You are here:
Sample Processing Method for Ricin Analysis
Shah, S. Sample Processing Method for Ricin Analysis. US Environmental Protection Agency, Cincinnati, OH, EPA/600/S-18/160, 2018.
Ricin biotoxin is one of the high-priority biological threat agents. Several ricin bioterrorism incidents have occurred in the U.S. During the EPA response to such incidents, environmental samples need to be collected for ricin analysis. During the 2013 ricin contamination incident in Tupelo, MS, inconclusive results for the post-decontamination phase samples were obtained due to interference with the sample analysis method used. During the subsequent ricin incidents in 2014-2015, the EPA Office of Emergency Management (OEM) faced difficulties with getting the post-decontamination samples analyzed by desired and appropriate methods. While providing the technical support, the EPA ORD’s National Homeland Security Research Center (NHSRC) determined that inclusion of a sample processing method is needed to clean up the post-bleach-decontamination samples before the analysis. Therefore, the NHSRC undertook a research and development (R&D) project to trouble-shoot the analytical method interference problem and develop a sample processing method. This R&D effort identified the need for a proper QC check and proper dilution of a critical reagent to mitigate the problem of analytical method interference. Also, an ultrafiltration device-based approach was developed to clean up environmental samples. This approach not only helps clean up the ricin samples, but also, helps concentrate the ricin in the samples, up to 20-fold, and thereby, enables detection of ricin at lower concentrations. This, in turn, helps with minimizing the false negative results during the sample analysis. This final report describes, in detail, the R&D work done in this project. Since this sample processing method is not specific for any analytical method, it could be used as a front-end to any ricin sample analytical method. This method is developed for use by the EPA’s Environmental Response Laboratory Network (ERLN) managed by the EPA-OEM and the Water Laboratory Alliance (WLA) network managed by the EPA Office of Water. It can also be useful to other Federal Agencies’ laboratory networks for a national level need. With several ricin contamination incidents reported over the past decade, rapid and accurate methods are needed for environmental sample analysis, especially after decontamination. A sample processing method was developed for common surface sampling devices to improve the limit of detection and avoid false negative/positive results for ricin analysis. Centrifugal ultrafiltration devices were evaluated for ricin concentration as a part of sample processing. 10 to 20-fold concentration of ricin was observed by the devices, which serve to remove soluble interferents and could function as the front-end sample processing step to other ricin analytical methods. The procedure has the potential to be used with a broader range of environmental sample types and with other potential interferences and to be followed by other ricin analytical methods, although additional verification studies would be required.