Low-Level VOCs Background
"Low-level" detections of halogenated VOCs including CFCs can be quite useful in determining whether fractions of post-1940s water are present in well discharge. A method is available to analyze a water sample for about 60 halogenated compounds. Of the 60 compounds, 25 are known and quantifiable with the balance being unknown compounds. The combination of knowns and unknowns in a sample can be used to trace water from a particular source through an aquifer. Here, the term "low-level" refers to concentrations that typically are below the minimum detection level (MDL) for VOCs determined by purge and trap capillary column gas chromatography with mass spectrometry (GC-MS), and can be at concentrations as low as 2 to more than 4 orders of magnitude below the commonly reported GC-MS MDL of 0.01 to 0.2 ug/L.
Plummer, L. N., Sibrell, P. L., Casile, G. C., Busenberg, E., Hunt, A. G., Schlosser, P., 2013, "Tracing groundwater with low-level detections of halogenated VOCs in a fractured carbonate-rock aquifer, Leetown Science Center, West Virginia, USA" Applied Geochemistry, Volume 33, June 2013, Pages 260–280. http://dx.doi.org/10.1016/j.apgeochem.2013.02.021
Shapiro, S. D., Busenberg, E., Plummer, L. N., and Focazio, M. J. (2003) "Data from archived chromatograms on halogenated volatile organic compounds in untreated ground water used for drinking water in the United States, 1997-2000." U.S. Geological Survey, Open-File Report, 03-352, 1-31.
Shapiro, S. D., Busenberg, E., Focazio, M. J., and Plummer, L. N. (2004) "Historical trends in occurrence and atmospheric inputs of halogenated volatile organic compounds in untreated ground water used as a source of drinking water." Sci. Total Environ., 321, 201-217.