Water disinfection processes play an essential role in protecting public health. The addition of disinfectants, such as chlorine and chloramine, prevents pathogen regrowth in water distribution systems. Nevertheless, disinfectants can react with organic matter to produce disinfection byproducts (DBPs), which pose several deleterious health effects. Accordingly, the U.S. EPA has established regulations for 11 DBPs. Nevertheless, growing evidence suggests that regulated DBPs account for less than two percent of total DBPs. Further, unregulated DBPs, such as haloacetonitriles (HANs), are more toxic than many regulated DBPs. To assess DBP toxicity, cell- and animal-based assays are traditionally employed. Nevertheless, these models do not fully capture human complexities. To determine the health implications of DBP exposure, this study involves creating a human-species specific model for investigating chemical fate and biotransformation post-ingestion. The primary objective of this study is to determine HAN (<i>i.e.</i>, bromochloroacetonitrile, dibromoacetonitrile, dichloroacetonitrile, and trichloroacetonitrile) and biotransformation products in a simulated human gut culture. As a first step to understand HAN fate in the presence of gut microbes, we will seed small (ca. 25 mL) continuous flow, anaerobic culture chambers with human fecal specimens and then add known HAN concentrations. We will employ GC-EI-MS to quantify HAN concentrations in culture. We hypothesized that matrix interferences may result in signal inhibition. We will report on the method’s performance in complex biomatrices (<i>e.g.</i>, post-extraction spike matrix comparison). We expect the results to indicate that sample preparation strategies can control matrix effects, and allow analyte detection at low levels. The results of this study will provide a novel analytical technique for identifying underlying mechanisms for toxic effects following DBP exposure.

Determination of haloacetonitrile fate in gastrointestinal tract culture: Application of GC-EI-MS and LC-MS/MS to identify haloacetonitriles and biotransformation products

ACS Fall 2021

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