EPA/600/R 22/120 | September 2022
www.epa.gov/emergency-response-research
United States
Environmental Protectior
Agency
oEPA
Improving Surface
Decontamination Methods for
Permeable Materials
Contaminated with Chemical
Warfare Agent Surrogates
Malathion and 2-CEPS
Office of Research and Development
Homeland Security Research Program
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EPA/600/R-22/120
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Improving Surface Decontamination Methods for Permeable
Materials Contaminated with Chemical Warfare Agent
Surrogates Malathion and 2-CEPS
Lukas Oudejans, Ph.D.
Anne Mikelonis, Ph.D.
Katherine Ratliff, Ph.D.
Center for Environmental Solutions and Emergency Response
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Barbara Wyrzykowska-Ceradini, Ph.D
Abderrahmane Touati, Ph.D.
Christopher Fuller
Jacobs Technology, Inc
Research Triangle Park, NC 27709
Eric Morris
Alexander Korff
Science Systems Applications, Inc.
Hampton, VA 23666
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Disclaimer
The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development's
Center for Environmental Solutions and Emergency Response (CESER), funded and managed this
investigation through Contract No. EP-C-15-008, work assignments 1-090, 2-090 and 2-092 through 4-092
with Jacobs Technology, Inc. (Jacobs). This report has been peer and administratively reviewed and has
been approved for publication as an Environmental Protection Agency document. It does not necessarily
reflect the views of the Environmental Protection Agency. No official endorsement should be inferred. This
report includes photographs of commercially available products. The photographs are included for purposes
of illustration only. They are not intended to imply that EPA approves or endorses the product or its
manufacturer. EPA does not endorse the purchase or sale of any commercial products or services.
Questions concerning this document, or its application should be addressed to the principal investigator:
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
Mail Code E343-06
109 T.W. Alexander Drive
Research Triangle Park, NC 27711
Telephone No.: (919) 541-2973
E-mail Address: Oudejans.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 options to improve on the decontamination of permeable materials that are
contaminated with a toxic chemical that has transferred into such material. Here, two surrogates of chemical
warfare agents are considered to investigate the degree of transport, material interaction and subsequent
efforts to degrade the chemical via in situ degradation.
Gregory Sayles, Ph.D., Director
Center for Environmental Solutions and Emergency Response
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Table of Contents
Disclaimer iv
Foreword v
Table of Contents vi
Figures viii
Tables xi
Acronyms and Abbreviations xiii
Acknowledgments xvi
Executive Summary xvii
1.0 Introduction 1
1.1 Project Objectives 1
2.0 Experimental Approach 3
3.0 Materials and Methods 4
3.1 Testing facilities 4
3.2 Test materials 4
3.2.1 Stainless-steel Coupons 5
3.2.2 Painted or Sealed Stainless-steel Coupons 5
3.2.3 Free Standing Paint or Sealant Film Coupons 7
3.2.4 Solid Phase Extraction Disks 8
3.2.5 Bulk Materials 9
3.3 Chemicals and Reagents 9
3.3.1. Contamination of Coupons 10
3.4 LVAP Apparatus 12
3.5 Decontamination Solutions and Application of Liquid Decontaminants 13
3.6 Method Development Tests 14
3.6.1 Chemical Recovery Tests 14
3.6.1.1. Bulk Extraction of Coupons 14
3.6.1.2. Surface Sampling of Coupons 15
3.7 Permeation Tests 16
3.7.1 Gasket Contamination and Nonpermeation Transport Tests 16
3.7.2 Baseline Permeation Tests 17
3.8 Decontamination Tests 18
3.8.1 Decontamination Baseline 18
3.8.2 Modified Decontamination Testing 19
3.9 Microscopy Analyses 20
4.0 Sampling and Analysis 21
4.1 Surface Sampling Methods 21
4.2 Extraction Methods 21
4.2.1 Extraction of Surface Wipes 22
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4.2.2 Extraction of Coupons and Bulk Materials 22
4.3 Preparation of Samples for Analysis 22
4.4 Instrumental Analyses 23
4.5 Data Reduction Procedures 24
4.5.1 Chemical Concentration Calculations 24
4.5.2 Decontamination Efficacy Calculations 25
5.0 Quality Assurance and Quality Control 27
5.1 Test Equipment Calibration 27
5.2 Data Quality Results for Critical Measurements 28
6.0 Results and Discussion 29
6.1 Verification of Surface Sampling and Material Extraction Methods 29
6.1.2 Efficacy of Surface Sampling Using Swabs 29
6.1.3 Coupon Extraction Efficacy 29
6.1.4 Comparison of Coupon Extraction Versus Surface Sampling 29
6.2. Gasket Contamination and Nonpermeation Transport 31
6.3 Permeation Testing 33
6.3.1 Permeation of2-CEPS 33
6.3.2 Permeation of Malathion 38
6.3.3 Permeation Comparisons 2-CEPS Versus Malathion 42
6.4 Decontamination Testing 47
6.4.1 Baseline Decontamination - 2-CEPS 48
6.4.2 Baseline Decontamination - Malathion 50
6.5 Modified Decontamination Processes 53
6.5.1 Decontamination Modifications - 2-CEPS 53
6.5.2 Decontamination Modifications - Malathion 53
Summary 61
References 62
Appendix A: Supporting Information 63
A-1 Methods for manufacturing paint and sealant layers 63
A-1.1 Preparation of Paint Coatings on Stainless-steel Substrates 63
A-1.2 Preparation of Free-standing Paint or Sealant Layers 65
A-1.2.1 Preparation of FSP layers 65
A-1.2.2 Preparation of FSS layers 67
A-2 LVAP Assembly Procedure 69
A-2.1 Preparation of the LVAP Parts 69
A-2-2 Assembly of the LVAP 69
A-3 Surface Sampling Procedure 75
Appendix B: Method Development Supporting Information 79
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Figures
Figure 2-1. General experimental scheme of permeation transport and decontamination testing 3
Figure 3-1. Stainless-steel (a), Painted-Stainless steel (b), and Sealed Stainless-steel (c) Coupons 6
Figure 3-2. Universal Blade Applicator 6
Figure 3-3. FSP (a) and FSS (b) layers and SPE (c) coupon 8
Figure 3-4. FSP and FSS layers assembled onto SEM stubs 8
Figure 3-5. Coupons of bulk materials 9
Figure 3-6. Discrete microdroplet application of chemicals onto the test surfaces; examples shown are
malathion droplets immediately after spiking onto (a) painted stainless steel; (b) sealed stainless steel; (c)
FSP layer in the LVAP; (d) FSS layer in the LVAP; (e) high-pressure laminate, and (f) vinyl plank flooring.. 11
Figure 3-7. Malathion microdroplets after application onto FSP (left) and FSS (right) layers assembled onto
SEM stubs 12
Figure 3-8. The prototype design of the LVAP apparatus 12
Figure 3-9. Top (a) and side view (b) of the LVAP system 13
Figure 4-1. Surface sampling of test coupons using prewetted cotton swab; examples shown are LVAP-FSP
(a) and SS (b) 21
Figure 4-2. FSP (a) and SPE (b) coupons immediately after the conclusion of hexane extraction 22
Figure 6-1. Recovery of 2-CEPS (A) and malathion (B) from reference and test materials; SS: stainless steel;
PSS: painted stainless steel; SSS: sealed stainless steel; FSP: free-standing paint layer; FSS: free-standing
sealant layer; SPE: solid-phase extraction disk; dashed lines are representing the lower (80%) and upper
(120%) limit of recovery acceptance criteria set for reference material (SS) 30
Figure 6-2. Average recoveries and migration of 2-CEPS (a) and malathion (b) for LVAP-FSP and LVAP-FSS
system components; recoveries were calculated against theoretical amount of chemical spiked determined
by analysis of associated CS samples. Chemical mass results for each layer are averages (n=3) ± 1 SD.. 32
Figure 6-3. 2-CEPS droplet on the surface of LVAP-FSP and LVAP-FSS layers immediately after spiking (a
and b, respectively) and after completion of the 72-h chemical weathering period, with no visible chemical
contamination present on the surface (c and d, respectively) 34
Figure 6-4. 2-CEPS droplet visible on the surface of the acrylic high-pressure laminate and vinyl composite
plank immediately after spiking (a, c, and e, respectively) and test materials 72 hours after spiking, with no
visible chemical contamination present on the surface (b, d, and f) 36
Figure 6-5. 2-CEPS permeation in LVAP-FSP and LVAP-FSS and bulk materials at CT = 72 h (A and C) and
CT = 24 h (B); FSP and FSS: free-standing paint and sealant layers from LVAP permeation tests (wipe-
sampled, then extracted); SPE: solid-phase extraction disk from LVAP permeation tests (extracted only); bulk
materials were wipe sampled, then extracted. Dashed red lines represent recovered mass from control spike.
Chemical mass results for each layer are averages (n=3) ± 1 SD 37
Figure 6-6. Malathion droplet on the surface of FS and FSS layers of LVAP immediately after spiking (a and
b, respectively) and 72 hours after spiking (c and d, respectively) 40
Figure 6-7. Malathion droplet visible on the surface of the acrylic high-pressure laminate and vinyl composite
plank immediately after spiking (a, c, and e, respectively) and test materials after 72 hours (b, d, and f,
respectively). Location of droplet after spiking identified by black arrow 41
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Figure 6-8. Malathion permeation in LVAP-FSP and FSS systems (a) and bulk materials (b) at CT = 72 h;
FSP and FSS: free-standing paint and sealant layers from LVAP permeation tests (wipe sampled, then
extracted); SPE: solid-phase extraction disk from LVAP permeation tests (extracted only); bulk materials were
wipe-sampled, then extracted. Dashed red lines represent mass recovered from control spike. Chemical mass
results for each layer are averages (n=3) ± 1 SD 42
Figure 6-9. Average percent distribution of the total 2-CEPS (a) and malathion (b) mass detected in LVAP
components and bulk materials during permeation testing, CT=72 h. FSP and FSS: free-standing paint and
sealant layers from LVAP permeation tests (wipe-sampled, then extracted); SPE: solid-phase extraction disk
from LVAP permeation tests (extracted only); bulk materials were wipe-sampled, then extracted 43
Figure 6-10. FESEM images of malathion-exposed FSP (a) and FSS (b) layers at different magnifications.
Contact time of malathion was 72 h for both layers; remaining chemical droplet was removed from surfaces
before testing using a cotton swab. Images of carbon-coated layers were taken using 15.0 kV accelerating
voltage at magnifications ranging from 24xto 3.53k x 44
Figure 6-11. Postsampling perforation of malathion-exposed FSP layer; FSP postsampling in the LVAP (a)
and prior extraction (b) 45
Figure 6-12. Blistering of paint layers observed after 72-h-long exposure of PSSto malathion, with a chemical
droplet still present on the surface (a) and PSS surface after surface sampling, with visible stainless steel
exposed in the previously blistered area (b) 45
Figure 6-13. FESEM images of nonexposed FSP (a) and FSS (b) layers. Images of carbon-coated layers
were taken using 15.0 kV accelerating voltage. Images of carbon-coated layers were taken using 15.0 kV
accelerating voltage at magnifications ranging from 436 xto 33,600 x 46
Figure 6-14. Example of baseline decontamination procedure. Shown are decontamination of malathion-
contaminated LVAP-FSP, LVAP-FSS, and VLP at CT=72 h (a, d, g, respectively) using concentrated
germicidal bleach (b, e, h), followed by overnight dwell of the decontaminant (DT=18 h) (c, f, i) 47
Figure 6-15. Decontamination baseline for 2-CEPS from FSS and FSP layers compared to associated positive
control samples; TC - decontaminated test sample; PC - non-decontaminated positive control sample.
Chemical mass recovery results (a) for each layer are averages (n=3), and chemical fraction results (b) are
relative percent contributions of each fraction to the total chemical mass detected in non-decontaminated and
decontaminated samples 49
Figure 6-16. Decontamination baseline results for malathion from LVAP-FSS and LVAP-FSP components
compared to associated positive control samples; TC - decontaminated test sample; PC - non-
decontaminated positive control sample. Chemical mass recovery results for each layer are averages, and
chemical fraction results are relative percent contributions of each fraction to the total chemical mass
recovered in non-decontaminated and decontaminated samples 51
Figure 6-17. Surface of concentrated germicidal bleach-exposed FSP (a) and FSS (b) layers after overnight
drying of decontaminant; surfaces were not contaminated before application of bleach. Images of carbon-
coated layers were taken using 15.0 kV accelerating voltage; magnification levels are shown in each image.
52
Figure 6-18. Surface of bulk materials after decontamination of malathion using two applications of
concentrated germicidal bleach; vinyl plank flooring material, VPL (a); acrylic countertop surface material (b),
and high-pressure laminate countertop material, HPL (c) 53
Figure 6-19. Average decontamination efficacy of malathion from FSP-LVAP for all single- and multistep
decontamination approaches tested; results are shown as x %DE ± 1 SD; CGB - concentrated germicidal
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bleach; SLB - Splash-Less Bleach; ED - EasyDECON DF200; 1x and 2 x - procedure using one or two
applications of decontaminant, respectively 55
Figure 6-20. Average malathion mass change in the LVAP-FSP test coupon (TC) components relative to the
corresponding components of the associated positive control (PC) samples. CGB - concentrated germicidal
bleach; SLB - Splash-Less Bleach; ED - EasyDECON DF200; 1x and 2x - procedure using one or two
applications of decontaminant 56
Figure 6-21. Surface of bleach-exposed FSP surfaces (a) and/or nonexposed laboratory blank FSP layers (b)
layers after overnight drying of decontaminant; surfaces were not contaminated before application of the
regular germicidal bleach. Images of carbon-coated layers were taken using 15.0 kV accelerating voltage;
magnifications levels are shown in each image 57
Figure 6-22. Surface of bleach-exposed FSS surfaces (a) and corresponding laboratory blanks, or
nonexposed FSS layers (b) layers after overnight drying of decontaminant; surfaces were not contaminated
before application of the regular germicidal bleach. Images of carbon-coated layers were taken using 15.0 kV
accelerating voltage; magnifications levels are shown in each image 58
Figure 6-23. Surface of malathion and bleach-exposed FSP (a) and FSS surfaces (b) after 72-h-long exposure
to chemical, followed by overnight drying of decontaminant. Images of carbon-coated layers were taken using
15.0 kV accelerating voltage; magnifications levels are shown in each image 59
Figure 6-24. Average cumulative decontamination efficacy of malathion from stainless steel for all single- and
multistep decontamination approaches tested; results are shown as x %DE ± 1 SD; CGB - concentrated
germicidal bleach; SLB - Splash-Less Bleach; ED - EasyDECON DF200; 1x and 2 x - procedure using one
ortwo applications of decontaminant, respectively; NT - not tested 60
Figure A-1. Step 1: Place bottom plate on clean surface 69
Figure A-2. Step 2: LVAP apparatus with bottom PTFE gasket 70
Figure A-3. Step 3: LVAP apparatus with aluminum support ring 70
Figure A-4. Step 4: LVAP apparatus with PTFE support ring 71
Figure A-5. Step 5: Placement of the first 36-mm PTFE spacer disk in LVAP 71
Figure A-6. Step 6: Placement of the second 36-mm PTFE spacer disk in LVAP 72
Figure A-7. Step 7: LVAP apparatus with SPE disk centered 72
Figure A-8. Step 8: LVAP apparatus with free standing layer; example shown is FSP 73
Figure A-9. Step 9: LVAP apparatus with top PTFE gasket centered 73
Figure A-10. Step 10: LVAP apparatus with top aluminum ring 74
Figure A-11. Step 11: LVAP apparatus with steel bolts finger tight 74
Figure A-12. Step 12: Completed LVAP 75
Figure A-13. Hot zone sampling for rectangular and round coupons 76
Figure A-14. Horizontal wiping pathway for rectangular and round coupons 77
Figure A-15. Vertical wiping pathway for rectangular and round coupons 77
Figure A-16. Perimeter wiping pathway for rectangular and round coupons 78
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Tables
Table 3-1. Specifications of building materials 5
Table 3-2. Specifications of PSS and SSS layers 7
Table 3-3. Specifications of FSP and FSS layers 7
Table 3-4. Physicochemical properties of target chemicals 10
Table 3-5. Chemical reagents 10
Table 3-6. Decontamination solutions 14
Table 3-7. Experimental parameters for gasket contamination and nonpermeation transport tests 16
Table 3-8. Test parameters for permeation testing and types of samples collected 17
Table 3-9. Test parameters for baseline decontamination testing: Single application of concentrated
germicidal bleach with a dwell time of 18 h 18
Table 3-10. Test parameters for modified decontamination testing 19
Table 3-11. Test matrix for microscopy analyses 20
Table 4-1. GC/MS parameters for analysis of 2-CEPS and malathion 23
Table 4-2. Initial and continuing laboratory proficiency results 24
Table 5-1. Instrument calibration frequency 27
Table 5-2. Acceptance criteria for critical measurements and corresponding test results 28
Table 6-1. Permeation of 2-CEPS through FSP layers - chemical mass recovery results in LVAP components
and associated control samples at CT = 72 h 33
Table 6-2. Permeation of 2-CEPS through FSS layers - chemical mass recovery results in LVAP components
and associated control samples at CT = 72 h 33
Table 6-3. Permeation of 2-CEPS through building material surfaces-chemical mass recovery results in bulk
material and associated control samples at CT= 24 h and 72 h 35
Table 6-4. Permeation of malathion through FSP layers - chemical mass recovery results in LVAP
components and associated control samples 38
Table 6-5. Permeation of malathion through FSS layers - chemical mass recovery results in LVAP
components and associated control samples 39
Table 6-6. Permeation of malathion through building material surfaces-chemical mass recovery results in bulk
material layers and associated control samples at CT= 72 h 39
Table 6-7. Decontamination baseline of 2-CEPS from LVAP-FSP components and chemical mass recovery
results for associated control samples 48
Table 6-8. Decontamination baseline of 2-CEPS from LVAP-FSS components and chemical mass recovery
results for associated control samples 48
Table 6-9. Decontamination baseline of malathion from LVAP-FSP components and chemical concentration
results for associated control samples 50
Table 6-10. Decontamination baseline of malathion from LVAP-FSS components and chemical concentration
results for associated control samples 51
Table 6-11. Decontamination baseline of bulk materials with malathion and chemical mass results for
associated control samples 52
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Table 6-12. Modified decontamination methods for LVAP-FSP components contaminated with malathion and
chemical concentration results for associated control samples 54
Table B1. Recoveries from surface sampling method development for2-CEPS 79
Table B2. Recoveries from surface sampling method development for malathion 79
Table B3. Extraction method development for2-CEPS 79
Table B4. Extraction method development for malathion 80
Table B5. Results of gasket contamination test for2-CEPS and malathion 80
Table B6. Results for SPE to FSP nonpermeation transport test for 2-CEPS 80
Table B7. Results for SPE to FSS nonpermeation transport test for 2-CEPS 80
Table B8. Results for SPE to FSP nonpermeation transport test for malathion 81
Table B9. Results for SPE to FSS nonpermeation transport test for malathion 81
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Acronyms and Abbreviations
inch(es)
2-CEPS 2-chloroethyl phenyl sulfide
AS acrylic solid surface countertop (material)
ASTM ASTM International (formerly The American Society for Testing and Materials)
ATH alumina trihydrate
BMC bulk material coupon
°C degree(s) Celsius
CAS Chemical Abstract Services
CESER Center for Environmental Solutions and Emergency Response
CGB concentrated germicidal bleach
cm2 square centimeter(s)
cm3 cubic centimeters)
CS control spike
CSL chemical safety level
COTS commercial off-the-shelf
CT contact time (chemical)
CWA chemical warfare agent
DE decontamination efficacy
Dl deionized (-water)
DQI data quality indicator
DT dwell time (decontaminant)
DUP duplicated)
ED EasyDECON DF200
EIDC environmental indoor dissipation chamber
EPA U.S. Environmental Protection Agency
FAC free available chlorine
FESEM field emission scanning electron microscopy
FSP free standing paint
FSS free standing sealant
GC gas chromatography
GC/MS gas chromatography/mass spectrometry
h hour(s)
HD sulfur mustard
HPL high-pressure decorative laminate (material)
HPLC high-performance liquid chromatography
HSMMD Homeland Security and Materials Management Division
HSRP Homeland Security Research Program
g gram(s)
ICAL instrument calibration
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ID
Identification
I PA
2-propanol (isopropanol, isopropyl alcohol)
IS
internal standard
ISO
International Organization for Standardization
L
liter(s)
LB
laboratory blank(s)
LOQ
limit of quantification
LVAP
low volatility agent permeation (apparatus)
ml
microliters)
mg
milligram(s)
min
minute(s)
mL
milliliters)
mm
millimeters)
MPC
(chemical-) mass positive control
MTC
(chemical-) mass test coupon
NA
not applicable
ng
nanogram(s)
NIST
National Institute of Standards and Technology
NT
not tested
ORD
Office of Research and Development (EPA)
OSL
Organic Support Laboratory (EPA)
PB
procedural blank(s)
PC
positive control
PMMA
polymethyl methacrylate
PTFE
polytetrafluoroethylene
ppm
part(s) per million
PSS
painted stainless steel
PVC
polyvinyl chloride
QA
quality assurance
QC
quality control
PI
principal investigator
R2
coefficient of determination
RH
relative humidity
RSD
relative standard deviation
RTP
Research Triangle Park
SD
standard deviation
SEM
scanning electron microscope/microscopy
SLB
Splash-Less Bleach
S/N
signal-to-noise
SPE
solid-phase extraction
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ss
stainless steel
sss
sealed stainless steel
TC
test coupon
TIC
toxic industrial chemical
UBA
universal blade applicator
VCP
vinyl composition plank (material)
VOC
volatile organic compound
VX
S-{2-[di(propan-2-yl)amino]ethyl} O-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 liquid-based decontamination methodologies for degradation of a
persistent chemical agent that has (partially) absorbed into a permeable building material. The results of this
work inform responders, governments, and health departments in their guidance development for
decontamination technology recommendations of permeable building materials contaminated with toxic
chemicals.
This effort was directed by the principal investigator (PI) from the Office of Research and Development's
(ORD's) Center for Environmental Solutions and Emergency Response (CESER), with support from
project team members. The contributions of the following individuals have been a valued asset throughout
this effort.
