Differential chemical profiling to identify ozonation by-products of estrone-sulfate and first characterization of estrogenicity in generated drinking water.

For a few years, the concern of water treatment companies is not only focused on the removal of target micropollutants but has been extended to the investigation of potential biologically active by-products generated during the treatment processes. Therefore, some methods dedicated to the detection and structural characterization of such by-products have emerged. However, most of these studies are usually carried out under simplified conditions (e.g. high concentration levels of micropollutants, drastic treatment conditions, use of deionized or ultrapure water) and somewhat unrealistic conditions compared to that implemented in water treatment plants. In the present study, a real field water sample was fortified at the part-per-billion level (50 µg L(-1)) with estrone-3-sulfate (E1-3S) before being ozonated (at 1 mg L(-1)) for 10 min. In a first step, targeted measurements evidenced a degradation of the parent compound (>80%) in 10 min. Secondly, a non-targeted chemical profiling approach derived from metabolomic profiling studies allowed to reveal 11 ozonation by-products, among which 4 were found predominant. The estrogenic activity of these water samples spiked with E1-3S before and after treatment was assessed by the ER-CALUX assay and was found to decrease significantly after 10 min of ozonation. Therefore, this innovative methodological strategy demonstrated its suitability and relevancy for revealing unknown compounds generated from water treatment, and permitted to generate new results regarding specifically the impact of ozonation on estrone-3-sulfate. These results confirm that ozonation is effective at removing E1-3S in drinking water and indicate that the by-products generated have significantly lower estrogenic activity.

Differential global profiling as a new analytical strategy for revealing micropollutant treatment by-products: application to ethinylestradiol and chlorination water treatment.

The detection and structural elucidation of micropollutants treatment by-products are major issues to estimate efficiencies of the processes employed for drinking water production versus endocrine disruptive compounds contamination. This issue was mainly investigated at the laboratory scale and in high concentration conditions. However, potential by-products generated after chlorination can be influenced by the dilution factor employed in real conditions. The present study proposes a new methodology borrowed to the metabolomic science, using liquid chromatography coupled to high-resolution mass spectrometry, in order to reveal potential chlorination by-products of ethinylestradiol in spiked real water samples at the part-per-billion level (5 µg L(-1)). Conventional targeted measurements first demonstrated that chlorination with sodium hypochlorite (0.8 mg L(-1)) led to removals of ethinylestradiol over 97%. Then, the developed differential global profiling approach permitted to reveal eight chlorination by-products of EE2, six of them being described for the first time. Among these eight halogenated compounds, five have been structurally identified, demonstrating the potential capabilities of this new methodology applied to environmental samples.