Fluoranthene PAHs

The predicted antiaromaticity in fluoranthene-PAH carbocations (NICS) could well be the origin of the observed paratropicity and proton shielding in these nonalternant-PAH carbocations. The observed broadening in the proton spectra in several cases, the appearance of upfield-shifted broad humps, and the formation of insoluble precipitates (which upon quenching returned the intact PAH) were taken as evidence for the concomitant presence of the RC which could additionally contribute to proton shielding. 

A limited number of persistent carbocations from fluoranthene PAHs have been generated.39 Available NMR data are collected in Fig. 53. The site of attack is the same for parent fluoranthene and benzo[b]fluoranthene. Methoxy substitution directs the attack ortho to the substituent. The resulting non-alternant carbocations are paratropic, and most proton resonances are shielded relative to their neutral precursors. The 13C NMR assignments and the derived A<5 values are gathered. The uniform charge alternation pattern in the carbocations derived from fluoranthene and benzo[b] fluoranthene breaks down at C-7b. The methoxy derivative exhibits limited charge delocalization. 

Fig. 53. H and 13C NMR data for arenium ions from fluoranthene PAHs (M13C values in parentheses).

Figure 3 depicts profiles of Total PAH fluxes vs. time (36). The following polycyclic hydrocarbons have been determined by high performance liquid chromatography, variable wavelength absorption detection Naphthalene, acenaphthylene, 7,12-dimethylbenzanthracene, 2-methylnaphtalene, fluorene, acenaphtene, phenanthrene, 2,3-dimethylnaphtalene, anthracene, fluoranthene, 1-methylphenanthrene, pyrene, 2,3-benzofluorene, triphenylene, benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, perylene, benzo(e)pyrene, 1,2,3,4-dibenzanthracene, benzo(a)pyrene, and 1,2,5,6-dibenzanthracene. 

Fig. 34.3. UV-visible spectra of two polyaromatic hydrocarbons (PAHs), fluoranthene and chrysene.

The most significant differences (i.e. independence) in the analytical methods are provided in the final chromatographic separation and detection step using GC/ MS and LC-FL. GC and reversed-phase LG provide significantly different separation mechanisms for PAHs and thus provide the independence required in the separation. The use of mass spectrometry (MS) for the GC detection and fluorescence spectroscopy for the LG detection provide further independence in the methods, e.g. MS can not differentiate among PAH isomers whereas fluorescence spectroscopy often can. For the GC/MS analyses the 5% phenyl methylpolysiloxane phase has been a commonly used phase for the separation of PAHs however, several important PAH isomers are not completely resolved on this phase, i.e. chrysene and triphenylene, benzo[b]fluoranthene and benzofjjfluoranthene, and diben-z[o,h]anthracene and dibenz[a,c]anthracene. To achieve separation of these isomers, GC/MS analyses were also performed using two other phases with different selectivity, a 50% phenyl methylpolysiloxane phase and a smectic liquid crystalline phase. 

BCR Analytical Approach for the Certification of PAHs in Natural Matrix CRMs Prior to the certification analyses for the CRM, each participating laboratory has to prepare standard solutions of the analytes to be determined from certified reference compounds (purity >99.0 %) to calibrate their instruments for response and response linearity (multiple point calibration), detection limit, and reproducibility. In the case of PAH measurements, reference compounds of certified purity are used as internal standards, which are not present at a detectable concentration in the matrix to be analyzed (e.g. indeno[i,2,3-cd]fluoranthene (CRM 267), 5-methylchrysene (CRM 081R), benzo[f ]chry-sene (CRM 046), picene (CRM 168), and/or phenanthrene-dio). 

Polycyclic (also called polynuclear) aromatic hydrocarbons (PAHs) are composed of multiple rings connected by shared carbon atoms (i.e., separate rings are combined by sharing two carbon atoms). All these compounds are pure hydrocarbons except for the two benzo-fluoranthenes, polychlorinated biphenyls (PCBs), and 2-chloronaphthalene. Moore and Ramamoorthy110 review the behavior of PAHs in natural waters. 

PAHs Benzo[a]pyrene, chrysene, fluoranthene Oil industry (P,D) Gasoline stations (P) Manufactured gas plants (P,D) Wood preservation sites (P) Municipal waste incineration (P,D) Automobile exhaust (D) 13.3 [43, 45]... 

