EPA/600/R-21/122 | October 2021
www.epa.gov/emergency-response-research
United States
Environmental Protection
Agency
oEPA
Assessment of Low-Level Hydrogen
Peroxide Fumigation for Remediation of
Indoor Environments Contaminated with
Persistent Toxic Chemicals
Office of Research and Development
Homeland Security Research Program

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EPA/600/R-21 /122
October 2021
This page left intentionally blank.

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Assessment of Low-Level Hydrogen Peroxide Fumigation for
Remediation of Indoor Environments Contaminated with
Persistent Toxic Chemicals
Lukas Oudejans
Environmental Protection Agency
Homeland Security and Materials Management Division
Research Triangle Park, North Carolina 2771 1
William S. Williamson, Jr
Southwest Research Institute
San Antonio, Texas 78238
and
Sujoy B. Roy
Tetra Tech, Inc.
Lafayette, California 94549
Homeland Security and Materials Management Division
Office of Research and Development
Research Triangle Park, North Carolina 2771 1

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Disclaimer
The United States Environmental Protection Agency (EPA) through its Office of Research and
Development (ORD) funded and managed the research described herein under Contract Number EP-C-
15-004, Task Order 68HERC19F0152 with Tetra Tech, Inc., Cincinnati, Ohio. It has been subjected to
the Agency's review and has been approved for publication. Note that approval does not signify that the
contents necessarily reflect the views of the Agency. Any mention of trade names, products, or services
does not imply an endorsement by the United States (U.S.) Government or EPA. The EPA does not
endorse any commercial products, services, or enterprises. The contractor role did not include
establishing Agency policy.
Questions concerning this document, or its application should be addressed to:
Lukas Oudejans, Ph.D.
Homeland Security and Materials Management Division
Center for Environmental Solutions and Emergency Response
Office of Research and Development
U.S. Environmental Protection Agency (MD-E343-06)
109 T.W. Alexander Drive
Research Triangle Park, NC 27711
Phone: 919-541-2973
Fax: 919-541-0496
E-mail: Oudeians,Lukas@epa.gov

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Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation's
land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to
formulate and implement actions leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. To meet this mandate, EPA's research program is
providing data and technical support for solving environmental problems today and building a science
knowledge base necessary to manage our ecological resources wisely, understand how pollutants affect
our health, and prevent or reduce environmental risks in the future.
The Center for Environmental Solutions and Emergency Response (CESER) within the Office of
Research and Development (ORD) conducts applied, stakeholder-driven research and provides
responsive technical support to help solve the Nation's environmental challenges. The Center's research
focuses on innovative approaches to address environmental challenges associated with the built
environment. We develop technologies and decision-support tools to help safeguard public water
systems and groundwater, guide sustainable materials management, remediate sites from traditional
contamination sources and emerging environmental stressors, and address potential threats from
terrorism and natural disasters. CESER collaborates with both public and private sector partners to foster
technologies that improve the effectiveness and reduce the cost of compliance, while anticipating
emerging problems. We provide technical support to EPA regions and programs, states, tribal nations,
and federal partners, and serve as the interagency liaison for EPA in homeland security research and
technology. The Center is a leader in providing scientific solutions to protect human health and the
environment.
This report addresses the application of low concentration hydrogen peroxide vapor for the remediation
of surfaces contaminated with the persistent chemical warfare agents VX and sulfur mustard (HD) and
the pesticide (and chemical warfare agent surrogate) malathion. A low concentration hydrogen peroxide
vapor environment can be created using low-cost indoor humidity control systems. Here, the focus is on
the concentration and fumigation requirements to achieve high efficacy through degradation of the
selected chemicals by the hydrogen peroxide vapor.
Gregory Sayles, Director
Center for Environmental Solutions and Emergency Response
iv

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Table of Contents
Disclaimer	iii
Foreword	iv
List of Figures	vi
List of Tables	vii
Acronyms and Abbreviations	viii
Acknowledgments	x
Executive Summary	xi
1.0 Introduction	1
1.1	Background	1
1.2	Goal	1
1.3	Project Objectives	1
1.4	Test Facility Description	2
2.0 Methods and Materials	3
2.1	Experimental Approach	3
2.2	Experimental Design	4
2.3	Development and Fabrication of Environmental Chamber	5
2.4	Surface Materials	8
2.5	Decontamination Solution	10
2.6	Test Chemicals	10
2.7	Materials Contamination	11
2.8	Weathering of Coupons	12
2.9	LCHPV Fumigation	13
2.10	Coupon Extraction	13
2.11	Analytical methods	16
2.12	Calculations	19
3	Results	21
3.1	Coupon Spike Precision, Accuracy and TP-0 Recoveries	21
3.2	Environmental Conditions during Weathering	23
3.3	Weathering and Fumigation Exposure Times	24
3.4	Environmental Conditions during LCHPV Fumigation	25
3.5	LCHPV Fumigation Concentrations	26
3.6	Natural Attenuation of Chemicals	27
3.7	LCHPV Fumigation Recoveries and Efficacies	30
3.8	Statistical Analysis	40
4	Quality Assurance/Quality Control	46
4.1	Data Quality Indicators	46
4.2	Process Quality Control Parameters for LCHPV Efficacy Testing	47
4.3	Instrument Calibration	48
4.4	Sample Custody and Archival	48
4.5	QAPP Deviations	48
5	Summary and Conclusions	50
6	References	52
7	Appendices	53
Appendix A	54
Appendix B	59
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List of Figures
Figure 1: Decontamination efficacy test scheme	3
Figure 2: Chamber block flow diagram	6
Figure 3: Picture of chamber	7
Figure 4: Chamber monitoring equipment attached to the recirculating loop	8
Figure 5: In order from left to right: Stainless-steel, painted-wood, rubber-molding, and vinyl-tile
coupons	9
Figure 6: Spiking HD on coupons for TP-1 in the fume hood, prior to the transfer into the main chamber
through the antechamber	11
Figure 7: Pictures depicting coupon transfer into the chamber for fumigation testing	12
Figure 8: Stainless-steel coupons spiked with HD	23
Figure 9: VX being spiked on coupons (left). Stainless-steel coupons 24 h after VX deposition (right). 23
Figure 10: HD detection in procedural blanks relative to TP-0 contaminated coupon	28
Figure 11: Relative VX recovery from stainless steel vs LCHPV exposure time	31
Figure 12: Relative VX recovery from painted wood vs LCHPV exposure time	31
Figure 13: Relative VX recovery from rubber molding vs LCHPV exposure time	31
Figure 14: Relative VX recovery from vinyl tile vs LCHPV exposure time	32
Figure 15: Relative HD recovery from stainless steel vs LCHPV exposure time	35
Figure 16: Relative HD recovery from painted wood vs LCHPV exposure time	35
Figure 17: Relative HD recovery from rubber molding vs LCHPV exposure time	35
Figure 18: Relative HD recovery from vinyl tile vs LCHPV exposure time	36
Figure 19: LCHPV decontamination efficacies for HD on four materials	36
Figure 20: Relative malathion recovery from stainless steel vs LCHPV exposure time	38
Figure 21: Relative malathion recovery from painted wood vs LCHPV exposure time	39
Figure 22: Relative malathion recovery from rubber molding vs LCHPV exposure time	39
Figure 23: Relative malathion recovery from vinyl tile vs LCHPV exposure time	39
Figure 24: Bayesian estimation of VX treatment. SS = stainless steel; VT = vinyl tile; RB = rubber
molding; PW= painted wood	42
Figure 25: Bayesian estimation of HD treatment. SS = stainless steel; VT = vinyl tile; RB = rubber
molding; PW= painted wood	43
Figure 26: Bayesian estimation of malathion treatment. SS = stainless steel; VT = vinyl tile; RB = rubber
molding; PW =painted wood	44
vi

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List of Tables
Table 1: Hydrogen Peroxide Fumigation Efficacy Test Matrix	4
Table 2: Hydrogen Peroxide Fumigation Efficacy Conditions	5
Table 3: Coupon Material Specifications	9
Table 4: Solvent Screening Test Results	14
Table 5: VX/EA-2192 Method Verification	14
Table 6: Comparison of Solvents for HD, Malathion, and Malaoxon Extraction	15
Table 7: Solvent Systems Used to Extract Coupons	16
Table 8: Analytical Procedures	16
Table 9: Calibration Acceptance Criteria	17
Table 10: Internal Standard Acceptance Criteria	17
Table 11: LC-MS/MS Parameters for VX and EA-2192 Analysis	18
Table 12: GC/MS Parameters for HD, Malathion, and Malaoxon Analysis	19
Table 13: VX Spike Delivery and Extraction Efficiency Performance	21
Table 14: HD Spike Delivery and Extraction Efficiency Performance	22
Table 15: Malathion Spike Delivery and Extraction Efficiency Performance	22
Table 16: Average Weathering Conditions	24
Table 17: Weathering and Fumigation Times for each Time Point	25
Table 18: Chamber Temperature and Humidity Conditions during Fumigation	26
Table 19: Average HPV Concentration during Fumigation	27
Table 20: VX Recovery Differences after 24 Hours of Weathering	28
Table 21: HD Recovery Differences after 3 Hours of Weathering	29
Table 22: Malathion Recovery Differences after 24 Hours of Weathering	29
Table 23: Average VX Mass Recovery	30
Table 24: EA-2192 Recoveries after LCHPV Fumigation of Vinyl-Tile Coupons	33
Table 25: Average HD Mass Recovery	34
Table 26: Average Malathion Mass Recovery	38
Table 27: Data Quality Indicators and Results	46
Table 28: Process Quality Indicators and Results	48
Table A1: Relative VX Recovery after LCHPV Fumigation of Stainless-Steel Coupons	55
Table A2: Relative VX Recovery after LCHPV Fumigation of Painted-Wood Coupons	55
Table A3: Relative VX Recovery after LCHPV Fumigation of Rubber-Molding Coupons	55
Table A4: Relative VX Recovery after LCHPV Fumigation of Vinyl-Tile Coupons	56
Table A5: Relative HD Recovery after LCHPV Fumigation of Stainless-Steel Coupons	56
Table A6: Relative HD Recovery after LCHPV Fumigation of Painted-Wood Coupons	56
Table A7: Relative HD Recovery LCHPV Fumigation of Rubber-Molding Coupons	57
Table A8: Relative HD Recovery after LCHPV Fumigation of Vinyl-Tile Coupons	57
Table A9: Relative Malathion Recovery after LCHPV Fumigation of Stainless-Steel Coupons	57
Table A10: Relative Malathion Recovery after LCHPV Fumigation of Painted-Wood Coupons	57
Table A11: Relative Malathion Recovery after LCHPV Fumigation of Rubber-Molding Coupons	58
Table A12: Relative Malathion Recovery after LCHPV Fumigation of Vinyl-Tile Coupons	58
vii

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Acronyms
and Abbreviations
%	percent
|iL	microliter(s)
|im	micrometer(s)
ACS	American Chemical Society
°C	degree(s) Celsius
CAS	Chemical Abstract Service
CASARM	Chemical Agent Standard Analytical Reference Material
CBC	Chemical Biological Center
CCV	continuing calibration verification
CESER	Center for Environmental Solutions and Emergency Response (U.S. EPA)
cm	centimeter(s)
cm2	square centimeter(s)
cm3	cubic centimeter(s)
CMAD	Consequence Management Advisory Division (U.S. EPA)
CT	concentration x time
CWA	chemical warfare agent(s)
DCM	dichloromethane
DEVCOM	(Combat Capabilities) Development Command
DIMP-dl4	diisopropyl methylphosphonate-dl4
EA-2192	s-[2-(diisopropylamino) ethyl] methylphosphonothioate
ECBC	Edgewood Chemical Biological Center
EPA	U.S. Environmental Protection Agency
ft	foot/feet
g	gram(s)
GC/MS	gas chromatography/mass spectrometry
GD	Soman
H2O2	hydrogen peroxide
HD	sulfur mustard, C4H8CI2S
HPV	hydrogen peroxide vapor
h	hour(s)
HSMMD	Homeland Security and Materials Management Division (U.S. EPA)
HSRP	Homeland Security Research Program
ICAL	initial calibration
ICV	initial calibration verification
ID	identification
IDL	instrument detection limit
in	inch(es)
IPA	isopropyl alcohol
ISB	instrument solvent blank
ISO	International Organization for Standardization
L	liter(s)
LC	liquid chromatography
LCHPV	low-concentration hydrogen peroxide vapor
LC/MS	liquid chromatography/mass spectrometry
LC-MS/MS	liquid chromatograph/triple quadrupole mass spectrometry
LCS	laboratory control spike
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LIMS
Laboratory Information Management System
m2
square meter(s)
mg
milligram(s)
min
minute(s)
mL
milliliter(s)
mm
millimeter(s)
in VHP®
modified vaporous hydrogen peroxide
ND
non-detect(s)
ng
nanogram(s)
NIST
National Institute of Standards and Technology
NMR
Nuclear Magnetic Resonance Spectroscopy
NRF
National Response Framework
O&M
Operating and Maintenance
OEM
Office of Emergency Management (U.S. EPA)
ORD
Office of Research and Development (U.S. EPA)
PAC
Programmable Automation Controller
PE
Performance Evaluation
PI
Principal Investigator
ppmv
part(s) per million by volume
Psig
pound(s) per square inch gauge
PVC
polyvinyl chloride
PW
painted wood
QA
quality assurance
QAPP
Quality Assurance Project Plan
QC
quality control
R2
coefficient of determination
RB
rubber molding
Rec
recovery
RH
relative humidity
RSD
relative standard deviation
SB
solvent blank
SD
standard deviation
SIM
selected ion monitoring
ss
stainless-steel coupons
STP
standard temperature and pressure
SwRI
Southwest Research Institute®
TP
time point
TSA
technical systems audit
U.S.
United States
UV
ultraviolet
VT
vinyl tile
VX
O-ethyl S-[2-(diisopropylamino) ethyl] methylphosphonothioate
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Acknowledgments
This research effort is part of the U.S. Environmental Protection Agency's (EPA's) Homeland Security
Research Program (HSRP) to evaluate decontamination approaches that would have no or minimal
impact on materials while remaining effective in degrading chemical warfare agents and/or pesticides on
surfaces.
This effort was directed by the principal investigator from the Office of Research and Development's
(ORD's) Homeland Security and Materials Management Division (HSMMD) within the Center for
Environmental Solutions and Emergency Response (CESER). The contributions of the following
individuals have been a valued asset throughout this effort.
EPA Project Team
Lukas Oudejans, ORD/CESER/HSMMD (PI)
Joseph Wood, ORD/CESER/HSMMD
Leroy Mickelsen, Office of Emergency Management (OEM), Consequence Management Advisory
Division (CMAD)
Southwest Research Institute
Yirgaalem Abrha
Guillermo Alonso
Christopher Garza
Robert Martinez
Antonio Menchaca
Bill Williamson
Albert Z wiener
Tetra Tech, Inc.
Sujoy Roy
EPA Technical Reviewers
Veera Boddu, ORD/CESER/HSMMD
Vince Gallardo, ORD/CESER/HSMMD
EPA Quality Assurance (QA) Review
Ramona Sherman, ORD/CESER/HSMMD
EPA Technical Editing
Joan Bursey
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Executive Summary
The U.S. Environmental Protection Agency's (EPA's) Homeland Security Research Program (HSRP)
conducts research necessary for the identification of methods and technologies that can be used during
hazardous materials remediation and cleanup efforts. The available processes to recover buildings and
structures that have been contaminated with chemical warfare agents (CWAs) or other toxic chemicals
have defaulted to the use of corrosive, yet effective, solutions that are labor intensive to apply and, in
most cases, incompatible with many materials of construction. At the forefront of decontamination
technology investigations are techniques that are easily applied and are effective to mitigate the hazard
plus allow for structure re-use. Hydrogen peroxide solutions or vapors of such solutions at relatively
high concentrations (> 250 parts per million [ppm]) have shown high (>90%) efficacy against chemical
agents [1],
The concept of low (less than 50 ppm) concentration hydrogen peroxide vapor (LCHPV) applied over a
long period of time (days) has merit to address the problems of applying liquid solutions to
decontaminate surfaces. LCHPV can be generated by, for example, commercial off the shelf room
humidifiers filled with a hydrogen peroxide solution. The efficacy of LCHPV applied to the CWAs O-
ethyl S-[2-(diisopropylamino) ethyl] methylphosphonothioate (VX) and sulfur mustard (HD), and the
pesticide malathion contaminating interior building materials was investigated here.
The study included the design and construction of a hydrogen peroxide vapor (HPV) generation system
and an environmental exposure chamber controlling ambient temperature and humidity. The CWAs, VX
and HD, and the pesticide malathion were procured and used to contaminate material coupons. Four
materials were investigated to include stainless steel, rubber molding, vinyl flooring, and painted wood.
These surfaces were contaminated with each of the chemicals. Representative material coupons were
then exposed to an HPV concentration at a specific relative humidity (RH) and fumigation time. Testing
was completed at a controlled temperature of 23 degrees Celsius (°C). Testing also included positive
control runs in which the same materials were exposed to air flowing through the same chamber with the
same RH and temperature but without the HPV present.
A total of thirteen trials were performed to evaluate LCHPV fumigation of the four materials. There
were five VX trials, five HD trials, and three malathion trials. Test conditions that were varied included
RH, hydrogen peroxide concentration, and fumigation time. In addition to measuring LCHPV
decontamination efficacy for these compounds on the four materials, the formation of EA-2192 and
malaoxon as toxic oxidation byproducts was also monitored during the tests with VX and malathion,
respectively.
The evaluation of the LCHPV started with VX with the HPV concentration held at 25 parts per million
volume (ppmv) and RH held in a range of 50 to 65 percent. The longest exposure time was 72 hours for
the first trial (concentration x time, CT = 1,800 ppmxhours) followed by four subsequent trials up to 144
hours (6 days, CT = 3,600 ppmxhours) with intermediate timepoints. Results show there was some
efficacy beyond natural attenuation for the VX on rubber molding and vinyl tile but none above the VX
natural attenuation for stainless steel and painted wood. EA-2192 was detected at the longest contact
time of VX with the material (7 days) but only for the positive control tests in which no HPV was
present.
Evaluation of HD was conducted using HPV concentrations of 25 ppmv, 50 ppmv, and 75 ppmv. During
these tests, the RH was held between 50 and 65 percent. Maximum exposure time was fixed at 29 hours
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with intermediate timepoints (CT = 725 - 2,175 ppmxhours). Results show significant losses in
recovered HD amounts from all four materials. However, these losses in HD mass were directly
attributed to the natural attenuation (predominantly evaporation) of HD with no measurable HPV
decontamination efficacy at any timepoint, material and any of the HPV and RH test conditions.
For the malathion pesticide, HPV was evaluated at 25 ppmv and 75 ppmv over a 144-hour exposure
time. RH was held at 40 percent. Malathion showed some hydrogen peroxide-induced decomposition on
painted wood and rubber molding, but none for stainless steel and vinyl tile. None of the samples
yielded detectable amounts of malaoxon.
Interpretation of results
In the case of VX and HD, the longest CT values (defined as the product of concentration and exposure
time) exceeded CTs for previously reported hydrogen peroxide efficacy data [1,2] by up to a factor of
two. While a significant degradation of VX and HD was observed in those higher HPV concentration
studies, this degradation does not translate to the lower concentration and longer fumigation times at
equal or higher CT values tested here. One difference between the previous study and this study is the
lack of ammonia vapor in this study. The concept of modified vaporous hydrogen peroxide (mVHP®)
was created to enhance the degradation of soman (GD) but not the degradation of VX or HD. Hence, the
addition of ammonia vapor in this study was not deemed essential.
Impact
The current results appear to indicate that LCHPV is not an effective approach towards remediation of
materials contaminated with VX, HD or malathion. While LCHPV efficacy was observed for some
materials, the impact is minimal considering the natural attenuation for these chemicals on surfaces.
Natural attenuation dominated the loss in recovered chemical from surfaces (except for malathion) over
any hydrogen peroxide degradation.
xii

