How It Works
The Proton Transfer Reaction – Time of Flight Mass Spectrometry (PTRTOF) mobile laboratory system is an analytic laboratory in a commercial van, providing real-time vapor analysis. The mobile laboratory includes LICOR CO2 direct-reading instruments (DRI) and can perform near real-time detection of 56 of the Hanford Site’s 59 chemicals of potential concern (COPCs). The PTRTOF is sensitive to mass only and requires other instrumentation, such as the Gas Chromatagraph - Mass Spectrometer (GC-MS), to identify chemical-vapors species. While the PTR-TOF is a real-time measurement, the GC-MS is not. Therefore, results are only useful once the data has been thoroughly analyzed, which requires two to three days. This unique detection technology is especially useful because of its high-fidelity detection, number of COPCs detected, and ability to characterize specific vapor release sources and/or “chase” plumes.
How It's Used
In the pilot-scale demonstration, the mobile laboratory will be used to determine baseline concentration of vapors while travelling and in stationary locations across the Hanford Site. The real-time results from the mobile laboratory will be compared to the real-time data from the DRIs and optical spectra instruments deployed in the pilot-scale test and later compared to the laboratory analysis results from the autosampler (whole-air grab samples analyzed by independent GC-MS). The mobile laboratory will be deployed directly to sensitive areas where vapors and odors or suspected emissions are postulated and expected. In addition, the system will be configured to analyze the AP Farm exhaust stack and A Farm passive breather filters.
Chemical Vapor Initiative
The Chemical Vapor Solutions Team (CVST) New Technology sub-committee is investigating additional monitoring technologies and equipment for use at the Hanford Site tank farms.
One such effort is the Mobile Laboratory van. The Mobile Lab is an analytical laboratory in a commercial van that provides air and vapor analysis around tank farm perimeters. A pilot-scale demonstration of this technology was conducted in 2016, with the results documented in the Chemical Vapor Initiative report. The Chemical Vapor Initiative report uses the term “plume” to refer to detections of chemicals. Thus, in the report, a plume is defined as any instance where compounds are detected above background and does not always equate to a chemical vapor release. The release could be attributed to a tank source, a nearby generator, septic pumping operations, or other chemical source.
From May 17 to September 9 of 2016, multiple sampling studies at the Hanford site. The studies included area sampling of the tank farm complex, the AP farm stack, and the A-103 passive breather system. The instrument used during these sampling events was a Proton Transfer Reaction Mass Spectrometer (PTR-MS). This instrument is able to continually monitor for a total of 175 chemicals, and includes 46 of the 59 Chemicals of Potential Concern (COPCs) identified within the tank farms. The mobile lab was also equipped with a carbon dioxide and moisture monitor, a full weather station, and additional ports for other instrumentation such as the Picarro ammonia analyzer.
The Chemical Vapor Initiative study had two primary objectives:
• To evaluate the quality of the data generated by the instrumentation currently installed at the passive breather filter and exhaust stack systems, and
• To perform mobile monitoring across the 200 East and 200 West areas on the Hanford site to identify and track plume emissions.
The sampling of the passive breather filter and stack systems was performed at the end of the monitoring campaign, and the results are still pending. The mobile monitoring performed on the site was considered successful in that the system was able to detect between 3 and 20 plumes per day. Most of these plumes were found to have been from diesel exhaust fumes from generators or construction equipment, although not all plumes were associated with combustion engines.
Data Collection Recommendations:
1. Increase ammonia monitoring sensitivity to the parts per billion (ppb) range. The current setup only allows for detecting extreme peaks in ammonia levels. This could be accomplished by adding separate instrumentation to detect only ammonia.
2. Consider the addition of a high-end PTR-MS with a higher mass resolution and sensitivity (such as a PTR-Qi-TOF) to allow a more precise differentiation between compounds of similar atomic masses.
3. Modify the calibration timing and methodologies to include additional automation. This would allow for easier and more time efficient plume identification during data collection.
4. Include additional monitoring instrumentation such as Nitrous Oxide (NOx) and Ozone monitors or other spectrometric instruments such as ultraviolet and infrared detectors. These direct-read instruments can take advantage of the same sample line as the PTR-MS, providing direct correlation of the results.
Data Processing Recommendations:
1. Use dedicated workstations to process the data. Due to the volume of collected data, this will allow for faster and more efficient processing of the large volume of spectrometric data the instrument produces
2. Automation of the processing methodology. This will reduce the labor intensive data analysis needed to support the project.
The full Chemical Vapor Initiative report can be read here. WRPS continues to evaluate these recommendations and determine how to improve the analytical capabilities of the Mobile Lab.