Abstract
A new high temperature transfer line, membrane inlet probe (HTTL-MIP) coupled to a photoionization detector (PID) and gas chromatograph/mass spectrometer (GC/MS) was used to rapidly profile and speciate polycyclic aromatic hydrocarbons (PAH) in the subsurface. PID signals were in agreement with GC/MS results. Correlation coefficients of 0.92 and 0.99 were obtained for discrete and composite samples collected from the same exact location. Continuous probe advancement with PID detection found coal tar, a dense nonaqueous phase liquid, in soil channels and saturated media. When samples were collected conventionally, split, solvent extracted, and analyzed in the field and confirmation laboratory, GC/MS measurement precision and accuracy were indistinguishable; despite the fact the field laboratory produced data five times faster than the laboratory using standard EPA methods. No false positive/negatives were found. Based on these findings, increased confidence in site conceptual models should be obtained, since PID response indicated total PAH presence/absence in “real-time,” while GC/MS provided information as to which PAH was present and at what concentration. Incorporation of this tool into a dynamic workplan will provide more data at less cost enabling environmental scientists, engineers, and regulators to better understand coal tar migration and its impact on human health and the environment.

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