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1.0 Introduction
1.1	Background
Under the National Response Framework (NRF), the United States Environmental Protection Agency
(EPA) is designated as the coordinating agency to prepare for, respond to, and recover from a threat to
human health and the environment caused by hazardous materials incidents. These incidents include
releases of chemical, biological, and radiological substances. The imminent threat of a chemical warfare
agent (CWA) release in infrastructure, building or transportation hub is driving EPA's Homeland
Security Research Program (HSRP) to develop a research program that systematically evaluates
potential decontamination technologies for chemical agents.
Recently, the use of low-concentration hydrogen peroxide vapor (LCHPV) fumigation has gained
attention as hydrogen peroxide is readily available, efficacious, a green technology, and relatively easy
to implement as a decontamination approach [3,4], Hydrogen peroxide is also a strong oxidizer but with
less, if any, material compatibility issues in comparison to the chlorine chemistry as present in, e.g.,
chlorine dioxide. In this study, the focus was to determine conditions under which LCHPV fumigation
could be used to decontaminate CWAs or a selected pesticide from interior structures composed of
nonporous, (semi)porous, and permeable materials.
1.2	Goal
The goal of the study was to assess the efficacy of LCHPV to decontaminate porous and/or permeable
building materials such as painted wood, rubber molding, and vinyl tile. This evaluation was conducted
on material coupons contaminated with the CWAs VX and distilled sulfur mustard (HD). The pesticide
malathion was also used as it is a contaminant, pesticide, and frequently used as a surrogate for the
organophosphate CWAs.
1.3	Project Objectives
The objectives for this study included:
•	To build an environmental test chamber and hydrogen peroxide vapor (HPV) generator.
•	To demonstrate the performance of the environmental test chamber and peroxide generator.
•	To perform LCHPV efficacy trials on four materials contaminated with VX, HD, and malathion.
Design requirements for the test chamber included: a minimum internal volume of 300 liters (L); access
port for coupon removal with minimal impact to set temperature; an operational temperature range of
15-25 degrees Celsius (°C) with temperature control ± 3°C; HPV concentration delivery and monitoring;
generation of HPV for up to 3 days using 3 percent (%) or 8% hydrogen peroxide solution; adequate air
mixing; shielded from direct ultraviolet (UV) light; and a minimal air exchange. The test setup included
continuous temperature and relative humidity (RH) monitoring.
The LCHPV fumigation was performed on four material types. Each fumigation trial of each material
included assays to determine efficacy at each of 5 time points (TPs). The concentration of peroxide,
chamber temperature, RH, and the duration of exposure were established for the initial trial, then
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adjusted for future trials based upon chemical agent mass recovery findings.
Five trials were performed for each CWA and three trials were performed using malathion. Test
materials were identified as painted wood (PW), vinyl tile (VT), rubber molding (RB), and stainless
steel (SS). Stainless steel was included as a nonporous reference material.
1.4 Test Facility Description
All tests were performed at Southwest Research Institute (SwRI) located in San Antonio, Texas. SwRI
holds a certified chemical agent facility (2018 Provisioning Agreement with US Army Materiel
Command).
2

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2.0 Methods and Materials
2.1 Experimental Approach
The approach to evaluate LCHPV decontamination efficacy is identified in the test scheme shown in
Figure 1.


y
r

m






m


—*~t=f—

Coupon
Preparation
and
Inspection
Coupon
Contamination
(Spike 4 x 0.5uL
drops)
Cou pons into
the Chamber
Test Time Line
Coupon
Extraction by
So ni cat ion
Ass ay to
Determine
Efficacy
Weathering Time
(VX, M = 24 h) H202 Fumigation
(HD = 3 h)
O TH CS| rn
Coupon Test Point (TP) Collection Intervals


Figure 1: Decontamination efficacy test scheme.
Coupons of each surface material were prepared by cutting coupons from larger sheets or items. All
coupons were visually inspected for defects. Each trial consisted of samples collected at five intervals
post-exposure (Timepoint (TP)-O to TP-4). Each TP included coupon samples in triplicate and a
negative control blank (no contamination). Chemicals VX, HD, or malathion were applied to test
coupons as four uniform droplets (oriented as 4 dots on a die) using a microliter syringe. After the
chemical application, TP-0 coupons were immediately (within five minutes [min]) extracted, and all
other coupons (TP-1 thru TP-4) were placed in the test chamber.
Prior to starting a trial, the chamber was opened and purged to remove residual HPV. After the
placement of the coupons, the chamber was closed, the temperature was set to 23°C, and conditions
were allowed to equilibrate. At the start of the trial, the chamber was set to the weathering conditions:
temperature at 23°C ±3°C, RH range between 25-45%, and a (residual) HPV concentration of less than
2 parts per million vapor (ppmv). The initial weathering duration was set to 24 hours (h) for VX and
malathion and 3 h for HD. Weathering duration for HD was shorter based on known higher volatility
and likely significant evaporation of this agent after 24 h in comparison to the highly persistent VX and
malathion.
At the end of the weathering period, TP-1 coupons were removed from the chamber and the hydrogen
peroxide fumigation cycle was started. HPV concentration and RH were set according to matrix
requirements. Coupon samples associated with timepoints TP-1, TP-2, TP-3, and TP-4 were transferred
from the main chamber into the antechamber from which the coupons could be extracted without
impacting the main chamber test conditions at their respective timepoints. Each trial ended after the TP-
4 coupon collection with a purge of the chamber. The antechamber was free of HPV based on the
frequent opening to the atmosphere in the hood to remove coupons.
Coupons were extracted by submerging the entire coupon into the organic solvent, sonicating for 10
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min, and allowing a one-hour post sonication solvent contact time. An aliquot of the extract was assayed
using liquid chromatography coupled to a triple quadrupole mass spectrometer (LC-MS/MS) for VX
analysis or gas chromatography coupled to a mass spectrometer (GC/MS) for HD and malathion
analysis.
2.2 Experimental Design
The LCHPV decontamination efficacy test matrix is presented in Table 1. The test matrix identifies the
number of trials performed for each agent, the materials tested, the number of coupons for each material
used for each time point, and total number of coupons. Each row represents a unique trial and includes
control trials that were performed without the hydrogen peroxide fumigation.
Table 1: Hydrogen Peroxide Fumigation Efficacy Test Matrix
Trial
Agent
Material Types
Coupons per Material Type per Test Point (TP)
Total
ID
TP-01
TP-12
TP-23
TP-33
TP-43
LB4
Coupons
VX-1
VX
SS, PW, RB, VT5
3C6 /1B7
3C/1B
3C/1B
3C/1B
3C/1B
1
84
VX-2
VX
SS, PW, RB, VT
3C/1B
6C/1B
3C/1B
3C/1B
3C/1B
1
96
VX-3
VX
SS, PW, RB, VT
3C/1B
3C/1B
3C/1B
3C/1B
3C/1B
1
84
VX-48
VX
SS, PW, RB, VT
3C/1B
3C/1B


3C/1B
1
52
VX-58
VX
SS, PW, RB, VT
3C/1B
3C/1B


3C/1B
1
52
HD-1
HD
SS, PW, RB, VT
3C/1B
3C/1B
3C/1B
3C/1B
3C/1B
1
84
HD-2
HD
SS, PW, RB, VT
3C/1B
3C/1B
3C/1B
3C/1B
3C/1B
1
84
HD-3
HD
SS, PW, RB, VT
3C/1B
3C/1B
3C/1B
3C/1B
3C/1B
1
84
HD-48
HD
SS, PW, RB, VT
3C/1B
3C/1B


3C/1B
1
52
HD-5
HD
SS, PW, RB, VT
3C/1B
3C/1B


3C/1B
1
52
M-1
Malathion
SS, PW, RB, VT
3C/1B
3C/1B
3C/1B
3C/1B
3C/1B
1
84
M-2
Malathion
SS, PW, RB, VT
3C/1B
3C/1B
3C/1B
3C/1B
3C/1B
1
84
M-38
Malathion
SS, PW, RB, VT
3C/1B
3C/1B


3C/1B
1
52
1TP-0 = Controls used to validate the amount of agent spiked and recovered from the coupons.
2	TP-1 = Collected after the weathering period and before start of fumigation.
3	TP-2 thru 4 = Collected after the weathering time and at designated times after the start of fumigation.
4	LB = Laboratory blank, a coupon from each material per trial, not contaminated with agent and not added to
the chamber
5SS =Stainless steel; PW= Painted Wood; RB = Rubber Molding; VT = Vinyl Tile
6	C — Number of (test) coupons from each material spiked with 2 |jL of chemical agent.
7	B = Number of procedural blank coupons for each material not contaminated with agent.
8	Control trials (shaded) performed without hydrogen peroxide fumigation
Each time point consisted of four coupons per material type. Three of the coupons were spiked with the
chemical agent and designated as test coupons. The fourth coupon was not spiked and served as a
procedural blank (negative control). The four coupons per material per time point were grouped together
in the chamber and remained together throughout the trial.
TP-0 coupons were included to validate the spiking process and immediate extraction efficiency, i.e.,
with no or minimal interaction of the chemical with the material. TP-1 coupons were collected at the end
of the weathering period prior to the start of the HPV exposure to document losses attributable to
chemical volatilization, absorption, nonperoxide degradation, or other chemical and material binding
without any influence from the hydrogen peroxide fumigation. Samples TP-2, TP-3, and TP-4 assess the
decontamination efficacy of hydrogen peroxide over associated time intervals.
4

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Several positive control trials were performed without hydrogen peroxide fumigation for comparing
efficacy with and without fumigation at the maximum exposure time tested. Trials without fumigation
include VX-4, VX-5, M-3, and HD-4. In each of these trials, there were only three timepoints, TP-0, TP-
1, and TP-4 at the longest exposure time.
The LCHPV conditions for each trial are presented in Table 2.
Table 2: Hydrogen Peroxide Fumigation Efficacy Conditions
Trial ID
Agent
H2O2 Air
Cone,
(ppmv)
Temperature
and RH
Conditions
Weathering Time
(h)
Fumigation Time (h)


TP-0
TP-1
TP-2
TP-3
TP-4
VX-1
VX
25
23°C, 50% RH
< 0.25
24
24
48
72
VX-2
vx
25
23°C, 40% RH
< 0.25
24
24
47
144
VX-3
VX
25
23°C, 65% RH
< 0.25
24
24
72
144
VX-4
vx
—
23°C, 65% RH
< 0.25
24


144
VX-5
vx
—
23°C, 40% RH
< 0.25
24


144
HD-1
HD
25
23°C, 65% RH
< 0.25
3
5
22
29
HD-2
HD
25
23°C, 50% RH
< 0.25
3
5
22
29
HD-3
HD
50
23°C, 65% RH
< 0.25
3
5
22
29
HD-4
HD
—
23°C, 65% RH
< 0.25
3


29
HD-5
HD
75
23°C, 65% RH
< 0.25
3


29
M-1
Malathion
25
23°C, 65% RH
< 0.25
24
24
72
144
M-2
Malathion
75
23°C, 65% RH
< 0.25
24
24
72
144
M-3
Malathion
--
23°C, 40% RH
< 0.25
24


144
Test conditions were not predefined in the Quality Assurance Project Plan (QAPP). Instead, results from
each trial were used to identify parameter changes for subsequent trials. The temperature set point was
held constant for all trials. Parameter changes for trials were HPV, RH, and the duration of coupon
exposure.
2.3 Development and Fabrication of Environmental Chamber
The fumigation chamber was installed within a chemical surety hood to maintain engineering control.
The chamber consisted of a glove box (main body) with a closed system recirculating loop and an
antechamber. The antechamber was used to facilitate adding and removing coupons with minimal
disruption of chamber conditions. A recirculating loop was connected to the chamber to ensure proper
mixing and to control hydrogen peroxide concentration. Ports were installed on the recirculating loop at
the inlet and outlet to monitor the temperature, RH, and HPV concentration. Delivery of LCHPV into
the recirculating loop was regulated by air pumps with a controlled feedback.
5

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2.3.1 Chamber Design and Control
The chamber, constructed by SwRI, consisted of a glovebox with an internal capacity over 339 L, an
antechamber with a capacity of 30 L, a recirculating air flow loop containing ports for monitoring
temperature, RH, and HPV concentration and a port for delivery of HPV. A block diagram of the
chamber is presented in Figure 2.
The main body and the antechamber were
constructed from 0.5-inch-thick Lexan
(Plastic Supply of San Antonio, Inc., 318
W. Josephine, San Antonio, TX). Heating
blankets (McMaster-Carr Supply Company,
Chicago, IL) were installed on the outside
walls of the main body (top, bottom, and
back), with separate thermocouples
(McMaster-Carr Supply Company) with
control feedback. The outside walls of the
main body and antechamber were insulated
with styrofoam (McMaster-Carr Supply
Company). The front face of the main body
contained two ports for connecting
glovebox gloves. A rubber foam
(McMaster-Carr Supply Company) was
used to cover the front face to insulate and
shield the test chamber from UV light
during testing when samples were not being
accessed.
The antechamber was used to pass coupons
into and out of the chamber. The outside
door of the antechamber opened inside a
surety fume hood. The inside door between the main and antechamber was accessed from inside the
main chamber using the Guardian Manufacturing butyl rubber glovebox gloves (Fisher Scientific,
Hanover Park, IL, Catalog number 19-321-162). During testing, only one door was opened at a time to
ensure chamber conditions were kept stable.
Chamber air was recirculated through the path shown in Figure 2 by the thick blue lines during normal
operation. Headspace vapor from the hydrogen peroxide solution was pumped into the recirculation loop
using feedback from the HPV monitor and the Programmable Automation Controller (PAC). The
recirculating loop consisted of two-inch diameter polyvinyl chloride (PVC) pipe (McMaster-Carr
Supply Company) from the chamber to the blower unit and two-inch diameter PVC pipe that expanded
to 4-inch diameter PVC pipe approximately three feet before entering the main body. Inside the
chamber, the 4-inch diameter pipe was connected to an inner box that contained three plates used to
distribute and diffuse the air flow and shelves to hold the test coupons. A picture of the inner box is
shown in Figure 3. Chamber air was continuously recirculated and distributed across coupon trays
through forced convection. Air was withdrawn from the chamber through a blower, treated with HPV
and returned to the chamber, all within a closed loop. The estimated flow rate through the loop was 275
liters per min at standard temperature and pressure (STP).
Figure 2: Chamber block flow diagram.
6

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Figure 3: Picture of chamber.
The HPV generator consisted of two 1-L bottles filled halfway with hydrogen peroxide solution. Heat
tape (McMaster-Carr Supply Company) was wrapped around the outside of the bottles with
thermocouples (McMaster-Carr Supply Company) to maintain a consistent temperature. The headspace
from the two bottles was continuously pumped into the recirculating loop. The air pumps (McMaster-
Carr Supply Company, part number 4404K25) were controlled via feedback based on the HPV detector
monitoring the chamber inlet.
Process control and data acquisition was provided by a PAC (Opto22, Temecula, CA). This system
controlled the heating blankets around the chamber, heaters for the HPV generator, sample pumps for
HPV monitoring, air pumps for HPV fumigation, and the chamber humidifier (Sweet Donut Humidifier,
Amazon). The PAC monitored seven thermocouples to control skin temperature of the chamber and the
HPV generator, two HPV sensors, and two temperature and humidity probes (specific details presented
in Section 2.3.2). The system scanned each device every second for changes exceeding a band width of
±0.5 °C for heating blanket thermocouples, ±0.5 ppmv for HPV concentration, ±1% for RH and ±0.2 °C
for humidity and temperature probes within the chamber. If the scanned value exceeded the band width,
the measurement was logged; otherwise, the measurement was logged every five min. All monitored
devices were logged in two separate files that were exported to Microsoft 8 Excel® for graphing and
interpretation. Logged data included data from the two temperature and humidity probes and the two
HPV sensors monitoring air in the recirculation loop entering and leaving the chamber.
2.3.2 Chamber Monitoring Equipment
A picture of the monitoring equipment and how the monitoring equipment attached to the recirculating
loop is presented in Figure 4. LCHPV monitoring was performed using a Series F12D Hydrogen
Peroxide Gas Transmitter 0-20 ppm (GasSensing, Inwood, IA). The instrument contains a hydrogen
peroxide sensor (Analytical Technology, Inc. or ATI, Collegeville, PA, part number 00-1042).
Specifications for the sensor identified in ATI's Operating and Maintenance (O & M) Manual identifies
the standard range as 0-10 ppm, minimum range 0-10 ppm, and maximum range of 0-200 ppm. For this
7

