EPA’s National Homeland Security Research Center has just published the latest updates on their research products.  Please take a few moments to look through these very interesting research efforts – and remember, many of them will have uses and applications beyond the “security” context.

Decontamination Related Products

A Rapid and Repeatable Method to Deposit Bioaerosols on Material Surfaces:  Journal Article

A simple method for repeatably inoculating surfaces with a precise quantity of aerosolized spores was developed. Laboratory studies were conducted to evaluate the variability of the method within and between experiments, the spatial distribution of spore deposition, the applicability of the method to complex surface types, and the relationship between material surface roughness and spore recoveries. Surface concentrations, as estimated by recoveries from wetted-wipe sampling, were between 5 × 103 and 1.5 × 104 CFU cm− 2 across the entire area (930 cm2) inoculated. Between-test variability (Cv) in spore recoveries was 40%, 81%, 66%, and 20% for stainless steel, concrete, wood, and drywall, respectively. Within-test variability was lower, and did not exceed 33%, 47%, 52%, and 20% for these materials. The data demonstrate that this method is repeatable, is effective at depositing spores across a target surface area, and can be used to dose complex materials such as concrete, wood, and drywall. In addition, the data demonstrate that surface sampling recoveries vary by material type, and this variability can partially be explained by the material surface roughness index. This deposition method was developed for use in biological agent detection, sampling, and decontamination studies, however, is potentially beneficial to any scientific discipline that investigates surfaces containing aerosol-borne particles.

Assessment of Liquid and Physical Methods for Decontamination of Surfaces Contaminated with Bacterial Spores: Evaluation and Refinement of the Procedural Steps:  Technical Brief

In this document, the Homeland Security Research Program reports on its evaluation of an 8-step, low technology approach to decontaminating anthrax-contaminated surfaces. This approach had been used previously by EPA in response to contamination incidents involving naturally occurring anthrax spores. The primary objective of this study was to determine through laboratory testing the effectiveness of individual and various combinations of steps of the procedure. A subsequent study, Assessment of Liquid and Physical Decontamination Methods for Environmental Surfaces Contaminated with Bacterial Spores: Evaluation of Spray Method Parameters and Impact of Surface Grime was conducted to further evaluate the decontamination approach. The results from these studies indicate that shorter, simpler decontamination procedures can be almost as effective as the previously employed 8-step procedure.

CBI Polymers DeconGel® 1108 for Radiological Decontamination of Americium:  Technology Testing and Evaluation Program (TTEP) Report

The performance of the CBI Polymers (Honolulu, HI) DeconGel® (DG) 1108 was evaluated to test its ability to remove radioactive americium (Am)-243 from the surface of unpainted concrete.  The decontamination efficacy (in terms of percent removal, %R) attained by DG 1108 was evaluated following the contamination of the coupons with approximately 50 nCi Am-243. Overall, DG 1108 decontaminated the concrete coupons with an average %R of 84% ± 5.7%. A limited evaluation of cross contamination was performed, and the results confirmed that slight cross contamination did occur.   The report contains additional details regarding efficacy, operational conditions and waste generation.

Decontamination of Concrete and Granite Contaminated with Cobalt-60 and Strontium-85:  Report

The performance of Environmental Alternatives, Inc.’s Rad-Release II (RRII), and Argonne National Laboratory’s SuperGel (ASG) were evaluated for their ability to remove radioactive cobalt (Co)-60 and strontium (Sr)-85 from the surface of unpainted concrete and split face granite.  The decontamination efficacy (in terms of percent removal, %R) attained by RRII and ASG was evaluated following contamination of the coupons with approximately one microCurie (μCi) Co-60 and Sr-85, measured by gamma spectroscopy. For the concrete coupons, the %Rs for Co-60 were determined to be 79% ± 6.0% for RRII and 62% ± 5.2% for ASG and for Sr-85, 70% ± 6.1% for RRII and 40% ± 7.1% for ASG. For the granite coupons, the %Rs for Co-60 were determined to be 64% ± 10% for RRII and 48% ± 14% for ASG and for Sr-85, 44% ± 4.4% for RRII, 32% ± 2.2% for ASG. Therefore, across all the decontamination technologies, on average, the Co-60 was more effectively decontaminated than the Sr-85 and the concrete was more effectively decontaminated than the granite.  The report contains additional details regarding efficacy, operational conditions and waste generation.

