水力压裂废水的精确质量数分析： 利用 LC/Q-TOF-MS 对聚乙二醇表面活性剂进行鉴定

Hydraulic fracturing (fracking) extracts oil and gas by forcing

fluids into oil and gas rich shale deposits. The fracking fluids

contain a mixture of proppants (sand), surfactants, biocides,

inorganic salts, and other compounds intended to facilitate

the release of the trapped gas. More than 7,000 wells have

been drilled in Colorado alone, and reports of groundwater

contamination have occurred most notably in Wyoming, New

York, and Pennsylvania [1]. The first water that returns from the fracking process (flowback) has the potential to contaminate nearby aquifers or surface water. Care is taken to recycle the flowback water, or to dispose of it properly, although the

Safe Drinking Water Act does not apply to hydraulic fracturing solutions [2]. Thus, there is a demand for tracer compounds that are indicative of the presence of contamination by hydraulic fracturing and do not occur in the subsurface [2].

In this application note, a combination of ultra high performance liquid chromatography (UHPLC) followed by quadrupole time-of-flight tandem mass spectrometry (Q-TOF-MS/MS) was used to detect a bimodal distribution of polyethylene glycols that may be used as indicator compounds for groundwater or surface water impacted by flowback waters. The Kendrick Mass Defect [2,3] was applied in a novel application to differentiate the various adducts of a suite of glycols, in particular, the proton, ammonium, and sodium adducts of each of the chains of glycols. The database of the accurate masses along with their retention times by

UHPLC is needed to provide a rapid and accurate analysis of either groundwater or surface water samples using Agilent MassHunter Software.

Conclusions

The Agilent 1290 Infinity LC System and Agilent 6540 LC/Q-TOF-MS enabled the UHPLC/MS/MS characterization of two sets of representative polyethylene compounds from hydraulic fracturing flowback samples. Applying the Kendrick

mass scale to the accurate masses of these PEGs and other ethoxylated surfactants [2] facilitates their identification using Agilent MassHunter Software, and the construction of a database of such compounds present in flowback samples. This database can, in turn, enable the use of these compounds as unique tracers of hydraulic fracturing.