Industrial wastewater analysis: a toxicity-directed approach

Methods of toxicity-directed analysis have been developed for the characterization and identification of toxic organic constituents in industrial wastewater. Sequential solid-phase extraction is followed by high-performance liquid chromatography (HPLC) fractionation or by automated multiple development thin-layer chromatography fractionation (AMD–TLC) of the toxic extracts. Toxic fractions were finally analyzed by gas chromatography–mass spectroscopy (GC–MS). Toxicity was detected before each of the analytical steps by the bioluminescence inhibition of Vibrio fischeri, which was performed on microtiter plates and on the developed TLC plates. While sequential extraction broadens the polarity range of the procedure, the new variants of the luminescence test make the method very versatile and fast. The potential of this kind of toxicity-directed analysis with respect to resolution and polarity of analytes is discussed and applications to partial effluents of a tannery, to molasses wastewater and a spent dyeing bath are presented. A variety of benzothiazoles and more polar organics were identified as major toxic compounds in tannery effluents. It is shown that the procedures are well suited to detect individual toxic components in complex industrial wastewaters. The use of LC-MS is proposed to extend the polarity range of the final identification step. ©