EPA Project Team
Lukas Oudejans, ORD/CESER/Homeland Security and Materials Management Division (HSMMD)
(PI)
Anne Mikelonis, ORD/CESER/HSMMD
Katherine Ratliff, ORD/CESER/HSMMD
Jacobs Technology, Inc. Team
Barbara Wyrzykowska-Ceradini
Abderrahmane Touati
Christopher Fuller
Science Systems Applications, Inc. Team
Eric Morris
Alexander Korff
U.S. EPA Technical Reviewers of Report
Matthew Magnuson
Vicente Gallardo
U.S. EPA Quality Assurance
Ramona Sherman, ORD/CESER/HSMMD
Jacobs Technology, Inc. Quality Assurance
Wendy Coss
U.S. EPA Editorial Review
Joan T. Bursey, ORD/CESER, HSMMD
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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
of concern have primarily focused on the remediation of nonporous materials. Most in situ chemical
decontamination technologies use aqueous oxidizers (e.g., bleach, liquid hydrogen peroxide), which
typically yield high degradation efficacies for nonporous materials. Many surfaces in the built environment
are, however, (semi)porous or permeable to the contaminants. Aqueous decontamination procedures
generally have limited efficacy if the contaminant (partially) migrates into a permeable surface or farther into
an underlying porous sublayer. This work determined the degree of transport/permeation of two CWA
surrogates, the organophosphate pesticide 2-[dimethoxyphosphorothioyl)sulfanyl]butanedioate (malathion)
and 2- chloroethyl phenyl sulfide (2-CEPS), into painted or sealed materials and into three permeable
building materials that are representative of common indoor flooring, walls, and other surfaces. This
determination was followed by decontamination approaches using commercially available off-the-shelf
bleach formulations (Clorox Concentrated Germicidal Bleach, and Clorox Splash-Less Bleach with
surfactants) and an activated hydrogen peroxide-based commercial decontaminant (EasyDECON DF200).
Selected material-chemical-decontaminanttest conditions were evaluated for structural changes and
material-compatibility effects using field emission scanning electron microscopy (FESEM).
Transport of Malathion and 2-CEPS into Paint and Sealant Layers
Results of the permeation studies showed that the permeation rates were chemical- and surface-
material-specific, with lower permeation rates observed for malathion compared to 2-CEPS. After 72 hours,
permeation was somewhat higher into an acrylic latex paint layer (30% and 95% for malathion and 2-CEPS,
respectively) than for the polyurethane sealant layer (10% and 95% for malathion and 2-CEPS,
respectively). Microdroplets of malathion remained visible on paint and sealant surfaces at the end of the
permeation period (72 h). The higher permeation of malathion through paint layers in comparison to the
sealant layer was attributed to evidence of some blistering of the paint layer observed during a visual
inspection of malathion exposed paint layer. The malathion-induced structural changes of the paint layers
were confirmed by microscopy analyses of the coatings. Additional FESEM analyses of coatings that were
not exposed to a chemical indicated higher overall surface pore morphology of the paint layers, which
suggest higher general pore morphology of acrylic-latex paint when compared to the tested polyurethane
sealant.
The lower recovery of 2-CEPS on the surface of the layers corresponded to findings of visual
assessment of 2-CEPS exposed layers, with no chemical contamination droplet noticeable on tested paint
or sealant surfaces at 72 h after spiking onto the surface. In addition to different permeation rates, 2-CEPS
had a lower overall recovery with less than 25% of the initial chemical surface loading detected in the
combined surface and paint/sealant layer after 72 h. This lower recovery of 2-CEPS can be attributed to the
higher volatility of 2-CEPS versus malathion leading to significant evaporation. The corresponding average
recovery of malathion was higher than 90% for both types of coatings.
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Transport of Malathion and 2-CEPS into Bulk Materials
All three bulk materials tested (acrylic countertop, high-pressure laminate, and vinyl composition
floor plank) were permeable to the targeted chemicals with different permeation rates for 2-CEPS versus
malathion. At 72 h after spiking, 2-CEPS was detected primarily in the sublayer extractable fractions (via
extraction of the material post surface swiping), with below level-of-quantitation ( 97% reported for all bulk
materials tested. No further decontamination optimization was conducted for these malathion-contaminated
bulk materials.
The performance of all decontamination product-decontamination procedure combinations tested
on the nonporous control material (stainless steel) was comparable for all methodologies tested, with
average DEs ranging from 91% to > 99% for malathion and average DE > 99.9% for 2-CEPS. The
comparison of degradation efficacies achieved for test materials and reference material suggests that the
surface characteristics and type of chemical to be decontaminated should be considered important factors in
the selection of oxidant-based decontamination strategies of toxic industrial chemicals and chemical warfare
agents.
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Impact
The research described in this report addresses many practical aspects of decontamination of toxic
industrial chemicals absorbed into various permeable environmental matrices. The results contribute to a
better understanding of how to remediate challenging types of permeable building materials. However,
additional research is needed to determine the effects of the environmental factors (e.g., temperature,
humidity, ventilation rates), material properties (e.g., porosity, chemical resistance), and physicochemical
properties of target chemical and decontaminants (e.g., volatility, corrosivity, concentration) on the sublayer
transport of both chemicals and decontaminants. Further, the adherence of a paint or sealant to a porous
subsurface may change the amount of chemical that permeates when compared to the separate layers
used in this study.
Analyses of possible post-decontamination chemical degradation products, including oxidation
byproducts, were not performed in the current study, and should be considered in future work to ensure that
procedures recommended for remediation do not result in the formation of toxic byproducts.
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1.0 Introduction
Cleanup and remediation activities following a release of a toxic persistent chemical are likely to
involve the in situ degradation of the chemical via oxidation or nucleophilic substitution. This situation
especially holds true for more persistent chemicals that remain present on surfaces for days or longer. Most,
if not all, of the efficacious decontamination technologies are water-based and can yield high efficacy if the
contaminant is found on the surface. Finding the contaminant on the surface would be the case for a
nonporous material [1-5], As has been observed in the case of the decontamination of chemical warfare
agents (CWAs) and other toxic industrial chemicals (TICs), including pesticides, the efficacy of a liquid
decontaminant is material-dependent, which can be partially attributed to the permeability or porosity of the
material [4,5], The transport of a chemical into a permeable material makes it more challenging to
decontaminate as a water-based decontaminant would likely not be able to reach the permeated chemical.
This issue can be compounded if the chemical is transferred even farther into a porous material under a
painted or coated surface film such in the case of a painted wall or sealed wooden floor. If chemical
migration into this more porous sublayer occurs, the chemical of concern may remain present and
eventually resurface after the decontamination has taken place, recreating the contaminated surface
hazard. A recent study confirmed that the CWAs bis(2-chloroethyl) sulfide (sulfur mustard; HD) and to a
lesser degree S-{2[di(propan-2-yl)amino]ethyl} O-ethyl methylphosphonothiolate (VX) can transport into a
paint or sealant layer and even transfer farther into a porous substrate below the paint or sealant layer [6],
The physical and chemical parameters that determine the rate of permeation of a chemical into a
permeable material are not well defined. The chemical nature (molecular vs ionic) is expected to be
important as well as parameters such as polarity, viscosity, zeta potential, solubility in water or solvents,
temperature, etc. Similarly, there is a wide variety in paints (oil, enamel, latex, or water-based) and sealants
(polyurethane, water, and solvent-based). The identification of potential CWA surrogates would allow for
research to be conducted outside surety agent facilities/programs which will increase the ability to study
permeation processes in more detail. Very little is known about the partitioning of chemicals that are
considered surrogates of CWAs into building materials and even less is known about the efficiency of
standard decontamination techniques for permeated chemicals.
This research focused on the development and modification of decontamination approaches for the
degradation of chemicals that have partially absorbed into permeable building materials. Information
gathered from this research will aid in the development of the most appropriate field cleanup and
decontamination procedures.
1.1 Project Objectives
The main objective of this research was to determine the performance of commercially available
decontamination solutions for degradation of more persistent and/or stable chemicals present in a
permeable material or in a porous sublayer of selected building materials. In general, it is nearly impossible
to separate surface layer(s) - e.g., paint or sealant - from a porous material such as drywall, wood, or
concrete without the use of solvents, reactive chemicals or by physical removal/separation methods that
would alter the residual chemical amounts. Therefore, in this project, a compartmentalized structure of
material layers (or permeation cell) was constructed to understand the transport of the target chemical as
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deposited on the permeable surface, into the surface, and potentially into the underlying porous material.
The subsequent phase of the research was the decontamination of the partially absorbed chemical.
The objectives of this project were:
Develop testing equipment and analytical methods to study the transport of selected chemicals into
the subsurface layers of permeable building materials at conditions mimicking indoor environmental
conditions. Permeation cell tests were performed beside testing of associated control samples
(coated and noncoated nonporous reference material, stainless steel).
Determine the efficacy of decontamination technologies and procedures for degradation of
chemicals that have (partially) absorbed into permeable building materials. This was to identify
whether oxidation-based decontamination techniques, previously established for nonporous
materials, were efficacious for degradation of the chemical compounds in this study without any
procedural modifications. This process also established a so-called decontamination baseline.
Evaluate possible modifications of decontamination solution/solutions to address potential
limitations of traditional techniques/unmodified decontaminants; this evaluation was only performed
if unmodified decontamination (as described above) did not provide the desired cleanup efficacy.
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2.0 Experimental Approach
This study was performed in three consecutive phases. The first phase was a determination of the
fate and transport of selected chemicals across a permeable layer into a porous subsurface. During this
initial research, custom-made low volatility agent permeation (LVAP) cells (Section 3.4) were utilized to
achieve controlled compartmentalization of a permeable surface layer consisting of free-standing paint
(FSP) or free-standing sealant (FSS) (Section 3.2.3) and a porous subsurface represented by a solid phase
extraction disk (SPE disk; Section 3.2.4). The use of this compartmentalized system permitted a distinct
sampling of the top surface layer, extraction of the layer, and extraction of the porous media underneath
leading to a full evaluation of the surface-specific permeation of chemicals. The transport of chemicals into
selected (bulk) building materials was also investigated (Section 3.7). The second phase was testing of
commercially available liquid decontaminants for (baseline) decontamination of permeated chemicals,
followed in the third phase by testing of a modified decontaminant and/or modified approaches for improved
degradation (Section 3.8). The general experimental scheme of testing is shown in Figure 2-1.
\
Phase 1: Studying permeation of chemicals through permeable layers
¦ Design and manufacturing of the LVAP permeation cells
¦ Manufacturing and characterization of artificial films of surface layers (FSPs
and FSSs)
¦ Evaluation of permeation transport of target chemicals through different types
of permeable surface layers into porous sublayer
¦ Evaluation of chemical permeation through surfaces of common building
materials into material sublayers
Phase 2: Decontamination baseline testing
¦ Initial testing of a selected commercially available decontaminant
(concentrated germicidal bleach) for degradation of permeated chemicals
¦ Determination of the cumulative decontamination efficacy, by measuring
concentration of surface-bound chemical fractions and permeated chemical
mass in layers (or materials) after decontamination and comparison to
chemical concentrations found in nondecontaminated positive control
samples
J
Phase 3: Modified decontamination testing
Evaluation of modified decontaminant and/or modified decontamination
procedure (e.g., a different decontaminant chemistry, reapplication of
decontaminant) for improved degradation of permeated chemicals
Comparison of chemical degradation efficacy of modified procedures to the
previously established decontamination baseline
Figure 2-1. Genera! experimental scheme of permeation transport and decontamination testing
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3.0 Materials and Methods
3.1 Testing facilities
All experimental work was performed in U.S. EPA Office of Research and Development (ORD)
Chemical Safety Level 4 (CSL-4) laboratories in Research Triangle Park (RTP), North Carolina (NC). The
contamination and decontamination of coupon procedures, LVAP apparatus assembly/disassembly,
sampling, extractions, and preparation of samples for analysis were performed within a chemical safety
hood.
Curing of coupons and chemical weathering were performed in an environmental indoor dissipation
chamber (EIDC) located in the chemical safety hood. The EIDC was a commercially available enclosure,
(24 inches (") x24" x 12" Indoor/Outdoor Steel Enclosures NEMA 1; Hammond Manufacturing, Guelph,
ONT, Canada) made of powder-coated 16-gauge steel, with stainless-steel cover and a 1/4-turn coin-slot
latch and concealed stainless-steel hinges. The enclosure was modified to include shelving constructed
from perforated stainless-steel sheeting. The relative humidity (RH), temperature, and air exchange rate
within the EIDC chamber were controlled and recorded, with target RH and temperature in the chamber set
to 50% and 24°C, respectively, at one air exchange per hour. Compressed air was metered through mass
flow controllers (Tylan Model FC260 Mass Flow Controller, Allen, TX, USA and Sierra Model 840 Mass Flow
Controller, Sierra Instruments, Monterey, CA, USA) and routed via %" tubing in one of two ways to the
chamber: If the RH sensor (HMD-53, Vaisala, Helsinki, Finland) indicated an RH increase above the
setpoint, dry air was flowing directly to the chamber. If the RH dropped below the setpoint, the air was
routed through an impinger containing deionized water, and humidified air was carried to the chamber.
All gas chromatography-mass spectrometry (GC/MS) analyses were performed by the U.S. EPA
Organic Support Laboratory (OSL) located at the U.S. EPA facilities in RTP, NC. Microscopy analyses were
performed using a Tescan Mira 3 Field Emission Scanning Electron Microscope (FESEM; Tescan Orsay
Holding, A.S., Brno, Czech Republic).
3.2 Test materials
Several types of building materials and two types of coatings with expected different permeabilities
were selected for the evaluation of permeation and decontamination procedures in this study. A zero-volatile
organic compound (VOC), 100% acrylic latex paint interior flat paint (Table 3-1) was used to make the FSP
coupons (Section 3.2.3 with manufacturing details in Appendix A-3.2). A water-based polyurethane sealant
(Table 3-1) recommended by the manufacturer for the protection of wood and concrete floors was used to
construct FSS coupons (Section 3.2.3 with manufacturing details in Appendix A-3.2). In addition,
multipurpose stainless steel, a relatively smooth and nonpermeable material, was used as a reference and
control material for sampling and recovery of target chemicals. The general specifications of all test
materials are provided in Table 3-1. Procedures for preparation of test coupons are given in Sections 3.2.1
through 3.2.5.
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Table 3-1. Specifications of building materials
Material (material ID)
Description
Manufacturer/
Supplier
Name/Location/Country
Coupon Type and
Dimensions,
Length x Width x
Thickness (mm)
Coupon
Preparation
Stainless steel (SS)
Multipurpose stainless steel (1.2 x
1.2 m), type 304, #2B mill
(unpolished), 0.091 cm thick
McMaster-Carr
Douglasville, GA, USA
SS: 40 x25x9.1
Section 3.2.1
Acrylic Paint (FSP or
PSS)a
Behr Ultra-Pure White, interior flat
paint, 100% acrylic latex paint, P/N
105001
Behr Companies
Santa Ana, CA, USA
FSP: 50 x 0.076
PSS: 40 x 25 x 0.076
Section 3.2.3
Section 3.2.2
Polyurethane Sealant
(FSS or SSS)a
Rust-oleum 6711 System Water-
Based Polyurethane P/N 4MG61,
Grainger
Chicago, IL, USA
FSS: 50x0.152
SSS: 40x 25x 0.152
Section 3.2.3
Section 3.2.2
Solid Phase Extraction
Disk (SPE)
3M Empore SDB-XC SPE disk, 47
mm diameter, P/N 14-386-4
VWR
Radnor, PA, USA
SPE: 36 (diameter) x
0.152
Section 3.2.4
Acrylic Solid Surface
Countertop (AS)
Everform Solid Surface Countertop,
River Rock Mosaic, P/N 656
Formica
Cincinnati, OH, USA
40x25
Section 3.2.5
High-Pressure Decorative
Laminate (HPL)
Amber Maple Matte Finish
P/N 7012-58
Formica
Cincinnati, OH, USA
40x25
Section 3.2.5
Vinyl Composition Plank
(VCP)
Polyvinyl chloride (PVC) floor plank
P/N 50SLV501
US Floors
Dalton, GA, USA
40x25
Section 3.2.5
a FSP and FSS are free layers of paint and sealant, respectively (Section 3.2.3), PSS and SSS are paint and sealant coatings on the stainless-
steel substrate
3.2.1 Stainless-steel Coupons
Stainless-steel (Table 3-1) coupons were cut from larger pieces of material by hydraulic shears to
obtain a uniform length (4.0 centimeters (cm)) and width (2.5 cm). Stainless-steel coupons were cleaned
with a laboratory-grade detergent solution to remove any lubricant/grease from shearing, then wiped clean
with water and wiped dry using a Kimwipe (Kimberley-Clark, Inc., Irving, TX, USA; P/N 34133) to remove
dust before use in the tests. A stainless-steel coupon ready for testing is shown in Figure 3-1 a.
3.2.2 Painted or Sealed Stainless-steel Coupons
A zero-VOC 100% acrylic latex paint interior flat paint (Table 3-1) purchased from a national retailer
(Home Depot, Reynoldsburg, OH, USA) was used forthe preparation of painted stainless-steel (PSS)
coupons. A polyurethane coating (Table 3-1) was used forthe preparation of sealed stainless-steel (SSS)
coupons. Paint or sealant was applied onto the 14" x 14" stainless-steel surface using a modified method
derived from ASTM D823 "Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish,
and Related Products on Test Panels" [7],
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a.
c.
Figure 3-1. Stainless-steei (a), Painted-Stainless steei (b), and Sealed Stainless-steel (c) Coupons
In this study, the Universal Blade Applicator (UBA, AP-G08, Paul N. Gardner Company, Pornpano
Beach, FL, USA; Figure 3-2) was used for paint and sealant application.
Figure 3-2. Universal Blade Applicator
The white paint was applied from the original container after mixing for 10 min (minutes) on a twin
arm paint shaker. The transparent sealant was applied after gentle mixing with a paint stirrer. The target
paint wet application thickness was 5 mils (0.127 mm), resulting in the dry paint film thickness of 3 mils
(0.076 mm). The target sealant wet application thickness was 7 mils (0.178 mm), resulting in the dry sealant
film thickness of 6 mils (0.152 mm). These thicknesses are representative of what can be found in the built
environment. The procedure for the manufacture of uniformly coated stainless-steel coupons is summarized
in Appendix A-1. The painted or sealed stainless-steel coupons were allowed to dry/cure for a minimum of
24 h (hours) at ambient environmental conditions prior to testing [8], The fully cured painted or sealed
stainless-steel sheets were cut with hydraulic shears into 4.0 cm x 2.5 cm coupons. The thickness of the
film was measured with the Eddy current gauge (PosiTector6000, DeFelsko Corporation, Ogdensburg, NY,
USA) per ASTM E376 [9], on the center, bottom, and top of each coupon, with acceptance criteria of 70 to
130% of target thickness, and relative standard deviation (RSD) of <30% between triplicate measurements
of each coupon. All coupon edges were cleaned with a laboratory-grade detergent solution to remove any
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lubricant/grease from shearing, then wiped clean with water and wiped dry using a Kimwipe to remove dust
before use in the tests.
The detailed procedure for manufacturing paint and sealant layers on stainless steel is summarized
in Appendix A-1.1. Specifications of PSS and SSS layers are summarized in Table 3-2. Painted and sealed
stainless-steel coupons ready for testing are shown in Figure 3-1 b and c, respectively.
Table 3-2. Specifications of PSS and SSS layers
Type of layer
Material
Dimensions
Target thickness
Measured thicknessa b
PSS
Acrylic latex paint
25 mm x 40 mm
0.076 ± 0.023 mm
0.086 ± 0.0097 mm (n=49)
SSS
Water-based polyurethane sealant
25 mm x 40 mm
0.051 ±0.015 mm
0.048 ± 0.0066 mm (n=37)
8 cured (dry) layer;b average for the stainless-steel layer coupons used in testing
3.2.3 Free Standing Paint or Sealant Film Coupons
The same type of paint and sealant as used for the preparation of painted and sealed steel (Section
3.2.2) was used to make FSP and FSS sheets. FSP and FSS sheets were prepared using a modified
method derived from ASTM D823 [7], Here, polytetrafluoroethylene (PTFE) sheets (American Sealing &
Packaging, Santa Ana, CA, USA) were used as the panel substrate instead of stainless steel for FSP
production. Multipurpose unpolished stainless steel (type 304, #2B mill, McMaster-Carr, Douglasville, GA,
USA) was used as the substrate for FSS production. The paint does not bond with PTFE, so following
curing, paint layers were removed from the substrate, creating free-standing layers. The sealant only mildly
bonds with the stainless-steel substrate so that the sealant layer can be physically peeled off following
curing. The FSP and FSS coupons were die-cut with an arch punch to a diameter of 50 mm and cleaned
using dry compressed air. The thickness of the coupons was then measured using ASTM D1005 "Standard
Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers" [10], on the
center, bottom, top, left and right of each free-standing layer coupon, with acceptance criteria of 70 to 130%
of target thickness, and RSD of <30% between quintuplicate measurements of each coupon. The procedure
for manufacturing FSP and FSS layer sheets is detailed in Appendix A-1.2. Specifications of FSP and FSS
layers are summarized in Table 3-3. FSP and FSS coupons ready for testing are shown in Figure 3-3a and
b, respectively.
Table 3-3. Specifications of FSP and FSS layers
Type of layer
Material
Diameter
Target thickness
Measured thicknessab
FSP layer
Acrylic latex paint
12or50mmc
0.076 ± 0.023 mm
0.079 ±0.0093 mm (n=56)
FSS layer
Water-based polyurethane sealant
12 or 50 mm
0.051 ±0.015 mm
0.049 ±0.0083 mm (n=68)
a cured (dry) layer;b average for free-standing layer coupons used in testing,c millimeters
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Figure 3-3. FSP (a) and FSS (b) layers and SPE (c) coupon.