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project, the sensor was configured to measure hydrogen peroxide in a range of 0-100 ppm in real time.
In this configuration, the lowest hydrogen peroxide concentration that can be quantified is 1 ppm (two-
digit display). Temperature and RH monitoring were performed using Rotonic Instrument Corp
(Hauppauge, New York) Hygroclip XD, Calibration certificates for the LCI-IPV sensors, temperature,
and RH probes were obtained from the manufacturer.
Figure 4: Chamber monitoring equipment attached to the recirculating loop.
2.4 Surface Materials
2.4.1 Coupon Types
Four material types representing interior structures including porous or permeable materials were
selected for testing. They included: stainless steel, painted wood, rubber molding, and vinyl tile.
Materials were purchased from local retailers and fabricated to requested coupon specifications of
approximately 10 square centimeters (cm2). Table 3 provides retail or manufacturer information, a short
description of the material as purchased, and final dimensions of the fabricated coupons.
8

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Table 3: Coupon Material Specifications
Material
Retailer or Manufacturer
Dimensions
Part Number
Description2
Stainless steel
Farmers Copper, LTD.,
San Antonio TX.
Length 1.25"
Width 1.375"
Thickness
0.125"
NA
Purchased 304 grade
bar stock and cut to
specifications.
Painted
Wood1
Home Depot,
San Antonio TX.
Length 1.375"
Width 1.375"
Thickness 0.
25"
NA
Purchased unpainted
Douglas Fir and Behr®
Premium Plus Ultra-
Pure White Flat Zero
VOC Interior Paint
Vinyl Tile
Armstrong Flooring,
Lancaster, PA.
Length 1.375"
Width 1.375"
Thickness
0.125"
5C803031
Purchased Premium
Excelon VCT from
Armstrong Flooring
Rubber Base
Molding
Home Depot
San Antonio TX.
Length 1,375"
Width 1.375"
Thickness
0.125"
#60CR1P100
Roppe "Pinnacle
Rubber Black" Wail
Cove Base
Purchased wood was unpainted.
2See Section 2.4.2 for coupon preparation.
2.4.2 Coupon preparation
The materials were procured and cut to approximately 1.375 inches (in) by 1.375 in square or (10 cm2)
to provide the necessary number of test coupons. After preparing all test coupons, they were i nspected
for inconsistencies and surface defects that might affect results. Defective coupons were discarded.
Examples of the fabricated coupons for each material type are presented in Figure 5.
Figure 5: In order from left to right: Stainless-steel, painted-wood, rubber-molding, and vinyl-tile coupons.
Stainless steel was purchased in the form of stainless-steel bars, 304 grade (1.25 in x 0.125 in x 8 feet
(ft)). The bars were cut to lengths of 1.385 in. The cut edges were ground using a grinder to remove any
burrs. Prior to testing, the stainless-steel coupons were solvent-washed using hexane (Optima Grade,
Fischer Scientific) to remove any machine oils from the coupon surface.
Painted wood: Unpainted wood and paint materials were purchased from Home Depot. The wood used
was a Douglas Fir 2 in x 4 in, which was sliced lengthwise to generate strips of 4 ft x 1.5 in x 0.25 in.
The top surface and edges were sanded with 120 grit sandpaper. The strips were painted with two coats
9

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of Behr® Premium Plus Ultra-Pure White Flat Zero VOC Interior Paint using a sprayer. The painted
strips were cut at increments of 1.375 in to generate coupons of 1.375 in x 1.375 in x 0.25 in. Coupons
containing knots, surface defects, uneven painted surfaces, or rough surfaces were discarded.
Vinyl tile was purchased from a local hardware. The vinyl tile (0.125 in thickness) was cut to the
dimension of 1.375 in x 1.375 in. Coupons containing nicks, scratches, or other surface defects were
discarded.
Rubber wall base molding was purchased from Home Depot. The strips were cut to the dimension of
1.375 in x 1.375 in. Coupons containing nicks, scratches, blemishes, or other surface defects were
discarded.
Prior to testing, all coupons were inspected to ensure that there were no surface defects. Coupons were
washed with Alconox® detergent Powder (Catalog number 1104-1, Fisher Scientific) and water, rinsed
with deionized water, and air dried to remove residues from coupon surfaces that could affect test
results.
2.5	Decontamination Solution
HPV, used for fumigation, was generated from the headspace of two 1 L bottles each filled with 500
milliliters (mL) of 35 wt % hydrogen peroxide solution, American Chemical Society (ACS) grade,
Catalog number 470226-998 (Ward's Science Plus, Rochester, NY). The use of the higher hydrogen
peroxide solution concentration allowed for control of the RH independently of the HPV concentration.
2.6	Test Chemicals
Two CWAs and one pesticide were considered in this study as the contaminants. The chemicals used
included VX (O-ethyl S-[2-(diisopropylamino) ethyl] methylphosphonothioate, Chemical Abstract
Service (CAS) Number 50782-69-9), HD (distilled sulfur mustard, bis(2-chloroethyl) sulfide, CAS
Number 505-60-2), and malathion (diethyl 2-dimethoxyphosphinothioylsulfanylbutanedioate, CAS
Number 121-75-5). In addition to measuring LCHPV decontamination efficacy for these compounds on
the four surfaces, the formation of EA-2192 and malaoxon were also monitored during the tests with VX
and malathion, respectively. EA-2192 is a stable oxidation product of VX [5] while malaoxon is an
oxidation product of malathion [6], Since both EA-2192 and malaoxon carry toxicities similar to the
parent compound, it is pertinent to document whether LCHPV fumigation treatment of surfaces
contaminated with VX or malathion leads to the formation of these toxic byproducts.
2.6.1 Primary Chemicals
VX used in this study was material received from U.S. Army Combat Capabilities Development
Command, known as DEVCOM, Chemical Biological Center (CBC), formerly known as Edgewood
Chemical Biological Center (ECBC), (DEVCOM, Edgewood, MD). The vial was sealed and opened for
this study. The certificate of analysis indicated purity greater than 95%.
HD used in this study was synthesized and distilled by SwRI. The original purity determination
performed in 2019 prior to efficacy testing by Nuclear Magnetic Resonance (NMR) indicated 99+%
purity. A second purity determination performed after the HD-4 efficacy trial indicated a purity of 96%
with the other 4% water associated with the freeze/thaw cycles from use.
Malathion used for this study was purchased from and certified by USP, Rockville, MD (Catalog
number 1374408, Lot# HOH133). The certificate of analysis indicated a 99.2% purity.
10

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2.6.2 Oxidation Products
EA-2192 (S-[2-(diisopropy 1 amino)ethy 11 hydrogen methylphosphonothioate) used in this study was
material received from DEVCOM CBC (Edgewood, MD). Purity was determined by NMR to be 95%.
Malaoxon used for this study was purchased from and certified by Sigma Aldrich, Saint Louis, MO
(Product number 36142, Lot# BCBV3131). The certificate of analysis indicated a 99.7% purity.
2.7 Materials Contamination
Tests were performed based on procedures identified in the Chemical Contaminant and Decontaminant
Test Methodology Source Document, Second Edition [7], Strict timelines were followed with actual
times recorded for each coupon set and procedural steps in the run logs. The test scheme previously
identified in Figure 1 was followed.
Prior to performing each trial, unique sample identifications (IDs) were generated for each test coupon
and entered in the laboratory information management system (LIMS). The sample description was
imbedded in the ID. For example, a coupon given an ID of "V1-SS-TP0-C3" indicates that the coupon
was for trial "VI", a stainless-steel "SS" coupon, collected at TP-0, and was the third spiked replicate
"C3".
The process for starting the trial included: performing final inspection of cleaned coupons, placing the
coupons on aluminum trays organized by material type, spiking the test coupons with the test agent, and
transferring the aluminum trays containing coupons into the test chamber. This entire process was
completed for one TP before proceeding to the next set. The process was performed starting with set TP-
1 followed by TP-2, TP-3, TP-4, and ending with TP-0.
Each set consisted of four aluminum trays with each tray holding four coupons representing the
procedural blank and three replicate spikes for a given coupon material type. The aluminum trays were
labelled with the set name (e.g., TP-1) and on the side "IV" for procedural blank, and "CI", "C2", and
"C3" for the triplicate spikes. The trays were placed in a Surety fume hood with access to the
antechamber of the chamber. Figure 6 depicts set TP-1 from HD-4 trial grouped together and being
spiked with HD.
Figure 6: Spiking HD on coupons for TP-1 in the fume hood, prior to the transfer into the main chamber through the
antechamber.
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After the coupons were placed on the aluminum trays for a given set, 2 microliters (uL) of the chemical
agent were spiked on "C1-", "C2-", and "C3-" designated coupons. Spiking with 2 |iL yields a nominal
contamination density of 2 gram per square meter (g/m2). Spiking was performed by dispensing four
drops containing 0.5 uL of neat chemical onto the center of each coupon in a square pattern
approximately 1 centimeter (cm) apart, using a Hamilton 25 |iL syringe part number 80400 attached to a
Hamilton PB600-1 Dispenser part number 83700 (Hamilton Company, Reno, NV)
After spiking a set of coupons, the antechamber access door was opened, and the aluminum trays were
transferred into the antechamber. When all four trays from the TP set were placed into the antechamber,
the outside antechamber door was closed. Once sealed, the inner antechamber door was opened to
transfer the coupons from the antechamber to the shelves inside the chamber. All TP-1 coupons were
stored on the top shelf. TP-2 coupons were stored on the second from the top shelf. TP-3 coupons were
stored on the third shelf from the top, and TP-4 coupons were stored on the bottom shelf. This process is
illustrated in Figure 7.
Figure 7: Pictures depicting coupon transfer into the chamber for fumigation testing.
For TP-1 on trial VX-2, three extra coupons were spiked with VX for each material. One of the three
additional coupons was added to each of the three shelves as to verify whether there was a
nonhomogeneous spatial distribution of the HPV inside the chamber. While regular test coupons I thru 3
were spatially grouped with their procedural blank, test coupon replicate 4 was grouped with the TP-2
coupons; replicate 5 was grouped with TP-3 coupons; and replicate 6 was grouped with TP-4 coupons.
TP-0 coupons were spiked last so that they could be extracted immediately. While spiking TP-0
coupons, three laboratory control spikes (LCSs) were prepared. For the LCS samples, 2 uL of agent was
spiked into a 20-mL glass vial. The vial was weighed before and after spiking to determine the mass
delivered. After collecting the final weight, 20 mL of solvent (see Section 2.10) was added to the vial
and prepared for assay.
2.8 Weathering of Coupons
Prior to placing any coupons in the chamber, the chamber was purged for a minimum of 24 hours. The
chamber temperature was set to 23 ±3 °C and allowed to equilibrate for a minimum of six hours. There
was no control for lowering RH; however, RH at the start of the run ranged between 25% and 45%.
The weathering period is defined as the tim e between the spiking of the agent onto the coupon and the
start of the LCHPV fumigation. For HD trials, the weathering period was 3 hours. For VX and
malathion, the weathering period was 24 hours. Weathering periods were selected based on the
persistence of the chemical and were therefore longer for the highly persistent VX and malathion in
12

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comparison to the less persistent HD. The affinity of the chemical to be absorbed into the porous and/or
permeable material plays an additional role in this weathering process. At the end of the weathering
period, TP-1 coupons were removed from the chamber and extracted immediately.
2.9	LCHPV Fumigation
At the end of the weathering period and after TP-1 coupons were collected and extracted, the LCHPV
fumigation pumps were turned on and the target HPV concentration was set. For fumigation trials
requiring higher humidity than what was measured by introduction of the HPV only, the RH was set in
the PAC and the humidifier was controlled using feedback from the temperature/ humidity probe
monitoring the chamber inlet. During the initial trials where the LCHPV target concentration was set to
25 ppmv, the temperature set point for the HPV generator bottles was set to 23°C. Trials requiring 50
and 75 ppmv HPV required the temperature on the HPV generator bottles to be set at 30 °C and 35°C,
respectively.
2.10	Coupon Extraction
Previous CWA decontamination studies performed extraction efficiency method development studies on
various building material types with hexane, ethyl acetate, dichloromethane (DCM), and 1 part by
volume hexane, 1 part by volume acetone (111 hexane (acetone) as extraction solvents [8-10], Any of
these solvents performed within acceptable limits for HD and VX extraction and using GC/MS for
analysis. However, these method development efforts did not assess the extraction efficiency of EA-
2192. Hence, method development and method verification were performed for a combined VX and EA-
2192 extraction and analytical method. Method verification was performed on a combined HD,
malathion, and malaoxon extraction and analytical method.
2.10.1 VX/EA-2192 Extraction Method Development
Detection and quantification of the VX hydrolysis product EA-2192 requires analysis by liquid
chromatography/mass spectrometry (LC/MS). Since both the primary and oxidation products need to be
collected in the same extract, several solvent systems were tested to optimize extraction efficiency for
the four material types for both analytes using an LC platform. Solvent selection was based on the prior
experience working with VX and VX extraction solvents [8-10], Solvent systems selected for screening
included: 1|4 acetone|DCM, acetone, DCM, 1|9 isopropyl alcohol (IPA)| DCM, 111 IPA| DCM, IP A, and
dimethylformanide. Solvents were purchased from Fisher Scientific: Acetone Optima grade (Catalog
No. A929-4), DCM Optima grade (Catalog No. D151-4), Isopropyl alcohol Optima grade (Catalog No.
A464-4), and Dimethylformanide certified ACS grade (Catalog No. D119-4).
Initially, three solvent systems were planned for screening. These tests were performed using replicate
coupons. With the lower-than-expected recoveries for both VX and EA-2192, additional solvent systems
were added for screening. For these tests, a single data point was collected for each material type and
solvent system to conserve coupons for testing. For screening, coupons for each material were spiked
with 5 |iL of a combination standard consisting of 100 nanograms per microliter (ng/|iL) of VX and 160
ng/|iL EA-2192 in methanol. The coupons were allowed to air dry in a fume hood for 30 min before
being submerged in 20 mL of the solvent system and sonicated for 10 min. Recovery results as
percentage of the spiked amounts are included in Table 4. The presence of methanol in the spiked
solution may have allowed for some enhanced permeation of VX and EA-2192 into a permeable
material. This would have led to possibly lower recoveries if the molecular bonding of the VX and/or
EA-2192 with the sublayers of the material is too strong to be broken during the extraction process.
13

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Table 4: Solvent Screening Test Results
Solvent System
Stainless Steel
Painted Wood
Rubber Molding
Vinyl Tile
(# of Replicates)
VX
EA-2192
VX
EA-2192
VX
EA-2192
VX
EA-2192
1|4 AcetonelDCM (1)
41%
95%
70%
63%
78%
67%
77%
36%
Acetone (1)
66%
82%
63%
56%
75%
64%
54%
18%
DCM (3)
61 ±1%
99±3%
16±28%
17±28%
76±3%
15±2%
3±6%
1±1%
119 IPAIDCM (2)
31 ±5%
74±9%
63±1 %
70±1%
81 ±1%
19±2%
79±1 %
14±3%
111 IPAIDCM (1)
47%
84%
218%1
78%
37%
86%
69%
71%
I PA (1)
36%
77%
52%
69%
39%
61%
34%
39%
Dimethylformamide (2)
24±10%
63±7%
72±4%
76±7%
18±21%
14±19%
31 ±17%
2±1 %
For single data point, recovery is presented in the table. For replicate data points, the average recovery and
standard deviation of the replicates are presented.
1 Interferent observed resulting in artificial high recovery
Highlighted values in Table 4 allude to selected solvent extraction system for the targeted material. See
Section 2.10.2 for the method verification results. The solvent selection was based on the recovery of
both VX and EA-2192 from these screening samples; however, more emphasis was placed on VX
recovery because the requirements of this study focused on the VX method to be quantitative and EA-
2192 to be semiquantitative. From these results, the 1|4 acetone|DCM solvent system was selected to
extract VX and EA-2192 from painted wood, rubber molding, and vinyl tile, and acetone was selected to
extract VX and EA-2192 from stainless steel.
2.10.2 VX/EA-2192 Extraction Method Verification
Method verification for the VX and EA-2192 extraction method was performed separately using seven
replicate spiked coupons for each material type. For VX verification, 2 |iL of neat VX was spiked onto
the seven coupons for each material type. The coupons were weathered in a surety fume hood for 1 hour.
The coupons were then submerged in 20 mL of the solvent (1|4 acetone|DCM for painted wood, rubber
molding, and vinyl tile; acetone for stainless steel) and sonicated for 10 min. For the EA-2192 extraction
verification, 5 |iL of a 1 milligram per milliliter (mg/mL) EA-2192 standard in methanol was spiked
onto the seven coupons for each material type. The coupons were weathered in a fume hood for 1 hour.
The coupons were then submerged in 20 mL of the solvent (1|4 acetone|DCM for painted wood, rubber
molding, and vinyl tile; acetone for stainless steel) and sonicated for 10 min. Average percent recovery
and percent relative standard deviation (RSD) from the seven replicates are presented in Table 5.
Table 5: VX/EA-2192 Method Verification
Material Type
Solvent
VX
EA-2192


