Toxic volatile organic compounds (VOCs) emitted from contaminated groundwater plumes represent a significant health risk at industrial sites throughout the nation and a specific need exists for VOC monitoring at Superfund sites. Accurate, real-time monitoring of toxic VOCs on site is critical to evaluating the success of remediation efforts, assessing human health risks, and developing robust exposure models that properly account for confounding factors such as temporal exposure variation and population-specific pharmacokinetics. Unfortunately, simple, rapid, and accurate VOC monitoring is an ongoing challenge, and available technology is costly, labor intensive, slow, and unable to characterize reactive gases (e.g. acrolein, ozone, etc.). In this Small Business Innovative Research (SBIR) project, Los Gatos Research (LGR) will develop an autonomous instrument for the real-time monitoring of sub-parts per billion (ppb) levels of VOCs in ambient air without requiring extensive consumables. LGR's VOC detector will significantly improve data quality at Superfund sites by allowing for more rapid and frequent measurements without labor-intensive collection and transport of sample traps, while remaining cost competitive with alternative technologies. The VOC analyzer will use LGR's mid infrared (MIR) incoherent cavity ringdown spectroscopy (iCRDS) technology, which utilizes a broadly tunable external cavity quantum cascade lasers (8.3 - 12.5 5m) and chemometric fitting algorithm to directly measure and analyze optical absorption due to multiple VOCs in ambient air. During Phase I of this project, LGR will refine an existing MIR iCRDS analyzer to include a larger wavelength range and improved optics. We will verify the instrument's ability to accurately identify and quantify VOCs in a variety of ambient air compositions, including an analysis of VOC-to-VOC measurement crosstalk. Additionally, LGR will deploy the prototype at a Superfund site in Mountain View, California to record, analyze, and report VOC concentrations in ambient air. At the conclusion of the project, LGR will have demonstrated the use of MIR iCRDS for the detection of VOCs at Superfund sites as a superior method of characterizing the risks to human health from toxic vapor intrusion.
The contamination of groundwater by industrial pollutants poses a significant risk to the health of individuals living and working above tainted sites. Measuring the concentration of pollutants that reach indoor air (worksites, offices and homes) is a critical first step to understanding and ultimately minimizing the human health hazards of contaminated ground water (especially at Superfund sites). Los Gatos Research's proposed instrument for measuring volatile organic pollutants will greatly improve on existing monitoring technology by increasing the data rate to characterize transient exposure, accurately measuring reactive species, and eliminating labor costs associated with sample collection.
| Leen, J Brian; O'Keefe, Anthony (2014) Optical re-injection in cavity-enhanced absorption spectroscopy. Rev Sci Instrum 85:093101 |
