Polyaromatic benzo pyrene

A1 Planar polyaromatic hydrocarbons (PAHs) Benzo[ ] pyrene 1-Ethynyl pyrene TCDD, PAHs Many PAHs... 

One of the most studied of the polyaromatic hydro-carbone (PAH) is benzo(a)pyrene (BaP), which is present in coal tar at coke oven plants. The BaP content of coal tar is between 0.1% and 1 % and it contributes to the serious potential health effects on employees exposed to coke oven emissions. The largest sources of BaP are open burning and home heating with wood and coal. The latter alone contributes 40 percent of all the BaP released each year in the USA. 

Figure 5.12 Polyaromatic hydrocarbon species (1) phenanthrene, (2) anthracene, (3) pyrene, (4) benz[o]anthracene, (5) chrysene, (6) naphthacene, (7) benzo[c]phenanthrene, (8) benzo[ghi] fluoranthene, (9) dibenzo[c,g]phenanthrene, (10) benzo[g/ ]perylene, (11) triphenylene, (12) o-terphenyl, (13) m-terphenyl, (14) p-terphenyl, (15) benzo[o]pyrene, (16) tetrabenzonaphthalene, (17) phenanthro[3,4-c]phenanthrene, (18) coronene...

Sometimes orthogonal offline SPE steps were used prior to online SPE LC/MS/MS. These preparation steps were used to remove interference and concentrate samples. In an application to measure urinary N7-(benzo[a]pyren-6-yl)guanine (BP-6-N7Gua), a biomarker for exposure to polyaromatic hydrocarbons (PAHs), a two-step offline SPE was first performed using Sep-Pak C8 (Waters, Milford, Massachusetts) and Strata SCX (Phenomenex, Torrance, California) cartridges to obtain high sensitivity (Chen et al. 2005). The extracts were applied to an online reversed phase SPE LC/MS system. The lower limit of detection was 2.5 fmol/mL when 10 mL of urine was used. 

Fowlie and Bulman [43] have carried out a detailed study of the extraction of anthracene and benzo[tf]pyrene from soil. They carried out a replicated [24] factorial experiment using Soxhlet extraction and Polytron techniques. Soxhlet extraction followed by thin layer chromatography gave higher recoveries of the two polyaromatic hydrocarbons. 

In this study the soil samples were spiked with labelled and unlabelled benzo[<2]pyrene, or anthracene at 5 and 50pg/g soil. The samples were incubated in biometer flasks at 20°C for three and five months for anthracene and benzo[a]pyrene, respectively, allowing degradation to be monitored and the polyaromatic hydrocarbon to interact with the soil matrix. 

Dunn and Stich [78] and Dunn [79] have described a monitoring procedure for polyaromatic hydrocarbons, particularly benzo[a]pyrene in marine sediments. The procedures involve extraction and purification of hydrocarbon fractions from the sediments and determination of compounds by thin layer chromatography and fluorometry, or gas chromatography. In this procedure, the sediment was refluxed with ethanolic potassium hydroxide, then filtered and the filtrate extracted with isooctane. The isooctane extract was cleaned up on a florisil column, then the polyaromatic hydrocarbons were extracted from the isoactive extract with pure dimethyl sulphoxide. The latter phase was contacted with water, then extracted with isooctane to recover polyaromatic hydrocarbons. The overall recovery of polyaromatic hydrocarbons in this extract by fluorescence spectroscopy was 50-70%. 

Stationary phases with a high density of bonded alkyl groups can differentiate between two molecules of identical size where one is planar and the other twisted out of plane. This shape selectivity has been described by Sander and Wise [53] for polymeric stationary phases, where in the preparation, water has been added on purpose and trichloro alkyl silanes have been used. The selectivity for the retention of tetrabenzonaphthalene (TEN) and benzo[a]pyrene (BaP) was taken as a measure to differentiate between polymeric and standard RP columns. With standard ( monomeric ) RP columns, the twisted TBN elutes after the planar BaP, which on the other hand is more strongly retarded as TBN on polymeric stationary phases. In these cases the relative retention of TBN/ BaP is smaller than 1, whereas with monomeric phases the value is >1.5. The separation of the standards on three different phases is shown in Figure 2.9. These stationary phases have superior selectivity for the separation of polyaromatic hydrocarbons in environmental analysis. Tanaka et al. [54] introduced the relative retention of triphenylene (planar) and o-terphenyl (twisted), which are more easily available, as tracers for shape selectivity. However, shape selectivity is not restricted to polymeric phases, monomeric ones can also exhibit shape selectivity when a high carbon content is achieved (e.g., with RP30) and silica with a pore diameter >15 nm is used [55]. Also, stationary phases with bonded cholestane moieties can exhibit shape selectivity. 

