Time dispersive ion-mobility mass spectrometry with accurate mass was applied to 5 different samples of hydraulic fracturing (HF) fluids. The purpose of this study was (1) to test the concept of “ fingerprinting” the flowback and produced water from HF with drift time versus retention time (DT-RT) heatmaps, (2) to discover any unknown series of ethoxylated surfactants that were hidden in the complex mass spectra, (3) and to apply collisional cross section (CCS) measurements to proton, sodium, and ammonium adducts to better understand the role that ion structure plays in mass spectral fragmentation. The HF fluids came from oil and gas wells from the Denver-Julesberg basin, which are part of a two-year study to determine the water chemistry and fate of chemicals used in the controversial and environmentally relevant topic of hydraulic fracturing. There were distinct 3-dimensional images from the DT-RT heat maps that do give a visual picture, a "fingerpint", of the 300 compounds that were identified in these samples. Two undiscovered classes of ethoxylated surfactants were found by using DT-RT heatmaps combined with accurate mass and MS/MS analysis. They included copolymers of polyethylene and polypropylene glycols. Finally, ammonium adducts gave the largest and most stable adducts based on CCS measurements and MS/MS fragmentation patterns. Apparently, ammonia is lost during MS/MS fragmentation while maintaining the "ball-like" structure of the protonated gaseous phase ion. This structure then undergoes a series of gentle fragmentations that include high mass ions, which allow a definitive assignment of chemical structure. This interpretation is well supported by the drift time of two different protonated gas phase ions, as well as the ammonium and soidium adducts of the ethoxylated surfactants.

Ion mobility mass spectrometry of hydraulic-fracturing fluids

253rd National Meeting (2017)

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