Decontamination of Concrete with Aged and Recent Cesium Contamination:  Report

The performance of a number of chemical-based radiological decontamination technologies  were evaluated to quantify the effect of residence time of radiological contamination, such as would result from an urban “dirty bomb”, on concrete relative to decontamination efficacy of various technologies. The technologies chosen for the evaluation were selected from among the best-performing chemical-based technologies tested to date. The four technologies chosen include:

  • Allen-Vanguard’s Surface Decontamination Foam (SDF™);
  • A modified formulation of SDF developed by Environment Canada called Universal Decontamination Formulation (UDF);
  • Environmental Alternatives, Inc.’s Rad-Release II (RRII); and
  • Argonne SuperGel (ASG).

These technologies were evaluated for their ability to remove radioactive cesium (Cs)-137 from the surface of unpainted concrete that had been recently contaminated (within approximately two weeks) compared to their ability to remove radioactive cesium from concrete that had been similarly contaminated approximately one year prior to decontamination.

The decontamination efficacy (in terms of percent removal, %R) achieved was evaluated following contamination the coupons with approximately one microCurie (μCi) Cs-137, measured by gamma spectroscopy. For the concrete coupons contaminated within two weeks of the decontamination evaluation, the %Rs were determined to be 51 ± 3.9 for SDF, 62 ± 8.9 for UDF, 74 ± 7.3 for RRII, 75 ± 4.4 for ASG, and 6.1 ± 1.0 for the water control. The %Rs for the coupons that had been contaminated approximately one year prior to decontamination were 29 ± 10 for SDF, 37 ± 10 for UDF, 50 ± 17 for RRII, 46 ± 5.7 for ASG, and 4.0 ± 0.4 for the water control. Therefore, across all the decontamination technologies, the aged coupons exhibited less effective decontamination.

Technology Evaluation Report Bartlett Services, Inc. Stripcoat TLC Free Radiological Decontamination of Americium:  Report

The performance of the Bartlett Services, Inc. Stripcoat TLCTM Free strippable coating (Stripcoat) was evaluated for its ability to remove radioactive americium (Am)-243 from the surface of unpainted concrete. The decontamination efficacy (in terms of percent removal, %R) attained by Stripcoat was evaluated following contamination of the coupons with approximately 50 nCi Am-243. These coupons were placed on a test stand to create a vertical concrete surface to which Stripcoat was applied, then removed. Overall, Stripcoat decontaminated the concrete coupons with an average %R of 46 ± 4.6%. A limited evaluation of cross contamination was performed, and the results confirmed that slight cross contamination did occur.  The report contains additional details regarding efficacy, operational conditions and waste generation.

Technology Evaluation Report Environment Canada’s Universal Decontamination Formulation:  Report

The performance of Environment Canada’s Universal Decontamination Formulation (UDF) was evaluated for its ability to remove radioactive cesium (Cs)-137 from the surface of anodized aluminum and unpainted concrete.  The decontamination efficacy (in terms of percent removal, %R) attained by the UDF was evaluated following contamination of the coupons with approximately one microCurie (μCi) of Cs-137, measured by gamma spectroscopy. For the anodized aluminum surfaces, the %R was determined to be 92 ± 8.9% for the UDF and 59 ± 10% for the water control. For the concrete coupons, the %R was determined to be 62 ± 8.9% for UDF, and 6.1 ± 1.0% for the water control. A limited evaluation of cross contamination (spread of contamination to previously uncontaminated areas) was performed, and the results confirmed that minimal cross contamination did occur.  The report contains additional details regarding efficacy, operational conditions and waste generation.