Avg. % Rec.
%RSD
Avg. % Rec.
%RSD
Stainless Steel
acetone
75
8
57
9
Painted Wood
114 acetone|DCM
100
9
33
13
Rubber Molding
114 acetone|DCM
101
16
67
13
Vinyl Tile
114 acetone|DCM
91
18
19
15
While EA-2192 recoveries were low for three out of the four materials, data were accepted as the
objective was on the extraction efficiency demonstration of VX from these surfaces with a 100 ±25%
recovery. The EA-2192 requirement was to demonstrate that EA-2192 could be extracted
14

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semi quantitatively.
2.10.3 HD, Malathion and Malaoxon Extraction Method Verification
In previous studies, both DCM and hexane showed good extraction efficiency for HD [8.9] and
malathion; however, there was concern that there may be high background interferences associated with
the materials selected for testing. To address this concern, coupons from each material type were
extracted with DCM Optima (Fisher Scientific, Catalog No. D151-4) or //-Hexane Optima (Fisher
Scientific, Catalog No. H306-4) using 20 mL of solvent. Five replicates from each extract were spiked
with a combination standard containing HD, malathion, and malaoxon in methanol such that the final
extract concentration was 50 ng/mL per chemical. Coupons were allowed to dry for 30 min prior to
extraction. Table 6 presents the relative average replicate recoveries and associated standard deviations.
Table 6: Comparison of Solvents for HD, Malathion, and Malaoxon Extraction	
Material Type
Recovery in DCM
Q
(O
-H
v?
oN
Recovery in Hexane
Q
(O
-H
v?
oN

HD
Malathion
Malaoxon1
HD
Malathion
Malaoxon1
Stainless steel
103 ±5
98 ±7
139 ± 16
103 ±2
168 ± 19
244 ± 38
Painted Wood
105 ± 6
189 ±37
556 ±105
100 ± 1
117 ± 7
150 ±10
Rubber Molding
123 ±4
320±123
Interferent2
101 ±3
141 ± 10
123 ±9
Vinyl Tile
122 ±8
359 ± 27
726 ± 68
102 ±3
239 ± 74
Interferent2
Significant matrix interferences were observed from painted wood, rubber molding, and vinyl-tile extracts near
the malaoxon retention time. In many cases, malaoxon could not be resolved from high background resulting
in artificial high recoveries.
background near malaoxon was too high to integrate.
Highlighted values allude to selected solvent extraction system for the targeted material.
For the DCM extracts, a high background was observed in the gas chromatograms from the painted-
wood, rubber-molding, and vinyl-tile coupon extracts in the regions where malaoxon and malathion
elute. Interferences from the matrix resulted in a significant analyte enhancement. Matrix carryover was
also observed during the GC/MS analyses through malathion and malaoxon detection in system blanks
and high recoveries in standards in subsequent assays. The GC/MS instrument was recoverable after
multiple solvent injections.
The background interferences were reduced for painted wood, rubber molding, and vinyl tile when the
extraction solvent was switched to hexane. This switch of the solvent resulted in malathion recoveries
closer to 100%. However, the use of hexane for stainless-steel coupon extraction resulted in matrix
interferences that artificially inflated malathion and malaoxon recoveries.
For both solvent systems tested, the interferences observed for malathion and malaoxon were reduced by
diluting the extract prior to analysis [results not shown], HD was not affected by the matrix
interferences. Based on the analytical results, DCM was selected to extract HD from all coupon
materials and malathion from stainless steel. Hexane was selected to extract malathion from painted
wood, rubber molding, and vinyl tile.
2.10.4 Summary Selected Solvent Systems Used for LCHPV Efficacy Testing
The solvent systems selected for LCHPV efficacy testing based on method verification results are
summarized in Table 7.
15

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Table 7: Solvent Systems Used to Extract Coupons
Coupon Type
VX
HD
Malathion
Stainless Steel
Acetone
DCM
DCM
Painted Wood
114 Acetone|DCM
DCM
Hexane
Rubber Molding
114 Acetone|DCM
DCM
Hexane
Vinyl Tile
114 Acetone|DCM
DCM
Hexane
2.10.5 Extraction procedure
Coupons were extracted in wide-mouth short-profile clear glass jars (ThermoFisher Scientific Inc., 2
ounces capacity, cat# 220-0060). Prior to sample collection, sample labels were placed on the jars and
20 mL of solvent was placed in the jars using an Eppendorf™ Repeater™ Stream Pipetter with a 25 mL
Eppendorf™ Combitip (Eppendorf, Hauppauge, NY, part numbers 022460803 and 0030089472).
The whole coupon was extracted by placing the coupon, with the spiked surface facing downward, into
the wide mouth jar filled with 20 mL of solvent. The jar was placed in an ultrasonic bath model FS20
(40 kHz frequency; Fisher Scientific) and sonicated for 10 min at room temperature. The coupon
remained submerged in the solvent for a minimum of 1 hour at room temperature prior to collecting the
extract for analysis. Extracts were stored in a freezer at -20 ± 10 °C.
2.11 Analytical methods
The focus of the analysis was to quantify residual VX, HD, or malathion on the coupons to calculate
efficacy. A secondary focus was to identify whether highly toxic oxidation byproducts, EA-2192 from
VX and malaoxon from malathion, are being formed. VX and EA-2192 extracts were assayed by LC-
MS/MS while HD, malathion, and malaoxon extracts were assayed using GC/MS. A list of the analytes
and the associated analytical procedures is presented in Table 8.
During analytical setup, the instrument detection limit (IDL) for each analyte was estimated based on
past use of the instrumentation. The lowest standard in the calibration range was 2 to 5 times higher than
the estimated IDL.
Table 8: Analytical Procedures
Analyte
Instrument
Estimated IDL
Calibration Range
Internal Standard
VX
LC-MS/MS
1 ng/mL
5 to 100 ng/mL
DIMP-di41
EA-2192
LC-MS/MS
1 ng/mL
5 to 100 ng/mL
DIMP-di4
HD
GC/MS
2 ng/mL
5 to 500 ng/mL
Naphthalene-ds2
Malathion
GC/MS
2 ng/mL
5 to 500 ng/mL
Naphthalene-ds
Malaoxon
GC/MS
2 ng/mL
5 to 500 ng/mL
Naphthalene-ds
1Diisopropyl methylphosphonate (DIMP-di4) (Cerilliant Corporation, Round Rock, TX)
2Naphthalene-d8 (Restek, Corporation., Bellefonte, PA)
Analyte calibration curves (see Section 2.6 for source information) consisted of at least five calibration
points. The initial calibrations (ICALs) were performed and met calibration criteria identified in Table 9
16

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prior to assaying samples. The calibration curves were verified using an initial calibration verification
(IC V) standard at the mid-level independently prepared. Samples were bracketed by passing continuing
calibration verification (CCV) standards, assayed at a minimum frequency of one every fifteen samples.
Instrument solvent blanks (ISBs) were assayed after CCVs to ensure that the instrument was clean and
free of carryover. Failure to meet the acceptance criteria required instrument maintenance, repreparation
of calibration standards, and performing another initial calibration curve.
Table 9: Calibration Acceptance Criteria
Type
Acceptance criteria
Frequency
Calibration Curve (ICAL)
(R2 > 0.99 or %RSD <20%) and
70-130% accuracy of the true concentration
Before sample analysis
begins and after ICV or CCV
failure
Initial Calibration
Verification (ICV)
75-125% accuracy
After Calibration but before
sample analysis begins
Continuing Calibration
Verification (CCV)
75-125% accuracy
Between the sample series
every fifteen samples at a
minimum
Instrument Solvent
Blank (ISB)
No hits in the agent retention time window
Bracketing CCV standards
Internal standards (listed in Table 8) were used for determining instrument drift or matrix interferences
that affect response. Internal standards were spiked into all standards and samples at the same level and
included in the calibration curve calculations. The internal standard acceptance criteria are identified in
Table 10. Results that did not meet these criteria were reanalyzed and flagged if the criteria were not
met.
Table 10: Internal Standard Acceptance Criteria
Type
Acceptance criteria
Frequency
Calibration (ICAL)
%RSD < 20%
All Standards
Continuing Calibration Verification (CCV)
100 ±25% of ICAL
All Standards
All Samples and quality control (QC)
100±50% of previous CCV
All Samples
2.11.1 LC-MS/MS Analysis
VX and EA-2192 were assayed using an Agilent 6410 Triple Quadrupole LC/MS instrument with
Agilent 1200 series pump and autosampler, operated in positive mode utilizing electrospray ionization
(ESI) multiple reaction monitoring (MRM) (Agilent, Santa Clara, CA). The acquisition parameters are
identified in Table 11. The samples were analyzed for VX and EA-2192 using a six-point standard
calibration curve ranging from 5 to 100 ng/mL calculated using linear regression. The instrument
detection limit was approximately 1 ng/mL. The internal standard deuterated diisopropyl
methylphosphonate (DIMP-dw) was spiked into all standards and samples at 2.0 ng/mL.
17

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Table 11: LC-MS/MS Parameters for VX and EA-2192 Analysis
Mass spectrometric source
Electrospray, positive ion mode
HPLC column
Allure PFP propyl, 2.1 x 150 mm, 5 jjm (Restek No. 9169562) or
InertSil ODS-3, 2.1 x 150 mm, 5 jjm (GL Science No. 5020-01741)
HPLC column temperature
Ambient
Mobile phase components
A = water containing 2 millimolar formic acid and 2 millimolar
ammonium formate
B = acetonitrile containing 0.1% formic acid
Gradient profile

Time (min)
% A
% B
Flow rate
(mL/min)

0
20
80
0.4
3
20
80
0.4
10
0
100
0.4

12
0
100
0.4
12.5
20
80
0.4
15
20
80
0.4
Injection volume
5 [it
Drying gas (Type, flow, Temp)
Nitrogen, 11 L/min, 300°C
Nebulizer
30 psig
Capillary Voltage
3500 V
Fragmentor
130 V
Acquisition Mode
Multiple reaction monitoring
VX transition ions: 268—>128 (quantification), 86, 167, and 139
EA-2192 transition ions: 240—>128 (quantification) and 86
DIMP-di4 transition ions: 195—>99 (quantification) and 80
psig: pounds per square inch gauge
2.11.2 GC/MS Analysis
HD, malathion, and malaoxon were assayed using an Agilent 6890 gas chromatograph and 5973
quadrupole mass spectrometer (Agilent) operated in electron ionization selected ion monitoring mode.
Acquisition parameters are provided in Table 12.
The samples were analyzed using a seven-point standard calibration curve ranging from 5 to 500 ng/mL
calculated using relative response factors. The instrument detection limit was approximately 2 ng/mL.
The internal standard naphthalene-d8 was spiked into all standards and samples at 100 ng/mL.
18

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Table 12: GC/MS Parameters for HP, Malathion, and Malaoxon Analysis
Column Type
RXI-1 MS, 30 m x 0.25 mm inner diameter 1 .Ojjm film thickness
(Restek No. 13353)
Column Program
60°C initial temp, hold 0 min., 15°C/min. to 300°C, hold 5 min.
Transfer line Temperature
290° C
Injection Port Temperature
210°C
Carrier Flow Rate
1.5 mL/min constant helium flow
Injection
Splitless (13.7 psi until 1.0 min., split. 80 mL/min. at 1 min.)
Injection Volume
2 m.L
Acquisition Mode
Selected ion monitoring (SIM)
HD ions: 158(quant), 109, and 111 m/z
Malathion ions: 173(quant), 158, and 93 m/z
Malaoxon ions: 127(quant), 99, and 109 m/z
Napthalene-ds: 136 (quant) and 108 m/z)
Electron Impact
70 electron volts (nominal)
Ion Dwell Time/Scan Rate
100 milliseconds or approximately 2 scans per second
MS Quad Temperature
150°C
MS Source Temperature
230°C
psi: pounds per square inch
2.12 Calculations
The following calculations were used to evaluate the data and determine decontamination efficacy. All
coupon extract results were converted to total mass (nanograms) using Equation 1. Average total mass
was calculated for each set.
Total massrng) = Extract Concentration,ng_ x Extract VolumermL) x Dilution Factor
ml'
Equation 1
Total mass refers to the mass of analyte in nanograms recovered from the coupon during extraction
determined by analysis of the extract. The extraction concentration refers to the analyte concentration in
the extract determined by the analytical system. The extract volume refers to the total volume of solvent
used to extract the samples. The dilution factor refers to the ratio of final dilution volume to extract
volume added to dilute the extract.
Recoveries were measured for all samples. The relative recovery for the LCS was based on the spike
amount using Equation 2. Average percent recovery and percent RSD were calculated for each set.
Recovered Total Mass
=			x 100
Spike Mass^g^
Equation 2
Here, the spike mass refers to the theoretical mass of analyte in nanograms spiked onto the coupon,
based on spiking volume, density, and purity of the spiked chemical. Percent recovery refers to the
percentage of total mass recovered during coupon extraction from the mass spiked onto the coupon.
Relative Recovery [LCSW)
The LCS recovery was used to establish the relative recovery at the first timepoint, TP-0, according to
19

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Equation 3.
Relative Recovery [TP0](o/o)
Recovered Total Mass rTPOlfr,^
			x 100
Recovered Total Mass [LCS](n5)
Equation 3
The TP-0 recovery was used to establish the relative recoveries at all other timepoints, TP-1 through TP-
4 according to Equation 4.
Efficacies were calculated using the longest time point TP-4 recovery results. TP-4 was the only test
point available to compare fumigation trials with the positive control tests. Since the LCHPV and
positive control tests were conducted on different days, differences in the spiked chemical agent were
observed. To correct for this bias, the efficacy was calculated using the relative average recoveries at
TP-4. Equation 5 normalizes test trial recoveries from the positive control trial to remove bias due to
different spiked chemical mass and cancels out losses due to natural attenuation, material extraction
efficiencies, etc., to focus on agent reductions associated with HPV fumigation only.
Relative Recovery [TPn](0/o)
Recovered Total Mass rTPnlfr,^
			x 100
Recovered Total Mass [TP0](n5)
Equation 4
where n=l,4 for TP-1 through TP-4.
Efficacy — 1
avg Relative RecoveryTP_4Test trial
x 100%
avg Relative RecoveryTP_4Controltrial _
Equation 5
20

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3 Results
3.1 Coupon Spike Precision, Accuracy and TP-0 Recoveries
To maintain chemical spike consistency throughout the study, one analyst spiked all coupons. There
were two identical syringes each with a dispenser used for spiking agent. One syringe was used for all
the VX depositions and depositions for the first three HD trials. The other syringe/ dispenser was used
for all malathion depositions and the deposition for the last two HD trials.
Agent spike delivery performance was determined by both LCS and TP-0 spike recovery results. The
LCS performance results are specific to agent spike delivery whereas the TP-0 recovery performance
includes both spike delivery and coupon extraction efficiency after a 30-min contact time of the
chemical with the material. Summaries of spike delivery and extraction efficiency performance are
presented in Tables 13-15 for VX, HD, and malathion. Each result is based on three replicates prepared
and assayed. The relative average recovery reported for the LCS is based on theoretical yield to include
density values of 1.00, 1.27, 1.23 grams per cubic centimeter (g/cm3) and purity of the agent 95%, 96%,
99.2% based on certificates of analysis for VX, HD and malathion, respectively. The relative recoveries
for TP-0 are in reference to the LCS recoveries.
Table 13: VX Spike Delivery and Extraction Efficiency Performance

LCS
TP-0 Control Spikes

Stainless Steel
Painted Wood
Rubber Molding
Vinyl Tile
Trial
Mean
Recovery1
(%)
%RSD
Mean
Recovery2
(%)
%RSD
Mean
Recovery2
(%)
%RSD
Mean
Recovery2
(%)
%RSD
Mean
Recovery2
(%)
%RSD
VX-1
75
2%
112
4%
109
2%
116
11%
112
5%
VX-2
109
2%
98
2%
94
2%
93
5%
81
27%
VX-3
86
17%
106
9%
106
14%
109
6%
80
3%
VX-4
84
3%
106
4%
103
5%
113
3%
107
1%
VX-5
73
2%
103
7%
89
5%
107
4%
97
5%
1	Mean recovery relative to the theoretical mass spiked
2	Mean recovery relative to the LCS
All three LCS replicates from VX-1 and VX-5 trials and one replicate from VX-3 failed recovery
performance criteria of 100 ± 20%. All VX TP-0 control spike samples met recovery criteria of 40 to
130%. Although the LCS recoveries that failed recovery criteria were not significantly low, they
identified trends between the VX trial sets. Except for a few triplicate sets, variability was less than 10%
within a trial. However, there was variability between trial sets (different days of research execution).
Recovery trended downward for stainless steel, painted wood, and rubber molding with the highest
recoveries associated with VX-2 and the lowest associated with VX-5 trials.
21

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Table 14: HP Spike Delivery and Extraction Efficiency Performance

LCS
TP-0 Control Spikes

Stainless Steel
Painted Wood
Rubber Molding
Vinyl Tile
Trial
Mean
Recovery1
(%)
%RSD
Recovery
(%)
Mean
Recovery1
(%)
%RSD
%RSD
Mean
Recovery1
(%)
%RSD
Recovery
(%)
Mean
Recovery1
(%)
HD-1
91
5%
94
14%
112
1%
107
5%
106
2%
HD-2
107
3%
93
15%
99
1%
112
10%
98
1%
HD-3
103
6%
93
3%
107
1%
110
5%
100
3%
HD-4
103
5%
92
8%
106
3%
109
3%
96
3%
HD-5
100
4%
100
3%
99
0%
113
3%
103
4%
1	Mean recovery relative to the theoretical mass spiked
2	Mean recovery relative to the LCS
All HD LCS samples met recovery performance criteria of 100 ± 20% and %RSD of the three replicates
less than equal to 15%. All HD TP-0 control spike samples met recovery criteria of 40 to 130%. No
issues were observed for HD agent spiking or extraction efficiency. There was low variability between
trials. The largest difference was noted from HD-1, which was approximately 10% lower than the other
four. Recoveries from rubber molding were consistently higher due to possibly drag of some additional
HD from the tip of the syringe onto this softer material in comparison to the other materials.
Table 15: Malathion Spike Delivery and Extraction Efficiency Performance

