This paper reports the synthesis of haptens and the generation and preliminary evaluation of polyclonal antibodies for the detection of dioxins such as TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) by ELISA (enzyme-linked immunosorbent assay). These novel haptens contain unsaturation between the halogenated dibenzo-p-dioxin ring system and the protein to which it is conjugated, presenting a rigid handle structure. The substitution pattern is identical with or similar to that of TCDD (i.e., 2,3,7,8- or 1,2,3,7,8-). Finally, the haptens lack polar groups for hydrogen bonding. In direct binding assays using the new polyclonal antibodies there was excellent recognition of hapten−protein conjugates, including recognition of those hapten conjugates that were not used as immunogens (i.e., assay systems heterologous in hapten structure). These haptens do elicit selective immune responses in rabbits. Their evaluation in an ELISA format demonstrated the usefulness of these haptens for the detection of dioxins. An IC50 of 0.8 ng/well (16 ng/mL) was observed for an unoptimized system that used 2,3,7-trichloro-8-methyldibenzo-p-dioxin as an analytical surrogate standard. Keywords: TCDD; dioxin; immunoassay; polyclonal antibodies; hapten synthesis; polychlorinated hydrocarbons

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This paper reports the synthesis and characterization of metal-binding indicators with diverse optical responses on exposure to various heavy metal ions. A combinatorial approach, based on azo coupling of diazonium salts with either phenolic compounds or aromatic amines, generated a library of azo dyes. Each reaction mixture, containing the product(s) of azo coupling, was incubated with a series of solutions, each containing a different heavy metal ion. The absorbance and, in some cases, fluorescence spectra of the resulting complexes were recorded. The metal chelates showed extensive diversity in their UV-visible absorbance spectra upon binding to selected metal ions. Of the azo dyes prepared, the terdentate dyes were particularly useful, providing distinct spectral responses to three or more metal ions in a panel of seven.