Development of analytical methods for speciation analysis of copper and zinc-based antifouling agents in surface water

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Surfaces in contact with the aquatic environment (e.g., ship´s fuselage, constructions in hydraulic engineering) are subjected to incrustation of fouling matter, so called bio-fouling. Bio-fouling leads to strong impairment with regard to, e.g., increase of ship´s water-friction, interference of operational capability of constructions in hydraulic engineering. Thus, today anti-fouling biocides on the basis of copper- and zinc-complexes are being used (e.g., pyrithiones). The environmental behavior of these metal-complexes is not fully unraveled yet, due to the fact that appropriate analytical tools for direct detection and speciation analysis are missing. Furthermore, transmetalation with further bivalent metal-cations is likely, thus influence the bioavailability and mobility of metal ions in the aquatic environment. However, investigations on this aspect are missing.Consequently, the main objectives of this project are:I) The development of appropriate complementary analytical methods for speciation analysis of metal-based anti-fouling biocides. Given the fact that ionic or at least polar substances are under investigation, method development is based on on-line coupling of capillary electrophoresis (CE) with high resolution molecular- as well as complementary elemental-mass spectrometry (CE/ESI-Q-ToF-MS <=> CE/ICP-SFMS). CE/ESI-Q-ToF-MS allows for an unambiguous species-identification on basis of exact molecular masses as well as MS/MS experiments and characteristic fragmentation pattern. Though, ESI-MS exhibits a species-specific detector response. Therefore, complementary CE/ICP-SFMS coupling will be deployed for species quantification on basis of a species-independent response. Furthermore, the determination of isotope ratios enables the application of enriched stabile isotopes (e.g., 65Cu, 67Zn) for tracing and quantification purposes.II) Upon method development lab-scale leaching-experiments will be conducted and complexity of the matrix will be increased during the course of experiments. On basis of these experiments the speciation and transmetalation behavior of metal-based anti-fouling biocides will be elucidated. Owing to the experience gained during the lab-scale experiments selective and invariant target species will be identified (acting as indicators of the formerly pristine metal-complexes).III) Based on the target species identified, analysis of real surface water samples collected from marinas/harbors will be conducted to assess the input as well as environmental pollution of antifouling biocides into the aquatic environment. Finally, the developed methods will be simplified to be widely applicable and transferable to other laboratories.Complete abandonment of anti-fouling substances is (currently) impossible, as environmentally justifiable alternative approaches are at present not robust enough. Thus, analytical methods are needed to end up with a more targeted and efficient use of anti-fouling substances.