LCS
TP-0 Control Spikes

Stainless Steel
Painted Wood
Rubber Molding
Vinyl Tile
Trial
Mean
Recovery1
(%)
%RSD
Recovery
(%)
Mean
Recovery1
(%)
%RSD
%RSD
Mean
Recovery1
(%)
%RSD
Recovery
(%)
Mean
Recovery1
(%)
M-1
87
2%
106
4%
100
5%
123
9%
104
11%
M-2
96
15%
91
5%
94
6%
126
12%
103
9%
M-3
85
4%
91
7%
85
7%
121
18%
84
8%
1	Mean recovery relative to the theoretical mass spiked
2	Mean recovery relative to the LCS
All malathion LCS samples met recovery performance criteria of 100 ± 20% and %RSD of the three
replicates less than equal to 15%. The %RSD for M-2 was high at 15%. One of the replicates had a
recovery of 111% while the other two replicates were like the average LCS recoveries from M-l and M-
3. All malathion TP-0 control spikes samples met recovery criteria of 40 to 130%. Recoveries from
rubber molding were consistently higher due to possibly drag of malathion from the tip of the syringe
onto this softer material in comparison to the other materials.
3.1.1 Coupon Spiking Notes
In some cases, the agent thickness and viscosity made it difficult to consistently spike the agent on the
coupons. Of the three agents, HD was the least erratic, consistently forming beads at the tip of the
syringe that were easily transferred to the coupon. This formation of beads is reflected in the consistency
of the LCS and TP-0 recovery results.
Figure 8 shows stainless-steel coupons approximately 5 min after being spiked with HD.
22

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^	
Lf /
^ CA ^'
	- __
¦

Figure 8: Stainless-steel coupons spiked with HD.
Malathion is very viscous. It took several seconds for malathion to dispense after pressing the dispenser
button and the dispensed beads appeared to be slightly smaller than beads from HD. On painted-wood
and vinyl-tile coupons, it was difficult to observe the malathion spikes.
VX tends to wick up the syringe needle making deposition more difficult. The analyst wiped the syringe
needle thoroughly after each triplicate set. Also, VX spread across the surfaces more than the other two
agents. An example of VX spreading across coupon surfaces is presented in Figure 9. Within a minute,
the VX is dispersed to a much larger droplet diameter and at 24 hours, the droplets merged covering the
coupon surface, probably due to a combination of the hydrophilicity of stainless steel and low surface
tension of VX on stainless steel.
Figure 9: VX being spiked on coupons (left). Stainless-steel coupons 24 h after VX deposition (right).
3.2 Environmental Conditions during Weathering
Two temperature and RH probes were used to monitor the temperature and %RH in the recirculating
loop entering and exiting the chamber. The PAC system scanned the probes for changes every second.
Data were logged if a temperature changed more than 0.2°C or RH changed more than 1%; otherwise,
data were logged at five-minute (min) intervals. Plots of recorded temperature, RH, and HPV
concentration for each trial are presented in Appendix B, Figures B1-B13
Average temperature and humidity readings during the weathering period for each trial are presented in
Table 16. All weathering period temperatures were 23 ± 2°C. All temperature standard deviations were
less than 0.5°C, except for trial VX-2, which was 0.6°C. The humidity standard deviations were all less
23

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than 4%.
Table 16: Average Weathering Conditions
Trial
Time
Entering Chamber
Exiting Chamber
Period (h)
Temp. (°C)
RH (%)
Temp. (°C)
RH (%)
VX-1
24
23.0
38
22.7
39
VX-2
24
23.4
35
23.5
36
VX-3
24
23.5
41
23.9
42
VX-4
24
23.3
37
23.7
37
VX-5
24
23.3
38
23.2
39
HD-1
3
23.7
42
23.4
43
HD-2
3
23.5
39
22.9
41
HD-3
3
22.4
27
22.4
28
HD-4
3
24.0
37
23.7
38
HD-5
3
24.6
37
23.5
40
M-1
24
23.6
36
23.2
37
M-2
24
23.4
36
22.4
39
M-3
24
23.3
38
23.2
39
As visible in Table 16, there are instances where the temperature of the air entering the chamber is over
0.5°C higher than the temperature leaving the chamber, specifically for trial HD-2 and HD-5. The cause
for this difference was associated with the heat transfer from the air blower.
During the weathering period, the pumps that run air by the HP bottles were off and the HPV monitors
indicated HPV concentration below 3 ppmv for all trials during the weathering time.
3.3 Weathering and Fumigation Exposure Times
The weathering time is defined as the time between the coupon contamination and the start of LCHPV
fumigation. The target weathering times were 3 hours for HD and 24 hours for VX and malathion. The
fumigation exposure time is the time interval between the start of fumigation and the TP set removal.
Actual coupon weathering and fumigation exposure times for each trial are presented in Table 17.
For each trial, it took approximately seven min to spike each set of material coupons and transfer the
coupon set into the chamber, resulting in a 20-min lag time between the spiking of the TP-1 and TP-4
sets. Since the fumigation time starts at the same time for all test coupons, there is a small difference in
the weathering times between the TP sets, that is, TP-1 vs TP-4.
24

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Table 17: Weathering and Fumigation Times for each Time Point
Trial
Weathering

Weathering Time (h]

H2O2 Exposure Time (h)
(h)
TP-1
TP-2
TP-3
TP-4
TP-2
TP-3
TP-4
VX-1
24
24.3
23.1
23.0
22.9
24
48
71
VX-2
24
24.1
24.0
23.9
23.8
24
71
144
VX-3
24
23.6
23.5
23.4
23.3
24
72
144
VX-41
24
23.3
--
--
23.1
--
--
1442
VX-51
24
23.3
--
--
23.2
--
--
1442
HD-1
3
3.07
2.95
2.85
2.75
4.68
21.88
28.80
HD-2
3
3.03
2.92
2.77
2.63
4.75
21.88
28.90
HD-3
3
2.98
2.88
2.77
2.67
4.80
21.98
28.90
HD-41
3
3.03
--
--
2.922
--
--
28.58
HD-5
3
2.80
--
--
2.68
--
--
29.03
M-1
24
23.8
23.7
23.6
23.5
24
72
144
M-2
24
24.1
23.9
23.7
23.5
24
72
144
M-31
24
23.9
--
--
23.72
--
--
1423
1	These trials were positive control trials used to compare results with and without fumigation.
Fumigation was not performed for these trials.
2	TP-4 exposure time of positive control trials matched with the TP-4 fumigation timepoints.
The weathering time criteria were 3 hours ±18 min for HD and 24 hours ± 2 hours for VX and
malathion. HD coupon weathering exceeded the specified time limits, but weathering times were
consistent across trials. This consistency is deemed more valuable as comparisons are made in recovery
results across trials. VX and malathion weathering times were within the time criteria.
The exposure time criteria presented of the designated time ± 10% was met for all trials. For VX and
malathion, the designated exposure times were 24, 48, and 144 hours, except for VX-1 trial, where the
designated time for TP-4 was 72 hours. For HD, the designated exposure times were 5, 22, and 29 hours.
Four positive control trials were performed in which LCHPV fumigation did not occur. They include:
VX-4, VX-5, HD-4, and M-l. These trials were performed so that agent recoveries after fumigation
could be compared with agent recoveries with no fumigation held for the same time-period to calculate
the HPV decontamination efficacy (Equation 5, Section 2.12). To show equivalent time spans for
weathering and fumigation exposure, between the fumigation trials and the positive control trials, an
arbitrary fumigation start time, based on TP-1 coupon removal from the chamber, was applied to the
positive control trials to calculate a weathering period and expected fumigation exposure period.
3.4 Environmental Conditions during LCHPV Fumigation
Tolerances for controlled conditions for temperature and humidity were ±3°C and ±10% RH. Two
temperature and RH probes were monitoring the temperature and %RH in the recirculating loop entering
and exiting the chamber. Average temperature and humidity readings from each probe during the
fumigation period for each trial are presented in Table 18. The readings from both probes were averaged
together to give the composite temperature and humidity inside the chamber. The composite number is
more representative of the actual conditions. All fumigation temperatures were 23 ± 2.5°C. All
temperature standard deviations were less than 0.8°C. The humidity standard deviations were all less
than 5%.
25

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Table 18: Chamber Temperature and Humidity Conditions during Fumigation
Trial
Entering Chamber
Exiting Chamber
Composite1
Temp. (°C)
RH (%)
Temp. (°C)
RH (%)
Temp. (°C)
RH(%)
VX-1
23.8
51
23.5
51
23.7
51
VX-2
23.0
42
23.0
41
23.0
42
VX-3
23.3
63
23.0
64
23.2
64
VX-4
22.8
68
22.9
65
22.9
67
VX-5
23.5
36
23.1
37
23.3
37
HD-1
24.0
64
23.6
65
23.8
65
HD-2
24.0
50
23.2
51
23.6
50
HD-3
23.0
60
22.7
58
22.9
59
HD-4
24.3
61
23.6
64
24.0
63
HD-5
25.0
60
23.6
67
24.3
64
M-1
24.3
61
23.7
67
24.0
64
M-2
24.2
63
22.9
70
23.6
67
M-3
23.5
36
23.1
37
23.3
37
1 Composite is the average temperature and RH from both probes.
There were instances where the temperature of the air entering the chamber was more than 1.0°C higher
than the temperature exiting the chamber, specifically trial HD-5, and M-2. The cause for this larger
difference was associated with the higher temperature of the bottle that held the H2O2 solution to
generate the higher HPV concentration. The relatively close distance of the warmer HPV containing air
pumped into the chamber and the location of the temperature and humidity probe (approximately 25 cm)
contributed to this apparent larger difference in temperature across the chamber.
3.5 LCHPV Fumigation Concentrations
The HPV concentration was controlled through a feedback loop. Typical tolerances for efficacy testing
under controlled conditions was ±10%. Considering the anticipated hydrogen peroxide decomposition, a
tolerance of ±20% was acceptable between the inlet and outlet HPV concentration. Two HPV monitors
were continuously sampling air from the recirculating loop entering and exiting the chamber. The HPV
monitor output that was sampling the air entering the chamber was used in the control feedback for the
HPV generator pumps.
The HPV concentration entering the chamber was in general 30% higher than the HPV concentration
leaving the chamber. Based on the location of the coupon samples between the two monitors and no
other source for HPV generation within that path, the average HPV concentration from both monitors
was the HPV concentration associated with each trial. An exchange of the two HPV monitors returned
the same values during the shakedown of the LCHPV testing which eliminated a calibration difference
between the two monitors. Considering that the RH values were well below 100% and there were no
expected cold spots in the chamber, condensation should not have occurred either. The difference may
be due to a material demand leading to some decomposition of HPV in the chamber.
The average readings for each HPV monitor and the composite for each trial are presented in Table 19.
The relative standard deviations of concentration readings associated with each HPV monitor were less
than 15 percent.
26

-------
Table 19: Average HPV Concentration during Fumigation
Trial
Target HPV
concentration
(ppmv)
Recorded HPV Cone, (ppmv)

Chamber "In" ±SD1
Chamber "Out" ±SD
Composite
VX-1
25 ±5
27.6 ±1.7
22.5 ±2.3
25.1
VX-2
25 ±5
26.3 ±2.0
18.5 ±2.0
22.4
VX-3
25 ±5
27.7 ±0.9
19.7 ±0.9
23.7
VX-4
—
0.0
0.0
0.0
VX-5
—
0.0
0.0
0.0
HD-1
25 ±5
27.5 ±2.7
19.1 ±2.1
23.3
HD-2
25 ±5
27.8 ±1.9
19.1 ±1.7
23.5
HD-3
50 ± 10
55.4 ±6.1
38.0 ±5.1
46.7
HD-4
—
0.0
0.0
0.0
HD-5
75 ± 15
88.8 ±4.9
59.4 ±6.5
74.1
M-1
25 ±5
28.0 ±0.8
20.5 ±1.0
24.3
M-2
75 ± 15
89.6 ±2.6
62.5 ±2.8
76.1
M-3
—
0.0
0.0
0.0
1 SD is standard deviation
3.6 Natural Attenuation of Chemicals
Any losses in the recovered chemical mass with time can be associated with: (1) the permeation of the
chemical into the material from where it cannot be extracted; (2) the nonperoxide degradation of the
chemical (independent of hydrogen peroxide presence) by, for example, hydrolysis; and (3) the
volatilization of the contaminant from the coupon surface. This latter aspect can lead to the transfer of
chemical by vapor onto noncontaminated surfaces. Such a process can be identified by the evaluation of
chemical agent recoveries from the procedural blanks (Section 3.6.1), comparing losses in mass during
weathering between TP-0 and TP-1 (Section 3.6.2), and comparing TP-4 data point recoveries from
trials with and without hydrogen peroxide present (Section 3.7).
3.6.1 Laboratory and Procedural Blanks
Two types of coupon blanks were collected during the efficacy studies: laboratory blanks and procedural
blanks. One laboratory blank for each material trial was prepared to determine if there was any matrix
interference. There was no detection of any of the three chemicals for any of the laboratory blanks
indicating there was no contamination from the extraction or analytical processes.
There was one procedural blank per material per TP set per trial. These coupons were placed on trays
next to contaminated coupons in the chamber to determine vapor transfer and material absorption.
Chemical agent was detected in the procedural blanks. Most of the procedural blank detections and the
highest amounts detected were associated with HD, the most volatile of the three agents tested. There
were HD detections for all painted-wood, rubber-molding, and vinyl-tile procedural blank coupons;
however, no HD detections on stainless-steel procedural blanks. Relating the detected amounts to the
mass spiked onto a single coupon, the ratio was found to be as high as 6.5% for HD. The HD
concentration trends were observed between the TP sets from all HD fumigation runs. These trends are
illustrated in Figure 10. Recovered HD mass on the procedural blanks at TP-0 was less than 0.15%.
27

-------
7.0%
o>
^ 6.0%
Q.
CO
O 5.0%
CL
3 4.0%
_oj
CUD
.E 3.0%
CO
4-
2 2.0%
c
QJ
U
5 i.o%
Q_
0.0%
III
TP-0	TP-1	TP-2	TP-3
¦ Painted Wood ¦ Rubber Molding ¦ Vinyl Tile
I
TP-4
Figure 10: HD detection in procedural blanks relative to TP-0 contaminated coupon.
The observed trends suggest that the procedural blank detections were caused by the evaporation of the
co-located contaminated coupons. There were no detections on the least permeable material, stainless
steel, while the permeable materials had relatively high levels of HD detected. The maximum HD
concentrations were observed between TP-1 and TP-2, both of which were within 8 hours of spiking the
coupons.
For malathion, the least volatile agent, approximately 30% of the procedural blanks had some malathion
mass recovered but recoveries were less than 0.05% relative to the initial coupon spike mass. There was
not an observed pattern associated with the malathion recoveries. For VX, approximately 40% of the
procedural blanks contained recoverable VX. The VX recovered mass on the procedural blanks was less
than 0.5% relative to a single coupon spike, except for two blanks that were 0.7% and 1.8%. There was
no observed pattern associated within these VX recoveries.
3.6.2 Recovery Differences from the Prefumigation Weathering
Differences in recoveries from weathering of the chemical on the materials are due to losses in mass
resulting from the exposure to the environmental conditions (temperature and RH) within the chamber.
This difference was assessed in a direct comparison of TP-0 and TP-1 recoveries. TP-0 and TP-1
recoveries were pooled from all trials since the weathering conditions for each were similar based on
near equal temperature and RH. VX recoveries after 24 hours of weathering for each material type are
presented in Table 20.
Table 20: VX Recovery Differences after 24 Hours of Weathering
Trial
Stainless Steel
Painted Wood
Rubber Molding
Vinyl Tile
Rec.
%RSD
Rec.
%RSD
Rec.
%RSD
Rec.
%RSD
Avg. TP-0
105%
5%
100%
8%
108%
8%
95%
16%
Avg. TP-1
26%
57%
73%
35%
86%
53%
95%
46%
The TP-0 results represent 15 replicate spiked coupons collected from the five VX trials while TP-1
28

-------
results represent 18 replicate spiked coupons as three additional coupons were included in the VX-2
trial. A high variability in recovered relative VX mass associated with all materials was observed for
TP-1. A closer look at the individual replicates for TP-1 showed that trial VX-1 replicates had the lowest
VX recoveries for TP-1 (22% average across all materials), while relative recoveries were higher for the
other VX trials (61%-100% range across VX-2 to VX-5 and averaged across all materials). This
variability raises some concerns with results associated with trial VX-1, TP-1 considering that the trials
represent equivalent conditions.
Across all trials, and after 24 hours of weathering, minimal losses were observed for rubber molding
(86% recovery) and vinyl tile (95% recovery) while a moderate loss was observed for painted wood
(73% recovery). Weathering on stainless steel results in highest loss in VX on the surface (only 26%
recovery).
HD relative recoveries with respect to the spike controls after three hours of weathering for each
material type are presented in Table 21.
Table 21: HD Recovery Differences after 3 Hours of Weathering
Trial
Stainless Steel
Painted Wood
Rubber Molding
Vinyl Tile

Rec.
%RSD
Rec.
%RSD
Rec.
%RSD
Rec.
%RSD
Avg. TP-0
94%
3%
105%
5%
110%
2%
101%
4%
Avg. TP-1
33%
31%
67%
15%
85%
4%
67%
13%
The results represent 15 replicate spiked coupons collected from the five HD trials for at TP-0 and TP-1.
The variability for TP-1 stainless steel was high compared to the other material types. More importantly,
stainless steel, the only nonporous material of the four materials in this study, had the highest level of
HD loss. This information in conjunction with high levels of HD found on procedural blanks (see
Section 3.6.1) suggest that the losses are associated with the HD volatility. The permeability of painted
wood, vinyl tile, and rubber molding allows for absorption of HD which slows the effective HD losses
by volatilization.
Malathion losses after 24 hours of weathering for each material type are presented in Table 22.
Table 22: Malathion Recovery Differences after 24 Hours of Weathering
Trial
Stainless Steel
Painted Wood
Rubber Molding
Vinyl Tile
Rec.
%RSD
Rec.
%RSD
Rec.
%RSD
Rec.
%RSD
Avg. TP-0
96%
9%
93%
8%
123%
2%
97%
12%
Avg. TP-1
113%
16%
98%
7%
65%
23%
101%
11%
The results represent 9 replicate spiked coupons collected from the three malathion trials. There were no
significant differences in relative malathion amount recovered between TP-0 and TP-1 as observed for
stainless steel, painted wood, and vinyl tile. There were significant differences observed for rubber
molding. However, in this case, the difference is most likely associated with a lower extraction
efficiency of malathion absorbed into the rubber molding after 24 hours rather than a higher
volatilization.