Hemoglobin is another heme-containing protein, which has been shown to be active towards PAH, oxidation in presence of peroxide [420], This protein was also modified via PEG and methyl esterification to obtain a more hydrophobic protein with altered activity and substrate specificity. The modified protein had four times the catalytic efficiency than that of the unmodified protein for pyrene oxidation. Several PAHs were also oxidized including acenaphthene, anthracene, azulene, benzo(a)pyrene, fluoranthene, fluorene, and phenanthrene however, no reaction was observed with chrysene and biphenyl. Modification of hemoglobin with p-nitrophenol and p-aminophenol has also been reported [425], The modification was reported to enhance the substrate affinity up to 30 times. Additionally, the solvent concentration at which the enzyme showed maximum activity was also higher. Both the effects were attributed to the increase in hydrophobicity of the active site. 

Fluoranthene is one of the more prevalent PAH in the human environment. Although fluoranthene is not active as a carcinogen, its 2- and 3-methyl derivatives have been shown to be active as tumor initiators (105). The major mutagenic metabolite of fluoranthene in the Ames assay has been identified as the 2,3-dihydrodiol (31)... 

Fluoranthenes. With the exception of 3-methylcholanthrene, much less work has been undertaken on nonalternant PAHs. Several recent studies have reported on the major metabolites and mutagenicity of various fluoranthenes (181-185), but little is known about the DNA adduct which they form. Some studies on dibenzo[a,e]fluoranthene showed that several adducts are formed by microsomal incubations (185) and additional studies will be required to provide complete structural elucidation of the products formed. 

Finally, three additional individual data matrices were obtained for soil (so1 so2, and so3), in this case with the same number of samples (rows) for each of them. A new soil data matrix (SO) was obtained after individual matrix concatenation containing 36 samples in total (12 samples analyzed in 3 sampling campaigns) (see Fig. 7). Fifteen variables (all of them detected in SE as well) were measured in every sample PAHs (acenaphtylene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(a)pyrene, indeno (l,2,3-cd)pyrene, dibenzo(a,h)anthracene, and benzo(g,h,i)perylene), an organophosphate compound (tributylphosphate), and an OC (4,4 -DDE). 

Fig. 10 Composition and spatial distribution of the main patterns of contamination identified in sediment of the Ebro River basin from year 2004 to 2006. Different temporal distribution of the PAHs pattern of contamination over the territory and constant distribution in time of the APs and heavier PAHs as well as the OCs pattern. Big circles representing higher levels of pattern contribution than small circles. Variables identification 1, naphthalene 2, acenaphtylene 3, acenapthene 4, fluorene 5, phenanthrene 6, anthracene 7, fluoranthene 8, pyrene 9, benzo(a) anthracene 10, chrysene 11, benzo(b)fluoranthene 12, benzo(k)fluoranthene 13, benzo(a)pyr-ene 14, indeno(l,2,3-cd)pyrene 15, dibenzo(a,h)anthracene 16, benzo(g,h,i)perylene 17, octyl-phenol 18, nonylphenol 19, tributylphosphate 20, a-HCH 21, HCB 22,2,4-DDE 23,4,4-DDE 24, 2,4-DDD 25, 4,4-DDD 26, 2,4-DDT 27, 4,4-DDT...

The numbering and lettering system for several PAHs is also given. Compounds are (1) naphthalene, (2) fluorene, (3) anthracene, (4) phenanthrene, (5) aceanthrylene, (6) benzo[a]-fluorene, (7) benzo[a]fluorene, (8) benzo[a]-fluorene, (9) fluoranthene, (10) naphthacene, (11) pyrene, (12) benzofluoranthene, (13) benzo[g,/r,fluoranthene, (14) perylene, (15) benzo[e]pyrene, (16) benzo[g,/),/]perylene, (17) anthanthrene, and (18) coronene. 

Human activities have resulted in exposure of Antarctic fishes to petroleum-derived PAHs (McDonald et al. 1992). Fish captured near Palmer station on the Antarctic peninsula had induced EROD activities and elevated concentrations of biliary PAH metabolites of phenanthrene and naphthalene when compared to conspecifics from reference sites (McDonald et al. 1995). Artificial reefs consisting of oil and coal flyash stabilized with cement and lime in Florida waters near Vero Beach contained elevated PAH levels ranging from as high as 1.2 mg fluoranthene/kg and 0.25 mg naphthalene/kg. But there is negligible leaching because seawater is not an effective medium for removing PAHs from reef bricks or the ash (Frease and Windsor 1991). 

---