Fractionation schemes that combine sample preparation and chemical analysis with biological measurements are presented and reviewed. Bioassay-directed chemical-analysis protocols involve solid phase extraction (SPE),followed by chromatographic techniques, such as liquid chromatography-mass spectrometry (LC-MS) or gas chromatography-mass spectrometry(GC-MS). Toxicity testing is carried out by either bioluminescence inhibition methods or a whole-cell bacterial biosensor. Other biological toxicity tests are also reviewed. Examples of using different bacterial acute toxicity assays are presented for phenols, polyethoxylate surfactants, linear alkyl benzene sulphonates (LASs) naphthalene and benzene sulphonates, polycyclic aromatic hydrocarbons (PAHs), pesticides and pharmaceutical drugs.