A radioimmunoassay for chlorinated dibenzo- p-dioxins

A double-antibody radioimmunoassay procedure has been developed for the determination of chlorinated dibenzo- p-dioxins in environmental samples including animal tissues. The limit of detection is approximately 25 pg of 2,3,7,8-tetrachlorodibenzo- p-dioxin. Assuming an appropriate cleanup procedure is used, chlorinated dibenzofurans are the only likely interferences and these can be distinguished through the use of the two antisera of different dibenzofuran/dibenzodioxin selectivities. The preparation of a reproducible antigen, an appropriate radiolabeled hapten, and effective sample extracts are described. A feature of the assay method is the use of nonionic detergent (Cutscum or Triton X-305) to solubilize the extremely hydrophobic dibenzo- p-dioxins in a manner permitting their binding by antibodies. The immunoassay is applicable to screening samples in order to minimize the demand for mass spectrometric screening and to routine monitoring for exposure to known chlorinated dibenzo- p-dioxins in potentially contaminated environments.