Evaluation of Expedient Decontamination Options with Activated Peroxide-based Liquid Sporicides:  Technical Report

This project evaluated “low tech” expedient decontamination options with an Activated Hydrogen Peroxide (AHP)-based liquid sporicide. The efficacy of liquid AHP was evaluated on common building materials (stainless steel, painted and unpainted plywood, concrete, carpet, linoleum, glass, and tile) experimentally inoculated with aerosolized spores of Bacillus atrophaeus (surrogate of Bacillus anthracis).  The data suggest that this “low-tech” decontamination process, using a two-application procedure described in the report, can provide > 6 LR in the number of viable spores on the common building materials tested, with the exception of unpainted treated wood. The longer exposure duration and increased volume of AHP applied afforded higher surface decontamination efficacy, especially for porous materials.

Evaluation of peracetic acid fog for the inactivation of Bacillus anthracis spore surrogates in a large decontamination chamber:  Journal

The purpose of this study was to evaluate the sporicidal (inactivation of bacterial spores) effectiveness and operation of a fogging device utilizing peracetic acid/hydrogen peroxide (PAA). Experiments were conducted in a pilot-scale 24 m3 stainless steel chamber using either biological indicators (BIs) or bacterial spores deposited onto surfaces via aerosolization. Wipe sampling was used to recover aerosol-deposited spores from chamber surfaces and coupon materials before and after fogging to assess decontamination efficacy. Temperature, relative humidity, and hydrogen peroxide vapor levels were measured during testing to characterize the fog environment. The fog completely inactivated all BIs in a test using a 60 mL solution of PAA (22% hydrogen peroxide/4.5% peracetic acid). In tests using aerosol-deposited bacterial spores, the majority of the post-fogging spore levels per sample were less than 1 log colony forming units, with a number of samples having no detectable spores. In terms of decontamination efficacy, a 4.78 log reduction of viable spores was achieved on wood and stainless steel. Fogging of PAA solutions shows potential as a relatively easy to use decontamination technology in the event of contamination with Bacillus anthracis or other spore-forming infectious disease agents, although additional research is needed to enhance sporicidal efficacy.

Inactivation of vegetative bacterial threat agents on environmental surfaces:  Journal Article

The purpose of this study was to determine the efficacy of several liquid decontaminants, when used to inactivate vegetative biological agents on environmental surfaces. Aluminum, carpet, concrete, glass, and wood coupons were inoculated with 1 × 108 CFU of Burkholderia mallei, Francisella tularensis, Vibrio cholerae, or Yersinia pestis. Using spray-based application methods, decontamination was then attempted with pH-adjusted bleach, 1% citric acid, 70% ethanol, quaternary ammonia, or Pine-Sol®. Results indicated that decontamination efficacy varied significantly by decontaminant and organism. Materials such as wood are difficult to decontaminate, even when using sporicides. The data presented here will help responders develop efficacious remediation strategies following a large-scale contamination incident.

WARRP Decon-13: Subject Matter Expert (SME) Meeting Waste Screening and Waste Minimization Methodologies Project:  Report

The U.S. Department of Homeland Security (DHS), in close coordination with the U.S. Environmental Protection Agency (EPA), the U.S. Department of Defense (DoD), the U.S. Department of Energy (DOE), the U.S. Department of Health and Human Services (HHS), and the Denver Urban Area Security Initiative (UASI), has initiated the Wide Area Recovery and Resiliency Program (WARRP). WARRP is designed to develop guidance to support the recovery of a large urban area (specifically, Denver) following a chemical, biological, or radiological (CBR) wide-area incident. One program activity completed under WARRP was the WARRP Systems Study. This study identified 25 key gaps, including the lack of waste minimization polices, processes, and technologies, particularly highlighted for wide‐area Radiological Dispersal Device (RDD) scenarios. Specifically, the amount of waste generated from an RDD that requires low-level radioactive waste (LLRW) disposal needs to be minimized by employing screening techniques and properly segregating different types of waste.

