There is an obvious need to develop chemical indicators to characterize the impact of anthropogenic influences on wetland ecosystems. This is an analytical chemistry challenge, requiring the development of a variety of methods and techniques including sample handling procedures, advanced separation methods and spectroscopic detection techniques. The chemical research will mainly focus on flavonoids, regarding their presence in the different compartments of the ecosystem (plants, water, soil). Emphasis will be on analytical chemistry and physical chemistry indicators. Collaboration with the Faculty of Biology will encourage development, evaluation and use of such indicator systems interrelated with or complementary to biological indicators. [Aim]: The project focuses on the development of chemical indicators using different analytical separation and detection techniques, such as LC-MS (liquid chromatography-mass spectrometry) and CE-LIF (capillary electrophoresis-laser induced fluorescence). [Research]: The main focus has been on method development for flavonoids. The performances of two different mass spectrometers, and ion-trap and a triple quadrupole MS, are compared for a set of eighteen standard flavonoids using different LC eluent conditions. Spectroscopic properties such as absorption, normal and low temperature (77 K) fluorescence of these flavonoids in different matrices have been studied. An LC-UV-MS method has been developed to analyze a red clover (Trifolium pratense L.) leaf extract from the wetland area Horstermeer Polder. Of the compounds in the sample, twenty-four flavonoids could be identified and ten relevant flavonoids were quantified. A systematic study of the stability and hydrolysis of flavonoid glycosides and glycoside malonates has been carried out under various conditions for identification and quantification and for further screening of other wetland plants. [Future research]: Variations of concentration (ratios) of flavonoids in red clover from different locations and under different environmental and stress conditions will be studied. Also other plant species will be considered and sample handling will be further optimized. Besides LC-UV-MS other separation and detection methods will be developed.