For FESEM analyses, smaller FSP and FSS coupons (approximately 12 mm in diameter) were
punched out from 50-mm material coupons that were characterized to confirm that they meet the average
target thickness criteria from an average of five measurements across each layer (Table 3-3), The small
FSS and FSP coupons were mounted to 12.7 mm scanning electron microscope (SEM) pin stubs (each
engraved in a unique stub identification (ID) on the underside of the stub) using adhesive black carbon tape.
Figure 3-4 shows stubs with FSP and FSS layers ready for testing.
Figure 3-4. FSP and FSS layers assembled onto SEM stubs.
3.2.4 Solid Phase Extraction Disks
The 47-mm in diameter 3M Empore SDB-XC solid-phase extraction (SPE) disk (Table 3-1) made of
poly(styrenedivinylbenzene) copolymer was used as a porous material surrogate for this project. The 47 mm
diameter SPE disks (0.15 mm thickness) were die-cut with an arch punch to a diameter of 36 mm to provide
a 10 square centimeter (cm2) contact area. An SPE coupon ready for testing is shown in Figure 3-3c.
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3.2.5 Bulk Materials
Bulk materials used in this study were representative of common polymer-based indoor surfaces,
were tested for chemical transfer to sublayers, and are listed below:
Solid Acrylic Surface Countertop (Table 3-1). A solid, nonporous, homogeneous surfacing
material, composed of acrylic resin (butyl acrylate-methyl methacrylate polymers, >30%),
and natural minerals (alumina trihydrate (ATH) derived from bauxite, and extracted
aluminum; 40-70%). A similar material (mix of polymethyl methacrylate (PMMA) and ATH)
is also manufactured by DuPont (Wilmington, DE, USA) and sold under the trademark of
Corian
High-Pressure (Decorative) Laminate (HPL), also known as 'Formica' (Table 3-1). This
common indoor material is made of resins (30-50%) and paper/fiber (40-70%).
Vinyl Composition Tile (Plank) (Table 3-1) is made of polyvinyl chloride (PVC). Some
manufacturers may utilize an additional sealant for high traffic areas. Such treatment was
not included in this study.
Bulk material coupons were cut from larger pieces of material using hydraulic shears to obtain a
uniform length (4.0 cm) and width (2.5 cm). Bulk material coupons were cleaned with acetone and hexane,
sequentially. Finally, isopropanol was used to remove any lubricant/grease from shearing, the coupon was
then wiped clean with water and wiped dry using a Kimwipe to remove dust before use in the tests.
Coupons of bulk materials readied for testing are shown in Figure 3-5, below.
Figure 3-5. Coupons of bulk materials: acrylic surface (a), vinyl composite plank (b), and high-pressure
laminate (c).
3.3 Chemicals and Reagents
The target chemicals used in this study, 2-[dimethoxyphosphorothioyl)sulfanyl]butanedioate
(malathion) and 2-chloroethyl phenyl sulfide (2-CEPS), are commonly used surrogates of CWAs. Malathion
is an organophosphate insecticide widely used in agriculture, pest control, and in residential landscaping,
and is a known surrogate for the VX nerve agent for decontamination studies [3], Based on chemical
similarity, 2-CEPS is considered a valid surrogate for the sulfur mustard (HD) for decontamination studies
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[2,4], It should be noted that differences in functional groups between a CWA and an identified surrogate
may also impact the permeation rate into a permeable material.
The malathion analytical standard was purchased from Chem Service (Chem Service, Inc., West
Chester, PA, USA; P/N N-12346-100MG; purity: 99.5%). The 2-CEPS analytical standard was purchased
from Sigma-Aldrich (Sigma-Aldrich Co. LLC, St. Louis, MO, USA; P/N 417602-25ML; purity 98%). The
relevant physical and chemical properties of these chemicals are listed in Table 3-4. Chemical application
procedures are described in Section 3.3.1.
Table 3-4. Physicochemical properties of target chemicals
Property
2-CEPS
Malathion
CASa Registry Number
121-75-5
5535-49-9
Molecular Weight
330.4
172.67
Formula
C10H19O6PS2
CsHgCIS
Density (g/cm3 b) at 20 °C
1.23
1.17
Physical Form at 20 °C
Liquid
Liquid
Vapor pressure
3.3E-6 mm Hg at 25 °C
1.86E-2 mm Hg at25°C
Solubility in Water
0.143 g/Lc
0.084 g/L
Log Kow
2.36-2.89
3.58
a Chemical Abstracts Service,b cubic centimeters,0 grams/liter
Information on internal standard and surrogate compound analytical standards used in this study
are given in Section 4.4. Other chemical reagents are listed in Table 3-5.
Table 3-5. Chemical reagents
Chemical Reagent
Purity/Grade
Product No.
Manufacturer
Hexane8
ACS/HPLC
H303-4
Fisher Scientific, Fair Lawn, NJ, USA
Acetone
ACS/HPLC
A949-1
Fisher Scientific, Fair Lawn, NJ, USA
Isopropyl alcohol
ACS Plus
A416-4
Fisher Scientific, Fair Lawn, NJ, USA
8 Mixture, as purchased, ofn-hexane (45-60%), hexane (-isomers) (15-40%), and cyclohexane (3%).
b HPLC - High-performance liquid chromatography.
3.3.1. Contamination of Coupons
Neat chemical solutions were applied to test coupons (TCs) using a discrete droplet (micro)
application method via a liquid spike. Prior to chemical microdroplet application, each clean coupon was
placed in an aluminum weighing boat for labeling and transport. The FSP and FSS coupons were secured
in LVAP cells and placed in prelabeled secondary containment boxes prior to spiking. Section 3.4 describes
the LVAP assembly.
Vials with analytical standards were removed from refrigeration and placed in the chemical hood for
at least two hours before use. Additionally, the vial of malathion analytical standard was placed in a 1-L
beaker filled with approximately 200 milliliters (mL) of warm water to reduce the viscosity of the neat
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chemical for spiking. The water temperature was tracked with a temperature probe, and the water was
replaced when the temperature of the bath decreased below 30 degrees Celsius (°C).
To spike coupons, a 2-microliter (pL) droplet of neat 2-CEPS or malathion analytical standard
(Table 3-4) was applied to the center of each coupon using a 2-|jL microsyringe (Microliter Microsyringe, 2.0
microliter [pl_], 25 gauge; Hamilton, Reno, NV, USA; P/N 88400), resulting in surface concentration of 2.34
milligrams [mg] and 2.46 mg pertest coupon, respectively. Before and after spiking, the syringe was
cleaned with a 50:50 acetone:hexane mixture. The accuracy and precision of spiking the neat solution
preparation was tested along with each experimental batch by analysis of control spike (CS) samples (see
Table 4-2 for results of the analysis of CSs).
Chemical solutions for gasket permeation testing (see Section 3.4 for definition of gasket and
Section 3.7.1 for test matrix) were applied to the coupons under room temperature conditions within a
chemical safety hood using a separate tip-programmable, electronic, repeater pipette (Eppendorf Repeater
Plus Single Channel Repeater Pipette, Eppendorf AG, Hamburg, Germany; P/N 22260201). After chemical
application, the test coupons were moved to the EIDC for simulated weathering or contact time (CT).
Figure 3-6 shows examples of the chemical droplet contamination on test surfaces immediately
after spiking.
Figure 3-6. Discrete microdroplet application of chemicals onto the test surfaces; examples shown are malathion
droplets immediately after spiking onto (a) painted stainless steel; (b) sealed stainless steel; (c) FSP layer in the
LVAP; (d) FSS layer in the LVAP; (e) high-pressure laminate, and (f) vinyl plank flooring.
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FSP and FSS layers for microscopy analyses were contaminated using the microdroplet application
described above but were not processed in the EIDC. The chemical weathering was performed in the
chemical hood with SEM stubs assembled in a piastic holder plate, placed in an acrylic box with lid for safe
transport to the FESEM laboratory. Figure 3-7 shows paint and sealant layers immediately after spiking with
malathion. Note that the sealant layer is highly transparent, and the black appearance is caused by the
(black) carbon tape.
Figure 3-7. Malathion microdroplets after application onto FSP (left) and FSS (right) layers assembled onto SEM
stubs.
3.4 LVAP Apparatus
A series of custom-built LVAP devices was used to evaluate the transport of chemicals through
FSP and FSS layers into a porous subsurface surrogate material (SPE disk). The LVAP cells were also
used to study the decontamination of chemicals. The FSP/FSS-SPE assembly was supported by custom-
made full face and O-ring PTFE gaskets and held in close contact using steel bolts. The initial design of the
LVAP apparatus is shown in Figure 3-8 with the top and side view of the constructed LVAP system shown in
Figure 3-8. The prototype design of the LVAP apparatus.
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Figure 3-9. Note that threaded bolts were replaced by machine screws as shown in Figure 3-9A. The
procedure for assembly of the LVAP cell is detailed in Appendix A-2.
Figure 3-9, Top (a) and side view (b) of the LVAP system.
Before testing, the PTFE gaskets, aluminum spacers, and steels nuts/bolts for the LVAP
apparatuses were cleaned with a 50:50 (volume:volume) acetone:hexane mixture and sonicated for 15 min.
The large aluminum LVAP bottom plate was cleaned with acetone then hexane and wiped dry with
Kimwipes. The assembled LVAP cells were placed inside a clean, labeled secondary containment (small
modular supply case; clear polypropylene; 5" x 5%" width x 2" height size; IRIS USA Inc., Surprise, AZ,
USA; P/N 585170) for spiking with a chemical (Section 3.3.1), and then the secondary containment was
closed to ensure safe transfer to the EIDC for weathering. After transfer to EIDC, the containers were
opened and remained open until weathering was completed. The polypropylene secondary containers were
precleaned using a laboratory-grade detergent solution in tap water, wiped with acetone and deionized (Dl)
water, and wiped dry.
3.5 Decontamination Solutions and Application of Liquid Decontaminants
Decontamination solutions used in this study were selected based on their reported acceptable
efficacy for malathion and 2-CEPS shown under previous EPA Homeland Security Research Program
(HSRP) research efforts or reported in the literature [3,4], General information and properties of
decontamination solutions are given in Table 3-6.
13
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EPA/600/R-22/120
September 2022
Table 3-6. Decontamination solutions
Decontamination
Solution
Manufacturer/Supplier
Active
Ingredient(s)3
Other functional ingredients'1
pH range
Clorox
Concentrated
Germicidal Bleach
The Clorox Company
Oakland, CA, USA
8.3% sodium
hypochlorite
Sodium hydroxide (pH adjuster stabilizer)
Sodium chloride (thickener and stabilizer)
Sodium carbonate (alkalinity builder and water
softener)
Sodium chlorate (breakdown product of sodium
hypochlorite)
11-12
Clorox Splash-
Less Bleach
The Clorox Company
Oakland, CA, USA
1-5% sodium
hypochlorite
Sodium hydroxide (pH adjuster stabilizer)
Sodium chloride (thickener and stabilizer)
Sodium carbonate (alkalinity builder and water
softener)
Sodium chlorate (breakdown product of sodium
hypochlorite)
Sodium polyacrylate (detergent and water locking
ingredient)
Cetyl betaine, sodium xylene sulfonate (surfactants
and wetting agents)
-12.5
EasyDECON
DF200
Envirofoam Technologies,
Pooler, GA, USA
Intelagard, Lafayette, CO,
USA
~ 8%hydrogen
peroxide (Part A);
<4% in the
finished blend
Quaternary ammonium compounds, dimethyl
benzyl alkyl, diacetin (surfactants and activators of
hydrogen peroxide)
9.6-9.7
8 Per Safety Data Sheet (SDS), all concentrations are in the finished blend;b Data from httpsJM/ww. thecloroxcompany.com/responsibility/healthy-lives/product-
stewardshiD/sds/httDs://www.thecloroxcomDanv.com/en-us/what-were-made-offmaredients-inside/clorox/clorox-SDlash-less-reaular-bleach-44f)003Q7848/and
httDsJMelaaard.com/wD-content/uDloads/2015/06EasvDECON-Part-1-SDS-2015.Ddf. httDsJMelaaard.com/wD-content/uDloads/2015/06EasvDECON-Part-2-
I SDS-2015.Ddf. and httDsJMelaaard.com/ti/D-content/uDloads/2015/06/EasvDECON-Part-3-SDS-2015.Ddf
I
All products were purchased from local suppliers or authorized distributors. Fresh batches of
EasyDECON DF200 solution were prepared daily through proportional mixing as per the manufacturer's
instructions. Before use, the manufacturer-recommended EasyDECON Fortifier Test Kit was used to test
the EasyDECON DF200 finished blend. This test (a "Go/No Go" test) measures the percentage of the active
ingredient and instills confidence that the decontamination solution is effective and ready to use. The
ongoing evaluations that occurred prior to use also included pH measurements of the finished blend (target
pH range: 9.6-9.9). Bleach products were used as is (no additional preparation steps); pretest evaluations of
the bleach solutions included free available chlorine (FAC), pH and temperature measurements as well.
3.6 Method Development Tests
3.6.1 Chemical Recovery Tests
3.6.1.1. Bulk Extraction of Coupons
Methods were optimized if needed to maintain a consistent level of analytical quality assurance
(QA) among the different types of samples. The bulk material extraction efficacy tests were designed to
determine the ability to recover target chemicals from the different types of test materials. These tests also
provided initial information on the stability and/or volatilization of target chemical spikes on permeable layers
14
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EPA/600/R-22/120
September 2022
of building surfaces, as compared to the reference material (stainless steel). The extraction method for
stainless steel was used for the extraction of bulk materials. The long-term (up to several days) surface
stability of chemicals was determined during permeation testing (Section 3.7.2).
All bulk material extraction efficacy tests were performed at a 30-min CT. The coupons were spiked
with 2 |jl_ of neat 2-CEPS or malathion analytical standard using techniques described in Section 3.3.1.
Tests were performed in triplicate (n = 3) for each chemical-test material combination. One procedural
blank (PB) of each uncontaminated material was extracted as well, to monitor for possible cross-
contamination or quantitative interferences that might result from the extraction procedure. Three CS
samples, generated by directly spiking of the chemical into the extraction solvent at concentrations
corresponding to 100% of the chemical amount applied to test materials, were prepared for each test day to
verify precision and accuracy of the chemical application. The recovery acceptance criteria were 80-120%
from the theoretical recovery value with a coefficient of variance between triplicates of less than 30%
(Section 5.2).
Material extraction procedures are detailed in Section 4.2.2. Recoveries of target chemicals for
each material and chemical combination are provided in Section 6.1.2.
3.6.1.2. Surface Sampling of Coupons
The wipe sampling method demonstration tests were conducted to evaluate the wipe (swab)
sample technique and wipe extraction efficiency from the surface swab. Like the bulk coupon extraction
tests described in Section 3.6.1.1, surface sampling optimization tests were performed at a 30-min CT and
chemical surface loadings of approximately 2.3 to 2.5 mg per coupon, resulting from a single 2-|jL liquid
spike of neat 2-CEPS or malathion, respectively. Surface samples were collected using four cotton swabs
(Puritan 3" Large Cotton Swab w/Wooden Handle; Puritan Medical Products Company LLC, Guilford, MA,
USA; P/N 803-WCL) per coupon using sampling procedure described in Section 4.1. Swabs were preferred
over gauze wipes considering the small surface area and limited access to the surface in the LVAP device.
The type of swab used for sampling has an extra-absorbent large tip that is approximately 6 mm (0.234") in
diameter and 17.5 mm (0.687") long and is made of medical-grade quality lint-free cotton. The wood handle
is approximately 74 mm (2.906") long and can fit inside the tubes used for extraction. Four swabs from the
sampling of each coupon were pooled together in the 50-mL polypropylene extraction tube (DigiTUBE, SCP
Science, Quebec, Canada; P/N 010-500-263) and extracted in 30 mL of hexane as one composite sample.
All surface sampling and extraction tests were performed in triplicate (n = 3) for each chemical and
coated stainless steel and free layer LVAP layer test combination, as well as for reference material. The
surface sampling method developed for stainless steel was used for swab sampling of bulk materials. One
PB of each uncontaminated material was swab-sampled as well. Three CS samples were prepared per test
event. The recovery acceptance criteria were 80-120% from the theoretical recovery value, with a coefficient
of variance between triplicates of less than 30% (Section 5.2).
The swab extraction procedure is described in detail in Section 4.2.1. Recoveries of target
chemicals from surface swab samples are presented in Section 6.1.1.
15
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EPA/600/R-22/120
September 2022
3.7 Permeation Tests
3.7.1 Gasket Contamination and Nonpermeation Transport Tests
Prior to the chemical permeation testing (Section 6.3), the LVAP setup was used to assess the
retention of the target chemicals in the SPE disks and to assess the potential for possible propagation of the
chemicals out of the SPE disks into the PTFE gaskets of the LVAP system. This gasket contamination test
was designed to demonstrate that gaskets do not serve as a sink for chemicals introduced to the LVAP
system. The SPE retention and gasket contamination tests were performed at the maximum contact time
(CT = 72 h) for each chemical-SPE-free layer (FSP or FSS) combination (Table 3-7). Briefly, the bottom
(flat face) gasket and SPE disk coupons were assembled in three clean LVAPs and spiked with a target
chemical solution of the chemical in ethanol at 50 mg/mL. A 10-|jL spike was delivered onto the center of
each SPE disk using an electronic pipette (Section 3.3.1). The resulting concentration was at approximately
20% of the chemical amount that was spiked onto the coupons as derived from an assumed 20%
permeation-related transfer through the paint layer into a (surrogate) porous material. After spiking of the
SPE, the LVAP assembly was completed for each cell by placing a clean O-ring gasket and unspiked FSP
coupon on the top of each contaminated SPE disk. After 72 hours, the SPE disks were extracted and
prepared for analysis using procedures described in Sections 4.2.2 and 4.3. In addition to the spiked SPE
disks, gaskets and unspiked FSP coupons were also extracted and analyzed to evaluate the potential
propagation of the target compound from the SPE disks to gaskets and to the paint layer; each gasket type
was extracted as a composite sample (n=3; Table 3-7).
Additionally, three blank LVAP cells were assembled to look for any nonpermeation related
transport of chemicals to LVAP components placed in the EIDC (nonpermeation transfer test, Table 3-7)
and followed the identical test setup and extraction scheme described above for test samples with
contaminated SPE discs.
Table 3-7. Experimental parameters for gasket contamination and nonpermeation transport tests
Test type
Chemical
LVAP
component
spiked
Spiked chemical
amount
[mg]a
Extraction
solvent
typeb
Extraction
solvent
volume
[mL]
LVAP components
extracted
2-CEPS
SPE
0.50
72
Hexane
30
SPE, FSP, gaskets0
Gasket
SPE
0.50
72
Hexane
30
SPE, FSS
contamination
Malathion
SPE
0.50
72
Hexane
30
SPE, FSP, gaskets1
SPE
0.50
72
Hexane
30
SPE, FSS
Nonpermeation
2-CEPS
None
No spike
72
Hexane
30
SPE, FSP, gaskets1
transfer
Malathion
None
No spike
72
Hexane
30
SPE, FSP, gaskets0
810-juL spike of chemical solution at 50 mg/mL;b detailed specifications of extraction solvent used in this study are in Table 3-4;c composite
extraction of three O-ring and three full-face gaskets below SPE disks
The acceptance criterion for the total recovery of each target compound from the gasket material
from the gas contamination test was set to be less than 1 % of the amount spiked onto the SPE disk (or less
than 0.005 mg) detected in the gasket materials.
16
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EPA/600/R-22/120
September 2022
The criterion for the total recovery of the target chemical from an uncontaminated SPE in the
nonpermeation transfer test was less than 1% of the (coupon) surface concentration (or less than 0.023 to
0.025 mg) detected in the SPE from the uncontaminated LVAP assembly. The results from gasket
contamination and nonpermeation transfer tests are summarized in Section 6-2.
3.7.2 Baseline Permeation Tests
Baseline permeation tests were designed to allow for the measurement of 2-CEPS and malathion
permeation through surface layers of FSP, FSS or into bulk materials at the longest CT of 72 h and
occasional shorter CTs (down to 3 h) following the deposition of a chemical on the surface, as compared to
the stainless-steel reference material, and other control samples including painted or sealed stainless steel
as warranted. After a discrete single 2-|jL droplet of neat chemical was deposited onto each test coupon
(Section 3.3.1), a 3 to 72 hours-long pesticide-surface interaction test was conducted in the EIDC. The
remaining amounts of target chemicals were determined through a combination of surface wiping followed
by extraction of the coupon types and quantities (Table 3-8). Tests were performed in triplicate (n = 3) for
each test configuration and time point. One PB of each uncontaminated material was extracted as well at
CT = 72 h. Three CSs were generated per each spiking event.
Table 3-8 summarizes the entire test matrix and key operational parameters for the test procedure
(sample types and number and sampling approaches used for each type of coupon/test material). Sampling
and analysis methods are described in detail in Section 4.0. Results are given in Section 6.3.