A Yersinia pestis-specific, lytic phage preparation significantly reduces viable Y. pestis on various hard surfaces experimentally contaminated with the bacterium:  Journal article

Five Y. pestis bacteriophages obtained from various sources were characterized to determine their biological properties, including their taxonomic classification, host range and genomic diversity. Four of the phages (YpP-G, Y, R and YpsP-G) belong to the Podoviridae family, and the fifth phage (YpsP-PST) belongs to the Myoviridae family, of the order Caudovirales comprising of double-stranded DNA phages. The genomes of the four Podoviridae phages were fully sequenced and found to be almost identical to each other and to those of two previously characterized Y. pestis phages Yepe2 and ϕA1122. However, despite their genomic homogeneity, they varied in their ability to lyse Y. pestis and Y. pseudotuberculosis strains. The five phages were combined to yield a “phage cocktail” (tentatively designated “YPP -100”) capable of lysing the 59 Y. pestis strains in our collection. YPP -100 was examined for its ability to decontaminate three different hard surfaces (glass, gypsum board and stainless steel) experimentally contaminated with a mixture of three genetically diverse Y. pestis strains CO92, KIM and 1670G. Five minutes of exposure to YPP -100 preparations containing phage concentrations of ca. 109, 108 and 107 PFU/mL completely eliminated all viable Y. pestis cells from all three surfaces, but a few viable cells were recovered from the stainless steel coupons treated with YPP -100 diluted to contain ca. 106 PFU/mL. However, even that highly diluted preparation significantly (p = < 0.05) reduced Y. pestis levels by ≥ 99.97%. Our data support the idea that Y. pestis phages may be useful for decontaminating various hard surfaces naturally- or intentionally-contaminated with Y. pestis.

Water Security Related Products

An Adsorption Model for Arsenate Transport in Corroded Iron Pipes, with Application to a Simulated Intrusion in a Water Distribution Network:  Journal article

Adsorption to pipe wall materials significantly affects the fate and transport of certain contaminants in water distribution systems. For example, arsenate has a strong affinity for iron oxide, a substance common in water distribution pipes. In this paper a mathematical model for arsenate adsorption to iron oxide pipe wall materials is developed. The effects of two common assumptions on modeled arsenate transport are explored: a theoretical smooth pipe mass transfer coefficient and an assumption of rapid equilibrium of adsorption at the pipe wall surface. The effects of these assumptions are explored in a single pipe sensitivity analysis and found to yield significantly different results than parameters estimated from experimental data. In simulations of a hypothetical arsenate contamination event in a model water distribution system, the two assumptions result in different predictions of system contamination and contaminant exposure to consumers. These results indicate that while water quality modeling plays an essential role in planning for distribution system decontamination, modeling assumptions must be carefully chosen.

Electronic Surveillance System for the Early Notification of Community-based Epidemics (ESSENCE) Water Security Module:  Report 

The purpose of this project was to design a prototype system for surveillance of certain water quality parameters and water distribution system operating conditions that may be correlated in space and/or time with public health events possibly related to drinking water contamination. Algorithms were developed and implemented to identify triggers that would initiate investigations by public health epidemilogists and/or water utility personnel. Visual and analytic tools were developed to aid an investigation and foster collaboration between the health departments and the water utilities.

Inactivation of Bacterial Bioterrorism Agents in Water: A Summary of Seven EPA and CDC Research Studies-Journal article:  Journal article

Past use of weaponized Bacillus anthracis spores has prompted increased interest in studying the inactivation of potential bacterial bioterrorism agents in drinking water. Conditions for chemically inactivating many regulated waterborne disease-causing species are well known, but there are only limited data available on inactivating microorganisms that could potentially be used as biological weapons. Information on the likelihood of such agents surviving in drinking water containing disinfectants is needed to ensure that end users are sufficiently protected.

