Session: Accurate Mass/High Resolution Mass Spectrometry for Environmental Monitoring & Remediation: Accurate Mass/High Resolution Mass Spectrometry for Environmental Monitoring & Remediation

Disinfection by-products (DBPs) are ubiquitous tap water contaminants, which are produced when disinfectant (e.g., chlorine, chloramine) reacts with organic matter. Over 700 DBPs have been identified in tap water, and these DBPs exhibit a spectrum of carcinogenic and toxic health effects. Nitrosamines are unregulated DBPs, yet present heightened health hazards (e.g., cytotoxicity, genotoxicity) in comparison to many regulated DBPs. Nevertheless, little is known about nitrosamine fate and mechanisms post-ingestion. Previous studies demonstrate that gastrointestinal tract microbiota have the potential to degrade xenobiotic compounds into biotransformation products with different toxic effects than the parent compound. Thus, defining the relationship between DBP ingestion and the gut microbiota may open new avenues to identify health consequences of DBP exposure. The long-term goal of this work is to identify biotransformation products of nine nitrosamines in the presence of human gut microbiota. The primary objective of this study is to characterize the matrix effects of biological samples. As a first step to understanding nitrosamine fate after ingestion, we will create a human gastrointestinal tract model by cultivating human gut microbes. The culture will be spiked with known nitrosamine concentrations. We developed an analytical method using solid phase extraction (Waters Oasis HLB & SepPak) and high resolution LC (EQuan MAX system) – MS (Exactive Plus Orbitrap) with a heated electrospray interface, which is employed to identify nitrosamine and biotransformation product concentrations. Specifically, target- and non-target analyses are utilized to quantify nitrosamine concentrations, and identify biotransformation products, respectively. We hypothesized that matrix interferences may result in signal inhibition. We will report on the method’s performance in complex biomatrices (e.g., post-extraction spike matrix comparison) and provide comprehensive strategies for mitigating signal interferences for nitrosamine and biotransformation product analysis. 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.

Nancy Love

Appearances