1. Instrumental Analytical Chemistry, University Duisburg-Essen, Universitätsstrasse 5, 45141 Essen, Germany
2. Centre for Aquatic and Environmental Research (ZWU), University Duisburg-Essen, Universitätsstrasse 2, 45141 Essen, Germany
3. Chair for Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany
4. IWW Water Centre, Moritzstr. 26, Mülheim an der Ruhr, Germany