A NOVEL NON-TARGETED METHOD FOR THE RAPID IDENTIFICATION OF CONTAMINANTS PRESENT IN COMPLEX CONTAMINATED AQUEOUS SAMPLES USING LIQUID-LIQUID EXTRACTION AND 1-D PROTON NMR

Many industrial sites remain a challenge for remediation efforts due to challenges associated with characterizing complex mixtures of unknown and degraded contaminants that may be present. Understanding the nature of contamination at these sites are benefited by analytical approaches that are rapid, non-targeted, inexpensive, and can inform next steps in the remediation plan. In general, the conventional analytical approaches available for site characterization rely on targeted methods. These targeted approaches benefit from being both well-established and relatively inexpensive, but run the risk of missing important compounds that are not being specifically investigated. Incomplete analysis can lead to ineffective remediation approaches, which potentially prolongs the timeframe for site closure while also increasing the costs for investigation and remediation. We have developed a novel approach for the characterization of groundwater from heavily contaminated sites based on nuclear magnetic resonance (NMR) spectroscopy that is simple, fast, non-targeted and inexpensive. This approach allows for a more thorough understanding of the classes of contaminants present and in what quantities. This new method is based on a liquid-liquid microextraction (LLME), with subsequent analysis by 1-H NMR. We demonstrate this method using a prepared mixture of chlorobenzene derivatives and find extraction efficiencies ranging from 70-99% based on a mass-balance of known starting concentrations. Our next steps will involve applying this method to real world samples with known and unknown contaminants of variable concentrations.