1. University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitätsstraße 5, D-45141 Essen, Germany
2. a.p.f Aqua System AG, Friedrich-Ebert-Staße 143 b-c, D-42117 Wuppertal, Germany
3. IWW Water Centre, Moritzstraße 26, D-45476 Mülheim an der Ruhr, Germany
4. Centre for Water and Environmental Research (ZWU), Universitätsstraße 5, D-45141 Essen, Germany