OCR Text |
Show FIGURE 1: STRUCTURE, NOMENCLATURE AND IS<»-fERS OF DIOXINS AND FURANS Dioxins and furans contain two benzene rings joined by one or two aloms of oxygen, with from one to eight chlorine atoms attached to the benzene rings. There are 75 possible dioxin isomers and l35 possible furan isomers. Seven of the dioxjn isomers mId len of the furan isomers have chlorine atoms attached in the 2, 3, 7 and 8 positions. 9 1 0 8 I 7 0 6 4 9 1 8 7 0 6 4 Homologues Monochlorinated dioxins (Dl) (D2 ) Trichlorinated dioxins (D3) Tetrachlorinated dioxins (D4) Pentachlorinated dioxins (Ds) Hexachlorinated dioxins (Ds) Heptachlorinated dioxins (D7) Octachlorinated dioxin (Da) Dichlorinated dioxins Total dioxins (D4-a) Monochlorinated furans (Fl) Dichlorinated furans (F2) Trichlorinated furans (F3) TelrachlorinHted furans (F4) Pentachlorinated furans (Fs) Hexachlorinated furans (Fs) Heptachlorinated furans (F7) Octachlorinated furan (Fa) Total furans (F4-a) The 2.3.7.8-substituted 2,3,7,8 D4 1,2,3,7,8 Ds 1,2,3,4,7,8 De 1,2,3,6,7,8 Ds 1,2,3,7,8,9 D6 1,2,3,4,6,7,8 D7 1,2,3,4,6,7,8,9 Da 3 2 3 DIOXINS (polychlorinated dibenzo-p-dioxins) (PCDD) Mol wt. 218.6 253.0 287.5 321.9 356.4 390.8 425.3 459.8 202.6 237.0 271.5 305.9 340.4 374.8 409.3 443.8 FURANS (polychlorinated dibenzofurans) (PCDF) Total 2,3,7,8-substituted Isomers Isomers 2 0 10 0 14 0 22 1 14 1 10 3 2 1 1 1 75 7 4 0 16 0 28 0 38 1 28 2 16 4 4 2 1 1 135 10 dioxin and furan isomers: 2,3,7,8 F4 1,2,3,7,8 Fs 2,3,4,7,8 Fs 1,2,3,4,7,8 F6 1,2,3,6,7,8 Fs 1,2,3,7,8,9 F6 2,3,4,6,7,8 Fe 1,2,3,4,6,7,8 F7 l,2,3,4,7,8,9 F7 1,2,3,4,6,7,8,9 Fa |