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(15-41) Toxicity-Directed Identification of Organic Substances and Determination of Metal-Toxicity in Fog. Weigl, Wolfgang*,1, Frank, Hartmut1, 1 Environmental Chemistry and Ecotoxicology, University of Bayreuth;, Bayreuth, Germany ABSTRACT- A method for toxicity-directed identification was developed in order to evaluate the ecotoxicological potential of organic xenobiotics in fog. The organic substances of three fog samples were separated into their acidic, basic and neutral compounds by liquid-liquid-extraction with dichloromethane. Subsequently they were fractionated by RP-HPLC and analysed by GC-MS. The acidic compounds were analysed after derivatisation with diazomethane. All analytical steps were accompanied by the detection of the toxicity by luminescence inhibition of Vibrio fischeri. Testing with a miniaturized algal growth inhibition test with the green alga Selenastrum capricornutum turned out to be insufficient in sensitivity. Several substances with ecotoxicological potential could be identified - among them 4-nitrophenol, two oxidized PAH's and phthalic esters. Most of the identified substances are acids. Mixtures containing a selection of the identified substances were tested for toxicity in order to check which part of the toxicity is attributed to these substances. They caused only a minor part of the toxicity of fog. The most relevant toxic substances of fog-samples are unknown. In addition to the toxicity-directed identification an EDTA-chelation test was conducted in order to check which part of toxicity is caused by cationic metals. By addition of different concentrations of EDTA to aliquots of the three fog samples, the original inhibitions of the luminescence were reduced differently - up to 73 %. This shows the ecotoxicological potential of cationic metals in fog. Altogether, these data show that numerous compound classes of medium polarity plus metal ions are cumulatively responsible for the considerable toxic potential of fog water. Key words: fog, metal-toxicity, organic compounds |