Table 3-8. Test parameters for permeation testing and types of samples collected
Test material
Chemical
Nominal
spiked
chemical
amount
[mg]
CT(s)
tested [h]
Components
analyzed11
Control
samples
sle
e
Sampling
method(s)
sle
e
Sampling
method(s)
LVAP tests
FSP over SPE
2-CEPS
2.3
72
FSP
SW + E
SS, PSS, PB, LB, CS
SW + E or E
SPE
E
Malathion
2.5
3,6,24,72
FSP
SW + E
SS, PSS, PB, LB, CS
SW + E or E
SPE
E
FSS over SPE
2-CEPS
2.3
72
FSS
SW + E
SS, SSS, PB, LB, CS
SW + E or E
SPE
E
Malathion
2.5
72
FSS
SW + E
SS, SSS, PB, LB, CS
SW + E or E
SPE
E
Bulk material tests
AS
2-CEPS
2.3
24,72
BMC
SW + E
SS, PB, LB, CS
SW + E or E
Malathion
2.5
72
BMC
SW + E
SS, PB, LB, CS
SW + E or E
HPL
2-CEPS
2.3
24,72
BMC
SW + E
SS, PB, LB, CS
SW + E or E
Malathion
2.5
72
BMC
SW + E
SS, PB, LB, CS
SW + E or E
VCP
2-CEPS
2.3
24,72
BMC
SW + E
SS, PB, LB, CS
SW + E or E
Malathion
2.5
72
BMC
SW + E
SS, PB, LB, CS
SW + E or E
FSP - Free standing paint layer coupon (wiped and extracted); FSP - Free standing paint layer coupon (wiped and extracted); SPE -
SPE disk coupon (extracted); AS - acrylic countertop surface (wiped and extracted); HPL - high-pressure laminate countertop surface (wiped and
extracted); VCP- vinyl composition plank flooring (wiped and extracted); BMC - bulk material coupon (wiped and extracted) SW + £ - surface
wipe sampled, then extracted; E - bulk material extaction only; PB - Procedural blank; LB - Laboratory blank; CS - control spike
17
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EPA/600/R-22/120
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3.8 Decontamination Tests
3.8.1 Decontamination Baseline
In the initial phase of the efficacy testing a decontamination procedure using a commercial off-the-
shelf (COTS) product (concentrated germicidal bleach) was deployed via surface application to investigate
its efficacy for degradation of the chemicals. The decontamination procedure consisted of a single
application of 200 |jl_ of decontaminant over the central portion of the coupon contaminated with the
chemical. The application was performed at 72 hours after spiking (CT=72 h). This procedure did not
include any mechanical scrubbing or rinsing after application of the decontaminant. The procedure was
based solely on the chemical oxidation reaction, or degradation of target chemical by high concentration
sodium hypochlorite and potentially other minor ingredients of decontaminant (e.g., pH stabilizer sodium
hydroxide). After a prescribed dwell time (DT) of 18 hours (indicative of an overnight drying), the
postdecontamination chemical mass on the surface and in subsurface layers was determined by wipe
sampling and extraction techniques, or a combination thereof. Due to the high natural attenuation rate of 2-
CEPS observed for bulk building material permeation testing (results in Section 5.3), the decontamination
baseline for bulk materials was tested only for more persistent malathion using one application of germicidal
bleach. The test matrix for baseline decontaminant testing is given in Table 3-9, below. Results are given in
Section 6.4.1.
Table 3-9. Test parameters for baseline decontamination testing: Single application of concentrated germicidal
bleach with a dwell time of 18 h.
Test
Chemical
Nominal
material
spiked
chemical
amount [mg]a
Decontaminant/
DT
Components
Control
decontaminant
Ul
analyzed11
samples
volume [|jL]
pie
Sampling
pie
Sampling
ie
method(s)
ie
method(s)
LVAP tests
2-CEPS
2.3
72a
Concentrated
18
FSP
SW + E
SS, PSS, PB,
SW + E or E
LVAP-FSP
germicidal bleach/200
SPE
E
LB, CS
Malathion
2.5
72
Concentrated
18
FSP
SW + E
SS, PSS, PB,
SW + E or E
germicidal bleach/200
SPE
E
LB, CS
2-CEPS
2.3
72a
Concentrated
18
FSS
SW + E
SS, SSS, PB,
SW + E or E
LVAP-FSS
germicidal bleach/200
SPE
E
LB, CS
Malathion
2.5
72
Concentrated
18
FSS
SW + E
SS, SSS, PB,
SW + E or E
germicidal bleach/200
SPE
E
LB, CS
Bulk material tests
AS
Malathion
2.5
72"
Concentrated
germicidal bleach/200
18
BMC
SW + E
SS, PB, LB, CS
SW + E
HPL
Malathion
2.5
72"
Concentrated
germicidal bleach/200
18
BMC
SW + E
SS, PB, LB, CS
SW + E
VCP
Malathion
2.5
72"
Concentrated
germicidal bleach/200
18
BMC
SW + E
SS, PB, LB, CS
SW + E
8 tested in the 'open' and 'closed'LVAP configuration; FSP - Free standing paint layer coupon (wiped and extacted); FSP - Free standing paint layer
coupon (wiped and extracted); SPE - SPE disk coupon (extracted); AS - acrylic surface countertop (wiped and extracted); HPL - high-pressure
laminate (wiped and extracted); VCP- vinyl composite plank flooring (wiped and extracted); BMC - bulk material coupon (wiped and extracted) SW+E
- surface wipe sampled, then extracted; E - bulk material extaction only; PB - Procedural blank; LB - Laboratory blank; CS - control spike
18
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EPA/600/R-22/120
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3.8.2 Modified Decontamination Testing
The modified decontamination approaches tested were developed for degradation of chemicals that
were identified to be remaining on the surface or within the subsurface layers after the baseline
decontamination using a single application of concentrated germicidal bleach (Section 3.8.1). The research
focused on targeted changes that may result in improvements in the decontamination procedure. The
changes tested were a combination of functional and operational modifications listed below:
use of different commercial decontaminant (i.e., different decontamination chemistry, e.g., activated
hydrogen peroxide)
use of modified decontaminant (e.g., bleach with additives)
use of modified multistep application of various decontaminants
The overall effectiveness of the modified decontamination approaches used an adaptive
experimental design. Namely, each subsequent decontamination procedure modification considered the
results from preceding procedures that did not offer a cumulative decontamination efficacy of surface-bound
or permeated chemical fraction. The executed test matrix for the modified decontamination testing is shown
in Table 3-10. The results are given in Section 6.4.2.
Table 3-10. Test parameters for modified decontamination testing
Test
Chemical
Spiked
material
chemical
amount
[mg]a
Decontaminant/decontaminant | DT
volume [|jL]
Modified Decontamination Procedure 1 (MDT-1)
Description: Two applications of concentrated germicidal bleach; application 1 at CT=72 h, application 2 at DT = 2 h; total DT = 2 +18 h
Components
Control
analyzed11
samples
Die
Sampling
sle
Sampling
e
method(s)
e
method(s)
LVAP-FSP
Malathion
2.5
72
Concentrated germicidal bleach/ 2 x 200
2+18
FSP
SPE
SW + E
SS, PB,
LB, CS
SW + E or
E
Modified Decontamination Procedure 2 (MDT-2) and 2a (MDT-2a)
Description: One or two applications of Splash-Less bleach; application 1 at CT=72 h, 2nd application 2 at DT = 2 h; total DT = 2 +18 h
LVAP-FSP
Malathion
2.5
72
Splash-Less Bleach / 200
18
FSP
SW + E
SS, PB,
LB, CS
SW + E or
E
SPE
E
Splash-Less Bleach / 2 x 200
2+18
FSP
SW + E
SS, PB,
LB, CS
SW + E or
E
SPE
E
Modified Decontamination Procedure 3 (MDT-3) and 3 a (MDT-3a)
Description: One ortwo applications of EasyDECON DF200; application 1 at CT=72 h, 2nd application 2 at DT = 2 h; total DT = 2 +18 h
LVAP-FSP
Malathion
2.5
72
EasyDECON DF200/200
18
FSP
SW + E
SS, PB,
LB, CS
SW + E or
E
SPE
E
EasyDECON DF200/2x200
2+18
FSP
SW + E
SS, PB,
LB, CS
SW + E or
E
SPE
E
FSP - free standing paint layer coupon (wiped and extracted); FSP - free standing paint layer coupon (wiped and extracted); SPE - SPE disk coupon
(extracted); SI/1/ + E- surface wipe sampled, then extracted; E - bulk material extraction only; PB - procedural blank; LB - laboratory blank; CS -
control spike.
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EPA/600/R-22/120
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3.9 Microscopy Analyses
FESEM was used to characterize general material properties and morphology like porosity,
thickness, and structural integrity of paint and sealant layers after exposure to a decontaminant, and after
malathion-only and bleach-only exposures. Microscopy images of malathion, malathion-decontaminant, and
decontaminant exposure areas were compared to those of the nonexposed areas of laboratory blank
coupons to determine if the malathion or bleach had an impact on the paint and sealant material properties
and morphology. After the exposure(s) at prescribed CTs and DTs, the coupons were coated with a thin
layer of carbon using a Cressington 208C carbon coater (CREST Gateway Technologies, Dublin, Ireland)
before microscopy analysis to mitigate the impacts of sample charging. The test matrix for microscopy
analyses is given in Table 3-11. Qualitative results are incorporated throughout Section 6.0 to support
experimental findings from permeation and decontamination studies.
Table 3-11. Test matrix for microscopy analyses
Test Material
Sample type
Material exposure(s) and contact times (CT)
Condition 1
FSP
SPC
Malathion (CT = 72 h)
FSS
SPC
Malathion (CT = 72 h)
Condition 2
FSP
STC
Malathion (CT = 72 h) + Clorox germicidal bleach3 (DT = 18 h)
FSS
STC
Malathion (CT = 72 h) + Clorox germicidal bleach3 (DT = 18 h)
Condition 3
FSP
SDC
Clorox germicidal bleach3 (DT = 18 h)
FSS
SDC
Clorox germicidal bleach3 (DT = 18 h)
Negative controls
FSP
SLB
Laboratory blank (no exposures)
FSS
SLB
Laboratory blank (no exposures)
8 regular (i.e., nonconcentrated) version of germicidal bleach was used in FESEM experiments due to limited market
availability of the concentrated product; per label, sodium hypochlorite concentration in the regular version is -6.25%
compared to -8.25% of the concentrated germicidal bleach (Table 3-6). SPC - contaminated positive control (on SEMstub);
TC - Contaminated and decontaminated test sample (on SEM stub); SPB - Decontaminated-only control sample (on SEM
stub); LB - Laboratory blank (on SEM stub); CT - contact time; DT- dwell time
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EPA/600/R-22/120
September 2022
4.0 Sampling and Analysis
4.1 Surface Sampling Methods
Each rectangular (SS, SSS, PS or bulk material) arid circular (FSP or FSS) coupon was wipe-
sampled using four cotton swabs (FisherBrarid Cotton-Tipped Applicators, Fisher Scientific, Thermo Fisher
Scientific, Waltham, MA, USA; P/N 23-400-101) prewetted with pesticide-grade isopropanol wetting solvent
(Table 3-5). All cotton-tipped applicators were precut to a total length of less than 4" before sampling to
allow the cotton swabs to fit inside the extraction vessels. The cotton swabs were used to sample the
coupon in separate sampling motions: the first swab sampled the "hot zone" with a rotating motion of the
wood handle; the second swab used overlapping horizontal strokes; the third swab used vertical
overlapping strokes; and the last swab sampled the perimeter. Given the small surface area of the coupons,
strokes were short (coupon length/width) and overlapped each other. The multistep wipe sampling
procedure is summarized in detail in Appendix A-3. Figure 4-1 shows examples of surface sampling using
the swab-based method.
Figure 4-1. Surface sampling of test coupons using prewetted cotton swab; examples shown are LVAP-FSP (a)
and SS (b).
Swab samples were collected directly to extraction vials (four swabs per extraction tube) and
immediately extracted using procedures described in Section 4.2.1. After the disassembly of LVAPs was
completed, the wipe-sampled FSS and FSP coupons were transferred to the prelabeled 50-mL extraction
vials (solvent- and acid-resistant digestion/extraction vial; DigiTube Non RackLock with caps; SCP Science,
Quebec, Canada, P/N 010-500-263). SPE disks were not wipe-sampled and underwent direct extraction -
as described in Section 4.2.2 - immediately after the disassembly of the LVAP was completed.
4.2 Extraction Methods
This section summarizes the extraction procedures used for all types of surface samples, coupons,
and bulk materials. All extraction methods were verified before persistence and decontamination testing.
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4.2.1 Extraction of Surface Wipes
After completion of wipe sampling using swabs (Section 4.1.3), four swab wipes used for surface
sampling of coupons (Section 4.1) were placed in a new prelabeled 50-mL vial (solvent- and acid-resistant
digestion/extraction vial; DigiTube Non RackLockwith caps) for composite extraction. Each extraction vial
was filled with 30 mL of hexane (Table 3-5) and capped. Lids were not tightened completely to avoid the
pressure buildup during extraction. Extraction vials were then placed in an extraction rack and transferred to
the sonicator (Branson 8510, Branson, Danbury, CT, USA) containing room-temperature water. Extraction
vials containing the swabs were sonicated for 15 minutes. After extraction, samples were refrigerated at 4 ±
2 °C until further processing. Sample extract preparation for instrumental analysis is described in Section
4.3.
4.2.2 Extraction of Coupons and Bulk Materials
After completion of permeation or decontamination testing, each coupon was placed in a new
prelabeled 50-mL vial (solvent- and acid-resistant digestion/extraction vial; DigiTube Non RackLockwith
caps). Each tube was then filled with 30 mL of hexane (Table 3-5) and capped. Lids were not tightened
completely to avoid pressure buildup during extraction. Extraction vials were then placed in an extraction
rack and transferred to the sonicator (Branson 8510, Branson, Danbury, CT, USA) containing room-
temperature water. Extraction vials containing the coupons were sonicated for 15 minutes. Figure 4-2 shows
FSP and SPE coupons immediately after extraction.
Figure 4-2. FSP (a) and SPE (b) coupons immediately after the conclusion of hexane extraction.
After extraction, samples were refrigerated at 4 ± 2 °C until further processing. Procedures for the
preparation of extracts for instrumental analysis are described in Section 4.3.
4.3 Preparation of Samples for Analysis
Extracts resulting from surface sampling (Section 4.2.1) and coupon extractions (Section 4.2.2)
were prepared for analysis in 1,8-mL amber glass gas chromatography (GC) vials (Sigma Aldrich, St. Louis,
MO, USA). Due to the lack of the cleanup step in the analytical procedure, all sample extracts were diluted
10-fold in hexane, including procedural blanks, laboratory blanks, and gasket contamination samples. The
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CS samples were also diluted up to 25-fold. If prepared samples were outside the upper limit of the
calibration range, the dilutions were adjusted using preliminary results, and samples were prepared from
archived extracts and reanalyzed. All samples were spiked at 1000 nanograms [ng]/mL level with
isotopically labeled internal standard (ISs) and surrogate standard: phenanthrene-d10 from EPA Method
8270 standard mix (ERS-020-1.2ML; Sigma Aldrich) and malathion-d10 (DLM-4476-1.2, Cambridge Isotope
Laboratories, Inc., Tewksbury, MA, USA), respectively. After the preparation of the sample for analysis was
completed, the sample level (solvent level) was marked on the vial. Samples were refrigerated at 4 ± 2 °C or
below before analysis. The remaining raw extracts were archived at 4 ± 2 °C or below. All analytical batches
were accompanied by a chain of custody form and inspected at the analytical laboratory upon receipt.
4.4 Instrumental Analyses
Instrumental analyses were performed by the EPA OSL using GC/MS. The exact conditions for the
GC/MS were optimized prior to sample analysis and are given below in Table 4-1.
Table 4-1. GC/MS parameters for analysis of 2-CEPS and malathion.
Parameter
Description/Conditions
Instrument
Thermo Trace 1300 Gas Chromatograph GC ISQ Mass Spectrometer (Thermo Fisher Scientific, Inc.,
Waltham, MA)
Autosampler
AS/A11310 Autosampler (Thermo Fisher Scientific, Inc)
Column
DB-5,20 m x 0.25 mm ID, 0.25 |jm df (Agilent, Santa Clara, CA, USA)
GC column program
60 °C initial temperature, hold 0 min, 8 °C/min to 260 °C, hold 8 min
Carrier gas flow rate
1.3 mL/min
Injection volume/type
1.0 pL/splitless
Inlet temperature
250 °C
MS source temperature
250 °C
MS transfer line
250 °C
df: film thickness
The calibration range was 100-10,000 ng/ml, with quantitation performed using two 5-point curves
that were dependent on the sample concentration. The high-concentration curve (1,000-2,500-5,000-7,500-
10,000 ng/mL) was used for the analysis of sample materials that had high sampling efficacy and CSs at a
100% target concentration. The low-concentration curve (100-250-500-750-1,000 ng/mL) was used for the
analysis of sample materials that had low sampling efficacy, CSs at a 10% target concentration, and blanks.
Each calibration standard included 1,000 ng/mL of the internal standard (IS), naphthalene-cfe (from EPA
8270 semivolatile internal standard mix [CRM46955, MilliporeSigma, St. Louis, MO]); IS was also present in
all test and CS samples at the same concentration level (Section 4.6.2). Prior to sample analysis, a
minimum 5-point instrument calibration (ICAL) was performed, and the coefficient of determination (R2) was
determined (target R2 >0.995). The continuous calibration was performed using a middle concentration
calibration standard, that is, approximately every 10 test samples and at the end of the analytical run, with
an acceptance control limit of 80-120% of the ICAL concentration. If quality control (QC) criteria were not
met, the instrument was recalibrated, and any affected samples were reanalyzed. Additional QC samples
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included duplicates (DUPs) of test samples (one DUP per analytical run; acceptance criteria: relative
percent difference [RPD] <20%) and analysis of blanks (PBs and laboratory blank [LBs]).
Prior to testing, an initial laboratory proficiency evaluation was performed. Accuracy and precision
were determined by analysis of multiple measurements of the CS solutions (n = 5 for two concentration
levels; single analytical run). CS samples were generated by spiking the target chemical or target chemical
solution used during testing directly into the injection solvent (hexane). All CSs were sonicated for 10
minutes and then diluted as needed per Section 4.4. Each CS set was accompanied by one LB sample (1
mL of solvent used for the preparation of samples for analysis). These CS experiments were used as
independent verifications of the results obtained from the analytical laboratory. The initial and continuing
laboratory proficiency results are listed in Table 4-2.
Table 4-2. Initial and continuing laboratory proficiency results
Control Spike Sample Analysis results
Target
Chemical
Accuracy and Precision
Number of samples
analyzed
Solvent
Blank
(% of true value ± 1 SDC; RSD [%])
(n)
Malathion, 10% target (initial8)
86% ± 6% SD; RSD = 7%
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The average concentration in mg per replicate coupon group;
SD and %RSD for each group of replicate coupons.
2. For control samples associated with a test condition:
Sampling and extraction controls (replicates, average, SD, %RSD);
Procedural blank coupons results (if detected above LOQ);
Laboratory blanks (if detected above LOQ);
Control spikes (replicates, average, SD, %RSD).
The GC/MS concentration results (ng/mL) were converted to the total mass of chemical per sample
(mg per sample) by multiplying by the extraction solvent volume and dilution factor, if applicable (Eq. 1):
Ms = Cs x Ve x Df/ 1.0E6 (Eq.1)
where:
Ms: mass of chemical in the sample (mg)
Cs: concentration (ng/mL) from an individual replicate sample
Ve: extraction solvent volume (mL)
Df: sample dilution factor (if any)
The percent recovery of chemical from samples was calculated against the chemical amount spiked
onto the surface (Eq. 2):
%R= Ms/Mcs x 100 (Eq.2)
where:
Ms: mass of chemical (mg) in a test sample
Mcs: mass of chemical (mg) in the control spike, corresponding to the chemical level spiked onto
the surface
The chemical mass (Ms) results used for decontamination efficacy (Section 4.5.2) calculations were
not adjusted for QC sample recovery (%R).
4.5.2 Decontamination Efficacy Calculations
The decontamination cleanup efficacy was calculated using the average of chemical mass
recovered from the replicate test coupons (TCs) and the average chemical mass recovered from the
associated set of positive control (PC) coupons (Eq. 3).
x DE = (1- Mien/ Mpcn) x 100 (Eq.3)
where:
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x DE: average decontamination efficacy (%)
Mien: average of the chemical amount remaining on a replicate TC (decontaminated) coupon or
LVAP set (mg)
Mpcn: average of the chemical amount remaining on replicate PC (nondecontaminated) coupons or
LVAP sets (mg)
The average decontamination efficacy, along with the SD, was a cumulative decontamination
efficacy (or resulting from the application of all procedural steps for each test). If the mass of remaining
agent on all subcomponents of one sample was found to be below the LOQ, the efficacy was calculated
using the LOQ value and reported as "greater than" the calculated value.
If the sample concentration was found to be below the lowest point of the calibration curve, but the
signal-to-noise (S/N) ratio was greater than 10, the results were reported as estimated and flagged as
estimated. All other results that were nondetect and detections at 3 < S/N < 10 were reported as below LOQ
(< LOQ). Student's Mests (two-tailed with unequal variance) were used to check if the observed differences
in decontamination efficacies of various methods tested were statistically significant. The p-values are
reported at a significance level of 95% (a=0.05).
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5.0 Quality Assurance and Quality Control
5.1 Test Equipment Calibration
All equipment was verified as calibrated at the time of use. Instruments were calibrated at the
frequency shown in Table 5-1. In case of any deficiencies, instruments were adjusted to meet calibration
tolerances or recalibrated before testing. In the case of the GC/MS instrument, any initial calibration
deficiencies were noted. The GC/MS instrument was recalibrated before the analysis. If the tolerances for
continuous calibration were not met, the GC/MS instrument was recalibrated, and affected samples were
reanalyzed.
Table 5-1. Instrument calibration frequency
Equipment
Calibration/Certification
Expected Tolerance
Results
Thermometer
Compare to independent NIST thermometer (a thermometer that is recertified
annually by either NIST or an ISO-17025 facility) value once per quarter.
±1 °C
100%
Stopwatch
Compare to official U.S. time at time.gov every 30 days.
± 1 min/30 days
100%
Micropipettes
Certified as calibrated at time of use; recalibrated by gravimetric evaluation of
performance to manufacturer's specifications every year.
±5%
100%
Microsyringes
Certified as calibrated at time of use
±5%
100%
Relative humidity
Vaisala probe (RH) certified as calibrated at time of use. Calibration verified yearly
by the EPA Metrology Laboratory.
± 3% RH
100%
Temperature
Vaisala probe (T)
± 0.35 °C
100%
Paint or sealant layer
thickness and
uniformity
Eddy current certified by manufacturer; calibration was checked and zeroed using
standards prior to each use.
± 1 |jm (0-50 |jm)
± 2 |jm (>50 |jm)
100%
Micrometer certified by manufacturer
± 2 |jm (at 20 °C)
100%
Universal blade applicator certified as calibrated at time of use. Thickness of layer
verified using Eddy current gauge or micrometers after each paint layer application
±0.5 mil (0-10 mil)
± 1 mil (0-50 mil)
100%
Solvent Volume
Solvent dispenser certified by manufacturer; checks performed with graduated
cylinder prior to use.
± 1 mL
100%
Scale
Certified as calibrated at time of use; calibration verified yearly by the EPA
Metrology Laboratory.
±1 g
100%
Graduated cylinder
Certified by manufacturer at the time of use. Certified as calibrated at time of use.