-------
3.7 LCHPV Fumigation Recoveries and Efficacies
3.7.1 VX Recoveries
As indicated in Table 2, there were five trials with VX. The first fumigation trial (VX-1) ended after 72
h of LCHPV fumigation. Results from that trial established the test conditions for the second trial (VX-
2)	by extending the LCHPV exposure to 144 h (6 days). For the third and final VX LCHPV trial, the RH
was increased to 65% as to assess whether this would have an impact on the LCHPV efficacy. The three
LCHPV trials were complemented with two positive control trials (VX-4 at 65% RH and VX-5 at 40%
RH), allowing for direct comparisons with the fumigation results from VX-1 to VX-3. Timepoints for
the positive control trials were limited to TP-0, TP-1, and TP-4.
The average VX mass recoveries and standard deviations for replicate test (Trials VX-1, VX-2, and VX-
3)	and positive control (Trials VX-4 and VX-5) coupons of all four material types are provided in Table
23.
Table 23: Average VX Mass Recovery


LCS
TP-0
TP-1
TP-2
TP-3
TP-4
Material
Trial
Mass
StDev
Mass
StDev
Mass
StDev
Mass
StDev
Mass
StDev
Mass
StDev


(H9)
(H9)
(H9)
(H9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
Stainless
Steel
VX-1
1492
36
1666
67
61
62
213
31
157
30
50
16
VX-2
2172
38
2130
44
619
289
353
49
250
38
23
3.4
VX-3
1705
296
1799
165
381
42
406
36
133
27
4
2.0
VX-4
1675
54
1769
75
549
96




0.64
0
VX-5
1454
32
1494
112
637
37




11
2.7
Painted Wood
VX-1
1492
36
1633
29
615
357
739
252
353
13
256
20
VX-2
2172
38
2042
42
2035
226
1086
77
349
17
196
105
VX-3
1705
296
1814
258
1081
83
706
16
395
15
128
3.4
VX-4
1675
54
1718
85
1266
31




17
1.9
VX-5
1454
32
1298
69
1253
26




50
6.5
Rubber
Molding
VX-1
1492
36
1733
189
375
71
619
149
428
282
373
24
VX-2
2172
38
2030
99
2867
181
2112
140
752
34
279
11
VX-3
1705
296
1853
116
1300
56
1169
50
582
65
196
20
VX-4
1675
54
1897
49
1551
162




533
53
VX-5
1454
32
1554
66
1808
106




1016
87
Vinyl Tile
VX-1
1492
36
1672
76
421
89
1404
457
342
3.2
219
7.5
VX-2
2172
38
1758
474
2266
426
1500
137
399
25
69
1.5
VX-3
1705
296
1360
41
1292
58
658
45
244
7.5
40
3.1
VX-4
1675
54
1797
26
1646
63




297
53
VX-5
1454
32
1415
66
1899
58




507
26
Graphical depictions of relative VX recoveries versus LCHPV exposure time are presented in Figures
11-14. Here, t=0 hours (h) represents the start of the fumigation (TP-1) while t= -24 h represents the
start of the initial weathering (TP-0). The relative VX recoveries and %RSD results (using Equation 4)
are also tabulated for each of the material types in Tables A1-A4 in Appendix A.
30

-------
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Ss
— 100%
oi
>
o
CJ
aj
0£
0)
ao
TO

<

<
0)
>
QJ
cd
48	72
H202 Exposure time (h)
144
-VX-1 (25 ppmv)
¦VX-2 (25 ppmv)
¦VX-3 (25 ppmv)
VX-4 (0 ppmv)
- VX-5 (0 ppmv)
Figure 13: Relative VX recovery from rubber molding vs LCHPV exposure time.
31

-------

160%
£
140%
£- 120%

o
100%
u
OJ
80%
cd


20%
<

<3J
0%
>

4-1

99% for stainless steel; 96-99% for painted wood;
35-72% for rubber molding; and 64-83% for vinyl tile). The added benefits to expose these materials to
the LCHPV appear to be not present at all or at best rather minimal.
32

-------
3.7.3 VX Degradation Byproduct EA-2192
Extracts from the LCHPV trials and associated positive control trials were evaluated for the presence of
EA-2192, a toxic VX hydrolysis product. The general objective was to verify whether any VX
degradation by the HPV would lead to formation of EA-2192. As discussed in Section 3.7.1, measurable
degradation of VX by LCHPV occurred only for rubber molding and vinyl tile leading to significant
amounts of VX remaining on the surface. Since the main objective was to quantify the VX mass, all test
coupon extracts were diluted to assure that the VX mass in the sample would be quantifiable, leading to
significant dilutions of the extracts which artificially increased the detection limits for EA-2192 to levels
where detection would be impossible. Table 24 summarizes the EA-2192 results.
Table 24: EA-2192 Recoveries after LCHPV Fumigation of Vinyl-Tile Coupons	
Material
Time
Point
Stainless Steel
Painted Wood
Rubber Molding
Vinyl Tile
VX-2
TP-0
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
TP-1
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
TP-2
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
TP-3
ND; < 20 jjg
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
TP-4
ND; < 2 jjg
ND; <10 |jg
ND; <10 |jg
ND; < 5 jjg
VX-3
TP-0
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
TP-1
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
TP-2
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
TP-3
ND; < 20 jjg
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
TP-4
ND; < 0.25 jjg
ND; < 20 jjg
ND; < 20 jjg
ND; < 2 jjg
VX-4
TP-0
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
TP-1
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
ND; < 100 |jg
TP-4
3.8 |jg
[VX: 0.6 ugl
4.3 |jg
[VX:17(jg]
19 uq
[VX: 533 |jg]
ND; < 20 jjg
VX-5
TP-0
ND; < 200 jjg
ND; < 200 jjg
ND; < 200 jjg
ND; < 200 jjg
TP-1
ND; < 200 jjg
ND; < 200 jjg
ND; < 200 jjg
ND; < 200 jjg
TP-4
7.8 |jg
[VX: 11 ugl
ND; < 40 jjg
ND; < 40 jjg
ND; < 40 jjg
ND: Non-Detects
There were four quantifiable amounts for EA-2192, and they were all associated with the positive
control trials. There were no detectable amounts in any of the samples from the LCHPV trials which
provides an upper limit of 10 and 20 |ig for EA-2192 for trials VX-2 and VX-3, respectively, at the end
of the fumigation period (TP-4). Those upper limits are in the same range as the EA-2192 mass detected
during VX-4 and VX-5. As can be derived from the data in Table 24, the EA-2192 quantities are similar
to the recovered VX amounts.
3.7.4 HD Recoveries
As indicated in Table 2, there were five trials with HD. The first LCHPV fumigation trial (HD-1)
occurred with elevated RH at 65%. The second trial (HD-2) was conducted at 50% RH as to assess
33

-------
differences in efficacy due to changes in RH in the presence of HPV. For the third HD LCHPV trial, the
HPV concentration was doubled to assess whether doubling the concentration would have an impact on
the efficacy. The first three LCHPV trials were complemented with a positive control trial (HD-4). A
final fifth trial was added based on the results from HD-1 to HD-3 with a 75 ppmv HPV concentration.
Timepoints for the positive control trial (HD-4) as well as HD-5 were limited to TP-0, TP-1, and TP-4.
The average HD mass recoveries and standard deviations for replicate test (Trials HD-1, HD-2, HD-3,
and HD-5) and positive control (Trial HD-4) coupons of all four material types are provided in Table 25
Table 25: Average HD Mass Recovery
Average Recovery


LCS
TP-0
TP-1
TP-2
TP-3
TP-4
Material
Trial
Mass
StDev
Mass
StDev
Mass
StDev
Mass
StDev
Mass
StDev
Mass
StDev


(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
Stainless
Steel
HD-1
2213
113
2076
294
553
148
ND
—
ND
—
ND
—
HD-2
2607
81
2418
374
748
390
ND
—
ND
—
ND
—
HD-3
2499
162
2312
78
1201
70
0.51
0.24
0.22
0.13
ND
—
HD-4
2511
131
2316
179
682
302




ND
—
HD-5
2442
94
2435
71
688
125




0.75
0.13
Painted
Wood
HD-1
2213
113
2479
30
1551
40
711
109
102
12
23
12.9
HD-2
2607
81
2584
14
2064
120
661
127
148
29
53
8.4
HD-3
2499
162
2664
40
1575
205
560
33
120
33
13
3.4
HD-4
2511
131
2661
81
1509
75




112
55
HD-5
2442
94
2421
7.4
1831
13




18
2.2
Rubber
Molding
HD-1
2213
113
2360
110
2094
101
1607
93
1022
53
871
17
HD-2
2607
81
2908
281
2358
74
1798
47
1451
81
1142
106
HD-3
2499
162
2754
125
2382
77
2008
62
1389
108
800
50
HD-4
2511
131
2736
79
2409
47




891
131
HD-5
2442
94
2758
72
2250
81




800
99
Vinyl Tile
HD-1
2213
113
2349
43
1458
85
993
83
609
34.0
469
16.0
HD-2
2607
81
2550
30
1779
86
1136
75
876
48.9
503
61.4
HD-3
2499
162
2500
83
2028
46
1087
64
692
51.9
499
12
HD-4
2511
131
2408
67
1414
96




549
13
HD-5
2442
94
2506
106
1625
150




438
21.0
| ND: Non-Detects |
Graphical depictions of relative HD recoveries versus LCHPV exposure time are presented in Figures
15-18. Here, t=0 represents the start of the fumigation (TP-1) while t= -3 h represents the start of the
initial weathering (TP-0). The relative HD recoveries and %RSD results (using Equation 4) are also
tabulated for each of the material types in Tables A5-A8 in Appendix A.
34

-------
_ 120%
3s
— 100% 4
£-
5	80%
o
oj 60%
cd
6	40%
ro
5 20%
>
« 0%
>
_CD
 80%
o
a; 60%
& 40%
03
5 20%
>
<
n%
















|









~

^—-
- *









OJ u/0
>
*->
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120%
9	12 15 18
H202 Exposure time (h)
¦ HD-1 (25 ppmv) •
¦ HD-2 (25 ppmv)-
• HD-3 (50 ppmv)
¦HD-4 (0 ppmv)
¦HD-5 (75 ppmv)
Figure 18: Relative HD recovery from vinyl tile vs LCHPV exposure time.
3.7.5 LCHPV Efficacy - HD
For HD, fumigation efficacy was determined from the ratio of the relative mass of HD recovery after
fumigation to the relative mass of HD recovery of the positive control (no hydrogen peroxide). (See
Equation 5 in Section 2.12). The relative average recoveries were used to normalize the data to the
amount recovered at the start of the trial (TP-0) and avoid a bias in the efficacy results due to different
HD amounts spiked/recovered at the start of each trial. Set TP-4 is the only set that offers a direct
comparison between all fumigation trials and the positive control (trial HD-4). Figure 19 summarizes the
measured efficacies.
100%
90%
>. 80%
£ 70%
£ 60%
^ 50%
£! 40%
5 30%
-1 20%
10%
0%
I 23 ppm/65% RH
I 23 ppm/50% RH
47 ppm/59% RH
74 ppm/64% RH
Stainless Steel Painted Wood	Rubber
Material
Vinyl Tile
Figure 19: LCHPV decontamination efficacies for HD on four materials.
For stainless steel, HD was not detected on most of the TP-4 coupons, due mainly to the evaporation
from the stainless-steel surface. The first collection time after fumigation was 5 hours (TP-2). Only trace
levels of HD were observed on these test coupons and a positive control was not collected at that time
point. Therefore, it is inconclusive whether there was LCHPV decontamination efficacy for HD on
stainless steel.
36
-------
For painted wood, HD was recovered after 29 hours (TP-4) of LCHPV exposure. Using the relative
recovery results from TP-4, the LCHPV efficacies were determined for each HPV fumigation
concentration (using Equation 4, Section 2.12). The two trials conducted with an HPV concentration
(different RH) of 25 ppmv yielded an efficacy of 78% (HD-1) and 51% (HD-2). An HPV concentration
of 50 ppmv yielded an efficacy of 89% and an HPV concentration of 75 ppmv yielded an 82% efficacy.
There does not appear to be a correlation between efficacy and the HPV concentrations of 25, 50, and 75
ppmv.
The efficacy for rubber molding was determined for the LCHPV fumigation tests using the TP-4 relative
recoveries. No efficacy was established at the 25 ppm HPV concentration level for both RH conditions
(50%) and 65% RH). An efficacy of 11% was calculated for trials HD-3 and HD-5 which are trials at
elevated HPV concentrations of 50 and 75 ppmv, respectively, for 29 h. Considering the variability in
the replicates, there is not a significant difference between the control (trial HD-4) and the test trials.
The calculated efficacy values are within the accuracy by which the efficacy can be measured.
For the vinyl tile, all LCHPV trials yielded HD amounts recovered at TP-4 that were marginally lower
than the amounts recovered for the positive control trial (HD-4). Calculated efficacies were 13% for
HD-1, HD-2, and HD-3; and 23% (HD-5). Based on variability of the spike replicates, there was not a
significant difference between the control trial and trials HD-1, HD-2, and HD-3. The 75-ppm trial (HD-
5) suggested that some degradation of HD by the LCHPV fumigation occurred.
These efficacy values should be considered against the much higher loss of HD from these surfaces
without LCHPV due to (mostly) evaporation over this one-day period. As can be seen in Figures 15-18,
most of the HD already dissipated (mostly by evaporation) at TP-4 except for the rubber molding
(>99.99%) for stainless steel; 96% for painted wood; 67% for rubber molding; and 77% for vinyl tile).
The added benefits to expose these materials to the LCHPV appear to be not present at all or, at best,
rather minimal in the case of the painted wood.
3.7.6 Malathion Recoveries
As indicated in Table 2, there were three trials with malathion. The first LCHPV fumigation trial (M-l)
occurred with an HPV concentration of 25 ppm. Results from the first trial were considered in the
execution of the second trial (M-2) which was conducted at the high (75 ppmv) HPV concentration. The
two malathion LCHPV trials were complemented with a positive control trial (M-3) under equal
environmental conditions. Timepoints for the positive control trial (M-3) were limited to TP-0, TP-1,
and TP-4.
The average malathion mass recoveries and standard deviations for replicate test (Trials M-l and M-2)
and positive control (Trial M-3) coupons for all four material types are provided in Table 26.
37
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Table 26: Average Malathion Mass Recovery
Average Recovery


LCS
TP-0
TP-1
TP-2
TP-3
TP-4
Material
Trial
Mass
StDev
Mass
StDev
Mass
StDev
Mass
StDev
Mass
StDev
Mass
StDev


(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
(M9)
Stainless
Steel
M-1
2133
49
2260
89
2595
110
2564
261
2416
112
2348
124
M-2
2339
345
2131
97
2787
103
2783
129
2517
67
2389
127
M-3
2085
88
1901
129
1787
294




2721
168
Painted
Wood
M-1
2133
49
2125
110
2231
102
2259
147
2162
173
2137
169
M-2
2339
345
2203
140
2015
93
1887
145
1735
109
1868
41
M-3
2085
88
1781
125
1719
111




2172
90
Rubber
Molding
M-1
2133
49
2627
234
2068
258
1415
222
953
145
601
47
M-2
2339
345
2948
351
1452
189
1014
143
685
62
588
71
M-3
2085
88
2528
461
1708
305




990
109
Vinyl Tile
M-1
2133
49
2220
240
2185
246
2282
206
1925
340
1905
268
M-2
2339
345
2402
205
2712
427
2011
226
1988
472
2315
333
M-3
2085
88
1747
145
1605
140




1630
170
Graphical depictions of relative malathion recoveries versus LCHPV exposure time are presented in
Figures 20-23. Here, t=0 h represents the start of the fumigation (TP-1) while t= -24h represents the start
of the initial weathering (TP-0). Relative average malathion recoveries and %RSD results are also
presented for each of the material types in Tables A9-A12 in Appendix A. For malathion, two LCHPV
concentrations were compared, 25 ppmv and 75 ppmv.
_ 160%
aS 140%
£¦ 120%
I 100%
01	80%
 20%
<
-------
_ 140%
£ 120%
100%
g 80%
ID
60%
§ 40%
| 20%
<
O)
>
O)
DC
-24
24	48	72
H202 Exposure time (h)
96
120
144
¦ M-l (25ppmv)
¦M-2 (50 ppmv)
¦ M-3 (0 ppmv)
Figure 21: Relative ma lath ion recovery from painted wood vs LCHPV exposure time.
M-l (25 ppmv) —•—M-2 (50 ppmv) —•—M-3 (0 ppmv)
Figure 22: Relative malathion recovery from rubber molding vs LCHPV exposure time.