The Potential for Using the CANARY Event Detection Software to Enhance Security and Improve Water Quality:  Symposium Paper

 The CANARY event detection software was developed to enhance the detection of contamination in water distribution systems. Working in conjunction with a network of water quality sensors placed strategically throughout the distribution system, CANARY increases the likelihood and speed of detection by interpreting sensor data in near real-time, identifying anomalies, and alerting the operator when a contaminant might be present. Through pilot studies, CANARY has demonstrated its ability to detect unexpected “normal” events, such as sensor malfunctions or pipe breaks. This study systematically investigates how CANARY could be used to provide multiple benefits to water utilities by improving water system operations, treatment, and security. The probable causes of standard distribution system water quality issues (e.g., maintenance of an acceptable disinfectant residual, biofilm control, customer concerns) are presented, as well as the associated changes in water quality parameters that could be detected by CANARY. The range of conditions under which CANARY could detect each of these water quality issues is evaluated. For water utilities of all sizes, the value of using this type of detection software to enhance detection and response to a wide range of water quality events is discussed.

Assessment of Relative Potential for Biological Threat Agent Exposure during Uses of Drinking Water:  Technical Brief

Although potential exposure risks from ingestion of contaminated water are well known, knowledge gaps for non-ingestion hazards from inhalation or skin contact are still being addressed. A screening level microbial exposure assessment was conducted to assist in better understanding potential exposures associated with pathogen contamination of drinking water supplies. The goals of the research included:

  • Understanding potential drinking water exposure pathways during common water uses
  • Estimating exposure doses from ingestion and inhalation
  • Developing a method for prioritizing exposure pathways that require additional or future assessment

Although, the overall screening-level exposure assessment, exampled with Legionella species data, was associated with high levels of statistical uncertainty some general conclusions could be made.

  • Adult and child exposures with potential human health consequences can occur when a drinking water system is contaminated with pathogens at concentrations similar or greater to those evaluated in this exposure assessment.
  • Exposure can result from ingestion of water or from inhalation of aerosolized pathogens from common water uses.
  • Exposure pathways that included the ingestion route of exposure consistently resulted in the highest calculated exposure doses.

Biodegradation by activated sludge from a municipal wastewater plant of an organophosphonate hydrolysis product of VX: . . . But not a drop to drink (pp.33-35):  Journal Article

Organophosphate chemical warfare agents (CWA) have been used in the past and continue to remain a threat to both national security. In the event of a CWA attack, it is possible that resulting response efforts will lead to CWA-impacted decontamination wastewater entering a municipal wastewater treatment plant. The fate of CWA compounds in a wastewater treatment plant is not well understood. This study investigated the fate of ethyl methylphosphonic acid (EMPA), a hydrolysis product of VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate), in activated sludge from a laboratory scale sequencing batch reactor. The reactor was fed peptone and sodium acetate to simulate wastewater. Sorption kinetics, sorption equilibrium isotherm and degradation batch experiments demonstrated that EMPA did not sorb to the biomass. Degradation results showed that approximately 30% of the initial concentration of 1 mg L-1 EMPA was degraded, with the degradation limited by a threshold effect. In addition, the results suggest that the nitrifying bacteria may be responsible for the degradation via co-metabolism. Therefore, unless a suitable microbial population is present, possible CWA, degradation products, like EMPA, and similarly sorbed and biodegraded compounds may pass through an activated sludge wastewater treatment plant largely unchanged. These results demonstrate that it cannot be assumed that any particular activated sludge will contain the requisite microbial population.

 CANARY User’s Manual version 4.3.2:  User manual

Follow this link to the CANARY Trac homepage. This site contains the most recent information on running CANARY, as well as providing a facility for reporting bugs and placing feature requests. While we will respond to bug requests as quickly as possible, please be aware that responses to feature requests may be limited due to time and other constraints on the project.

