Screening estrogenic oxidized by-products by combining ER binding and ultrafiltration

Ozonation and chlorination of 17β-estradiol (E2), 17α-ethynylestradiol (EE2), bisphenol A (BPA), and nonylphenol (NP) were performed to evaluate the estrogenic activity of the by-products of these endocrine disrupting chemicals (EDCs). After 15 min oxidation, samples were extracted using solid phase extraction (SPE) cartridges, and tested in vitro to measure the estrogenic activities of the oxidized products. MCF-7 cell proliferation assay showed that chlorinated BPA solution displayed slightly stronger estrogenicity than BPA, while chlorinated NP retained about one-tenth of its bioactivity. The estrogenic mono-, di-, tri-, and tetra-ClBPAs and di-ClNP were screened out from the corresponding chlorinated products by a combined application of estrogen receptor (ER) binding with ultrafiltration and identified by high performance liquid chromatography coupled with mass spectrometry (LC/MS). Ozonation of the above four estrogens and chlorination of E2 and EE2 significantly decreased their estrogenic activities under the applied conditions.