Estrogens are potent endocrine-disrupting steroid hormones that are excreted by vertebrates and are mainly introduced into the environment through raw and treated sewage. Often, hypochlorite is added as a means of disinfection for wastewater. However, hypochlorite can react with estrogens and ambient bromide to produce chlorinated and brominated estrogens. Halogenated estrogens can be readily decomposed by sunlight but the photolysis products are not well known. Batch experiments (1L) were conducted using 2,4-dibromo-17β-estradiol (1mg/mL) in deionized water. The flasks were exposed to sunlight and 100mL samples were collected at four time points: 0 min, 30 min, 60 min, 120 min. These samples were frozen, lyophilized, and extracted then analyzed using high pressure liquid chromatography coupled with a high resolution mass spectrometer (Sciex TripleTOF 5600, resolution 30,000 @ m/z 400) in both positive and negative electrospray ionization mode with tandem mass spectrometry. A total of 30 unique photoproducts were identified. Of these, 14 were only detected in negative mode, 14 were only detected in positive mode, and 2 were detected in both modes. The photoproducts contained 12-20 carbons, 2-9 oxygens, 0-2 bromines, and had 1-9 double bond equivalences. Most of the photoproducts contained 0 bromines (13 compounds) or 1 bromine (13 compounds). Based on the carbon number and double bond equivalences, we hypothesize that most of these compounds have structures similar to estrogens with oxygen and carbonyl additions. The free (17β-estradiol) and monobromo (2-bromo-17β-estradiol) forms of 2,4-dibromo-17β-estradiol were not observed in the photolyzed samples. Dimer-type products were not observed either. More polar compounds (12) increased in concentration over 2 hours of sunlight expsoure while more nonpolar compounds (8) increased in concentration before 30 min then decreased over the next 90 min. In general, photoproducts are more oxygenated and, we hypothesize, less estrogenic. This work will be extended to include experiments performed in filtered wastewater effluent.

Evaluating photolysis products of brominated estrogens with high resolution mass spectrometry

2019 Spring National Meeting

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