Sampling and Analysis Related Products

Evaluation of Surface Sampling for Bacillus Spores Using Commercially Available Cleaning Robots:  Journal Article

Five commercially available domestic cleaning robots were evaluated on their effectiveness for sampling aerosol-deposited Bacillus atrophaeus spores on different indoor material surfaces. The five robots tested include three vacuum types (R1, R2, and R3), one wet wipe (R4), and one wet vacuum (R5). Tests were conducted on two different surface types (carpet and laminate) with 106 colony forming units of B. atrophaeus spores deposited per coupon (35.5 cm ×35.5 cm). Spores were deposited on the center surface (30.5 × 30.5 cm) of the coupon’s total surface area (71.5 × 71.5 cm), and the surfaces were sampled with an individual robot in an isolation chamber. Chamber air was sampled using a biofilter sampler to determine the potential for resuspension of spores during sampling. Robot test results were compared to currently used surface sampling methods (vacuum sock for carpet and sponge wipe for laminate). The test results showed that the average sampling efficacies for R1, R2, and R3 on carpet were 26, 162, and 92% of vacuum sock sampling efficacy, respectively. On laminate, R1, R2, R3, R4, and R5 average sampling efficacies were 8, 11, 2, 62, and 32% of sponge wipe sampling efficacy, respectively. We conclude that some robotic cleaners were as efficacious as the currently used surface sampling methods for B. atrophaeus spores on these surfaces.  This report Evaluation of Surface Sampling for Bacillus Spores Using Commercially-available Cleaning Robots accompanies the journal article of the same title.  The report contains additional detail not included in the article.

High Throughput Determination of VX in Drinking Water by Immunomagnetic Separation and Isotope Dilution High Performance Liquid Chromatography Tandem Mass Spectrometry (HPLC/MS/MS):  Methods Report

This document provides the standard operating procedure for determination of the chemical warfare agent VX (O-Ethyl S-2-Diisopropylamino-Ethyl Methylphosphonothioate) in drinking water by isotope dilution liquid chromatography tandem mass spectrometer (LC/MS/MS). This method was adapted from one that was initially developed by the Centers for Disease Control and Prevention, in the National Center for Environmental Health for the determination and quantitation of VX in aqueous matrices. This method is designed to support site-specific cleanup goals of environmental remediation activities following a homeland security incident involving this analyte.

Stability Study for Ultra-Dilute Chemical Warfare Agent Standards:  Report

This shelf life study demonstrates that the stabilities of the CWAs vary greatly between compound classes (e.g., G-, H- and V-agents), and VX stability can be affected by the presence of other CWAs. Currently, CWA standards are being supplied to the ERLN laboratories as two solutions – the first, 10 ppm VX in dichloromethane  and the second, a mixture of GB (10 ppm), GD (5 ppm), GF (10 ppm), and HD (5 ppm) in dichloromethane. Based on the results of this study, the research team recommends that, for convenience in planning and as a simple rule of thumb, all CWA standards, prepared in dichloromethane, in sealed ampoules be used within six months of receipt and that, once opened and mixed into five-component solutions containing GB, GD, GF, HD, and VX, all CWA standards be kept for no longer than one week. The team further recommends that future work be performed to determine how VX can be stabilized in the ultra-dilute standards. Such stabilization strategies could include the removal of ethyl methylphosphonic acid and  isopropyl methyl phosphonic acid  from the standard solution, implementation of a stringent water removal strategy and the use of a stabilizer to prevent VX degradation.

