Development of an enzyme linked receptor assay (ELRA) for estrogens and xenoestrogens Original Research Article

Enzyme-linked receptor assays (ELRAs) represent a bioeffects-related approach to the analysis of xenoendocrines. The receptor assay employs the same principles as competitive immunoassays based on ligand–protein interactions. However, receptor binding implicates a biological effect, either agonistic or antagonistic. In this paper, the human estrogen receptor α was used for binding estrogenic substances in environmental samples. A BIAcore biosensor was applied for receptor characterisation and assay development. The ELRA was calibrated using different estrogens and xenoestrogens including o,p′-isomers of DDT and its metabolites. It yielded a detection limit up to 0.1 μg l−1 for 17β-estradiol. A close correlation was obtained when ELRA cross-reactivity data of different estrogenic and non-estrogenic substances were compared with data published for radioreceptor assays. Real-water samples were spiked with 17β-estradiol and measured with the ELRA. Recoveries between 90% and 100% and no significant matrix effects were observed. The ELRA can be used for cost-effective and high throughput screening of estrogens and xenoestrogens in environmental samples.