4 Sample preparation & fractionation for EDA

The extraction, concentration and clean-up of mixtures of chemicals from environmental samples with a focus on water, sediment and biota, including human tissues and blood, requires specialized sample reparation procesdures. The methods cover samples from polluted sites as well as background locations. The first step includes filtration of water (1) or homogenization of condensed samples (5,6). The chemicals are then extracted from the sample using solid phase extraction (2,3) partitioning-based passive sampling into a polymer such as silicone (7). Solvent extracts and concentrated in the automated concentration unit (4). In some cases, the extracts are submitted to clean-up steps, e.g., using gel permeation chromatography (8).
For effect-directed analysis (EDA) fractionation methods based on liquid chromatography are used to reduce the complexity of raw sample extracts containing thousands of chemicals to direct chemical identification of toxicants to fractions showing a significant activity for different biological endpoints of interest. If the single fractions are still too complex, a second fractionation step with an orthogonal separation phase may be necessary (or even more). Depending on the sample amount required, fractionation can be done by semi-preparative LC or in high-throughput fashion for small volumes combining analytical-scale LC and the Fractiomate device (9), which allows for a high temporal resolution of the fractions.

Application: Transfer of mixtures of pollutants from the environment into a solvent extract (a) to be analyzed chemically or (b) to determine mixture effects

Selected literature references
 

Schulze, T.; Neale, P. A.; Ahlheim, J.; Beckers, L.-M.; König, M.; Krüger, J.; Petre, M.; Piotrowska, A.; Schlichting, R.; Schmidt, S.; Krauss, M.; Escher, B. I., "A guidance for the enrichment of micropollutants from wastewater by solid-phase extraction before bioanalytical assessment." Environmental Sciences Europe 2024, 36, 165; DOI 10.1186/s12302-024-00990-x.

Alvarez-Mora, I.; Arturi, K.; Béen, F.; Buchinger, S.; El Mais, A.; Gallampois, C.; Hahn, M.; Hollender, J.; Houtman, C.; Johann, S.; Krauss, M.; Lamoree, M.; Margalef, M.; Massei, R.; Brack, W.; Muz, M., "Progress, applications, and challenges in high-throughput effect-directed analysis for toxicity driver identification - is it time for HT-EDA?" Analytical and Bioanalytical Chemistry 2024; DOI 10.1007/s00216-024-05424-4.

Reiter, E. B.; Escher, B. I.; Rojo-Nieto, E.; Nolte, H.; Siebert, U.; Jahnke, A., "Characterizing the marine mammal exposome by iceberg modeling, linking chemical analysis and in vitro bioassays." Environmental Science-Processes & Impacts 2023, 25, 1802-1816; DOI 10.1039/d3em00033h.

Braun, G.; Krauss, M.; Escher, B. I., "Recovery of 400 Chemicals with Three Extraction Methods for Low Volumes of Human Plasma Quantified by Instrumental Analysis and In Vitro Bioassays." Environmental Science & Technology 2023, 57, 19363-19373; DOI 10.1021/acs.est.3c05962.