Determination of the Sampling Efficiency of Biosamplers to Collect Inhalable Particles:  Report

Three bioaerosol samplers were chosen for evaluation of sampling efficiency (SE) in the aerosol wind tunnel according to 40 CFR Part 53 Subpart D (U.S. EPA, 1998): the XMX/2L-MIL, manufactured by Dycor Technologies, Ltd.; the portable sampling unit (PSU) sampler, manufactured by Hi-Q Environmental Products; and the DryCloneTM sampler, manufactured by Evogen, Inc. Wind tunnel testing of the samplers was carried out with monodisperse liquid aerosols (oleic acid and uranine) with particle diameters of 5, 10, 15, and 20 μm. The DryCloneTM and PSU samplers were tested in the wind tunnel in triplicate with each of the four particle sizes at wind speeds of 2, 8, and 24 kilometers/hour (km/h). The sampling efficiency for inhalable particulate (5 to 20 μm aerodynamic diameter, dpae) is reported versus dpae and the square root of the Stokes number (a nondimensional number relating velocity and aerodynamic particle size to relaxation time). Neither of the samplers showed wind speed insensitivity, and both had a rapid decline in efficiency with rising Stokes number. The XMX sampler was tested with 5-μm aerosol at 2 and 8 km/h, but the SE did not compare well with the manufacturer’s results for solid monodisperse aerosols under the same experimental conditions. The manufacturer indicated that testing with liquid aerosol was not appropriate. For this reason, we suggest retesting the XMX sampler using solid particles prepared from fluoroscein and ammonium hydroxide.

High Throughput Immunomagnetic Scavenging Technique for Quantitative Analysis of Live VX Nerve Agent in Water, Hamburger, and Soil Matrices:  Journal Article

We have developed a novel immunomagnetic scavenging technique for extracting cholinesterase inhibitors from aqueous matrixes using biological targeting and antibody-based extraction. The technique was characterized using the organophosphorus nerve agent VX. The limit of detection for VX in high-performance liquid chromatography (HPLC)-grade water, defined as the lowest calibrator concentration, was 25 pg/mL in a small, 500 μL sample. The method was characterized over the course of 22 sample sets containing calibrators, blanks, and quality control samples. Method precision, expressed as the mean relative standard deviation, was less than 9.2% for all calibrators. Quality control sample accuracy was 102% and 100% of the mean for VX spiked into HPLC-grade water at concentrations of 2.0 and 0.25 ng/mL, respectively. This method successfully was applied to aqueous extracts from soil, hamburger, and finished tap water spiked with VX. Recovery was 65%, 81%, and 100% from these matrixes, respectively. Biologically based extractions of organophosphorus compounds represent a new technique for sample extraction that provides an increase in extraction specificity and sensitivity.

Performance of a Novel High Throughput Method for the Determination of VX in Drinking Water Samples:  Journal Article

 VX is a highly toxic organophosphorous nerve agent, and even low levels of contamination in water can be harmful. Measurement of low concentrations of VX in aqueous matrices is possible using an immunomagnetic scavenging technique and detection using liquid chromatography/tandem-mass spectrometry. Performance of the method was characterized in HPLC-grade water preserved with sodium omadine, an antimicrobial agent, and sodium thiosulfate, a dechlorinating agent, over eight analytical batches with quality control samples analyzed over 10 days. The minimum reporting level was 25 ng/L with a linear dynamic range up to 4.0 ug/L. The mean accuracies for two quality control samples containing VX at concentrations of 0.250 and 2.00 ug/L were 102 ± 3% and 103 ± 6%, respectively. The stability of VX was determined in five tap waters representing a range of water quality parameters and disinfection practices over a 91 day period. In preserved tap waters, VX recovery was between 81 and 92% of the fortified amount, 2.0 ug/L, when analyzed immediately after preparation. Recovery of VX decreased to between 31 and 45% of the fortified amount after 91 days, indicating hydrolysis of VX. However, the preservatives minimized the hydrolysis rate to close to the theoretical limit. The ability to detect low concentrations of VX in preserved tap water 91 days after spiking suggests applicability of this method for determining water contamination with VX and utility during environmental remediation.



Comments are closed.