Calibration verified yearly by the EPA Metrology Laboratory.
± 1 mL
100%
Solvent dispenser
Certified by manufacturer at the time of use; rechecked volume delivered using
graduated cylinder prior to use.
± 1 mL
100%
Gas
chromatograph/mass
spectrometer
5-point calibration prior to analysis; continuous calibration prior to each analytical
run; recalibrate when continuous calibration fails acceptance criteria and/or after
system maintenance; details in Section 4.4.
±20% at mid-point
100%
NIST - National Institute of Standards and Technology; ISO - International Organization for Standardization;
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5.2 Data Quality Results for Critical Measurements
The following measurements were deemed critical to accomplishing project objectives:
• Surface concentration of target chemicals as determined by instrumental analysis
• Chemical concentration in coupons, including SPE disk
• Chemical concentration in extracts
• Contact and dwell times
• Environmental conditions during weathering
• Thickness and uniformity of all paint and sealant layers.
The data quality indicators (DQIs) for test measurements are provided in Table 5-2. The limited
number of results/tests that were not within acceptance criteria (as determined in the project-specific quality
assurance project plan) were not indicative of any systematic error introduced into the experimental results
and do not change the general findings of this study.
Table 5-2. Acceptance criteria for critical measurements and corresponding test results
Critical Measurement
Target Value and Acceptance
Criteria
Results
Contact/weathering time
3-72 h ± 5 min
3 hCT: 3:00:00 h± 00:00 min
6 h CT: 6:00:00 h ± 00:00 min
24 h CT: 24:00:00 h ± 00:00 min
72 h CT: 72:00:00 h ± 00:00 min
Dwell time
18 to 20 h ±5 min
18 h DT: 18:00:04 h ± 00:13 min
20 h DT: 19:58:44 h ± 04:14 min
Environmental conditionsa
Temperature: 24 ± 3 °C
Relative humidity: 50 ± 5% RH
Temperature: 22.9 ± 1.0 °C
Relative humidity: 47.6 ±6.0 % RH
Delivery of target surface
concentration of chemicalb
80-120% of target chemical mass
Malathion: 88% ± 15%SD (RSD =17%)
2-CEPS: 97% ± 6.6% SD (RSD =6.9%)
Thickness and uniformity of pain
layers
70-130% of target thickness (3 mils for
FSP layers; 2 mils for FSS layers)
FSP: 3.1 ±0.37 (RSD = 12%)
FSS: 1.9 ±0.33 (RSD = 17%)
Recovery of chemical from surface
samplesc
<30% coefficient of variation for
identical test setd
Malathion: bulk material extraction RSD: 3.2 - 21%;
surface sampling RSD: 1.8 - 8.4%
2-CEPS: bulk material extraction RSD: 2.5 - 6.8%;
surface sampling RSD: 1.1 -10.1%
Procedural blank
<5% of the analyte amount recovered
from the positive control.
All procedural blank samples within acceptance criteria; all reported
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6.0 Results and Discussion
6.1 Verification of Surface Sampling and Material Extraction Methods
6.1.2 Efficacy of Surface Sampling Using Swabs
Average percent recoveries - calculated as chemical mass recovered in comparison to control
spike results - were 63 to 87% for 2-CEPS and 66 to 89% for malathion across the various surfaces (CT of
30 min). The recovery of 2-CEPS from the surface of stainless steel was 87 ± 7%; RSD = 8%, hence within
project-specific acceptance criteria of 80-120% for reference material, with a coefficient of variance between
triplicates of less than 30%. The average recovery of malathion was 78 ± 3%; RSD = 3% or only minimally
lower than the 2-CEPS results above. The detailed results of the surface sampling method development
tests for different types of test materials are shown in Appendix B Tables B1 and B2, for 2-CEPS and
malathion, respectively. The sampling method efficiencies were deemed satisfactory to study the 2-CEPS
and malathion permeation and measure decontamination efficacies and were not further optimized. This
surface sampling method was also used for sampling of bulk materials without prior evaluation for these
materials.
As expected, the recovery from surface wipe samples of stainless-steel reference coupons
generally exceeded the recovery from wipe (swab) samples collected from other more permeable test
materials, indicating that both the surface layers and free-standing layers of paint and sealant had a
noticeable amount of permeation and/or adherence of malathion and 2-CEPS into the paint layers even
during the relatively short CT of 30 min that was used for surface sampling method development. The
contaminant retention by the paint and sealant layer was further evaluated during the fate and transport
studies (Section 6.3).
6.1.3 Coupon Extraction Efficacy
Recoveries of 2-CEPS and malathion, average 95 ± 3%; RSD = 3% and 95 ± 6%; RSD = 6%,
respectively, were observed for reference nonpainted SS coupons during extraction testing. These values
were within the acceptance criteria for SS, namely, 80-120% of chemical amount spiked onto the surface
with less than 30% RSD between replicates. Detailed results for the extraction method development tests
for different types of test materials are shown in Appendix B, Tables B3 and B4 for 2-CEPS and malathion,
respectively. The high percent recoveries indicate the high effectiveness and reproducibility of the analytical
method for the extraction of target chemicals present on the surface of the reference material. Similar or
better recoveries were observed for other test materials (Tables B3 and B4). The extraction method
validated for stainless steel was deployed during bulk materials testing without further prior evaluation.
6.1.4 Comparison of Coupon Extraction Versus Surface Sampling
A comparison of relative recoveries for surface wipe sampling versus coupon extraction for 2-CEPS
and malathion is shown in Figure 6-1, with lower and upper limit QA acceptance criteria for reference
material shown as red dashed lines.
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September 2022
120
100
80
CD
§ 60
01
& 40
20
(A) 2-CEPS recovery (30 min contact time)
Bulk extraction c Surface sampling
SS
PSS
SSS
FSP
FSS
SPE
120
100
^ 80
§ 60
01
40
20
0
(B) Malathion recovery (30 min contact time)
Bulk extraction C Surface sampling
-h
SS
PSS
SSS
FSP
FSS
SPE
Figure 6-1. Recovery of 2-CEPS (A) and malathion (B) from reference and test materials; SS: stainless steel; PSS:
painted stainless steel; SSS: sealed stainless steel; FSP: free-standing paint layer; FSS: free-standing sealant
layer; SPE: solid-phase extraction disk; dashed lines are representing the lower (80%) and upper (120%) limit of
recovery acceptance criteria set for reference material (SS).
The implemented sampling protocols were reproducible, with coefficients of variance ranging from
1.1 to 21% RSD among triplicates (Figure 6-1 and Appendix B, Table B3 and B4). For four out of five
materials - 2-CEPS and three out of five material-malathion combinations tested, average percent
recoveries (relative to the control spikes) were statistically significantly (p<0.05) higher for the direct
extractions than the average percent recoveries for wipe sampling, with an average 8 to 17% reduction in
the absolute percent recovery of 2-CEPS and malathion from extraction and wiping, respectively (Figure 6-1
and Appendix B, Table B3 and B4). Only recoveries of 2-CEPS from stainless steel by extraction versus
wipe sampling were not significantly different (p=0.27). This is not too surprising considering the relative
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ease of sampling a smooth, nonporous and nonpermeable material. The two materials for which no
significant difference was observed between extraction and surface wipe sampling for malathion were
painted stainless steel (p=0.45) and free-standing paint (p=0.11). A statistically significant difference in
recovery between extraction and surface wipe sampling of malathion from stainless steel (p=0.04) was
observed, which is the opposite from what was observed for2-CEPS and could be attributed to a generally
poorer surface wipe sampling efficiency for malathion.
Chemical recoveries from the extraction of painted and sealed stainless-steel surfaces and their
free-standing layer counterparts were not statistically different for 2-CEPS (p>0.05 for all 10 intramaterial
comparisons) and similarly not statistically different for malathion in 9 out of the 10 intramaterial
comparisons. The only significant difference was found in the comparison of the extracted malathion amount
from FSP versus FSS (p=0.03).
Chemical recoveries from the surface sampling using swabs of painted and sealed surfaces and
free layers were mostly (7 out of 10 intramaterial comparisons for 2-CEPS and 8 out of 10 intramaterial
combinations for malathion) not statistically different with recoveries from extraction of the material
consistently higher than the recoveries from extraction of surface wipe sampling. Statistically significantly
differences for the 2-CEPS recovery were found between the SS and FSP (p=0.04), SS and FSS (p=0.02),
and PSS and FSS (p=0.02) while differences in recovery for malathion were different between SS and FSS
(p=0.02) as well as FSP and FSS (p= 0.02).
6.2. Gasket Contamination and Nonpermeation Transport
The results from the LVAP gasket contamination and nonpermeation transport evaluation for 2-
CEPS and malathion are shown in detail in Appendix B, Tables B5 through B7. No target chemical was
recovered from any gasket samples above the <1% mass recovery criterion established as target QA
criterion prior to testing (Table B5). No malathion detections were observed for the top gasket, which was
located between the FSP and the aluminum top plate from the LVAP apparatus. Trace amounts of
malathion -below LOQ - were observed in the PTFE O-ring (gasket around the SPE disk) data set and all
three-spacer gaskets (PTFE gasket directly below the SPE disk). All gaskets had ultra trace-level
concentrations of 2-CEPS («LOQ at an estimated 1 to 4 jjg per composite sample). These minor
detections in the O-ring and spacer gaskets means that only a very small amount (<1%) of each target
chemical may migrate through the SPE disk into the PTFE gaskets, but without introducing any significant
bias into studying permeability of chemicals using LVAP devices.
The 2-CEPS and malathion recoveries from the SPE, FSP, and FSS used in the gasket
contamination tests are shown in Appendix B Tables B6 and B7 for 2-CEPS and Tables B8 and B9 for
malathion. In these tests, the SPE was spiked at 20% of the target test matrix concentration and an FSP or
FSS was placed immediately on top of the SPE. During the 72-hour long CT, approximately 93 to 99% of 2-
CEPS contamination migrated back from the spiked SPE disk into the free layers of paint or sealant, with
the LVAP mass balance showing an average chemical recovery of approximately 41% (Z FSP+SPE
recoveries) to 42% (Z FSS+SPE recoveries) (Tables B6 and B7). The mass balance of malathion was an
average of 101% (Z FSP+SPE recoveries) to 108% (Z FSS+SPE recoveries), with only an average of 12 to
25% retained by previously uncontaminated FSS and FSP layers. Figure 6-2 shows average recoveries and
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partitioning of target chemicals from contaminated SPE to previously uncontaminated surface layers of
LVAP systems.
(a) Propagation of 2-CEPS from contaminated SPE
back to FSP and FSS layers of LVAP (CT=72 h)
¦ SPE (extracted) ¦ FSP (extracted) ¦ FSS (extracted)
120%
100%
^ 80%
I 60%
O
& 40%
20%
0%
FSP LVAP FSS LVAP
(b) Propagation of malathion from contaminated SPE
back to FSP and FSS layers of LVAP (CT=72 h)
¦ SPE (extracted) ¦ FSP (extracted) ¦ FSS (extracted)
120%
„ 100%
- 80%
> 60%
| 40%
20%
0%
FSP LVAP FSS LVAP
Figure 6-2. Average recoveries and migration of 2-CEPS (a) and malathion (b) for LVAP-FSP and LVAP-FSS
system components; recoveries were calculated against theoretical amount of chemical spiked determined by
analysis of associated CS samples. Chemical mass results for each layer are averages (n=3) ± 1 SD.
The lower total mass recovery of 2-CEPS can be attributed to the more volatile characteristics (in
comparison to malathion) leading to higher evaporation-related losses (physicochemical properties of target
chemicals are given in Table 3-4). 2-CEPS also has a much higher reverse migrated amount from the
contaminated porous sublayer (SPE disk) to the paint/sealant material, which may make it more susceptible
to surface-based decontamination. The less volatile malathion is more persistent in contaminated sublayers,
with no natural attenuation observed during controlled 72 hour-long weathering. Malathion had a limited and
surface layer type-dependent potential for reverse migration to the paint/sealant surface layer. Polyurethane
sealant seems to be particularly resistant to malathion, which is in line with the follow-on permeation studies,
as described in Section 6.3.
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6.3 Permeation Testing
Test specific summaries of the permeation test results for different types of test and control
materials are provided in the following sections for2-CEPS and malathion separately.
6.3.1 Permeation of 2-CEPS
At 72 hours after application of 2-CEPS onto LVAP top surface layers, approximately 1 to 2% of the
recovered chemical mass was detected in the SPE disk, with 95% detected in the extracted FSP or FSS
layers, and approximately 4% on the surface, as determined by wipe sampling (Table 6-1 and 6-2). This
study did not use a wipe to recover agent from the SS coupon (direct extraction only; amount recovered
below the LOQ) while the painted or sealed SS (PSS and SSS) coupons were not tested. The overall
chemical recovery for 2-CEPS was below 25% (compared to spike controls) of the initial surface
concentration which can be attributed to noticeable volatilization of this chemical from the paint or sealant
surface over the 72-h CT. This volatilization occurs as a process competing with the observed transportation
of 2-CEPS into and through paint and sealant layers.
Table 6-1. Permeation of 2-CEPS through FSP layers -chemical mass recovery results in LVAP components
and associated control samples at CT = 72 h
CT
SS
PSS
FSP
SPE
Chemical mass recovery [mg]
lnJ
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
Extraction
72 h
Average (n=3)
NT
<0.03
NT
NT
0.020 (J)
0.44
0.0052
SD
NT
NA
NT
NT
0.001 (J)
0.019
0.0025
PB
NT
<0.03
NT
NT
<0.03
<0.03
<0.03
Results reported at < 0.03 were below LOQ; (J) - estimated value, detected at below LOQ (S/N >10).; NT-not tested; NA - not applicable
SS: Stainless Steel; PSS: Painted Stainless Steel; FSP: Free Standing Paint [layer]; SPE: Solid Phase Extraction [-disk; below FSP]
Table 6-2. Permeation of 2-CEPS through FSS layers - chemical mass recovery results in LVAP components
and associated control samples at CT = 72 h
CT
rhi
SS
SSS
FSS
SPE
C
hemical mass recovery [mg]
LnJ
Wipe I Extraction
Wipe
Extraction
Wipe
Extraction
Extraction
72 h
Average (n=3)
See Table 6-1 (shared
SS coupons)
NT
NT
0.019 (J)
0.50
0.010 (J)
SD
NT
NT
0.0030 (J)
0.064
0.0019 (J)
PB
NT
NT
<0.03
<0.03
<0.03
Results reported at < 0.03 were below LOQ; (J) - estimated value, detected at below LOQ (S/N >10); NT-not tested; NA - not applicable
SS: Stainless Steel; SSS: Sealed Stainless Steel; FSS: Free Standing Sealant [layer]; SPE: Solid Phase Extraction [-disk; below FSS]
The low detections of 2-CEPS in the surface (wipe) fractions of the LVAP paint and sealant (Tables
6-1 and 6-2) corresponded to noticeable visual changes on the FSP and FSS layers, with no chemical
contamination droplet visually present after 72 hours after spiking as visible in Figure 6-3.
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Figure 6-3. 2-CEPS droplet on the surface of LVAP-FSP and LVAP-FSS layers immediately after spiking (a and b,
respectively) and after completion ofthe72-h chemical weathering period, with no visible chemical contamination
present on the surface (c and d, respectively).
Most notably, at CT=72 h, no 2-CEPS was detected in the associated extracted stainless-steel
control samples (Tables 6-1 and 6-2), indicating that over 99% reduction could be attributed to volatilization
of the chemical at normal indoor environmental conditions and one air exchange per hour.
The 2-CEPS permeation results for the three bulk materials and stainless steel as a nonporous
reference material are summarized in Table 6-3. Considering the negligible detection of 2-CEPS on SS after
72 h as part of the paint and sealant permeation test, the bulk material permeation tests were also
performed at shorter contact times (CT = 24 h); see Table 6-3 for results.
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Table 6-3. Permeation of 2-CEPS through building material surfaces-chemical mass recovery results in bulk
material and associated control samples at CT= 24 h and 72 h.
CT
rhi
SS
AS
HPL
VCP
C
hemical mass recovery [mg]
LnJ
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
24 h
Average
NT
1.47
0.64
0.16
1.1
0.0079 (J)
0.63
0.26
SD
NT
0.10
0.23
0.06
0.53
0.0028 (J)
0.24
0.041
PB
NT
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
72 h
Average
NT
<0.03
0.0003 (J)
0.0069(J)
0.022 (J)
0.0013 (J)
0.0008 (J)
0.12
SD
NT
NA
NA
0.0019 (J)
NA
0.0010 (J)
0.0003 (J)
0.02
PB
NT
<0.03
<0.03
0.0002 (J)
<0.03
0.000010(J)
<0.03
0.003 (J)
Results reported at < 0.03 were below LOQ; (J) - estimated value, detected at below LOQ (S/N >10); NT-not tested; NA - not applicable
AS: acrylic solid surface countertop; HPL: high-pressure decorative laminate; VCP: vinyl composition plank
After 24 hours, as calculated by Eq. 2 in section 4.5.1, recoveries of 2-CEPS (sum of wipe +
extraction recoveries) ranged from average 32 to 45%, with 71 to 99% of the recovered chemical detected
on the surface (Table 6-3). The high-pressure laminate surface was least permeable to 2-CEPS, with the
sublayer chemical fraction accounting for less than 1% of the total amount detected. Vinyl flooring had the
highest permeability to 2-CEPS, with approximately 29% of a chemical mass detected in the subsurface
layer, as determined by direct extraction (Table 6-3).
After 72 hours, the recoveries of 2-CEPS (sum of wipe + extraction recoveries) dropped to 0.3 to
5%, with nearly all the 2-CEPS remaining on the surface for HPL (95%) while nearly all 2-CEPS (> 96%)
was found within the bulk material for the AS and VCP materials (Table 6-3). These results are consistent
with what was observed after 24 h. Most of the 2-CEPS dissipates from the surface, predominantly by
evaporation.
Figure 6-4 shows surfaces of bulk materials after spiking and after simulated weathering under
normal environmental conditions. Figure 6-5 summarizes average recoveries and partitioning of target
chemicals from permeation tests for both LVAP systems (CT = 72 h) and three bulk materials (CT = 72 h
and 24 h).
35
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EPA/600/R-22/120
September 2022
Figure 6-4.2-CEPS droplet visible on the surface of the acrylic high-pressure laminate and vinyl composite plank
immediately after spiking (a, c, and e, respectively) and test materials 72 hours after spiking, with no visible
chemical contamination present on the surface (b, d, and f).
36
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EPA/600/R-22/120
September 2022
(A) Permeation of 2-CEPS, FSP versus FSS, CT = 72 h
O)
_E_
T3
0
>
O
O
0
O
1.5
¦ Extraction
o
(D
1.0
Wipe
(/)
03
0.5
0.0
AS
HPL
VCP
Figure 6-5. 2-CEPS permeation in LVAP-FSP and LVAP-FSS and bulk materials at CT = 72 h (A and C) and CT =
24 h (B); FSP and FSS: free-standing paint and sealant layers from LVAP permeation tests (wipe-sampled, then
extracted); SPE: solid-phase extraction disk from LVAP permeation tests (extracted only); bulk materials were
wipe sampled, then extracted. Dashed red lines represent recovered mass from control spike. Chemical mass
results for each layer are averages (n=3) ± 1 SD.
37
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EPA/600/R-22/120
September 2022
6.3.2 Permeation of Malathion
Malathion had limited ability to transfer into and through tested paint and sealant. At three days after
spiking onto a paint surface (CT = 72 h), 18% of total malathion mass recovered was detected in SPE, 10%
in the FSP layer and 72% remained on the surface (Table 6-4). The corresponding ratios for the sealant
were approximately 0.1% in SPE disk, 10% in the extracted FSS, and 90% on the sealant layer surface, as
determined by wipe sampling (Table 6-5). The sum of recoveries from SPE, layer, and remaining malathion
on the surface was 95% of the amount recovered from the stainless-steel coupon after 72 h. The same
number (95%) was calculated for the sealant material.
The transport of malathion through the LVAP-FSP layer was studied at four different time-points: 3,
6, 24 and 72 h (Table 6-4). A consistent trend of decreasing and increasing average recovery of malathion
among coupons versus permeable materials was apparent for the first 24 hours after application of
malathion onto painted surfaces or FSP layers placed over a SPE disk. After 24 hours, a reverse
phenomenon seemed to occur, where the chemical was diffusing back to the surface from the SPE and
paint layer deposits, as the relative proportion of surface available chemical (recovered from wipe samples)
had increased in the cumulative chemical mass recovered from wipes and extracted materials at 72 hours
after application (Table 6-4). The total chemical mass recoveries from permeation cells versus CS results
were equal at 95% for the combined components of LVAP-FSP and LVAP-FSS, indicating that malathion
was stable on the two test surfaces and - unlike 2-CEPS - was not prone to volatilization-related losses in a
simulated indoor environment.
Table 6-4. Permeation of malathion through FSP layers - chemical mass recovery results in LVAP components
and associated control samples
SS
PSS
FSP
SPE
u
Chemical mass recovery [mg]
[h]
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
Extraction
3 h
Average
1.80
0.23
1.40
0.56
1.71
0.15
0.21
SD
0.12
0.19
0.07
0.01
0.22
0.04
0.10
6 h
Average
1.60
0.12
1.63
0.40
1.50
0.14
0.29
SD
0.08
0.06
0.08
0.06
0.21
0.08
0.15
24 h
Average
1.62
0.24
1.21
0.58
1.25
0.28
0.65
SD
0.12
0.12
0.30
0.08
0.20
0.12
0.03
72 h
Average
1.67
0.32
1.55
0.47
1.42
0.20
0.35
SD
0.48
0.28
0.27
0.071
0.14
0.032
0.13
PB
Average
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
| Results reported at <0.03 were below LOQ \
38
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EPA/600/R-22/120
September 2022
Table 6-5. Permeation of malathion through FSS layers - chemical mass recovery results in LVAP components
and associated control samples
CT
SS
FSS
SPE
Chemical mass recovery [mg]
[h]
Wipe
Extraction
Wipe
Extraction
Extraction
72 h
Average
NT
2.1
1.41
0.20
0.0013
SD
NA
0.02
0.31
0.033
0.0008
PB
Average
<0.03
<0.03
<0.03
<0.03
<0.03
| Results reported at <0.03 were below LOQ; NT-not tested; NA - not applicable \
The average malathion mass transferred into bulk materials is provided in Table 6-6. The bulk
material recoveries (sum of wipe and extraction masses) were, on average 63% (VCP) to 97% (HPL) of the
CS, which demonstrates minimal natural dissipation from test surfaces at a CT = 72 h. For comparison, 2-
CEPS was either nondetected or present at less than 1 % of the initial surface loadings spiked onto bulk
materials (Table 6-3) and was nondetected on the surface of stainless steel. The highest percentage of
malathion that transferred into the material was 24% of the total for acrylic while this percentage was 15%
for both the laminate and vinyl.
