounds – in this case, polycyclic aromatic hydrocarbons (PAHs). In the study, PAHs were extracted from three dust samples: winter and summer filter dust and tunnel dust. The measurement was performed using the method validated in our laboratory using pure, solid compounds and EPA 610 reference assortment.

CSIA required an appropriate clean-up method to avoid an unresolved complex in the gas chromatographic analysis usually found in the chromatography of PAHs. Extensive sample clean-up for this particular matrix was found to be necessary to obtain good gas chromatography–combustion–isotope ratio mass spectrometry analysis results. The sample purification method included two steps in which the sample is cleaned up and the aliphatic and aromatic hydrocarbons are separated.

The concentration of PAHs in the measured samples was low; so a large volume injection technique (100 μl) was applied. The δ_VPDB ¹³C was measured with a final uncertainty smaller than 1 ‰. Comparison of the δ_VPDB ¹³C signatures of PAHs extracted from different dust samples was feasible with this method and, doing so, significant differences were observed.     

Polycyclic aromatic hydrocarbon and ionic compositions of atmospheric bulk deposition samples at a national park under the influence of intense barbecue smoke

The main aim of this study was to present the effects of barbecue smoke on a small-scale environment, a national park under the influence of intense barbecue smoke, and to scientifically support the sustainable usage of the park. Twelve-weekly bulk deposition samples were collected directly at the barbecuing area, and the samples were analysed for 16 US EPA’s priority PAH compounds and major ions. The mean concentrations of the individual PAHs in the bulk deposition samples ranged from 11.8 ng L^?1 (Ane) to 1085 ± 581 ng L^?1 (IcdP). The most frequently observed PAH compounds in the bulk deposition samples were Np, Anp, Flr, Phe, An, Flu, BkF, BaP and IcdP. The mean total PAH deposition fluxes were determined as 3.6 ± 5.6 µg m^?2 day^?1. The chloride, potassium and the sulphate fluxes were determined as 145.2 ± 267.8 µg m^?2 day^?1, 182.9 ± 291.9 µg m^?2 day^?1, and 111.9 ± 65.9 µg m^?2 day^?1, respectively. Dominant ions in the bulk deposition samples were potassium ion, chloride and sulphate which addressed as the fingerprint of barbecue grilling.     

On the preferential solvation of drugs and PAHs in binary solvent mixtures

The preferential solvation parameters, i.e., the differences between the local and bulk mole fractions of the solvents in solutions of certain drugs and polycyclic aromatic hydrocarbons (PAHs) are derived from their solubilities in binary solvent mixtures by means of the inverse Kirkwood-Buff integral (IKBI) and the quasi-lattice quasi-chemical (QLQC) methods. The solutes include caffeine, niflumic acid, diazepam, benzocaine, phenacetin, paracetamol, nalidixic acid, anthracene, and tr-stilbene and both aqueous and non-aqueous mixtures are considered. The findings are rationalized in terms of the interactions between the solute and solvents and the solvent components among themselves.     

Multivariate optimization of a GC-MS method for determination of sixteen priority polycyclic aromatic hydrocarbons in environmental samples

This paper describes the development and optimization, by using multivariate analysis, of a GC-MS-SIM method for evaluation of the 16 polyaromatic hydrocarbons considered as priority pollutants in atmospheric particulate material by the US EPA. In order to assure an adequate separation in the shortest analysis time, a multivariate design was used to set the conditions of the oven temperature program. The optimization process was carried out using factorial fractional design and Box-Behnken design. The following factors were evaluated: initial temperature, temperature rate #1, intermediary temperature, temperature rate #2, and final temperature. The optimized conditions were set at: 70 degrees C (2 min) --> 200 degrees C (30 degrees C/min, 5 min) --> 300 degrees C (5 degrees C/min, 1.67 min). Moreover, we have also optimized the injector temperature as 310 degrees C and sampling time as 0.8 min. The total analysis time was 33 min. Validation of GC-MS-SIM yielded satisfactory results for repetitivity of the detector response and retention times, and linearity of calibration curves. LOD were established as 0.13-0.34 ng/mL (peak area) and 0.18-0.72 ng/mL (peak height). The method has been shown to be appropriate for the analysis of samples of atmospheric particulate material and/or other environmental matrices.     

Reactive matrix clean-up of naturally occurring perylene in young lignite

Young lignite from two locations in Sendai City, Japan, were analyzed for polynuclear aromatic compounds (PACs). Lignite samples were extracted with toluene and PACs were isolated by a compound-class-selective, reactive matrix clean-up. This clean-up separates all compounds of polynuclear aromatic structure, for example hydrocarbons and ketones and their primary metabolites, from interfering organic compounds. The result of this isolation procedure is, therefore, a group of a large number of polycyclic compounds with different functional groups. Further analysis is done by glass capillary gas chromatography. Perylene was identified as the only compound obtained by the reactive matrix clean-up of lignite samples from both locations. Concentrations were in the range of 1–10 mg kg⁻¹. Conversely, PACs resulting from particulate emissions from fossil fuel combustion always contain isomeric PAHs (polynuclear aromatic hydrocarbons) with some polycyclic aromatic ketones and thousands of primary and secondary metabolites at very low concentrations. This was demonstrated for a sample of urban air particulate matter, which is the source of PAC contamination of surface soil. The absence of accompanying PAHs and polynuclear aromatic ketones in the lignite samples confirms that perylene did not originate from a combustion process. It is assumed that the high concentrations of perylene are the result of a reduction of perylene quinone. Thus, the high perylene content of the lignite samples investigated is of biogenic origin.     

磺化杯芳烃修饰的金纳米粒的合成及其对多环芳烃的比色检测

通过偶联修饰的方法合成了水溶性磺化杯芳烃修饰的金纳米粒, 并研了其对多环芳烃的比色检测. 结果表明, 磺化杯芳烃修饰的金纳米粒对蒽具有良好的识别选择性. 该比色探针对蒽的检测限可达到2×10-6 mol/L. 这种比色传感器能够实现现场原位检测.     

Novel β-cyclodextrin modified quantum dots as fluorescent probes for polycyclic aromatic hydrocarbons （PAHs）

Water-soluble CdSe/ZnS quantum dots （QDs） were prepared via a simple sonochemical procedure using β-cyclodextrin （CD） as surface coating agent. The QDs displayed a sensitive emission enhancement for anthracene over other related polycyclic aromatic hydrocarbons, and the detection limit was around 1.6 × 10^-8 mol/L.     

Preparation of PDMS-coated microspheres by sol-gel method for sorptive extraction of PAHs

In this paper, a novel SPME mode, PDMS-coated solid glass microspheres （SGMs）, were prepared by sol-gel method. Using homemade thermal desorption unit coupled with CGC-FID, six PAHs as model analytes, the performance of the new mode was characterized. The new extractive phase exhibited high thermal stability and satisfactory extraction capability. The detection limits were 0.01-0.045 ng/mL, and the linearity was from 0.5 ng/mL to 96 ng/mL. The R.S.D.s of repeatability for retention time and peak area were all within 0.074% and 6.7%, respectively. The recoveries of the PAHs were 78-127% from the samples taken from river water.