Bioassay-directed fractionation and chemical analysis

For example, Legzdins and co-workers (1994) used the bioassay-directed fractionation and chemical analysis technique to isolate, identify, and quantify 2-nitrofluoranthene in extracts of ambient particles collected in Hamilton, Ontario, Canada. They found it accounted for 70% of the total nonpolar direct bacterial mutagenicity (strain YG1021, standard reversion assay, Maron and Ames, 1983). 

Environmental samples often contain swathes of different chemicals in mixtures. An important question for risk assessment, regulation, and remediation is to establish whether the majority of chemicals contribute to the overall mixture effect, or whether joint toxicity can be traced back to a few substances. This issue has been the topic of considerable research efforts in the field of ecotoxicology. Its resolution has required whole mixture approaches, where environmental samples were subjected to extraction procedures, followed by fractionation and chemical analysis (toxicity identification evaluation (TIE), bioassay-directed fractionations). There are interesting examples in the literature where such approaches were combined with component-based mixture assessments with the aim of identifying chemicals that contribute to mixture effects (see Chapter 4). 

Zinbo, M., D. Schuetzle, D. P. H. Hsieh, N. Y. Kado, J. M. Dasiey, and L. A. Gundel, An Improved Fractionation Procedure for the Bioassay-Directed Chemical Analysis of Ambient Air Particulate Extracts, Anal. Sci., 8, 461-468 (1992). 

During the past three years several procedures have been developed for simplifying the analysis of complex environmental samples. These techniques have included "Bioassay Directed Chemical Analysis," (15) which uses short-term bioassays for determining which chemical fractions should be prioritized for detailed chemical analysis and "Survey Chemical Analysis", which utilizes analytical techniques such as hl h resolution mass... 

In order to identify compounds responsible for specific effects (i.e., endocrine disrupting or AhR hgands) observed in field studies, TIE or bioassay directed analysis approaches have increasingly been apphed over the last decade. In such approaches, sensitive bioassays are used to direct the fractionation of a sample extract until its complexity is sufficiently reduced to enable identification of those compoimds responsible for the activity measured in the bioassay. This strategy is based on differential extraction and fractionation methods and identification by chemical and biochemical analysis. TIE is a well-established technique having been originally developed by... 

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