Table 6-6. Permeation of malathion through building material surfaces-chemical mass recovery results in bulk
material layers and associated control samples at CT= 72 h.
CT
rhi
SS
AS
HPL
VCP
C
hemical mass recovery [m<
2]
LnJ
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
72 h
Average
NT
1.86
1.3
0.40
1.50
0.26
0.96
0.18
SD
NA
0.065
0.26
0.10
0.021
0.091
0.31
0.13
PB
NT
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
Results reported at <0.03 were below LOQ; NT-not tested; NA - not applicable
AS: acrylic solid surface countertop; HPL: high-pressure decorative laminate; VCP: vinyl composition plank
For both LVAP systems, the chemical analysis results agreed with visual characterizations of test
surfaces performed immediately after spiking and at 72-h-long malathion permeation study. Figure 6-6
shows visible malathion contamination present on paint and sealant surfaces assembled in LVAP cells. The
visual inspection tests also revealed a blistering of latex paint exposed to malathion (Figure 6-6c).
39
-------
Figure 6-6. Malathion droplet on the surface of FS and FSS layers of LVAP immediately after spiking (a and b,
respectively) and 72 hours after spiking (c and d, respectively).
For bulk materials, there was no visible malathion droplet on the surface of the acrylic surface
(Figure 6-7b) and high-pressure laminate (Figure 6-7d) at CT=72 h. However, chemical analysis results
indicated that chemical was mostly present in the surface-bound fraction collected via wiping, that was
performed prior to bulk material extraction of the entire coupon. The observed visual differences could be
related to the different surface-chemical interactions between surface materials and malathion, potentially
affecting the spread of the droplet.
EPA/600/R-22/120
September 2022
40
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EPA/600/R-22/120
September 2022
Figure 6-7. Malathion droplet visible on the surface of the acrylic high-pressure laminate and vinyl composite
plank immediately after spiking (a, c, and e, respectively) and test materials after 72 hours (b, d, and f,
respectively). Location of droplet after spiking identified by black arrow.
Figure 6-8 summarizes average recoveries and partitioning of malathion in permeation tests for
both LVAP systems and bulk materials (CT = 72 h).
41
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EPA/600/R-22/120
September 2022
SPE
Extraction
¦ Wipe
(b) Permeation of malathion, bulk materials, CT = 72 h
2
O)
F T
Mass recovered (i
o
o cn cn
¦ Extraction
¦ Wipe
AS
HPL
VCP
(a) Permeation of malathion, FSP versus FSS, CT = 72 h
2.5
FSP FSS
Figure 6-8. Malathion permeation in LVAP-FSP and FSS systems (a) and bulk materials (b) at CT = 72 h; FSP and
FSS: free-standing paint and sealant layers from LVAP permeation tests (wipe sampled, then extracted); SPE:
solid-phase extraction disk from LVAP permeation tests (extracted only); bulk materials were wipe-sampled, then
extracted. Dashed red lines represent mass recovered from control spike. Chemical mass results for each layer
are averages (n=3) ± 1 SD.
6.3.3 Permeation Comparisons 2-CEPS Versus Malathion
Overall, the surface permeation patterns of 2-CEPS and malathion were very different. Figure 6-9
shows a summary of the chemical fraction distribution in wiped surface fractions, extracted subsurface
layers, and - for LVAP cells - extracted SPE disks representing porous subsurface below the FSP and FSS
layers. Except for HPL material, 2-CEPS was detected primarily in the extractable fractions (minimal on the
surface), while malathion was detected primarily on the surface.
42
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EPA/600/R-22/120
September 2022
¦
(a) 2-CEPS permation: chemical fraction distribution
in LVAP components and bulk materials, CT = 72 h
Surface fraction i Subsurface layer (bulk extraction) ¦ Porous subsurface (SPE extraction)
FSS
FSP
VCP
HPL
AS
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
¦
(b) Malathion permation: chemical fraction distribution
in LVAP components and bulk materials, CT = 72 h
Surface fraction i Subsurface layer (bulk extraction) ¦ Porous subsurface (SPE extraction)
FSS
FSP
VCP
HPL
AS
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Figure 6-9. Average percent distribution of the total 2-CEPS (a) and malathion (b) mass detected in LVAP
components and bulk materials during permeation testing, CT=72 h. FSP and FSS: free-standing paint and
sealant layers from LVAP permeation tests (wipe-sampled, then extracted); SPE: solid-phase extraction disk from
LVAP permeation tests (extracted only); bulk materials were wipe-sampled, then extracted.
43
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EPA/600/R-22/120
September 2022
Material impacts of malathion on free-standing layers were further studied using FESEM.
Microscopy images of malathion-exposed FSP and FSS layers are shown in Figure 6-10. Bulk material-
malathion surface interactions were not included. The higher permeation of malathion through FSP layers
was linked to the blistering of paint observed during a visual inspection of surfaces (Figure 6-6c) and
confirmed by FESEM analyses (Figure 6-10a). No significant blistering or "bubbling" was observed during a
visual inspection of malathion-exposed FSS layers (Figure 6-6d). However, microscopy indicated some
structural changes that appeared to be a result of expanding and shrinking, resulting in the uneven, wrinkled
appearance of the edge of the malathion-exposed areas (Figure 6-10b).
Figure 6-10. FESEM images of malathion-exposed FSP (a) and FSS (b) layers at different magnifications. Contact
time of malathion was 72 h for both layers; remaining chemical droplet was removed from surfaces before testing
using a cotton swab. Images of carbon-coated layers were taken using 15.0 kV accelerating voltage at
magnifications ranging from 24 x to 3.53k x.
Coupons were vacuumed in a desiccator with an attached carbon filter in chemical hood to volatilize
any residual malathion on coupons prior to sputter coating and FESEM analysis under vacuum. The
"bubble"-like appearance of paint blisters - as shown in Figure 6-10a - was likely due to thinning of the paint
at the location of the blister, and due to changes in elasticity of the paint that was then lifted from the SEM
stub surfaces during vacuum microscopy analyses. These observed structural changes are in line with
findings of post-sampling visual inspection of FSP layers, where surface perforations - hole or multiple
smaller holes - were observed after sampling of malathion (the perforations were not visible before wipe
sampling). An example malathion-exposed FSP layer with the visible hole after sampling is shown in Figure
6-11.
44
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EPA/600/R-22/120
September 2022
mm
M
I %
i
Figure 6-11. Postsampling perforation of malathion-exposed FSP layer; FSP postsampling in the LVAP (a) and
prior extraction (b).
Like FSP layers, most of the PSS surfaces showed blistering and damage to the paint layer after
sampling (swabbing) of malathion (Figure 6-12), suggesting that exposure to malathion significantly affected
the structural integrity of both types of acrylic-latex layers, i.e., free layers placed on the top of porous SPE
and painted directly over the nonporous stainless-steel material.
Figure 6-12. Blistering of paint layers observed after 72-h-long exposure of PSS to malathion, with a chemical
droplet still present on the surface (a) and PSS surface after surface sampling, with visible stainless steel exposed
in the previously blistered area (b).
The visual inspection of PSS surfaces did not indicate any material changes, and no perforations of
sealant layers were observed after the surface sampling or extraction of polyurethane coated stainless steel
exposed to malathion. Noteworthy is that no damages of paint or sealant layers were observed for 2-CEPS-
contaminated coupons (Figure 6-3); consequently, 2-CEPS exposed materials were not analyzed using
FESEM.
45
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EPA/600/R-22/120
September 2022
High-magnification FESEM analyses of procedural blank paint and sealant layers (materials that
were not exposed to malathion) suggested a higher surface pore morphology of FSP versus FSS layers
(Figure 6-13).
Figure 6-13. FESEM images of nonexposed FSP (a) and FSS (b) layers. Images of carbon-coated layers were taken
using 15.0 kV accelerating voltage. Images of carbon-coated layers were taken using 15.0 kV accelerating voltage
at magnifications ranging from 436 x to 33,600 x.
Overall, the permeation of target chemicals to the sublayer disk was believed to be due to the
combined effects of the chemical volatility that governed the surface stability (persistence) of 2-CEPS and
malathion, the surface layer permeability, and the chemical resistance of the surface layer to target
chemicals.
46
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EPA/600/R-22/120
September 2022
6.4 Decontamination Testing
All decontamination experiments were performed against permeated chemicals using either LVAP
or standalone bulk material coupons (acrylic, laminate, and vinyl). LVAP allowed for a multilayered
measurement of residual chemical contamination in the subsurface porous layer (SPE) and top paint and
sealant layer following surface decontamination. For bulk material testing, postdecontamination sampling
allowed for the measurement of residual chemical masses on the coupon surface and in the subsurface
layer. Figure 6-14 shows an example of different types of materials subjected to a single application of liquid
decontaminant, followed by an overnight dwell time. This baseline decontamination procedure using
concentrated germicidal bleach as decontaminant was generally highly efficacious for decontamination of 2-
CEPS and malathion from the LVAP system, with results described in Section 6.4.1. Malathion
decontamination from LVAP-FSP systems was lower (Section 6.4.2), and modifications to the baseline
decontamination procedure were evaluated with results given in Section 6.5.
Figure 6-14. Example of baseline decontamination procedure. Shown are decontamination of malathion-
contaminated LVAP-FSP, LVAP-FSS, and VLP at CT=72 h (a, d, g, respectively) using concentrated germicidal
bleach (b, e, h), followed by overnight dwell of the decontaminant (DT=18 h) (c, f, i).
47
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EPA/600/R-22/120
September 2022
6.4.1 Baseline Decontamination - 2-CEPS
The efficacy of the baseline decontamination procedure, one application of concentration of
concentrated germicidal bleach, followed by an overnight (18-h) DT of the decontaminant, is given in Tables
6-7 through 6-11. Figures 6-15 and 6-16 summarize 2-CEPS and malathion distribution in the chemical
fraction associated with different types of LVAP components, before decontamination treatment and after
decontamination. Positive controls were wiped and extracted at the same time as the LVAP components.
The baseline decontamination procedure resulted in high (average DE> 95%) reduction of 2-CEPS
in decontaminated LVAP-FSP and LVAP-FSS samples (TCs) versus nontreated controls (PCs) (Table 6-7
and 6-8). However, this significant reduction is associated with only a small fraction of 2-CEPS remaining at
the start of the baseline decontamination due to the significant volatilization of 2-CEPS from test surfaces,
estimated as 75 to 99% depending on the type of material. The volatilization-related attenuation of 2-CEPS
from LVAP systems was discussed in more detail in Sections 6-2 and 6-3.
Table 6-7. Decontamination baseline of 2-CEPS from LVAP-FSP components and chemical mass recovery
results for associated control samples
SS
PSS
FSP
SPE
Sample type
Chemical mass recovery [mg]
x DE
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
Extraction
[% +1 SD]
Decontamination Procedure: 1 application of concentrated germicidal bleach, DT = 18 h
TC
Average
<0.03
NT
<0.03
0.057 (J)
<0.03
0.015
0.003 (J)
95.7 ±1.0
SD
NA
NA
NA
0.006
NA
0.003
0.001
PC
Average
<0.03
NT
0.020 (J)
0.87
0.003 (J)
0.42
0.0054 (J)
SD
NA
NA
0.005
0.08
0.001
0.030
0.002
PB
Average
<0.03
NT
<0.03
<0.03
<0.03
<0.03
<0.03
Results reported at <0.03 were below LOQ; (J) - estimated value, detected at below LOQ (S/N >10); NT- not tested; NA - not applicable
Table 6-8. Decontamination baseline of 2-CEPS from LVAP-FSS components and chemical mass recovery
results for associated control samples
SS
sss
FSS
SPE
Sample type
Chemical mass recovery [mg]
x DE
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
Extraction
[% ± 1 SD]
Decontamination Procedure: 1 application of concentrated germicidal bleach, DT = 18 h
TC-V
Average
<0.03
NT
<0.03
0.0026 (J)
<0.03
0.014 (J)
<0.03
97.0 ± 3.5
SD
NA
NA
NA
0.001
NA
0.01
NA
PC-V
Average
<0.03
NT
0.0035 (J)
0.61
0.011 (J)
0.41
0.008 (J)
SD
NA
NA
0.001
0.05
0.002
0.05
0.009
PB
Average
<0.03
NT
<0.03
<0.03
<0.03
<0.03
<0.03
Results reported at <0.03 were below LOQ; (J) - estimated value, detected at below LOQ (S/N >10); NT- not tested; NA
- not applicable
48
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EPA/600/R-22/120
September 2022
Recoveries from the SPE disk, paint/sealant layer, and surface wipe are shown in Figure 6-15a.
(a) 2-CEPS: FSS and FSP Baseline
Decontamination - Chemical Mass Recovery
0.50
OJO
0.40
E
-—-
>
s_
0)
0.30
>
o
u
0)
0.20
en
l/)
to
ro
0.10
0.00
FSS TC
Wipe I Extraction I SPE
FSS PC FSP TC
Sample Type
FSP PC
(b) 2-CEPS: FSS and FSP Baseline
Decontamination - Chemical Mass Fractions
¦ Wipe I Extraction ¦ SPE
FSP PC
FSP TC
FSS PC
FSS TC
0% 20% 40% 60% 80% 100%
Chemical amount detected in LVAP components (%)
Figure 6-15. Decontamination baseline for 2-CEPS from FSS and FSP layers compared to associated positive
control samples; TC - decontaminated test sample; PC - non-decontaminated positive control sample. Chemical
mass recovery results (a) for each layer are averages (n=3), and chemical fraction results (b) are relative percent
contributions of each fraction to the total chemical mass detected in non-decontaminated and decontaminated
samples.
49
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EPA/600/R-22/120
September 2022
Figure 6-15b shows 2-CEPS chemical mass fraction distribution in decontaminated and non-
decontaminated LVAP samples. Analysis of chemical amounts detected in decontaminated TC samples
showed no detection of 2-CEPS on the surface or in the top surface layers that were sampled as part of the
surface wipe. The extracted FSP layer had a higher relative reduction of extractable chemical mass than
FSS, with a 3% and 13% reduction in 2-CEPS concentration in the SPE disk, respectively. However, the
relative contribution of the SPE-bound chemical amount to the total chemical detected increased slightly
(4.4%) in the decontaminated paint layer, when compared to the nontreated PC. The decontaminated
LVAP-FSS had no detection of 2-CEPS in the SPE (Figure 6-15b).
Decontamination tests of bulk materials contaminated with 2-CEPS were not performed, as
volatilization-related losses rendered concentrations of this chemical on the surface to below LOQ levels
after 72-h-long CT under normal indoor environmental conditions (see Table 6-3, Figure 6-5c; Section
6.3.1).
6.4.2 Baseline Decontamination - Malathion
Decontamination of malathion that transferred through the LVAP-FSP paint layer into SPE was not
effective when using one application of concentrated germicidal bleach (DT = 18 h). The average reduction
of total chemical mass in the decontaminated LVAP-FSP samples was just above 50% (average DE = 54 ±
8.7; Table 6-9). The decontamination occurred mostly on the paint surface, with less than 20% relative
reduction of chemical concentration in the SPE (Table 6-9, Figure 6-16b). The average total reduction of
malathion in the LVAP-FSS tests - for which no appreciable permeation of malathion to the SPE was
observed - was 99% (average DE = 99 ± 0.77%; Table 6-10), with no malathion detections, post
decontamination, in the wipe-sampled surface of the sealant. The average reduction in the malathion
amount in the extracted sealant fraction of decontaminated TCs was over 0.9 mg - or 90% - when
compared to nondecontaminated PCs (Figure 6-16a). The extractable sealant layer chemical fraction was
the only component of the LVAP-FSS with trace-level detections of malathion (Table 6-10, Figure 6-16b).
The sealant-based test had overall lower recovery of malathion than the paint-based decontamination
experiments, with average 1 mg versus 1.4 mg malathion recovered from nonexposed LVAP-FSS and
LVAP-FSP samples, respectively (Figure 6-16a), corresponding to an average 47 and 67% chemical
recovery, when compared to the associated CS results. Since no analytical problems with spiking,
extraction, or instrumental analysis were identified for FSS samples and high decontamination efficacy was
reported consistently among replicates, no further optimization of decontamination conditions was deemed
necessary.
Table 6-9. Decontamination baseline of malathion from LVAP-FSP components and chemical concentration
results for associated control samples
SS
PSS
FSP
SPE
Sample type
Chemical mass recovery [mg]
x DE
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
Extraction
[% ± 1 SD]
Decontamination Procedure: 1 application of concentrated germicidal bleach, DT = 18 h
TC
Average
<0.03
NT
0.24
0.20
0.24
0.19
0.23
54 ± 8.7
SD
NA
NA
0.03
0.08
0.07
0.04
0.004
PC
Average
1.86
NT
0.67
0.51
0.86
0.31
0.27
SD
0.10
NA
0.27
0.19
0.13
0.07
0.08
PB
Average
<0.03
NT
<0.03
<0.03
<0.03
<0.03
<0.03
Results reported at <0.03 were below LOQ; (Jj - estimated value, detected at below LOQ (S/N >10); NT- not tested; NA - not applicable
50
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EPA/600/R-22/120
September 2022
Table 6-10. Decontamination baseline of malathion from LVAP-FSS components and chemical concentration
results for associated control samples
SS
sss
FSS
SPE
Sample type
Chemical mass recovery [mg]
xDE
Wipe | Extraction
Wipe
Extraction
Wipe
Extraction
Extraction
[% ± 1 SD]
Decontamination Procedure: 1 application of concentrated germicidal bleach, DT = 18 h
TC
Average
0.23 (J)
0.02 (J)
<0.03
0.0089 (J)
<0.03
99 ± 0.77
SD
NA
0.03
NA
0.0063
NA
PC
Average
See Table 6-9
1.51
0.10
0.91
0.090
0.0005 (J)
SD
0.29
0.01
0.31
0.015
NA (S)
PB
Average
<0.03
<0.03
<0.03
<0.03
<0.03
Results reported at <0.03 were below LOQ; (J) - estimated value, detected at below LOQ (S/N >10); NT- not tested; NA - not applicable
O)
2.0
1.5
1.0
0.5
0.0
(a) Malathion: FSS and FSP Decontamination
baseline - chemical mass recovery
Wipe i Extraction ¦ SPE
< LOQ
FSS TC
I
FSS PC FSP TC
Sample type
FSP PC
(b) Malathion: FSS and FSP Decontamination
baseline - chemical mass fractions
¦ Wipe ¦ Extraction ¦ SPE
FSP PC
CD
Q.
>*
H—<
FSP TC
_(D
Q_
E
CO
w
FSS PC
FSS TC
0% 20% 40% 60% 80% 100%
Mass recovery (mg)
Figure 6-16. Decontamination baseline results for malathion from LVAP-FSS and LVAP-FSP components
compared to associated positive control samples; TC - decontaminated test sample; PC - non-decontaminated
positive control sample. Chemical mass recovery results for each layer are averages, and chemical fraction
results are relative percent contributions of each fraction to the total chemical mass recovered in non-
decontaminated and decontaminated samples.
51
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EPA/600/R-22/120
September 2022
The higher efficacies of decontamination obseived for LVAP-FSS are likely related to the lower
permeability of the sealant layer to malathion, with a higher relative amount of chemical fraction available for
surface decontamination. Additionally, based on the analysis of the FESEM images of bleach exposed paint
and sealant layers (Figure 6-17), the FSS appeared to be less permeable to bleach than FSP, with larger
and more pronounced salt crystal formations visible on the surface of the sealant after overnight drying
corresponding to decontamination DT (18 h) (Figure 6-17b). The higher amount of concentrated
hypochlorite solids present on the surface of the sealant was likely one of the surface-dependant
experimental variables contributing to higher decontamination efficiency observed for FSS layers.
Figure 6-17. Surface of concentrated germicidal bleach-exposed FSP (a) and FSS (b) layers after overnight drying
of decontaminant; surfaces were not contaminated before application of bleach. Images of carbon-coated layers
were taken using 15.0 kV accelerating voltage; magnification levels are shown in each image.
After completion of the LVAP decontamination experiments, one application of concentrated
germicidal bleach with overnight drying - was used for the decontamination of malathion from bulk building
materials. The procedure resulted in the degradation of malathion to below detectable levels in both surface
and subsurface of the decontaminated test materials, corresponding to average DE > 98%. The material-
specific results for decontamination of malathion are given in Table 6-11.
Table 6-11. Decontamination baseline of bulk materials with malathion and chemical mass results for associated
control samples
SS
AS
HPl
VCP
Sample type
Chemical mass recovery [mg]
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
Wipe |
Extraction
Decontamination Procedure: 1 application of concentrated germicidal bleach, DT = 18 h
TC
Average
NT
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
SD
NA
NA
NA
NA
NA
NA
PC
Average
2.06
NT
1.04
0.41
1.10
0.63
0.87
0.78
SD
0.18
NA
0.32
0.13
0.58
0.28
0.41
0.10
PB
Average
NT
NT
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
x DE (%)
NA
>
98
>98
>98
Results reported at <0.03 were below LOQ; NT-not tested; NA - not applicable
AS: acrylic solid surface countertop; HPL: high-pressure decorative laminate: VCP: vinyl composition plank
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EPA/600/R-22/120
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Concentrated germicidal bleach was compatible with all bulk materials tested in this study, with no
visible damage or discoloration to any test materials after decontamination. Like the LVAP experiments,
dried out sodium hypochlorite crystals were visible on test surfaces with overnight drying of bleach (Figure
6-18). FESEM analyses were not performed for bulk material testing.
