Introduction PAHs

History. Interest in sites containing PAHs that antedate the introduction of modern synthetic chemicals. Gas works and the prodnction of tar residues are common in conntries that used coal as a source of coal gas for lighting and heating. Many of these sites have now been abandoned since the industry has been replaced by the dominance of electricity and oil. 

Oxidation is intimately linked to the activation of polycyclic aromatic hydrocarbons (PAH) to carcinogens (1-3). Oxidation of PAH in animals and man is enzyme-catalyzed and is a response to the introduction of foreign compounds into the cellular environment. The most intensively studied enzyme of PAH oxidation is cytochrome P-450, which is a mixed-function oxidase that receives its electrons from NADPH via a one or two component electron transport chain (10. Some forms of this enzyme play a major role in systemic metabolism of PAH (4 ). However, there are numerous examples of carcinogens that require metabolic activation, including PAH, that induce cancer in tissues with low mixed-function oxidase activity ( 5). In order to comprehensively evaluate the metabolic activation of PAH, one must consider all cellular pathways for their oxidative activation. 

Oxygen introduction is appropriate for the degradation of BTEX, mineral oil, phenols, MTBE, PAHs and vinyl chloride. In rare cases, electron acceptors such as nitrate of sulphate may be considered. 

Fig. 8.2 Response of SPR immune biosensor to the introduction of the blood serum at the dilution of 1 500 in the measuring ceU which has a different transducer surface 1 - bare gold, 2 - dodecanethiol, 3 - PAH, 4 - dextran sulfate...

Mobile phases are usually binary or ternary mixtures of solvents. Selectivity is affected mostly by mobile phase composition rather than strength, and peak shape and retention are both influenced by the addition of organic modifiers.101 Some compounds naturally have 77-donor or 77-acceptor groups and can be resolved directly. In many cases, however, introduction of 77-donating groups by derivatization steps is necessary. Figure 2.20 shows the proposed three-point interaction of 3-aminobenzo[a]pyrene, a polycyclic aromatic hydrocarbon (PAH), with a Pirkle-type stationary phase.111 Two possible interactions are illustrated, showing the best orientations for maximum interaction. 

The DLLME technique was introduced by Rezaee et al. and applied for extraction of polycyclic aromatic hydrocarbons (PAHs), pesticides, and alkylbenzenes [17] UV filters [18] and chlorophenols [19] from water samples. Summarized applications can be found in review articles [20-24]. An interesting concept is the introduction of ionic liquids as extractants [25-28]. 

The analysis of PAHs by fluorescence detection HPLC is often the water analysts first introduction to HPLC. The analysis of the WHO six PAHs (section 11.8.1.1) namely fluoranthene, benzo[6]fluoranthene, henzo[k]fluoranthene, benzo[a]pyrene, benzo[g/j/ perylene and indeno[l,2,3-cd]pyrene was carried out using fixed excitation and emission E wavelengths. With the advent of relatively cheap variable wavelength programmable fluorescence detectors, the detectors can be optimised for each separate PAH with a resultant lowering of detection limit. Ultratrace determination of PAHs down to 180fg of benzo[a]pyrene was reported as early as 1983. 

Drilling, pumping, and transporting of crude oil invariably results in some spills of petroleum. These spills result in the introduction of aliphatic hydrocarbons, aromatic hydrocarbons, and PAHs into surface and ground-waters. Many of the chemicals listed on the EPA s list of 129 priority water pollutants (see Section 8.8) enter drinking water sources. 

HPLC with ESI produces mostly molecular ions and few to no molecular fragments. This limits the use of LC-MS in the differentiation of isomers. Two atmospheric pressure ionization (API) interfaces allow for the formation of molecular ion, [PAH]" , yet in general, derivatization and additives are required to induce fragmentation. ESI is an interface that transfers ions from the mobile phase into the gaseous phase for introduction into the mass spectrometer so that atmospheric pressure chemical ionization (APCI) can cause ionization of chemical species in the gaseous phase. Both techniques can be operated in the positive- or negative-ion mode. Reports exist for the ionization of PAHs by both techniques, although there are few actual applications to the analysis of real environmental samples. 

In the introduction to their publication on lung and pancreatic cancer, Hecht and Hoffmann (1571a) reiterated their previous conclusion on the role of PAHs and NNK in cancer causation in tobacco smokers ... 

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