Unlike 36, 37 is not carcinogenic because the fluorine atom at position 1 blocks bioactivation of the 1,2-position and, hence, the 1,2-epoxide metabolite is not formed [74]. Replacement of the hydrogen atom at position 2 of 36 with a fluorine atom also abolishes carcinogenicity [74]. Similar observations have been made with fluorine substitution of specific hydrogen atoms of other anthracenes, and of other polyaromatic compounds such as chrysenes and benzo[a]pyrenes [75]. 

Pairs of polyaromatic hydrocarbons eg benzo(a)pyrene and benzo(e)pyrene [214]... 

Arsenic, asbestos, benzo(a)pyrene, hK(chloromethyl)ether, chromium, nickel subsulfide, zinc chromate, tobacco, mustard gas, uranium, acrylonitrile, beryllium, cadmium, l,2-dibromo-3-chloropropane, polyaromatic hydrocarbons (PAHs)... 

Arsenic, benzo(a)pyrene, polyaromatic hydrocarbons, tetrachloroethylene... 

Fig. 4.4.10. Separation of a polyaromatic hydrocarbon mixture on 5 different brands of chemically bonded ODS-silica, the carbon content of the individual materials are given in brackets, a, HC-ODS (8.5%) b, LiChrosorb RP-18 (19.8%) c, Partisil-10 ODS-2 (16%) d, Zorbax ODS (10%) e, pBondapak C,g (10%). Peaks 4, benz[a]anthracene 5, chrysene 6, benzo[e]pyrene 7, benzo b]fluoroanthrene 8, benzo k]fIuoroanthrene 11, benzo[ghi]perylene 12, indeno[l,2,3-c,d]pyrene. Reprinted from Ref. 14 with permission.

Special attention is paid to polyaromatic hydrocarbons, since some of them are carcinogenic. Benzo[o]pyrene is the most typical of such species. Its greatest amounts are formed during engine idling at minimum rpm. 

The reader shonld also be aware that the soldier s skin was in most cases exposed either simnltaneonsly or sequentially to more than one chemical. Veterans were also exposed to petrolenm byproducts such as polyaromatic hydrocarbons (such as benzo[a]pyrene) and heavy metals during the burning of oil fields in Kuwait (Madany and Raveendran, 1992). This complicates any toxicological risk assessment exercise as little is known abont how these various classes of hazardous chemicals influence the dermal absorption of each other. 

To prevent oxidation, either ascorbic acid or sodium thiosulfate is often added to samples to remove free chlorine that could otherwise form trichloro-methane. Polyaromatic hydrocarbons (PAHs), in particular benzo[a]-pyrene, are unstable in chlorinated water and sodium thiosulfate is added to preserve the analytes from degradation by chlorine. To ensure stability of the PAH analytes, the water sample is also acidified, again showing that often a single preservative is not always effective for some analytes. 

Abbreviations NADPH-cytochrome c reductase activity (P-450R), radiometric BPH assay (BPH-R), fluorometric BPH assay (BPH-F), 3-methylcholanthrene (3MC), benzo[a]pyrene (BaP), phenobarbital (PB), 3,4,3 4 -tetrachlorobiphenyl (3MC-type inducer) (3,4,3 4 -TCBP), 2,4,5,2 4 5 -hexachlorobiphenyl (non-coplanar PB-type inducer) (HCBP), j8-naphthoflavone (BNF), polyaromatic hydrocarbons (PAH), — (not determined). 

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