Figure 6-18. Surface of bulk materials after decontamination of malathion using two applications of concentrated
germicidal bleach; vinyl plank flooring material, VPL (a); acrylic countertop surface material (b), and high-
pressure laminate countertop material, HPL (c).
6.5 Modified Decontamination Processes
Changes to the baseline decontamination approach were considered only for materials that had
measurable amounts of the targeted chemical remaining on the surface after the single application of
concentrated germicidal bleach with a DT=18 h.
6.5.1 Decontamination Modifications - 2-CEPS
The 2-CEPS mass recoveries following decontamination with bleach (DT = 18 h) from the LVAP-
FSP and LVAP-FSS systems yielded amounts near the LOQ (Tables 6-7 and 6-8, respectively, Section
6.4.1), attributed to the high degree of volatilization of this chemical after a 72-hour contact time of 2-CEPS
with the FSP and FSS layers (as also observed in the permeation tests described in Section 6.3.1) plus the
effective degradation (95.7% decontamination efficacy) of 2-CEPS by bleach (DT=18 h). Further
modifications to the decontamination of these materials were not considered so that research could focus on
more difficult-to-clean materials that were contaminated with malathion.
6.5.2 Decontamination Modifications - Malathion
Recoveries for malathion from the LVAP sealant wipe and extraction following the decontamination
with bleach (DT=18 h) yielded amounts near or below the LOQ (Table 6-10. Section 6.4.1). A single
application of bleach resulted in a 99% decontamination efficacy. Therefore, modifications to the baseline
decontamination approach using bleach were not considered for this sealant. Instead, the effectiveness of
other decontamination procedures was tested for the simulated painted surfaces. The first step was testing
of the efficacy of a repeated application of the same concentrated germicidal bleach, followed by testing of
different specialized and COTS decontaminants, with single and two-step applications tested in parallel to
each other. All decontamination solutions used in this phase of this study were either hypochlorite- or
hydrogen peroxide-based oxidizers (Table 3-6),
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Both classes of decontaminants were previously reported as chemistries effective for surface
degradation of both malathion and structurally similar CWAs such as VX [3,4], Selected decontaminants
(Splash-Less Bleach and EasyDECON DF200) contain surfactants and other active ingredients (Table 3-6)
that are intended to improve decontamination efficacy of chemical (and biological) agents. These additives
were considered as potentially advantageous for decontamination of malathion that (partially) permeated
into and through painted surfaces. Table 6-12 shows results for each decontamination method tested for
improved efficacy of malathion degradation from LVAP-FSP components. The corresponding
decontamination baseline results established in the initial experiments were provided in Table 6-9 (Section
6.4.1.).
Table 6-12. Modified decontamination methods for LVAP-FSP components contaminated with malathion and
chemical concentration results for associated control samples
SS
PSS
FSP
SPE
Sample type
Chemical mass recovery [mg]
xDE
Wipe
Extraction
Wipe
Extraction
Wipe
Extraction
Extraction
[% ± 1 SD]
Modified Decontamination Procedure #1:2 applications of concentrated germicidal bleach, D
T = 2 h +18 h
TC
Average
NT
NT
0.35
0.38
0.23
0.08
0.11
70 ±26
SD
NA
NA
0.17
0.07
0.17
0.06
0.074
PC
Average
NT
NT
0.86
0.59
0.93
0.18
0.24
SD
NA
NA
0.15
0.08
0.10
0.08
0.12
PB
Average
NT
NT
<0.03
<0.03
<0.03
<0.03
<0.03
Modified Decontamination Procedure # 2:1 application of Splash-Less Bleach, DT = 18 h
TC
Average
0.18
NT
0.64
0.93
0.218
0.67
0.83
16 ±7.0
SD
0.05
NA
0.07
0.02
0.119
0.47
0.50
PC
Average
1.96
NT
0.57
1.17
0.55
0.48
0.97
SD
0.16
NA
0.16
0.14
0.21
0.12
0.28
PB
Average
<0.03
NT
<0.03
<0.03
<0.03
<0.03
<0.03
Modified Decontamination Procedure # 3:2 applications of Splash-Less Bleach, DT = 2 h +18 h
TC
Average
0.03 (J)
NT
0.44
0.74
0.23
0.47
0.41
45 ±17
SD
NA(S)
NA
0.24
0.15
0.19
0.27
0.35
PC
Average
1.96
NT
0.57
1.17
0.55
0.48
0.97
SD
0.16
NA
0.16
0.14
0.21
0.12
0.28
PB
Average
<0.03
NT
<0.03
<0.03
<0.03
<0.03
<0.03
Modified Decontamination Procedure # 4:1 applications of EasyDECON DF200, DT = 18 h
TC
Average
0.005 (J)
NT
0.15
1.44
0.26
0.79
0.38
9.7 ±0.63
SD
0.0032
NA
0.11
0.22
0.03
0.07
0.12
PC
Average
0.90
NT
0.42
1.33
0.49
0.50
0.63
SD
0.23
NA
0.23
0.26
0.31
0.20
0.28
PB
Average
<0.03
NT
<0.03
<0.03
<0.03
<0.03
<0.03
Modified Decontamination Procedure #5:2 applications of EasyDECON DF200
DT = 2 h +18 h
TC
Average
<0.03
NT
0.30
1.12
0.20
0.15
0.76
37 ± 9.9
SD
NA
NA
0.20
0.25
0.07
0.19
0.13
PC
Average
0.90
NT
0.42
1.33
0.49
0.50
0.63
SD
0.23
NA
0.23
0.26
0.31
0.20
0.28
PB
Average
<0.03
NT
<0.03
<0.03
<0.03
<0.03
<0.03
Results reported at <0.03 were below LOQ; (Jj - estimated value, detected at below LOQ (S/N >10); NT- not tested; NA -
not applicable
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Only one out of five procedures tested outperformed a single application of concentrated germicidal
bleach (Table 6-11; included in Figure 6-19), namely, the procedure using a double application of the same
concentrated germicidal bleach (CGBx2 on Figure 6-19). However, the intra-test variation between the
decontaminated subset of LVAP-FSP components was relatively high (RSD = 70%), with two out of three
replicate samples showing a DE of approximately 50% and one LVAP-FSP showing DE > 98%, with no
detections of malathion in subsurface layer and below LOQ detections in SPE and surface layers. The
analytical results were confirmed by the repreparation of samples from extracts and reanalysis. No visual
differences were observed for replicate LVAP-samples at the end of the decontaminant dwell time or during
sampling or extraction. A Student's f-test confirmed that a statistically significant difference could not be
determined (p<0.05) between the efficacies recorded with a single application of the concentrated
germicidal bleach versus the double application of the same product (p=0.71).
Decontamination effiacy of malathion from FSP-LVAP for
single and double decontaminant applications
100%
80%
60%
40%
20%
0%
Type of decontaminant and decontamination procedure
Figure 6-19. Average decontamination efficacy of malathion from FSP-LVAP for all single- and multistep
decontamination approaches tested; results are shown as x %DE ± 1 SD; CGB - concentrated germicidal bleach;
SLB - Splash-Less Bleach; ED - EasyDECON DF200; 1x and 2 x - procedure using one or two applications of
decontaminant, respectively.
A two-step application of Splash-Less Bleach and the procedure using two applications of
EasyDECON DF200 resulted in moderate decontamination efficacies (average DEs <50%; Table 6-12,
Figure 6-19), which were similar to a single application of concentrated germicidal bleach, suggesting that
the presence of surfactants in the Splash-Less Bleach does not improve overall DE in comparison to the
germicidal bleach. Further, a change in oxidizer from sodium hypochlorite to activated hydrogen peroxide in
EasyDECON DF200 did not improve overall efficacy either. The oxidizer concentration was highest in
concentrated germicidal bleach (65,000 parts per million (ppm) free available chlorine (FAC)), followed by
Splash-Less Bleach (34,500 ppm FAC), followed by EasyDECON DF200 (hydrogen peroxide concentration
in the finished blend approximately 3.6%). A direct comparison of the impact of oxidant chemistries and
£
j
X
1
CGB (1x) CGB (2x) SLB (1x) SLB (2x) ED (1x) ED (2x)
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EPA/600/R-22/120
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concentrations should also consider the reaction mechanism on a molar basis which may be oxidant-
dependent.
The reapplication of a decontaminant improved the overall decontamination efficacy with an
average increase of 29% and 27% for the Splash-Less Bleach and EasyDECON DF200, respectively
(Figure 6-19). A Student's Mest indicated that this apparent improvement in efficacy values between a
single and double application is insignificant considering calculated p-values of 0.09 and 0.16 for the
pairwise comparisons of single versus double application of the Splash-Less Bleach and EasyDECON
DF200, respectively.
A detailed analysis of the LVAP component-specific chemical mass reductions shows that
degradation occurred mainly at the surface-bound non-permeated fraction (Figure 6-20). Two applications of
concentrated germicidal bleach resulted in the overall largest decrease in chemical mass that was observed
in all chemical components.
Malathion mass change in decontaminated LVAP-FSP
components
TC ED (2x) TCED(lx) TC SLB (2x) TCSLB(lx) TC CGB (2x) TC CGB (lx)
3
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EPA/600/R-22/120
September 2022
the "negative" mass changes for the FSP layer and the SPE disk suggest degradation of malathion but are
also associated with high SDs. Hence, within the limits of this study, there is no clear evidence that any of
the tested decontaminants (germicidal concentrated bleach, Splash-Less Bleach, and EasyDECON DF200)
and decontamination approaches (single versus double application) degrades malathion that permeated
into the FSP and farther into the SPE disk. All degradation of malathion is limited to malathion on the
surface. A double application of a decontaminant appeared to improve the decontamination of the surface
(Table 6-12; Figure 6-20). However, these improvements in comparison to a single application were not
statistically significant. Concentrated germicidal bleach was shown to effectively degrade malathion from
FSP surfaces without apparent changes in the chemical permeation between surface and sublayers of
treated samples (CGB (1x) and (2x) Figure 6-20).
The effect of concentrated germicidal bleach on material properties of paint and sealant layers was
studied by FESEM. Figures 6-21 and 6-22 show microscopic images of FSP and FSS layers exposed to
germicidal bleach with sodium hypochlorite solid formed on the decontaminated surface after overnight
exposure, compared to corresponding laboratory blank coupons. Bleach-exposed FSS and FSP layers
have both abundant crystals and amorphous solids. The paint layers seemed to be more structurally
affected by bleach (Figure 6-21). However, the topography of the bleach-exposed polyurethane sealant has
visually changed as well (Figure 6-22).
Figure 6-21. Surface of bleach-exposed FSP surfaces (a) and/or nonexposed laboratory blank FSP layers (b)
layers after overnight drying of decontaminant; surfaces were not contaminated before application of the regular
germicidal bleach. Images of carbon-coated layers were taken using 15.0 kV accelerating voltage; magnifications
levels are shown in each image.
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EPA/600/R-22/120
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Figure 6-22. Surface of bleach-exposed FSS surfaces (a) and corresponding laboratory blanks, or nonexposed
FSS layers (b) layers after overnight drying of decontaminant; surfaces were not contaminated before application
of the regular germicidal bleach. Images of carbon-coated layers were taken using 15.0 kV accelerating voltage;
magnifications levels are shown in each image.
Bleach treatment of FSP and FSS layers previously contaminated with malathion showed similar
salt formations, with visible agglomerations of solids over the contamination hot spots (Figure 6-23). Bands
of sodium hypochlorite solids were also visible near the edge of paint blisters that appeared to be
compromised by chemical exposure to malathion. That structural damage to the paint was likely allowing
easier migration of bleach into the paint, layer itself as well as into SPE. However, the interaction of
malathion and bleach with paint layers over a porous substrate was not studied during the microscopy
portion of this work - all microscopy experiments were performed using FSP and FSS materials assembled
onto metal stubs (Section 3.9). Additional experiments, including FESEM analyses of actual building
surfaces treated with different types of oxidizers - with and without surfactants - may assist in a better
understanding of material-chemical-decontaminant interactions that happen in real life.
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EPA/600/R-22/120
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Figure 6-23. Surface of malathion and bleach-exposed FSP (a) and FSS surfaces (b) after 72-h-long exposure to
chemical, followed by overnight drying of decontaminant. Images of carbon-coated layers were taken using 15.0
kV accelerating voltage; magnifications levels are shown in each image.
A comparison of results from the malathion decontamination from LVAP-FSP (Figure 6-16) to
decontamination efficacy results for the reference material (stainless steel) showed that decontamination
efficacies of nonporous stainless steel were significantly higher than the decontamination for LVAP tests for
which average DE values ranged from 91% to > 99.4% (Figure 6-24) and did not vary significantly between
the type of decontaminant and decontamination procedures tested with calculated Student's p-values
always greater than 0.05 except for the single application of Splash-Less Bleach against all other
approaches.
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EPA/600/R-22/120
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Decontamination effiacy of malathion from SS reference material
for single- and multistep decontamination approaches tested
120%
100%
80%
60%
40%
20%
0%
CGB (1x) CGB (2x) SLB(1x) SLB (2x) ED (1x) ED (2x)
Type of decontaminant and decontamination procedure
Figure 6-24. Average cumulative decontamination efficacy of malathion from stainless steel for all single- and
multistep decontamination approaches tested; results are shown as x %DE ± 1 SD; CGB - concentrated
germicidal bleach; SLB - Splash-Less Bleach; ED - EasyDECON DF200; 1x and 2 x - procedure using one or
two applications of decontaminant, respectively; NT - not tested.
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Summary
The main objectives were to develop testing equipment and analytical methods to study the
transport of selected chemicals into the subsurface layers of permeable building materials at conditions
mimicking indoor environmental conditions. For that purpose, permeation cells were developed, and tests
were performed to determine the efficacy of decontamination technologies and procedures for degradation
of chemicals that have (partially) absorbed into permeable building materials. Modifications of
decontamination solution/solutions were considered to address potential limitations of traditional
techniques/unmodified decontaminants.
The main findings of this study are:
I. Material properties of building materials - permeability, porosity, chemical resistance, type of the
surface coating - and physicochemical properties of chemicals affect the chemical absorption and
permeation mechanisms. Polyurethane sealant coating was found to be relatively nonpermeable by
tested chemicals when compared to latex-acrylic paint.
II. Volatilization related losses can be a significant factor contributing to the natural attenuation of
chemicals from building materials. In the absence of a chemical decontaminant or other types of
degradation, indoor environmental conditions should be considered essential factors contributing to
surface dissipation of chemicals.
III. Chemical oxidation-based degradation occurs mainly on surfaces, with no or very limited
decontamination of subsurface layers observed for decontamination procedures tested, with volatile
compounds being rendered to nondetectable levels with a one-step application of concentrated
germicidal bleach. For noncoated building materials, 2-CEPS dissipated from indoor surfaces due
to volatilization (chemical-surface contact time of 72 h). For more surface-persistent malathion, the
highest overall degradation from both surface and subsurface layers of building materials was
achieved by using two applications of concentrated germicidal bleach, followed by an overnight
dwell time. Other decontamination procedures using two different types of oxidation chemistries
with the addition of surfactants - had lower degradation efficacies for permeated malathion.
IV. Current and past research indicates that the use of stronger oxidizers appears to be a better
decontamination option for permeated chemicals. However, decontaminant corrosivity - and overall
material compatibility with the surface materials and underlaying substrate - should be considered
during the selection of decontamination procedure. Based on visual assessments of test materials,
and confirmed by microscopy analyses, both chemical and decontaminant applications can affect
material properties of the surface coatings.
This study provides a detailed understanding of the permeation of chemicals into indoor building
materials and building material surrogates covered with custom-made layers of different commercial
coatings. This research contributes to the understanding of the material-, chemical- and decontaminant-
specific effects on the degradation of permeated chemicals for several oxidation-based methods.
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References
1. U.S. EPA. Evaluation of Household or Industrial Cleaning Products for Remediation of Chemical
Agents. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-11/055, 2011.
2. Stone H, See D, Smiley A, Ellingson A, Schimmoeller J, Oudejans L. Surface decontamination for
blister agents Lewisite, sulfur mustard and agent yellow, a Lewisite and sulfur mustard mixture. J
Hazard Mater. 2016; 314, 59-66.
3. Oudejans L, Mysz A, Gibb Snyder E, Wyrzykowska-Ceradini B, Nardin J, Tabor D, Starr J, Stout D 2nd,
Lemieux P. Remediating indoor pesticide contamination from improper pest control treatments:
Persistence and decontamination studies. J Hazard Mater. 2020; 122743.
4. Oudejans, L, Wyrzykowska-Ceradini B, Morris E, Korff, A (2018) Assessment of Decontamination
Solution Application Methods for Decontamination of Surfaces Contaminated with Pesticides. U.S.
Environmental Protection Agency, Washington, DC, EPA/600/R-17/394, 2018.
5. Gorzkowska-Sobas A. (2013) Chemical warfare agents and their interactions with solid surfaces.
Norwegian Defence Research Establishment (FFI) FFI-rapport 2013/005741238. ISBN 978-82-464-
2223-7
6. U.S. EPA. (2016) Fate and Transport of Chemical Warfare Agents VX and HD across a Permeable
Layer of Paint or Sealant into Porous Subsurfaces. U.S. EPA Office of Research and Development,
Washington, DC, EPA/600/R-16/173, 2016.
7. ASTM D823-95 "Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and
Related Products on Test Panels Method Practice E -Hand-Held Film Application"
8. ASTM D3924-16 "Standard Specification for Standard Environment for Conditioning and Testing Paint,
Varnish, Lacquer, and Related Materials"
9. ASTM E376 "Standard Practice for Measuring Coating Thickness by Magnetic-Field or Eddy-Current
(Electromagnetic) Testing Methods"
10. ASTM D1005 "Standard Test Method for Measurement of Dry-Film Thickness of Organic Coatings
Using Micrometers"
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Appendix A: Supporting Information
A-1 Methods for manufacturing paint and sealant layers
The methods below were used to prepare PSS, FSS, FSP and FSS coupon materials for this study.
Test materials are listed in Section 3-2. The methods below are intended to be step-by-step instructional
material for the analyst
A-1.1 Preparation of Paint Coatings on Stainless-steel Substrates
Painted stainless-steel surface will be produced using a modified method from ASTM D823
"Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on
Test Panels" [7], In this study, the Universal Blade Applicator (UBA, AP-G08, Paul N. Gardner Company,
Pompano Beach, FL, USA) was used for paint application.
The production of PSS coupons is summarized below:
Prepare 14"x 14" stainless-steel coupons.
1. Don disposable gloves (double glove). For work with acetone, latex gloves (Thermo Fisher
Scientific, Waltham, MA, USA; or equivalent) shall be used as personal protective
equipment; for work with 2-propanol (IPA), nitrile gloves (Thermo Fisher Scientific,
Waltham, MA, USA; or equivalent) shall be used.
1. Wet surface of stainless-steel coupon with acetone and wipe dry using a Kimwipe
(Kimberley-Clark, Inc., Irving, TX, USA; P/N 34133; or equivalent) Proceed to wipe
sampling immediately.
2. Wet surface of stainless-steel coupon with hexane and wipe dry using a Kimwipe SA or
equivalent.
E Place paint or sealant on paint shaker for 10 minutes.
E Apply paint or sealant following ASTM D823 Practice E.
1. Place stainless-steel sheet on aluminum foil sheet that is secured to the countertop.
2. Adjust the Universal Blade Applicator (UBA) (AP-G08, Paul N. Gardner Company,
Pompano Beach, FL, USA) to the desired wet thickness (5 mils). The wet paint thickness
partially can be adjusted by shifting the blade up or down within the two side vertical
support plates.
3. Pipette 8 x2 mL of paint in a line near the edge of the stainless-steel coupon using an
Eppendorf Repeater Plus Single Channel Repeater Pipette (EPR-1000R, Eppendorf,
Hauppauge, NY, USA; or equivalent).
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4. Position the UBA behind the line of paint and uniformly pull the blade (250-300 mm/s)
toward the operator, with a constant horizontal and vertical pressure. Make sure to pull the
blade past the end of the surface to create a uniform layer.
5. Wipe all excess paint off the UBA with Kimwipes and then clean the UBA with Kimwipes
wetted with hexane. Allow to dry before storage.
Step 4
J Allow the painted stainless steel to dry at standard atmosphere: 21-25°C and 40-60% RH in
accordance with ASTM D3924-16 [8]
1. Allowed to dry for a minimum of 24 hours before measuring and/or cutting. Do not place
painted coupons in the fume hood for drying. The increased ventilation rates cause
nonuniform drying and cracking to occur during method development testing.
Step 5
Step 6
Clean all coupons with dry air prior to testing paint film thickness.
Measure the paint layer thickness on the stainless-steel coupons using ASTM E376 [9],
1. Check the calibration of the Eddy current gauge (PosiTector 6000, DeFelsko Corporation,
Ogdensburg, NY, USA) at the start and routinely throughout the testing event using a
reference standard included by manufacturer with instrument (1-20 mils thickness range). If
needed perform calibration adjustment following procedures detailed in the user manual.
Note calibration results in the laboratory notebook.
2. Follow all procedures outlined in the user manual to obtain multiple readings over the
surface. Record measurements in the laboratory notebook or electronic spreadsheet; the
target application thickness for these samples is 3 mils (±20%).
| Grid the zones of the painted stainless steel that pass thickness requirements in the shapes
of the target coupon sizes (4 x 2.5 cm)
Step 6
Step 7
Die cut the painted stainless-steel coupons with assistance from the EPA Mechanical Shop
using shears to obtain a uniform length (4.0 cm) and width (2.5 cm). Clean excess grease and oil off the
PSS coupons using a Kimwipe wetted with deionized (Dl) water.
Step 8
Using the calibrated Eddy current gauge, measure the center, top, and bottom of the cut,
cleaned PSS coupons to check uniformity and ensure all coupons meet QA requirements. The target
application thickness for these samples is 3 mils (± 20%). Ideally, thickness readings within 13 mm (1/2 in)
of the edge of the surface shall be avoided, but due to the small coupon size, readings need to be taken
within this zone.
Step 8
Record all measurements in an electronic spreadsheet and place PSS coupons into clean
prelabeled storage container.
