Polycyclic aromatic hydrocarbon differences

Polycyclic aromatic hydrocarbons have been classified as human carcinogens because they induce cancers in experimental animals and because smoking and exposure to mixtures of chemicals containing polycyclic aromatic hydrocarbons in the workplace increase the risk of lung cancer in exposed individuals. In experimental animals, benzo(a)pyrene induces cancer in different organs depending on the route of administration.Furthermore, exposure to polycyclic aromatic hydrocarbons commonly occurs in occupations related to traffic (use of diesel engines in transportation and railways). 

All polycyclic aromatic hydrocarbons can be represented by a number of different resonance forms. Naphthalene, for instance, has three. 

Bota et al. [84] used the PCA method to select the optimum solvent system for TLC separation of seven polycyclic aromatic hydrocarbons. Each solute is treated as a point in a space defined by its retention coordinates along the different solvent composition axes. The PCA method enables the selection of a restricted set of nine available mobile phase systems, and it is a useful graphical tool because scatterplots of loading on planes described by the most important axes will have the effect of separating solvent systems from one other most efficiently. 

Figure 4.6 Separation of SRM 1647 and SRM 869 polycyclic aromatic hydrocarbon test mixtures on a series of polymeric octadecylsiloxane reversed-phase columns differing in pore diameter. (Reproduced with permission from ref. 36. Copyright Elsevier Scientific Publishing Co.)...

Chemicals degraded by WRF include pesticides such as organochlorines DDT and its very toxic metabolite DDE [8, 9] and organophosphate pesticides such as chlorpyrifos, fonofos and terbufos [10] polychlorinated biphenyls (PCBs) of different degrees of chlorine substitution [11-13], some even to mineralization [14, 15] diverse polycyclic aromatic hydrocarbons (PAHs) in liquid media and from contaminated soils or in complex mixtures such as creosote [16-18] components of munition wastes including TNT and its metabolites DNT [19-23], nitroglycerin [24] and RDX [25]. 

In complex organic molecules calculations of the geometry of excited states and hence predictions of chemiluminescent reactions are very difficult however, as is well known, in polycyclic aromatic hydrocarbons there are relatively small differences in the configurations of the ground state and the excited state. Moreover, the chemiluminescence produced by the reaction of aromatic hydrocarbon radical anions and radical cations is due to simple one-electron transfer reactions, especially in cases where both radical ions are derived from the same aromatic hydrocarbon, as in the reaction between 9.10-diphenyl anthracene radical cation and anion. More complex are radical ion chemiluminescence reactions involving radical ions of different parent compounds, such as the couple naphthalene radical anion/Wurster s blue (see Section VIII. B.). 

Krauss, M., Wilcke, W. (2001) Predicting soil-water partitioning of polycyclic aromatic hydrocarbons and polychlorinated biphenyls by desorption with methanol-water mixtures at different temperatures. Environ. Sci. Technol. 35, 2319-2325. 

A wide variety of different classes of fluorescent molecules has been investigated in the peroxyoxalate chemiluminescent systems. Among those screened were fluorescent dyes such as rhodamines and fluoresceins, heterocyclic compounds such as benzoxazoles and benzothiazoles, and a number of polycyclic aromatic hydrocarbons such as anthracenes, tetracenes, and perylenes. The polycyclic aromatic hydrocarbons and some of their amino derivatives appear to be the best acceptors as they combine high fluorescence efficiency with high excitation efficiency in the chemiluminescent reaction [28],... 

Berset JD, Ejem M, Holzer R, Lischer P (1999) Comparison of different drying, extraction and detection techniques for the determination of priority polycyclic aromatic hydrocarbons in background contaminated soil samples. Anal Chim Acta 383(3) 263-275... 

In another AT study, Terrado et al. [15] characterised pollution patterns in different parts of the Ebro catchment. In the upper part of the Ebro, pollution was found to be mainly in the form of heavy metals (Zn, Cu, Cr, Pb, Cd and Hg), polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs) and trichlorobenzenes (TCBs). Etrophic conditions were also found. Pollution was found to source mainly from industry and urbanisation. The central Ebro was characterised by nutrient pollution such as the accumulation of Ca, Na, Mg and K, which highlighted the importance of salinisation effects from intensive irrigation and soils with high salt content. In the lower Ebro, organic [DDTs, hexachlorobenzene (HCB) and hexachlorobutadiene (HCBu)] and heavy metal (Hg, Cd, Zn and As) contamination was found to derive mainly from industrial and agricultural activities. 

