Highly sensitive dioxin immunoassay and its application to soil and biota samples

Tetrachlorodibenzo-p-dioxin (TCDD) is a well-known highly toxic compound th at is present in nearly all components of the global ecosystem, including a ir, soil, sediment, fish and humans. Dioxin analysis is equipment intensive and expensive requiring low ppt or even ppq levels of detection. A simple, rapid, cost-effective method of analysis is desired to enable researchers to explore issues involving dioxin more quickly and to make more rational r egulatory decisions. A sensitive immunoassay for TCDD has been developed in this laboratory. In the present study, this assay is further optimized usi ng a new coating antigen system and validated with biota samples by HRGC-HR MS. The I-50 of current assay to 2,3,7-trichloro, 8-methyldibenzo-p-dioxin (TMDD), a surrogate standard for TCDD, is 36 +/- 6.0 ppt, and the lower det ection limit (LDL) is 4 ppt in the buffer. A good agreement between immunoa ssay and GC/MS was achieved for fish and egg samples. To interface with the immunoassay, a rapid sample preparation method was developed for soil samp les. Without any further cleanup, the soil extracts can be directly used in the ELISA with a detection limit at the low ppt level. It can be used as a n on-site tool for environmental monitoring. (C) 2001 Elsevier Science B.V. All rights reserved.