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A-1.2 Preparation of Free-standing Paint or Sealant Layers
Free-standing paint and sealant sheets were prepared using modified methods from ASTM D823
"Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on
Test Panels" [7], PTFE sheets (American Sealing & Packaging, Santa Ana, CA, USA) were used as the
panel substrate instead of stainless steel for FSP production. Stainless steel (multipurpose stainless-steel
type 304, #2B mil, unpolished, 0.036" thick, McMaster-Carr, Atlanta, GA, USA) were used as the substrate
for FSS production. The thickness of the sheets will be measured using ASTM D1005 "Standard Test
Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers" [10], Coupons
were die-cut to a diameter of 50 mm to provide a 10 cm2 contact area and cleaned using dry compressed
air.
A-1.2.1 Preparation of FSP layers
The procedure for manufacturing FSP layer sheets is as follows:
Prepare 10" x 10" PTFE sheets.
2. Don disposable gloves (double glove). For work with acetone, latex gloves (Thermo Fisher
Scientific, Waltham, MA, USA; or equivalent) shall be used as personal protective
equipment; for work with 2-propanol (IPA), nitrile gloves (Thermo Fisher Scientific,
Waltham, MA, USA; or equivalent) shall be used.
1. Wet surface of PTFE sheet with acetone and wipe dry using a Kimwipe (Kimberley-Clark,
Inc., Irving, TX, USA; P/N 34133; or equivalent) Proceed to wipe sampling immediately.
Step 2
2. Wet surface of PTFE with hexane and wipe dry using a Kimwipe or equivalent.
Mix paint using a paint shaker for 10 minutes.
Apply paint following ASTM D823 Practice E:
1. Place PTFE sheets on aluminum foil sheet that is secured to the countertop.
2. Adjust the UBA (AP-G08, Paul N. Gardner Company, Pompano Beach, FL, USA) to the
desired wet thickness (7 mils). The wet paint thickness can be partially adjusted by shifting
the blade up or down within the two side vertical support plates.
3. Directly before applying paint, spray PTFE sheets with IPA and gently wipe with a Kimwipe.
The PTFE sheets can accumulate static charge which can affect the paint application and
removal process. Depending on ambient conditions, additional static removal steps might
be necessary to produce uniform paint layers.
4. Pipette 5 x2 mL of paint or sealant in a line near the edge of the PTFE sheet using an
Eppendorf Repeater Plus Single Channel Repeater Pipette (EPR-1000R, Eppendorf,
Hauppauge, NY, USA; or equivalent).
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Step 4
Position the UBA behind the line of paint and uniformly pull the blade (250-300 mm/s)
toward the operator, with a constant horizontal and vertical pressure. Make sure to pull the blade past the
end of the surface to create a uniform layer.
Step 5
j Allow the painted sheets to dry at standard atmosphere: 21-25°C and 40-60% RH in
accordance with ASTM D3924-16 8], Allowed to dry for a minimum of 24 hours before measuring and/or
cutting.
Step 6
j After curing is completed, don nitrile gloves and gently peel the FSP sheet from the PTFE
surface.
Step 7
Step 8
Clean all coupons with dry compressed air prior to testing the thickness.
Measure the FSP layer thickness per ASTM D1005 "Standard Test Method for
Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers" [10]:
1. Using a micrometer (Mitutoyo Digital Micrometer, Mitutoyo America Corporation, Melville,
NY, USA, P/N H-2780), separate the anvils to at least twice the distance of the film and
place the film, perpendicular to the micrometer, between the anvils. A diagram of the
micrometer, including nomenclature for parts can found in ASTM D1005 [10],
2. Bring the anvils into contact with the film without compressing the film.
3. Record film thickness to 0.1 mil (2.5 um).
Place 2 layers of aluminum foil on a cutting board and then place the FSP film on the foil.
1. Die-cut to a diameter of 50 mm using a 50 mm die and arc-punch and rubber mallet.
Step 9
Step 10
| Using the micrometer, measure the center, top, bottom, left and right of the cut FSP
coupons to check uniformity and ensure all coupons meet QA requirements. Record all measurements in a
spreadsheet and place FSP coupons into clean prelabeled storage container.
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A-1.2.2 Preparation of FSS layers
The procedure for manufacturing FSS layer sheets is as follows:
Prepare 14" x 14" stainless-steel sheets:
3. Don disposable gloves (double glove). For work with acetone, latex gloves (Thermo Fisher
Scientific, Waltham, MA, USA; or equivalent) shall be used as personal protective
equipment; for work with 2-propanol (IPA), nitrile gloves (Thermo Fisher Scientific,
Waltham, MA, USA; or equivalent) shall be used.
1. Wet surface of stainless steel with acetone and wipe dry using a Kimwipe or equivalent.
Proceed to wipe sampling immediately.
Step 2
2. Wet surface of stainless steel with hexane and wipe dry using a Kimwipe or equivalent.
Stir sealant gently with a paint stirrer for 5 minutes. Be careful not to force air into the sealant
liquid.
] Apply sealant following ASTM D823 Practice E [7]:
1. Place a stainless-steel sheet on aluminum foil sheet that is placed in the fume hood.
2. Adjust the UBA (AP-G08, Paul N. Gardner Company, Pompano Beach, FL, USA) to the
desired wet thickness (9 mil). The wet sealant thickness can be partially adjusted by shifting
the blade up or down within the two side vertical support plates.
3. Pipette 14x1 mL of sealant in a line near the edge of the stainless-steel sheet using an
Eppendorf Repeater Plus Single Channel Repeater Pipette (EPR-1000R, Eppendorf,
Hauppauge, NY, USA; or equivalent).
Step 4
Position the UBA behind the line of sealant and uniformly pull the blade (250-300 mm/s)
toward the operator, with a constant horizontal and vertical pressure. Make sure to pull the blade past the
end of the surface to create a uniform layer.
Step 5
j Allow the sealed sheets to dry at standard atmosphere: 21-25°C and 40-60% RH in
accordance with ASTM D3924-16 [8], Allow to dry for a minimum of 96 hours before measuring and/or
cutting.
j After curing is completed, don nitrile gloves and clean all coupons with dry compressed air
prior to testing the thickness.
Step 6
Step 7
Measure the FSS layer thickness per ASTM D1005 "Standard Test Method for
Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers" [10]:
1. Using a micrometer (Mitutoyo Digital Micrometer, Mitutoyo America Corporation, Melville,
NY, USA, P/N H-2780), separate the anvils to at least twice the distance of the film and
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Step 9
Step 10
EPA/600/R-22/120
September 2022
place the film, perpendicular to the micrometer, between the anvils. A diagram of the
micrometer, including nomenclature for parts can found in ASTM D1005 [10],
2. Bring the anvils into contact with the film without compressing the film.
3. Record film thickness to 0.1 mil (2.5 um).
Place 2 layers of aluminum foil on a cutting board and then place the FSS film on the foil.
Die-cut to a diameter of 50 mm using a 50 mm die and arc-punch and rubber mallet.
| Using the micrometer, measure the center, top, bottom, left and right of the cut FSS
coupons to check uniformity and ensure all coupons meet QA requirements. Record all measurements in a
spreadsheet and place FSP coupons into clean prelabeled storage container.
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A-2 LVAP Assembly Procedure
This procedure describes the assembly of LVAP cells using the FSP or FSS, SPE, arid custom-
made gaskets. It is intended to be step-by-step instructional material for the analyst assembling the LVAP.
A-2.1 Preparation of the LVAP Parts
Prior to testing, clean the PTFE gaskets, aluminum spacers, and steel nuts/bolts for the LVAP
apparatuses with a 50:50 (volume:volume) mixture of acetone and hexane. Place all parts in a clean beaker
prefilled with the solvent mixture and sonicate for 15 minutes. Place parts on a clean, lint-free laboratory
paper for drying. Clean the large aluminum LVAP bottom plate with a laboratory wipe (e.g., Kimwipe or
equivalent) prewetted with acetone, then with a second wipe prewetted with hexane and wiped dry with a
third wipe.
A-2-2 Assembly of the LVAP
Prior to assembly, don a fresh pair of nitrile gloves {Thermo Fisher Scientific, Waltham, MA, USA, or
equivalent)
Place clean aluminum foil in the fume hood in H-224 and set the bottom aluminum plate on
the foil (Figure A-1),
Figure A-1. Step 1: Place bottom plate on clean surface
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Step 2
(Figure A-2).
T Place the bottom, full PTFE gasket with bolt holes on the bottom stainless-steel plate,
Figure A-2. Step 2: LVAP apparatus with bottom PTFE gasket
Place aluminum support ring on top of bottom PTFE gasket (Figure A-3).
Figure A-3. Step 3: LVAP apparatus with aluminum support ring
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Place PTFE support ring inside of aluminum spacer ring (Figure A-4).
Figure A-4, Step 4: LVAP apparatus with PTFE support ring.
Step 5
Place the first 36 mm diameter PTFE spacer disk inside of PTFE support ring (Figure A-5).
3ft
Figure A-5. Step 5: Placement of the first 36-mm PTFE spacer disk in LVAP
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Step 6
Place the second 36 mm diameter PTFE spacer disk inside PTFE support ring and on top of
first 36-mm diameter PTFE spacer disk (Figure A-6).
Figure A-6. Step 6: Placement of the second 36-mm PTFE spacer disk in LVAP
Step 7
Place SPE disk on top of 36 mm diameter PTFE spacer disk and inside of PTFE support
ring (Figure A-7).
4^^
Figure A-7. Step 7: LVAP apparatus with SPE disk centered
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Center free standing layer - FSP or FSS - on top of SPE disk (Figure A-8).
Figure A-8. Step 8: LVAP apparatus with free standing layer; example shown is FSP
Qyjj] Place top PTFE gasket on the FSP layer and line up edges with aluminum support ring
(Figure A-9)
•
•
• • a
* ft
•
•
Figure A-9. Step 9: LVAP apparatus with top PTFE gasket centered
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Step 10
Place top aluminum plate on the PTFE gasket and line up edges with the rest of the
column (Figure A-10).
Figure A-10. Step 10: LVAP apparatus with top aluminum ring
Step 11
Place washers on bolts and finger tighten into the predrilled holes in the bottom aluminum
plate (Figure A-11).
Figure A-11. Step 11: LVAP apparatus with steel bolts finger tight
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Tighten the bolts to 20 ft-lb using a %" torque wrench with Philips drive. The torque wrench
will make a clicking noise when it reaches 20 ft-lb of torque. The assembled LVAP is shown on Figure A-12;
NOTE: Do not overtighten the bolts. This could strip the threads, pit the top plate, and/or cut the FSS or FSP
layer.
Figure A-12. Step 12: Completed LVAP
A-3 Surface Sampling Procedure
The method below was used to collect surface samples in this study. List of materials is listed in
Section 3-2. The method below is intended to be step-by-step instructional material for the analyst.
The procedural steps are as follows:
Prepare cotton swabs for sampling
4. Don disposable gloves (double glove). For work with acetone, latex gloves (Thermo Fisher
Scientific, Waltham, MA, USA; or equivalent) shall be used as personal protective
equipment; for work with 2-propanol (IPA), nitrile gloves (Thermo Fisher Scientific,
Waltham, MA, USA; or equivalent) shall be used.
5. Dip cotton swab in 2-propanol container (15-mL glass vial) and tap to remove excess
solvent by gentle tapping on the edge of the solvent tube.
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6. Proceed to wipe sampling (Step 2) immediately.
BE Perform 'hot spot' sampling
1. Don a fresh pair of latex or nitrile gloves.
2. Open the transportation box and move the coupon to the sampling location. Start sampling
by rotating the first cotton swab on the location where the malathion droplet is placed on the
coupon (hot zone) (Figure A-13). Place the cotton swap in the labeled digitube (50 mL
disposable digestion/extraction vial; DigiTube 50 mL Non RackLock with caps; SCP
Science, Quebec, Canada, P/N 010-500-263 or equivalent) and prepare the next swab.
Figure A-13. Hot zone sampling for rectangular and round coupons
•E Perform the horizontal sampling of the entire coupon area
1. Start sampling in the top right corner of the coupon. Wipe the surface horizontally, working
from the right to left, to completely cover the coupon surface. (Figure A-14) Add the cotton
swab to the labeled digitube and prepare the next swab.
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Figure A-14. Horizontal wiping pathway for rectangular and round coupons
Perform the vertical sampling of the entire coupon area
1. Starting in the top left corner, wipe the surface vertically, working toward the right, to
completely cover the surface. The vertical wipe sampling pathway is shown in Figure A-15.
Add the cotton swab to the extraction tube and prepare the next swab.
nrti
A t
Figure A-15. Vertical wiping pathway for rectangular and round coupons.
~ Perform the perimeter sampling.
Step 5
1. Starting in any corner, wipe the perimeter of the coupon. The perimeter wipe sampling
pathway is shown in Figure A-16. Add the cotton swab to the labeled extraction tube.
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Figure A-16. Perimeter wiping pathway for rectangular and round coupons
Prepare for extraction
1. After completion of sampling, all swabs are extracted as a composite-sample. Place all
four (4) swabs resulting from one material coupon into a prelabeled extraction tube.
2. Then, place each wipe-sampled material coupon into a separate prelabeled extraction
tube.
3. SPE disks do not undergo wipe sampling and are placed in another set of prelabeled
extraction tubes.
4. Extraction procedures are described in Section 4.2 of this report.
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Appendix B: Method Development Supporting Information
Table B1. Recoveries from surface sampling method development for 2-CEPS
CS
ss
PSS
sss
FSP
FSS
[mg]
(%r
[mg]
(%)2
[mg]
(%)2
[mg]
(%)2
[mg]
(%)2
[mg]
(%)2
PB-1
<0.02
<0.02
<0.02
<0.02
<0.02
<0.02
TC-1
2.29
1.93
1.89
1.57
1.79
1.56
TC-2
2.38
1.94
1.92
1.88
1.58
1.53
TC-3
2.38
2.27
1.94
1.50
1.54
1.32
Average
2.35
100
2.05
87
1.92
82
1.65
70
1.64
70
1.47
63
SD
0.04
1.8
0.16
6.7
0.02
0.9
0.17
7.1
0.11
4.8
0.10
4.5
RSD
1.8%
I 7.7%
I 1.1%
I 10%
I 6.9%
I 7.1% |
' Percentage with respect to theoretical mass applied
2 Percentage with respect to control spike recovery
Results reported at <0.02 were below LOQ: SD - Standard Deviation; RSD - Relative Standard Deviation
Table B2. Recoveries from surface sampling method development for malathion
CS1
SS
PSS
FSP
CS2
SSS
[mg]
(%r
[mg]
(%)2
[mg]
(%)2
[mg]
(%)2
PB-1
<0.02
<0.02
<0.02
<0.02
<0.0
<0.0
<0.02
TC-1
2.25
1.69
1.18
1.42
2.00
1.70
1.86
TC-2
2.30
1.81
1.36
1.53
1.65
1.40
1.84
TC-3
2.20
1.80
1.92
1.74
2.42
1.30
1.72
Average
2.25
92
1.77
78
1.48
66
1.56
69
2.02
82
1.47
72
1.81
89
SD
0.04
1.7
0.06
2.5
0.32
14
0.13
5.8
0.32
13
0.17
8.6
0.06
3.0
RSD
2%
I 3.2%
I 21%
I 8.4%
I 16%
I 12%
I 3.4% |
' Percentage with respect to theoretical mass applied
2 Percentage with respect to control spike 1 (CS1) recovery
3 Percentage with respect to control spike 2 (CS2) recovery
Results reported at <0.02 were below LOQ: SD - Standard Deviation; RSD - Relative Standard Deviation
Table B3. Extraction method development for 2-CEPS
CS
SS
PSS
SSS
FSP
FSS
SP
I
fmgl I (%)1
fmgl | (%)2
fmgl | (%)2
fmgl | (%)2
fmgl | (%)2
fmgl | (%)2
2-CEPS
PB-1
<0.02
<0.02
<0.02
<0.02
<0.02
<0.02
<0.02
TC-1
2.13
2.31
2.15
2.11
2.11
2.34
2.06
TC-2
2.41
2.16
2.09
2.13
2.07
2.11
2.43
TC-3
2.47
2.18
2.12
2.23
2.35
2.29
2.30
Average
2.34
100
2.22
95
2.12
91
2.16
92%
2.18
93
2.25
96
2.26
97
SD
0.15
6.4
0.07
3.0
0.02
1.1%
0.05
2.3%
0.12
5.3
0.099
4.2
0.15
6.6
%RSD
6.5%
I 3.1%
I 1.2%
I 2.5%
I 5.7%
I 4.4%
I 6.8% |
' Percentage with respect to theoretical mass applied
2 Percentage with respect to control spike recovery
Results reported at <0.02 were below LOQ: SD - Standard Deviation: RSD - Relative Standard Deviation
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Table B4. Extraction method development for malathion
CS
SS
PSS
sss
FSP
FSS
SPE
[mg]
(%r
[mg]
(%)2
[mg]
(%)2
[mg]
(%)2
[mg]
(%)2
[mg]
(%)2
[mg]
(%)2
Malathion
PB-1
<0.0
<0.02
<0.02
<0.02
<0.02
<0.02
<0.02
TC-1
2.08
2.04
1.18
2.40
1.42
1.87
1.69
TC-2
2.09
2.27
1.36
2.12
1.53
1.98
1.81
TC-3
2.34
2.36
1.92
2.02
1.74
2.04
1.80
Average
2.17
88
2.22
95
1.48
79
2.18
100
1.56
83
2.0
104
1.77
94
SD
0.12
4.9
0.14
5.8
0.32
17
0.16
7.5
0.13
6.9
0.07
3.8
0.06
3.7
%RSD
5.5%
| 6.1%
| 21%
| 7.5%
| 8.4%
| 3.7%
| 3.2% |
' Percentage with respect to theoretical mass applied
2 Percentage with respect to control spike recovery
Results reported at <0.02 were below LOQ: SD - Standard Deviation; RSD - Relative Standard Deviation
Table B5. Results of gasket contamination test for 2-CEPS and malathion
Top Gasket
O-ring Gasket
Gasket Below SPE Disk
Sample Type
Recovered [mg]
Recovered (%)
Recovered [mg]
Recovered (%)
Recovered [mg]
Recovered (%)
2-CEPS
PB-1
<0.02
<1%
<0.02
<1%
<0.02
<1%
TC-1/2/3
<0.02 (D)
<1 % (D)
<0.02 (D)
<1 % (D)
<0.02 (D)
<1 % (D)
Malathion
PB-1
<0.02
<1%
<0.02
<1%
<0.02
<1%
TC-1/2/3
<0.02
<1%
<0.02 (D)
<1 % (D)
<0.02 (D)
<1 %(D)
Results reported at <0.02 were below LOQ; (D) - below LOQ trace-level detections (S/N<10) were present
Table B6. Results for SPE to FSP nonpermeation transport test for 2-CEPS
Sample Type
SPE
FSP
FSP+SPE Mass Balance
Recovered [mg]
Recovered (%)
Recovered [mg]
Recovered (%)
Recovered [mg]
Recovered (%)
2-CEPS
PB-1
<0.02
<1%
<0.02
<1%
<0.02
<1%
TC-1
0.0027 (J)
0.59%
0.080
18%
0.083
18%
TC-2
0.014 (J)
3.2%
0.29
63%
0.30
63%
TC-3
0.013 (J)
2.9%
0.19
42%
0.21
43%
Average
0.010(J)
2.2%
0.19
41%
0.20
41%
SD
0.0006
0.32%
0.10
23%
0.10
23%
RSD
| 64%
| 56%
| 55% |
Results reported at <0.02 were below LOQ; (Jj - estimated value, detected at below LOQ (S/N > 10)
Table B7. Results for SPE to FSS nonpermeation transport test for 2-CEPS
Sample Type
SPE
FSS
FSP+SPE Mass Balance
Recovered [mg]
Recovered (%)
Recovered [mg]
Recovered (%)
Recovered [mg]
Recovered (%)
2-CEPS
PB-1
<0.02
<1%
<0.02
<1%
<0.02
<1%
TC-1
0.0013 (J)
0.3%
0.12
18%
0.082
18%
TC-2
0.0071 (J)
1.6%
0.18
63%
0.30
65%
TC-3
0.0070 (J)
1.5%
0.18
42%
0.20
44%
Average
0.0051
0.51%
0.19
41%
0.19
42%
SD
0.0032
0.32%
0.10
23%
0.12
26%
RSD
| 64%
| 56%
| 61% |
Results reported at <0.02 were below LOQ; (J) - estimated value, detected at below LOQ (S/N > 10)
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Table B8. Results for SPE to FSP nonpermeation transport test for malathion
Sample Type
SPE
FSP
FSP+SPE Mass Balance
Recovered [mg]
Recovered (%)
Recovered [mg]
Recovered (%)
Recovered [mg]
Recovered (%)
Malathion
PB-1
<0.02
<1%
<0.02
<1%
<0.02
<1%
TC-1
0.34
91%
0.10 (J)
27%
0.45
119%
TC-2
0.29
77%
0.09 (J)
24%
0.38
102%
TC-3
0.22
59%
0.08 (J)
22%
0.31
82%
Average
0.29
76%
0.09 (J)
25%
0.38
101%
SD
0.05
13%
0.01
2%
0.06
15%
RSD
| 17%
| 8.4%
| 15% |
Results reported at <0.02 were below LOQ; (Jj - estimated value, detected at below LOQ (S/N > 10)
Table B9. Results for SPE to FSS nonpermeation transport test for malathion
Sample Type
SPE
FSS
FSP+SPE Mass Balance
Recovered [mg]
Recovered (%)
Recovered [mg]
Recovered (%)
Recovered [mg]
Recovered (%)
Malathion
PB-1
<0.02
<1%
<0.02
<1%
<0.02
<1%
TC-1
0.49
100%
0.012 (J)
2%
0.50
103%
TC-2
0.49
100%
0.012 (J)
2%
0.50
103%
TC-3
0.52
106%
0.057
12%
0.57
118%
Average
0.50
102%
0.027
5.5%
0.52
108%
SD
0.02
3.3%
0.026
5.4%
0.042
8.7%
RSD
I 3%
| 98%
I 8% |
Results reported at <0.02 were below LOQ; (Jj - estimated value, detected at below LOQ (S/N > 10)
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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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