Polychlorinated dibenzofUrans isomers

Kuroki, H., Haraguchi, K., Masuda, Y. (1984) Synthesis of polychlorinated dibenzofuran isomers and their gas chromatographic profiles. Chemosphere 13(4), 561-573. 

Nagayama J, Kiyohara C, Masuda Y, et al. 1985. Genetically mediated induction of aryl hydrocarbon hydroxylase activity in human lymphoblastoid cells by polychlorinated dibenzofuran isomers and... 

Bradley JC, Nichols AW, Bonaparte K, Campana JE, Clement RE, Czuczwa M, De Roos FE, Lamparski LL, NestrickTJ (1990), Chemosphere 20 487-493. Interlaboratory testing study on 2,3,7,8-substituted polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran isomer standard solutions"... 

Of additional concern is the thermal conversion of PCBs to polychlorinated dibenzofurans, especially when PCB—filled electrical transformers are involved (16). Further, PCB isomers with no chlorine atoms substituted in the ortho. ortho -biphenvl positions are particularly potent as inducers of aryl hydrocarbon hydroxylase activity. The potency of certain dibenzofurans and non-ortho, ortho chlorine substituted PCBs in inducing activity of these enzymes is similar to that of the highly toxic 2,3,7,8-tetrachloro-dibenzo- -dioxin (15. 17., 18). 

Polychlorinated dibenzodioxins (PCDDs) Polychlorinated dibenzofurans (PCDFs) Polychlorinated biphenyls (PCBs) Polyaromatic hydrocarbons (PAHs) Pentachlorophenol Short chain chlorinated paraffins Hexachlorocyclohexane isomers Mercury and organic mercury compounds Cadmium... 

For the quantitative determination of polychlorinated diben-zodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), sample treatment and conservation play crucial roles, too. Only some of the 75 PCDD isomers and 135 PCDF isomers are highly toxic. The collection and analysis of the hazardous compounds present at ultratrace levels in environmental samples must preferably be isomer-specific. The exposure routes for these compounds originate from combustion processes (18-19). 

Group of isomers with the same carbon skeleton and number of chlorines, e.g., TeCDDs Rat hepatoma cell line Polychlorinated biphenyls Polychlorinated dibcnzo-p-dioxin Polychlorinated dibenzofuran Polychlorinated dibenzo-p-dioxin and -furan Tetrachlorodibenzo-p-dioxin (-furan) Pentachlorodibenzo-p-dioxin ( furan) Hexachlorodibenzo-p-dioxin (-furan) Heptachlorodibenzo-p-dioxin ( furan)... 

There are 75 possible isomers of polychlorinated-p-dibenzodioxin (PCDD) and 135 such isomers of polychlorinated dibenzofuran (PCDF). These related compounds are known as congeners. In addition, PCBs form a similar group of 209 related congeners that differ only in the number and pattern of chlorine atoms attached to the parent biphenyl molecule. 

Wakimoto, T., Kannan, N., Ono, M., Tatsukawa, R., Masuda, Y., 1988. Isomer-specific determination of polychlorinated dibenzofurans in Japanese and American Polychlorinated biphenyls. Chemosphere 17, 743-750. 

Kuehl DW, Cook PM, Batterman AR, et al. 1987c. Isomer dependent bioavailability of polychlorinated dibenzofurans from municipal incinerator fly ash to carp. Chemosphere 16 657-666. 

Schecter A, Constable JD, Bangert JV, et al. 1989b. Isomer specific measurement of polychlorinated dibenzodioxin and dibenzofuran isomers in human blood from American Vietnam veterans two decades after exposure to Agent Orange. Chemosphere 18 531-538. 

Bell RA, Gara A (1985) in Chlorinated Dioxins and Dibenzofurans in the Total Environment 11 ,. .Synthesis and characterization of the isomers of polychlorinated dibenzofurans, tetra-through octa , p. 3-19. Butterworth Publishers, Ann Harbor... 

Buser HR, Rappe C (1979), Chemosphere 8 157-174.. .Formation of polychlorinated dibenzofurans (PCDF) from the pyrolysis of individual PCB isomers"... 

