Fractionation and toxicity evaluation of waste waters

Several toxicity-based procedures have been proposed for waste water risk a ssessment but the toxic agents could never be identified in these very comp lex mixtures. A procedure was adopted using disposable solid-phase extracti on cartridges to extract organic chemicals and preparative HPLC to fraction ate them in relation of their hydrophobicity. Acute toxicity of whole sampl es and their fractions was measured on Daphnia magna, using a commercially available biokit. The procedure was applied to leachate from an industrial landfill and a textile effluent. In both cases the toxic effects due to xen obiotics were highest in the most hydrophobic HPLC fraction. The compounds responsible for the observed toxicity were identified and quantified by GC- MS. Reconstructed mixtures were analysed to assess their fitting with GC pr ofiles and tested for toxicity to compare the responses of individual chemi cals and mixtures. (C) 2000 Elsevier Science B.V. All rights reserved.