Ratola N, Lacorte S, Alves A et al (2006) Analysis of polycyclic aromatic hydrocarbons in pine needles by gas chromatography-mass spectrometry. Comparison of different extraction and clean-up procedures. J Chromatogr A 1114 198-204... 

Grimmer, G., H. Brune, R. Deutsch-Wenzel, G. Dettbam, J. Misfeld, U. Able, and J. Timm. 1985. The contribution of polycyclic aromatic hydrocarbon fractions with different boiling ranges to the carcinogenic impact of emission condensate from coal fired residential furnaces as evaluated by topical application to the skin of mice. Cancer Lett. 28 203-211. 

Kennedy, C.J. and F.C.P. Law. 1990. Toxicokinetics of selected polycyclic aromatic hydrocarbons in rainbow trout following different routes of exposure. Environ. Toxicol. Chem. 9 133-139. 

Figure 4. Calculation of the substrate uptake driven diffusive transfer of the polycyclic aromatic hydrocarbon anthracene to Mycobacterium sp. LB501T (solid line) and three other imaginary bacterial strains differing from strain LB501T by their 100-fold lower (dots), 10-fold lower (long dashes) and 10-fold higher (short dashes) specific affinities,...

The alteration of hemoprotein(s) P-450 subpopulations in the rat may be observed spectrally, because after treatment of rats with polycyclic aromatic hydrocarbons, the Soret maximum of the carbonmonoxyferrocytochrome complex undergoes a hypsochromic shift from 450 to 448nm (50). This blue shift was not seen with rainbow trout hepatic microsomes (29,30). However, this does not preclude the induction of novel hemoproteins P-450 since (a) the induced hemoprotein(s) maty not differ spectrally from the constitutive enzymes and (b) the induced-hemoprotein may account for only a small proportion of total hemoprotein P-450, and hence its contribution to the position of the Soret maximum of carbon monoxide-treated reduced microsomes may be negligible. The latter suggestion is supported by the work of Bend et al. with the little skate. These workers have shown that hepatic microsomes from 1, 2,3,4-dibenzanthracene treated skates did not exhibit a hypsochromic shift when compared to control microsomes, however, partially purified hemoprotein exhibited an absorbance maxima at 448 nm (51). 

In summary, it would appear that rainbow trout are responsive to cytochrome P -450-type inducers (e.g. planar polychlorinated biphenyls and polycyclic aromatic hydrocarbons), but are not responsive to cytochrome P-450-type inducers (e.g. phenobar-bital and non-planar polychlorinated biphenyls). Although induced rainbow trout hemoprotein(s) P-450 show high activity with cytochrome P -450 substrates, the induced hemoprotein at 57,000 daltons appears, in electrophoretic and spectral properties, to differ from rodent cytochrome P -450. 

In summary, the different joint effect models of multicomponent pollutant mixtures (i.e., the toxic unit, additive and mixture toxicity indices) were presented. Using such models to analyze the joint effect of a group of toxic and carcinogenic organic compounds such as polycyclic aromatic hydrocarbons will be presented and evaluated in Sect. 3.2. 

The relationship of the selectivity towards rc-electrons can be understood from the differences in the retention factors of polycyclic aromatic hydrocarbons (Figure 3.13). The difference in the retention factors on end-capped and non-endcapped stationary phase materials is less than that of alkylbenzenes. This is due to the water content of the stationary phase. The content may be higher in non-endcapped bonded phases. 

Figure 3.13 n-Electron selectivity of different octadecyl-bonded silica gels towards the retention of polycyclic aromatic hydrocarbons. Columns. , LOC-ODS-E, O, LOC-ODS-NE O, HIC-ODS-E, A, HIC-ODS-NE, eluent, 80% aqueous acetonitrile at 30°C. Compounds polycyclic aromatic hydrocarbons 1, benzene, 2, naphthalene 3, pyrene 4, 3,4-benzopyrene. 

As above, the log k values of the different types of compounds [alkanols (ROH), polycyclic aromatic hydrocarbons (PAH), alkyl benzenes (RB), and alkyl benzoates (ROB)] each demonstrated a linear relationship with their log P values and this relationship was observed with different ratios of acetonitrile and water. The experiment was then performed in eluents containing different organic modifiers and it was found that the behaviour of analytes containing different functional groups differed and the effect depended on the log P of the analyte. 

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