The aim of the project was the development and evaluation of reagent-free, optical probes for the (semi-) quantitative online detection of dissolved and emulsified oil components. Here, especially polycyclic aromatic hydrocarbons (PAH) within aquatic complex environments, influenced by biologically active and/or by scatter particles, were the main target. The sensors based on light-conducting components with special polymer coatings. The optical properties of these light-conducting components, in particular absorption and fluorescence properties, are changing reversibly by contact with targeted substances, which will be absorb by the coating. This can consequently be measured optically. The subproject focused on the development of measurement technology and its evaluation by development of algorithms. Furthermore, field trials were part of the subproject.