This study used a non-targeted approach and database searches to identify chemicals in a hydraulic fracturing fluid, and the returning wastewater (flowback and produced water) overtime from a hydraulically fractured well in Colorado. The goal of this work was to identify indicator compounds that are present in the fracturing fluid, and that persist in the returning flowback and produced water. This research provides the first ever look into the GC amenable compounds from an actual fracturing fluid and its associated produced water. This study combined accurate mass and both a soft and hard ionization technique, to putatively identify numerous chemicals (Figure 1). This research was performed with a JEOL Resonance AccuTOF GCv 4G with high resolution mass spectrometry. The AccuTOF was operated in both field ionization (soft; FI) and electron ionization (hard; EI) using dichloromethane (DCM) extracted samples. EI was performed first, which allowed for data base searching to identify compounds that had high match scores (&gt;900). Following database searching, high-resolution mass spec was used for compounds that had match scores below 900 (700-900), with their accurate masses of molecular ions used to increase confidence of their putative identification (EI or FI). These compounds, and others with high relative abundance were then targeted using FI, to identify the molecular ion. Using the accurate mass of the molecular ion from FI, along with the EI data we were able to reconstruct the chemicals; with our EI data acting as a pseudo MS/MS experiment to identify major fragments and re-construct our unknown compound. Ultimately, this work allowed us to identify numerous chemicals with database searching (i.e., Naphthalene, 1,6,7-trimethyl-, Biphenyl) and numerous others using our non-targeted approach (i.e., Bis(2-ethylhexyl) phthalate, 4-Chloro-1,3-benzenediol) for the samples studied.

Utilization of soft and hard ionization techniques with 2-dimensional gas chromatography and high-resolution mass spectrometry for unknown identification in hydraulic fracturing fluid, flowback and produced water samples

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.