Homologue specific analysis of a polyether trisiloxane surfactant in German surface waters and study on its hydrolysis

The occurrence of a polyether trisiloxane surfactant in the ng L−1 range in German surface waters is reported for the first time. The studied surfactant does not ubiquitously occur in the aquatic environment but can reach surface waters on a local scale. As a first step towards the understanding of the environmental fate, the hydrolysis was studied according to the OECD guideline 111. It confirmed that the trisiloxane surfactant is sensitive to hydrolysis and that the hydrolysis rate strongly depends on the pH and the temperature. If one takes only into account the hydrolysis, the trisiloxane surfactant could persist several weeks in river water (the half-life in water is approximately 50 days at pH 7, 25 °C, and an initial concentration of 2 mg L−1). A degradation product, more polar than the initial trisiloxane surfactant, was identified by high resolution mass spectrometry. -- Highlights: • A trisiloxane surfactant was detected in surface waters for the first time. • Hydrolysis of the siloxane chain is one important degradation mechanism. • The hydrolysis rate of the trisiloxane surfactant depends on pH and temperature. • A hydrolysis product was tentatively identified by high resolution mass spectrometry. • Hydrolysis did not modify the homologue distribution of the trisiloxane surfactant. -- The first positive detect of a trisiloxane surfactant in surface waters is reported and hydrolysis of this chemical is confirmed as one possible environmental degradation process