120%
100% (











&
£-

O
u

=J





	=1
t
80%
60%
40%
20%
rw

:	
> —
		1~=	

	1
»
cc

<
















aj
>
_ro
a)
DC
-24
0 24
48 72 96
H202 Exposure time (h)
120
144



• M-l (25 ppmv)
—•—M-2 (50ppmv)
• M-3 (0 ppmv)



Figure 23: Relative malathion recovery from vinyl tile vs LCHPV exposure time.
39
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3.7.7 LCHPV Efficacy - Malathion
Fumigation efficacy of malathion was determined by comparing the relative average malathion
recoveries from various fumigation trials with the positive control run, M-3. The relative average
recoveries were used to normalize the data to the amount recovered at the start of the trial (TP-0) and
avoid a bias in the efficacy results due to different malathion amounts spiked/recovered at the start of
each trial. Set TP-4 is the single set that provides a direct comparison between the two fumigation trials
and the positive control trial (M-3).
For stainless steel, the calculated malathion efficacy at an HPV concentration of 25 ppmv was 27% and
at a concentration of 75 ppmv, the calculated efficacy was 22%. While both HPV concentrations suggest
some efficacy, the change in HPV concentration between trials M-l and M-2 did not significantly
change the observed efficacy. Further, the apparent efficacy is likely based on a noticeably higher
relative recovery (143%) of the positive control trial (M-3) at TP-4 which exceeds other values at TP-0
and TP-1. Considering that relative recoveries at TP-4 (six days after the start of the fumigation) are the
same as the initial starting amount, the LCHPV does not appear to degrade malathion on stainless steel.
For painted wood, efficacy was observed at an HPV concentration of 25 ppmv (18% efficacy) which
increased to 30% at a concentration of 75 ppmv. Like the stainless-steel results, the recovery at TP-4 for
the positive control trial (M-3) exceeds earlier (TP-0 and TP-1) values. Considering that relative
recoveries at TP-4 (six days after the start of the fumigation) are the same for M-l as the initial starting
amount, the LCHPV does not appear to degrade malathion on stainless steel at 25 ppm. Some efficacy at
a 75-ppm concentration was observed.
For rubber molding, the reduction in malathion relative recoveries with time appears to be caused by the
degradation of malathion caused by interaction with the rubber molding. The calculated malathion
efficacy at an HPV concentration of 25 ppmv was 42% and, at a concentration of 75 ppmv, the
calculated efficacy was 49%. While both HPV concentrations showed observable efficacy, the change in
HPV concentration between trials M-l and M-2 did not significantly change the calculated efficacy.
Relative recoveries for malathion at TP-4 from vinyl tile from the positive control trial (M-3) were
identical to the relative recoveries from the two LCHPV trials considering the associated standard
deviation in the data, indicating that there is no efficacy associated with LCHPV for either HPV
concentration against malathion on vinyl tile.
3.7.8 Malathion Degradation Byproduct Malaoxon
Extracts from the three LCHPV trials were screened for the presence of malaoxon, a toxic oxidation
byproduct of malathion. None of the samples yielded detectable amounts of malaoxon. This statement
should be considered in combination with the high artificial detection limit (more than 40 |ig) due to the
required dilution of the samples to allow for the quantification of malathion.
3.8 Statistical Analysis
A statistical analysis of the data set was performed using a multiple sample, Bayesian estimation of
treatment. The analysis is analogous to the traditional Mest for difference in mean between two samples
[8], The data set included all spiked test data except for TP-0 as TP-0 is not directly connected to the
LCHPV fumigation. Data included each combination of agent, material type, and time point. Results of
the statistical analysis is presented in Figures 24-26 and represent probability density plots that compare
groups of triplicate spike results to determine if the groupings are significantly different.
40
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The probability density plots show the estimated triplicate average recovery (x-axis) versus probability
density (y-axis) for each of the test conditions on each material type. Each peak is a statistical
representation of a spiked triplicate grouping, where overlap with another peak shows similarity and
resolved peaks show significant differences.
41
-------
0.5-
TP1
TP2
TP3
TP4








I


U.4 "










U.o "
0.2-
. . I

i


L




cn
CD
0.1 -
0.0-








0.3-
0.2-
0.1 -
0.0-I
XI
50
100
150
I
J
1
50 100 150 0 50 100 150
Estimate of group-level average recovery %
k

L
Treatment
23°C, 50% RH, 25 ppmv H202
23°C, 40% RH, 25 ppmv H202
23°C, 65% RH, 25 ppmv H202
23°C, 65% RH
I	1	
0 50
23°C, 40% RH
100
150
Figure 24: Bayesian estimation of VX treatment. SS = stainless steel; VT = vinyl tile; RB = rubber molding; PW = painted wood.
42
-------
TP1
ui

TP2





A



JL

I

30 60
T reatment
90

TP3
L	


JL	



J
Li.


L

TP4
co
M
<
73
on
0 30 60 90	0 30 60 90
Estimate of group-level average recovery %
30
60
90
¦
23°C, 65% RH, 25 ppmv H202

23°C, 65% RH, 50 ppmv H202

23°C, 50% RH, 25 ppmv H202
¦
23°C, 65% RH
23°C, 65% RH, 75 ppmv H202
Figure 25: Bayesian estimation of HD treatment. SS = stainless steel; V'T = vinyl tile; RB = rubber molding; PW = painted wood.
43
-------
TP1



J|

11

^ L

0.15-
0.10 -
0.05-
0.00 -I
TP2


















TP3
50
100
50	100	0	50	100
Estimate of group-level average recovery %
TP
4

SS
4
1

J


73
CD


J
r
Md
50
100
Treatment
23°C, 65% RH, 25 ppmv H202 11 23°C, 40% RH
23°C, 65% RH, 75 ppmv H202
Figure 26: Bayesian estimation of maiathion treatment. SS = stainless steel; VT = vinyl tile; RB = rubber molding; PW =painted wood.
44
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3.8.1 Statistical Results for VX
As can be derived from probability densities in Figure 24 for the TP-4 timepoint, distributions from the
positive control test for stainless steel and painted wood overlap with the distributions for the LCHPV
fumigation while there is minimal overlap for vinyl tile and rubber molding, which may indicate that
some degradation occurred for the latter two materials.
3.8.2	Statistical Results for HD
For HD, the statistical analysis does not indicate decontamination efficacy from LCHPV fumigation on
any of the materials. Probability densities, shown in Figure 25, overlap for the TP-4 timepoint for all
materials and independent of HPV concentration. The relatively fast evaporation of HD from especially
stainless steel and painted wood complicates the interpretation of the results.
3.8.3	Statistical Results for Malathion
In the case of malathion, the probability density peak, as shown in Figure 26, for vinyl tile appears to the
left of the other two peaks indicating that LCHPV fumigation resulted in slightly higher malathion
recoveries. Therefore, there was no malathion decontamination on vinyl tile. For stainless steel and
rubber molding, the positive control peak appears on the right side of the other two peaks. The
separation between the brown peak from the others is an indication of efficacy; however, there is not a
significant difference due to the peak overlap. For painted wood, the peaks representing HPV fumigation
at 25 ppmv and no fumigation completely overlap, indicating no difference between the two data
groups. There was resolution between no fumigation and HPV fumigation at 75 ppmv indicating that
some degradation of malathion occurred at 75 ppm HPV after 144 hours.
45
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4 Quality Assurance/Quality Control
This work was conducted under a certified quality system meeting International Organization for
Standardization (ISO) 9001:2015 Quality Management requirements [9], Quality objectives and
performance criteria described in the sections below provide the requirements for determining the
adequacy of the data generated. Methods were considered acceptable and valid data were assumed if the
data quality objectives for the test measurements were met. Further, the Technical Systems Audit (TSA),
Performance Evaluation (PE), and data quality audits required acceptable results.
4.1 Data Quality Indicators
Data quality indicators and results are provided in Table 27. Data quality indicator results were
acceptable per the QAPP, including checks of the measurement methods for temperature, RH, hydrogen
peroxide concentration, time, volume, mass, chemical recovery from blank samples and spike controls.
Attainment of these data quality indicator results limited the amount of error introduced into the
evaluation results.
Table 27: Data Quality Indicators and Results
Parameter
Measurement
Method
Data Quality Indicator
Results
Temperature (°C)
NIST-traceable
thermometer
Certificate of calibration (new
instrument); agree ±0.2 °C
The Rotonic Hygroclip XD T/RH sensors
were received with a manufacturer
RH (%)
NIST-traceable
hygrometer
Certificate of calibration (new
instrument); agree ±0.8% RH
certificate of calibration which expired
past the research completion date
Time (h:sec)
Timer, PAC
Compare to time provided at
NIST.time.gov once before
testing; agree ±2 s/h.
No differences observed between timer
and NIST time
HPV
Concentration
(ppmv)
Gas Detector
Certificate of calibration (new
instrument); agree ±10%
ATI Gas Detector Calibration Certificate
Volume (|jL)
Calibrated pipette
(LC-MS/MS
sample dilution)
Pipettes were verified for
accuracy and repeatability
once before use by
determining mass of water
delivered. The
syringe/pipette was
acceptable if the range of
observed masses for five
replicate droplets was ±10%
of expected.
Seven pipettes used for LC-MS/MS sample dilution
were verified. Systematic and random percent error
ranges for each are provided below:
•	Pipette 1 at 100, 500, and 1000 |jL - 0.37% to
2.10%
•	Pipette 2 at 50, 100, and 200 |jL - 0.46% to 1.2%
•	Pipette 3 at 10, 50, and 100 |jL - 0.00% to 2.0%
•	Pipette 4 at 20, 100, and 200 |jL - 0.05% to 0.75%
•	Pipette 5 at 10, 100, 500, and 1,000 |jL - 0.14% to
1.0%
•	Pipette 6 at 10, 100, 500, and 1,000 |jL -
0.17% to 0.57%
•	Pipette 7 at 10, 100, 500, and 1,000 |jL -
0.00% to 0.48%
46
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Parameter
Measurement
Method
Data Quality Indicator
Results
Volume (|jL)
Syringe for
chemical
application
Syringe was checked for
accuracy and repeatability
once before use by
determining mass of water
delivered.
Triplicate readings of 1,2, 4, 6, 8, 10 |jL
yielded error ranges from 0.00% to 0.42%
Chemical agent in
Laboratory
Control Spike
(MQ/mL)
Extraction, LC-
MS/MS or GC/MS
Recovered mass 100±20%
%RSD1 < 15% with respect
to theoretical amount applied
See Section 3.1. Table 13: VX-1, VX-3,
and VX-5 LCS failed recovery
performance criteria (low); Table 14: All
HD LCS met performance criteria; Table
15: All malathion LCS met performance
criteria.
Chemical agent
on Positive
Control (jjg/mL)
Extraction, LC-
MS/MS or GC/MS
Recovered mass 40 to 130%
of spike control recovery
See Section 3.1, Tables 13-15: All VX,
HD and malathion TP-0 control spike
samples met recovery criteria.
Chemical agent in
Laboratory Blank
Coupon Extracts
(MQ/mL)
Extraction, LC-
MS/MS or GC/MS
<5 nanograms (ng) of VX,
HD, or malathion in
laboratory blank
No chemical outside of the stated criteria
was measured in any laboratory blank
sample extracts throughout testing.
Chemical agent in
Procedural Blank
Coupon Extracts
(|jg/mL)
Extraction, LC-
MS/MS or GC/MS
<10 ng of VX, HD, or
malathion in procedural
blank
See Section 3.6.1. Detectable amounts
for VX and malathion were less than 1.8%
and 0.05%, respectively. ForHD, up to
6.5% of spiked amount was found on PB
due to vapor redistribution
1 %RSD is percent relative standard deviation
NIST: National Institute of Standards and Technology
4.2 Process Quality Control Parameters for LCHPV Efficacy Testing
Additional quality parameters linked to the weathering and fumigation process are provided in Table 28
and include a review of the collected (real time) data for temperature, RH, weathering, and fumigation
times, and HPV concentration.
47
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Table 28: Process Quality Indicators and Results
Parameter
Measurement
Method
Data Quality Indicator
Results
Temperature -
Weathering Period
Temp./RH Probes
(PAC)
23 ± 3°C
See Section 3.2, Table 16. All
temperatures fell in this range.
RH - Weathering
Period
Temp./RH Probes
(PAC)
< 40% RH
See Section 3.2, Table 16. VX-3,
HD-1, HD-2 reported a higher
than 40% RH (but less than 45%).
Weathering Time
PAC System
Clock
HD: 3 h ± 18 m;
VX and Malathion: 24 h ± 2 h
See Section 3.3, Table 17. All
times were met except for HD
(TP-4)
Temperature -
Fumigation Period
Temp./RH Probes
(PAC)
23 ± 3°C
See Section 3.4, Table 18. All
temperatures fell in this range
RH - Fumigation
Period
Temp./RH Probes
(PAC)
Set point ±10%
See Section 3.4, Table 18. All RH
fell in this range
Fumigation Time
PAC System
Clock
Set point ±10%
See Section 3.3, Table 17. All
times were met
HPV Delivery
HPV Monitor
Set point ±20%
See Section 3.5, Table 19. All
HPV concentrations were within
range
4.3	Instrument Calibration
Instrumentation that was required to conduct this project was maintained and operated according to
quality and safety requirements and documentation of Southwest Research Institute. Calibration
procedures for the LC-MS/MS and GC/MS were described in Section 2.11. Calibration of all other
instrumentation was specified by the particular manufacturer with a minimal annual recalibration
requirement.
4.4	Sample Custody and Archival
Sample identifications were generated in the LIMS system several days prior to test start for logistics;
however, actual coupon samples originated at the time of coupon spiking. Run logs posted in controlled
laboratory notebooks were used to track samples through the test process from origination to extraction.
LIMS identified that the samples were consumed during extraction. After collecting an aliquot of the
extract, the contaminated coupons were disposed of through the hazardous waste stream. Sample
extracts were stored in an approved freezer at -20 ± 10 °C.
Analytical results from each trial were assembled into data packages to include a narrative, summary
results, sample preparation, standard preparation, method information, calibration certificates, and raw
data with chromatograms.
4.5	QAPP Deviations
There were several deviations from the QAPP. These deviations include the chamber temperature range,
humidity control, additional coupons added for a VX trial, monitoring for malaoxon, and adjusted HD-5
to a fumigation trial. All deviations were discussed with the PI and approved prior to implementation.
48
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The operational temperature range for the chamber was initially set to 15°C to 25°C; however, the heat
exchanger in the recirculation line scrubbed the HPV. The heat exchanger was removed, limiting the
temperature control to above 20°C. This heat exchanger removal did not impact the results of this study.
Humidity control was not required with the assumption that HPV generation would increase RH above
70%. Since HPV was generated at ambient conditions from a high (35%) liquid solution, RH remained
below 50%. The Donut Humidifier was installed inside the chamber with feedback based on a
temperature and RH probe. This change did not impact the results of this study.
For TP-1 on trial VX-2, three additional spiked coupons were added for each material to compare
natural attenuation across the shelves (spatially). Spike replicates, 1 through 3, were grouped with the
procedural blank. Replicate 4 was grouped with TP-2 coupons; replicate 5 was grouped with TP-3
coupons; and replicate 6 was grouped with TP-2 coupons. The recoveries agreed with those obtained at
other shelf locations suggesting that the air was adequately mixed and that there was no evidence of a
nonuniform temperature distribution within the chamber.
For malathion trials, extracts were assayed for malaoxon as a toxic byproduct in addition to malathion.
The HD-5 trial was identified in the QAPP as a positive control. Based on results from previous trials,
HD-5 was changed into a fumigation trial, although there were no time points for TP-2 or TP-3 unlike
the other fumigation trials.
The QAPP identified decontamination efficacy control parameter for identifying coupon interferences
using the TP-0 procedural blanks; however, all procedural blanks were within proximity of the spiked
coupons with air flow moving across coupons. To mitigate potential vapor transfer detections, true
laboratory blanks were substituted for TP-0 procedural blank to determine matrix interferences. This
change did not impact the results of this study.
49
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5 Summary and Conclusions
An environmental test chamber was constructed to perform LCHPV fumigation testing. The test
chamber consists of a glove box chamber, a closed system recirculating loop, and an antechamber for
adding and removing test coupons with minimal disruption of chamber conditions. A recirculating loop
was used to ensure proper mixing HPV with air and to monitor and control conditions. Prior to efficacy
testing, the chamber was tested over a 24-hour period to verify that the temperature of 23 ± 3°C and
HPV concentration of 25 ± 5 ppm were maintained.
A total of thirteen trials were performed to evaluate LCHPV fumigation on four porous materials
representing interior structures which were contaminated with VX, HD, or malathion. Material types
tested included stainless steel, painted wood, rubber molding, and vinyl tile. There were five VX trials,
five HD trials, and three malathion trials. For VX, two humidity conditions and one HPV fumigation
concentration were evaluated. For HD, three HPV fumigation concentration were evaluated. For
malathion, two HPV fumigation concentrations were evaluated. Efficacy data were calculated through
extraction and analysis of the coupon extracts that measured any residual contaminants with or without
HPV treatment.
In general, most of the chemical agent loss was associated with natural attenuation. As a result, efficacy
was determined by comparing endpoint (TP-4) results with and without fumigation.
VX trials included a 24-h weathering time followed by 144 h of fumigation, except for one trial that
spanned 72 hours. Test results indicated no LCHPV efficacy on stainless steel or painted wood.
However, there are indications of limited efficacy for rubber molding and vinyl tile.
HD trials included a 3-hour weathering time followed by 29 hours of fumigation. Statistical results
indicate that LCHPV fumigation did not improve decontamination efficacy over natural attenuation for
all four material types.
Malathion trials included a 24-hour weathering time followed by 144 hours of fumigation. Test results
indicated no HPV efficacy on stainless steel and vinyl tile. However, there are indications of some
efficacy for rubber molding, and painted wood but only at elevated (75 ppm) HPV concentration.
For VX, the longest fumigation time (144 h) and 25 ppmv HPV concentration equates to 3,600 ppm x h.
This value exceeds the previously tested 1,700 ppm x h of modified vaporous hydrogen peroxide testing
[1] which showed better than 80% efficacy at the longest fumigation time (7 h). Based on the results
from this study, there is a lower concentration limit on the applicability of HPV to degrade VX which
cannot be overcome through longer exposure times. One other difference is that the previous study
included ammonia in the fumigation based on research by Wagner et al. [2], Nevertheless, that
publication provides no evidence that the addition of ammonia improved the VX degradation (it is
important for degradation of soman, GD).
The longest HD fumigation time was 29 h, which equates to 2,175 ppm x h for the highest tested
concentration here (75 ppm). Higher efficacies were expected as lower ppm hour values (100 ppm x h)
lead to significant HD degradation [1], although the exact efficacy analysis is sensitive to the actual
evaporation of the agent.
There is no direct comparison possible for malathion as previous work did not consider this pesticide
50
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and chemical warfare agent simulant. Oxidation of malathion into malaoxon was not observed.
51
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References
[1]	U.S. EPA. Assessment of Fumigants for Decontamination of Surfaces Contaminated with
Chemical Warfare Agents. U.S. Environmental Protection Agency. Washington, DC.
EPA/600/R-10/035, 2010.
[2]	Decontamination of VX, GD, and HD on a Surface Using Modified Vaporized Hydrogen
Peroxide, Wagner, G.W., D.C. Sorrick, L.R. Procell, M.D. Brickhouse, I.F. Mcvey, and L.I.
Schwartz. Langmuir 23: 1178-1186 (2007).
[3]	A Simple Decontamination Approach Using Hydrogen Peroxide Vapour for Bacillus anthracis
Spore Inactivation, Wood, J.P., W. Calfee, S. Ryan, L. Mickelsen, M. Clayton, and V. Rastogi.
Journal of Applied Microbiology 121(6): 1603-1615 (2016).
[4]	Richter, W. and J.P. Wood. Decontamination of Materials Contaminated with Spores of
Bacillus anthracis Ames and Vollum Strains Using Low Concentrations of Hydrogen Peroxide
Vapor. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-18/215, 2018.
[5]	Chemical Detoxification of Nerve Agent VX, Yang, Yu-Chu. Accounts of Chemical Research
32: 109-115 (1999).
[6]	Monitor of Malathion and Its Impurities and Environmental Transformation Products on
Surfaces and in Air Following an Aerial Application, Brown, M.A., M.X. Petreas, H.S.
Okamoto, T.M Mischke, and R.D. Stephens. Environmental Science & Technology 27(2): 388-
397(1993).
[7]	Chemical Contaminant and Decontaminant Test Methodology Source Document, Second
Edition., Lalain, T., B. Mantooth, M. Shue, S. Pusey, and D. Wylie. ECBC-TR-980 (2012).
[8]	Bayesian Estimation Supersedes the t-Test, Kruschke, J.K. Journal of Experimental Psychology:
General 142(2): 573-603 (2013).
[9]	International Organization for Standardization, ISO 9001:2015 Quality management systems
Requirements, https://www.iso.Org/obp/ui/#iso:std:iso:9001:ed-5:vl:en. Last accessed April 16,
2021
52
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Appendices
53
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Appendix A
Table A1: Relative VX Recovery after LCHPV Fumigation of Stainless-Steel Coupons
Table A2: Relative VX Recovery after LCHPV Fumigation of Painted-Wood Coupons
Table A3: Relative VX Recovery after LCHPV Fumigation of Rubber-Molding Coupons
Table A4: Relative VX Recovery after LCHPV Fumigation of Vinyl-Tile Coupons
Table A5: Relative HD Recovery after LCHPV Fumigation of Stainless-Steel Coupons
Table A6: Relative HD Recovery after LCHPV Fumigation of Painted-Wood Coupons
Table A7: Relative HD Recovery LCHPV Fumigation of Rubber-Molding Coupons
Table A8: Relative HD Recovery after LCHPV Fumigation of Vinyl-Tile Coupons
Table A9: Relative Malathion Recovery after LCHPV Fumigation of Stainless-Steel Coupons
Table A10: Relative Malathion Recovery after LCHPV Fumigation of Painted-Wood Coupons
Table A11: Relative Malathion Recovery after LCHPV Fumigation of Rubber-Molding
Coupons
Table A12: Relative Malathion Recovery after LCHPV Fumigation of Vinyl-Tile Coupons
54
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Table Al: Relative VX Recovery after LCHPV Fumigation of Stainless-Steel Coupons
Trial
(H2O2 Cone.)
RH
(%)
TP-0 (-24 h)1
TP-1 (0 h)2
TP-2 (24 h)2
TP-3 (72 h)2
TP-4 (144 h)2
Relative Recovery during
Weathering (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
VX-4 (0 ppmv)3
65
106 ±4
31 ±5


