Determination of estrogenic endocrine disruptors in water at sub-ng L-1 levels in compliance with Decision 2015/495/EU using offline-online solid phase extraction concentration coupled with high performance liquid chromatography-tandem mass spectrometry

The growing use of pharmaceutical drugs and other bioactive compounds, discharged mainly into waterways via wastewater, has received in the last decade an increasing attention by European institutions. Three estrogens (17-alpha-ethinylestradiol (EE2), 17-beta-estradiol (E2) and Estrone (E1)) were recently included in the EU watch list of emerging substances to be monitored by the Member States (European Decision EU 2015/495), at sub-ng L-1 levels a challenge for environmental analytical laboratories. This paper describes a method based on dual solid phase extraction (SPE) in series, an off-line SPE, conducted on 1 L of water, followed by an on-line SPE coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) using negative electrospray ionization (ESI) for the simultaneous determination of E1, E2 and EE2 in 8 min. Sub ng L-1 levels for limit of quantification, LOQ (from 0.035 to 0.1 ng L-1), linearity (from 0.035 to 2.24 ng L-1), accuracy (from 80 to 120%), and precision expressed as Relative Standard Deviation, RSD (less 15% at LOQ levels) were assessed. The developed method was applied for quantitative analysis of steroidal-estrogenic hormonesin surface water samples from different Italian sites during monitoring activities by the Regional Environmental Protection Agencies in 2016 and 2017.