Modified neglect of diatomic overlap (MNDO) calculations have been shown to accurately predict the isomer distribution of polychlorinated dibenzo-1,4-dioxins and polychlorinated dibenzofurans in industrial combustion processes, an indication of thermodynamic control in these processes <2002MI1287>. 

Oehme, M., Mano, S., Brevik, E., and Knutzen, J. 1989. Determination of polychlorinated dibenzofuran (PCDF) and dibenzo-p-dioxin (PCDD) levels and isomer patterns in fish, Crustacea, mussel and sediment samples from a fjord region polluted by Mg-production. Fresenius Z. Anal. Chem., 335, 987-997. 

Chloro substitution in the aromatic rings, similar to dioxins, can give rise to several polychlorinated dibenzofurans and then-isomers. 

Polychlorinated dibenzofurans are high to moderately toxic compounds showing toxic actions similar to those associated with the chlorinated dioxins. The toxicity, however, is lower to 2,3,7,8-TCDD. Table 15.3 presents the toxic potency of some of the isomers as compared with TCDD. Diets containing 200 mg/kg to rats, 2,3,4,7,8-pentachlorodi-benzofuran for 13 weeks, caused thymus atrophy, decreased food consumption and body weight, severe lesions in the liver, and death (Pluess et al. 1988). 

Buser, H.R. and C. Rappe, Formation of Polychlorinated Dibenzofurans (PCDFs) from the Pyrolysis of Individual PCB Isomers, Chemosphere, (3), 115-124 (1979). 

Loganathan BG, Kannn K, Watanabe, et al. 1995. Isomer-specific determination and toxic evaluation of polychlrinated biphenyls, polychlorinated/brominated dibenzo-p-dioxins and dibenzofurans, polybrominated biphenyl ethers, and extractable organic halogen in carp from the Buffalo River, New York. Environ Sci Technol 29(7) 1832-1838. 

Polychlorinated hydrocarbons, such as polychlorinated dibenzodioxins, dibenzofurans, and biphenyls exist as a number of different congeners. Some of these are geometric isomers. Many cause a range of toxic effects that are believed to be mediated by interaction with the aryl hydrocarbon receptor (AhR) (they are known as pleiotropic effects). However, not all the isomers cause these effects because they do not all interact with the AhR receptor. To interact with this receptor, the molecule needs to be flat (planar). It can be seen in the diagram (Fig. 5.2)... 

The polychlorinated dioxins and dibenzofurans are separated on a fused silica capillary column. A 60 m long and 0.25 pm ID DB-5, SP-2330, or equivalent column having 0.2 pm film thickness should adequately resolute most isomers. 

DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs) and hexachlorobenzene. Residues levels of industry-derived contaminants such as polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-/>-dioxins and dibenzofurans (PCDD/Fs) were also reviewed. Concentrations of these contaminants in different environmental compartments were expressed as unit equivalent to part-per-billion (ppb) level, unless otherwise specified. The cited values of concentrations from various literature sources were rounded to two significant digits for comparison. A number of factors can influence the concentrations in biological samples. Therefore, whenever possible, for biological samples the lipid normalized concentrations were cited for comparison. 

Handbook of Chemistry and Physics" (1983), 63. Edition, CRC Press, Boca Raton Kurz J, Ballschmiter K (1995), Fresenius J. Anal. Chem. 351 98-109. Isomer-specific determination of 79 polychlorinated diphenyl ethers (PCDE) in cod liver oils, chlorophenols and in a fly ash" Nestrick TJ, Lamparski LL, Crummett WB (1987), Chemosphere 16 777-790. Thermolytic surface reaction of benzene and iron(III) chloride to form chlorinated dibenzo-p-dioxins and dibenzofurans"... 

Tandem MS monitoring selected fragment ions produced in the collision cell of a sector or multiquadrupole instrument or in an ion-trap chamber offers advantages over single-stage MS in terms of selectivity of analysis and specificity in molecular structure determination [104]. Tandem MS techniques have been widely used with good results for the analysis of polyhalogenated compounds, such as isomers of the polychlorinated dibenzo-y dioxines and dibenzofurans [105], PCBs [106], PCNs, and related compounds [107]. However, the applica tion of MS-MS to the analysis of PCTs and toxaphene has been very limited. 

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