Quantification of estrogenic compounds as pyridine-3-sulfonyl derivatives by UHPLC-ESI-MS/MS at trace level in different aqueous matrices

Natural estrogens (estrone: E1, 17-β-estradiol: E2, estriol: E3) and synthetic estrogen (17-α-ethinylestradiol: EE2) are powerful endocrine disruptors harmful for aquatic wildlife and human at extremely low concentration. Therefore, the European Commission included these molecules in a watch list (2018) regarding emerging aquatic pollutants, proposing maximum detection limits of 0.035 ng/L for EE2 and 0.4 for E1 and E2. Attaining these limits represents a challenge even with the up-to-date analytical tools. In this work a UHPLC-ESI-MS/MS method allowing the quantification of E1, E2, E3 and EE2 in water was developed. Estrogenic compounds were derivatized using pyridine-3-sulfonyl chloride to enhance the response in ESI (+). This derivatization procedure allowed to obtain at least two transitions for each analyte which were proved to be specific and hence selected for quantification and confirmation. At first, a method dedicated to clean aqueous matrices (groundwater, tap water) was developed and validated. This method consisted in a single step of SPE extraction and was suitable to reach low LODs. However, as underlined by the EU in the watch list, surface water should be monitored as well to have an overview of the presence and the transport of E1, E2, E3 and EE2 in the environment. The analysis of such a complex matrix required the optimization of an additional clean-up step to achieve the sensitivity required, allowing at the same time a high sample throughput.