Mass spectrometric target analysis and proteomics in environmental toxicology

Abstract

Mass spectrometric techniques are widely used in environmental toxicology. One major application is the quantitative determination of chemical pollutants in environmental compartments. This is increasingly linked with biological effects assessment in an approach called effect-directed analysis, which, as the term says, allows focusing on samples that cause an effect in in vitro or in vivo test systems. Identification of the chemical(s) causing an effect is done by submitting the active sample to a classical target analysis using established methods. If the causative agent is not part of the list of target analytes, scandependent MS/MS analyses have to be performed and active samples compared to controls. This then allows to narrow- down the elemental composition of compounds primarily found in active samples, find functional groups and substructures, and potentially identify the unknowns. Equally important for a refined risk assessment is the determination of actual internal concentrations in organisms, which reduces uncertainties in predicting toxicity thresholds across chemicals and species. An entirely new level in environmental toxicology has been reached with the application of novel techniques such as proteomics and metabolomics. They allow investigating the molecular response of a model organism to environmental challenge. Ideally this leads to the identification of robust biomarkers of exposure and the identification of conserved stress response pathways which can be used to extrapolate to other species and predict adverse effects of novel chemical stressors or even their mixtures. This chapter gives an introduction into effect-directed analysis and environmental proteomics.