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Examining chemical space coverage of solid phase extraction methods on environmental waters for use with non-targeted analysis methods
Citation:
Brunelle, L., E. Stebel, AND A. Batt. Examining chemical space coverage of solid phase extraction methods on environmental waters for use with non-targeted analysis methods. Society of Environmental Toxicology and Chemistry, Louisville, KY, November 12 - 16, 2023.
Impact/Purpose:
This abstract and poster presentation describes ongoing method development work for sample preparation methods to compliment non-targted analysis workflows. These methods are applied to environmental water samples to study the fate and transport of chemical contaminants present in water systems.
Description:
Non-targeted analysis is an emerging technique for studying environmental contaminants, with the ability to detect hundreds to thousands of unidentified chemicals in environmental samples. While the presence of a chemical detected with non-targeted analysis can be confirmed with a certain level of confidence, the absence of a chemical of interest is much more difficult to interpret with the non-targeted approach. Most current non-targeted extraction methods use broad extractions that are often not well categorized for chemical extraction efficiency across multiple classes of chemicals. However, bias from extraction is important to explore and understand; knowledge on which classes of compounds are amendable to extraction and instrumental methods provides valuable insight into the chemical space covered within a given method. In this work, over 250 reference standards, representative of chemical classes in our larger 1400 standard in-house database, were used to explore extraction efficiencies for non-targeted analysis in environmental waters. Standards cover a vast range of chemical space, ranging in LogKow from -3.4 to 8.7, with neutral masses ranging from under 100 Da to over 1400 Da. Standards were selected from multiple classes and uses: including over 100 pesticides and pesticide metabolites (ex. organochlorines, organophosphates, urea derived, carbamates, pyrethroids, triazine, neonicotinoids), per-and polyfluoroalkyl substances, personal care products, drugs of abuse, and over 100 pharmaceuticals (ex. antibiotics, antidepressants, antivirals, veterinary drugs, commonly used medications). Multiple extraction methods were examined, including a previously used and common method utilizing Oasis® hydrophilic-lipophilic balanced (HLB) SPE cartridges, as well as methods combining various SPE sorbents together to improve recovery and overall chemical coverage. Sorbents were acquired from multiple vendors, including weak anion exchange, weak cation exchange, mixed-mode cation exchange, graphitized carbon black, and reversed phase sorbents. Our goal is not necessarily to develop a single method capable of extracting all chemicals of interest, but to provide more confidence and understanding of the chemical space coverage of our non-targeted methods.