0.04 ±0.02
VX-5 (0 ppmv)3
50
103 ±8
43 ±3


0.71 ±0.18
VX-1 (25 ppmv)
50
112 ±4
3.7 ±3.7
13 ±2
3.0 ±0.9 4
..5
VX-2 (25 ppmv)
40
98 ±2
29 ± 14
17 ±2
12 ±2
1.1 ±0.2
VX-3 (25 ppmv)
65
106 ± 10
21 ±2
23 ±2
7.4 ± 1.5
0.20 ±0.11
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
4	For Trial VX-1, result displayed is TP-4 collected at 72 to show equivalent exposure time.
5	No result; TP-4 was collected at 72 hours for trial VX-1
Table A2: Relative VX Recovery after LCHPV Fumigation of Painted-Wood Coupons
Trial
RH
TP-0 (-24 h)1
TP-1 (0 h)2
TP-2 (24 h)2
TP-3 (72 h)2
TP-4 (144 h)2
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
VX-4 (0 ppmv)3
65
103 ±5
74 ±2


0.98 ±0.11
VX-5 (0 ppmv)3
50
89 ±5
97 ±2


3.8 ±0.5
VX-1 (25 ppmv)
50
109 ±2
38 ±22
45 ± 15
16 ± 1 4
	5
VX-2 (25 ppmv)
40
94 ±2
100 ± 11
53 ±4
17 ± 1
9.6 ±5.1
VX-3 (25 ppmv)
65
106 ± 15
60 ±5
39 ± 1
22 ± 1
7.1 ±0.2
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
4	For Trial VX-1, result displayed is TP-4 collected at 72 to show equivalent exposure time.
5	No result; TP-4 was collected at 72 hours for trial VX-1
Table A3: Relative VX Recovery after LCHPV Fumigation of Rubber-Molding Coupons
Trial
RH
TP-0 (-24 h)1
TP-1 (0 h)2
TP-2 (24 h)2
TP-3 (72 h)2
TP-4 (144 h)2
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
VX-4 (0 ppmv)3
65
113 ± 3
82 ±9


28 ±3
VX-5 (0 ppmv)3
50
107 ±5
116 ± 7


65 ±6
VX-1 (25 ppmv)
50
116 ± 13
22 ±4
36 ±9
22 ± 1 4
	5
VX-2 (25 ppmv)
40
93 ±5
141 ±9
104 ±7
37 ±2
14 ± 1
VX-3 (25 ppmv)
65
109 ±7
70 ±3
63 ±3
31 ±4
11 ± 1
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
4	For Trial VX-1, result displayed is TP-4 collected at 72 to show equivalent exposure time.
5	No result; TP-4 was collected at 72 hours for trial VX-1
55
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Table A4: Relative VX Recovery after LCHPV Fumigation of Vinyl-Tile Coupons
Trial
RH
TP-0 (-24 h)1
TP-1 (0 h)2
TP-2 (24 h)2
TP-3 (72 h)2
TP-4 (144 h)2
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
VX-4 (0 ppmv)3
65
107 ±2
92 ±3


17 ± 3
VX-5 (0 ppmv)3
50
97 ±5
134 ±4


36 ±2
VX-1 (25 ppmv)
50
112 ± 5
25 ±5
84 ±27
13 ±0.4 4
..5
VX-2 (25 ppmv)
40
81 ±22
129 ±24
85 ±8
23 ± 1
3.9 ±0.1
VX-3 (25 ppmv)
65
80 ±2
95 ±4
48 ±3
18 ±0.5
3.0 ±0.2
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
4	For Trial VX-1, result displayed is TP-4 collected at 72 to show equivalent exposure time.
5	No result; TP-4 was collected at 72 hours for trial VX-1
Table A5: Relative HP Recovery after LCHPV Fumigation of Stainless-Steel Coupons
Trial
RH
TP-0 (-3 h)1
TP-1 (0 h)2
TP-2 (5 h)2
TP-3 (22 h)2
TP-4 (29 h)2
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
HD-4 (0 ppmv)3
65
92 ±7
29 ± 13


ND4
HD-1 (25 ppmv)
50
94 ± 13
27 ±7
ND4
ND4
ND4
HD-2 (25 ppmv)
65
93 ± 14
31 ± 16
0.0044 ±
0.001
ND4
ND4
HD-3 (50 ppmv)
65
93 ±3
52 ±3
0.022 ±0.010
0.009 ± 0.006
ND4
HD-5 (75 ppmv)
65
100 ±3
28 ±5


0.031 ±0.005
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
4	ND, Non-Detect (equivalent to < 0.004% relative recovery)
Table A6: Relative HP Recovery after LCHPV Fumigation of Painted-Wood Coupons
Trial
RH
TP-0 (-3 h)1
TP-1 (0 h)2
TP-2 (5 h)2
TP-3 (22 h)2
TP-4 (29 h)2
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
HD-4 (0 ppmv)3
65
106 ±3
57 ±3


4.2 ±2.1
HD-1 (25 ppmv)
50
112 ± 1
63 ±2
29 ±4
4.1 ±0.5
0.93 ±0.52
HD-2 (25 ppmv)
65
99 ±0.5
80 ±5
26 ±5
5.7 ±1.1
2.0 ±0.3
HD-3 (50 ppmv)
65
107 ±2
59 ±8
21 ± 1
4.5 ± 1.2
0.48 ±0.13
HD-5 (75 ppmv)
65
99 ±0.3
76 ± 0.5


0.76 ±0.1
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
56
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Table A7: Relative HP Recovery LCHPV Fumigation of Rubber-Molding Coupons
Trial
RH
TP-0 (-3 h)1
TP-1 (0 h)2
TP-2 (5 h)2
TP-3 (22 h)2
TP-4 (29 h)2
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
HD-4 (0 ppmv)3
65
109 ±3
88 ±2


33 ±5
HD-1 (25 ppmv)
50
107 ±5
89 ±4
68 ±4
43 ±2
37 ± 1
HD-2 (25 ppmv)
65
112 ± 11
81 ±3
62 ±2
50 ±3
39 ±4
HD-3 (50 ppmv)
65
110 ± 5
87 ±3
73 ±2
50 ±4
29 ±2
HD-5 (75 ppmv)
65
113 ± 3
82 ±3


29 ±4
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
Table A8: Relative HP Recovery after LCHPV Fumigation of Vinyl-Tile Coupons
Trial
RH
TP-0 (-3 h)1
TP-1 (0 h)2
TP-2 (5 h)2
TP-3 (22 h)2
TP-4 (29 h)2|
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
HD-4 (0 ppmv)3
65
96 ±3
59 ±4


23 ±0.5
HD-1 (25 ppmv)
50
106 ±2
62 ±4
42 ±4
26 ± 1
20 ± 1
HD-2 (25 ppmv)
65
98 ± 1
70 ±3
45 ±3
34 ±2
20 ±2
HD-3 (50 ppmv)
65
100 ±3
81 ±2
43 ±3
28 ±2
20 ±0.5
HD-5 (75 ppmv)
65
103 ± 4
65 ±6


17 ± 1
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
Table A9: Relative Malathion Recovery after LCHPV Fumigation of Stainless-Steel Coupons
Trial
RH
TP-0 (-24 h)1
TP-1 (0 h)2
TP-2 (24 h)2
TP-3 (72 h)2
TP-4 (144 h)2
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
M-3 (0 ppmv)3
65
91 ±6
94 ± 16


143 ±9
M-1 (25 ppmv)
65
106 ±4
115 ± 5
113 ± 12
107 ±5
104 ±5
M-2 (75 ppmv)
40
91 ±4
131 ±5
131 ±6
118 ±3
112 ±6
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
Table A10: Relative Malathion Recovery after LCHPV Fumigation of Painted-Wood Coupons
Trial
RH
TP-0 (-24 h)1
TP-1 (0 h)2
TP-2 (24 h)2
TP-3 (72 h)2
TP-4 (144 h)21
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
M-3 (0 ppmv)3
65
85 ±6
97 ±6


122 ±5
M-1 (25 ppmv)
65
100 ±5
105 ±5
106 ±7
102 ±8
101 ±8
M-2 (75 ppmv)
40
94 ±6
91 ±4
86 ±7
79 ±5
85 ±2
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
57
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Table All: Relative Malathion Recovery after LCHPV Fumigation of Rubber-Molding Coupons
Trial
RH
TP-0 (-24 h)1
TP-1 (0 h)2
TP-2 (24 h)2
TP-3 (72 h)2
TP-4 (144 h)21
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering Recovery (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
M-3 (0 ppmv)3
65
121 ±22
68 ± 12


39 ±4
M-1 (25 ppmv)
65
123 ± 11
79 ± 10
54 ±8
36 ±6
23 ±2
M-2 (75 ppmv)
40
126 ±15
49 ±6
34 ±5
23 ±2
20 ±2
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
Table A12: Relative Malathion Recovery after LCHPV Fumigation of Vinyl-Tile Coupons
Trial
RH
TP-0 (-24 h)1
TP-1 (0 h)2
TP-2 (24 h)2
TP-3 (72 h)2
TP-4 (144 h)21
(H2O2 Cone.)
(%)
Relative Recovery during
Weathering Recovery (%) ± SD
Relative Recovery during
LCVHP Fumigation (%) ± SD
M-3 (0 ppmv)3
65
84 ±7
92 ±8


93 ± 10
M-1 (25 ppmv)
65
104 ± 11
98 ± 11
103 ±9
87 ± 15
86 ± 12
M-2 (75 ppmv)
40
103 ±9
113 ± 18
84 ±9
83 ±20
96 ± 14
1	TP-0 value is relative to LCS
2	TP-1 - TP-4 values are relative to TP-0
3	Positive Control Trial - (No fumigation)
58
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Appendix B
Figures B1-B13 show chamber monitoring results for each trial. Chart data plotted includes
temperature, percent RH, and HPV concentration of air entering and exiting the chamber from the
recirculation loop over the time duration of the trial.
Figure B1: Chamber monitoring data for VX-1 (23°C, 50% RH, 25 ppmv H202)
Figure B2: Chamber monitoring data for VX-2 (23°C, 40% RH, 25 ppmv H202)
Figure B3: Chamber monitoring data for VX-3 (23°C, 65% RH, 25 ppmv H202)
Figure B4: Chamber monitoring data for VX-4 (23°C, 65% RH, 0 ppmv H202)
Figure B5: Chamber monitoring data for VX-5 (23°C, 40% RH, 0 ppmv H202)
Figure B6: Chamber monitoring data for HD-1 (23°C, 65% RH, 25 ppmv H202)
Figure B7: Chamber monitoring data for HD-2 (23°C, 50% RH, 25 ppmv H202)
Figure B8: Chamber monitoring data for HD-3 (23°C, 65% RH, 50 ppmv H202)
Figure B9: Chamber monitoring data for HD-4 (23°C, 65% RH, 0 ppmv H202)
Figure B10
Figure B11
Figure B12
Figure B13
Chamber monitoring data for HD-5 (23°C, 65% RH, 75 ppmv H202)
Chamber monitoring data for malathion-1 (23°C, 65% RH, 25 ppmv H202)
Chamber monitoring data for malathion-2 (23°C, 65% RH, 75 ppmv H202)
Chamber monitoring data for malathion-3 (23°C, 40% RH, 0 ppmv H202
59
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Temperature Out		Temperature In		HPV-Out		HPV In		RH Out		RH In
Figure B1: Chamber monitoring data for VX-1 (23°C, 50% RH, 25 ppmv H2O2).
60
-------
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Figure B2: Chamber monitoring data for VX-2 (23°C, 40% RH, 25 ppmv H2O2).
61
-------
Time, h:m
Temperature Out		Temperature In		HPV-Out		HPV In		RH Out		RH In
Figure B3: Chamber monitoring data for VX-3 (23 C, 65% RH, 25 ppmv H2O2).
62
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Figure B5: Chamber monitoring data for VX-5 (23°C, 40% RH, 0 ppmv H2O2).
64
-------
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Figure B6: Chamber monitoring data for HD-1 (23°C, 65% RH, 25 ppmv H2O2).
65
-------
Temperature Out		Temperature In		HPV-Out		HPVIn		RH Out		RH In
Figure B7: Chamber monitoring data for HD-2 (23°C, 50% RH, 25 ppmv H2O2).
66
-------
20 -	, 	1	1	1	r	1	1	1	1	1	1	1	1	1	1	r
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Figure B8: Chamber monitoring data for HD-3 (23°C, 65% RH, 50 ppmv H2O2).
67
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Figure B9: Chamber monitoring data for HD-4 (23°C, 65% RH, 0 ppmv H2O2).
68
-------
Temperature Out		Temperature In	HPV-Out		HPV In		RH Out		RH In
Figure B10: Chamber monitoring data for HD-5 (23°C, 65% RH, 75 ppmv H2O2).
69
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Temperature Out		-Temperature In		HPV-Out		-HPVIn		RH Out		RH In
Figure B12: Chamber monitoring data for malathion-2 (23°C, 65% RH, 75 ppmv H2O2).
71
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Figure B13: Chamber monitoring data for malathion-3 (23°C, 40% RH, 0 ppmv H2O2)
72
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vvEPA
United States
Environmental Protection
Agency
PRESORTED STANDARD
POSTAGE & FEES PAID
EPA
PERMIT NO. G-35
Office of Research and Development (8101R)
Washington, DC 20460
Official Business
Penalty for Private Use
$300
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