EPA/600/R-20/449 | December 2016
www.epa.gov/homeland-security-research
United States
Environmental Protection
Agency
oEPA
Analysis of Organophosphorus-Based
Pesticides from Surfaces Using Liquid
Chromatography Tandem Mass
Spectrometry (LC-MS/MS)
Sampling and Analytical Method for
Analysis of Surface Wipes
Revision 1
Office of Research and Development
Homeland Security Research Program
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EPA/600/R-20/449
December 2016
Analysis of Organophosphorus-Based Pesticides from Surfaces Using Liquid
Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Sampling and Analytical Method for Analysis of Surface Wipes
Revision 1
United States Environmental Protection Agency
National Homeland Security Research Center
26 W. Martin Luther King Jr. Drive
Cincinnati, OH 45268
and
Centers for Disease Control and Prevention
National Institute for Occupational Safety and Health
5555 Ridge Ave
Cincinnati, OH 45213
Last Revised: 12/16
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Disclaimer
The United States Environmental Protection Agency through its Office of Research and
Development (ORD), National Homeland Security Research Center (NHSRC), funded and
managed the research described here (IA #DW-75-922440001-02) in collaboration with the
National Institute of Occupational Safety and Health (NIOSH), Centers for Disease Control and
Prevention (CDC), a division of the U.S. Department of Health and Human Services (DHHS). It
has been subjected to the Agency's administrative review and approved for publication. The
views expressed in this paper do not necessarily reflect the views or policies of the Agency.
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
Questions concerning this document or its application should be addressed to:
Stuart Willison, Ph.D.
Project Officer
U.S. Environmental Protection Agency
National Homeland Security Research Center
26 W. Martin Luther King Drive, MS NG16 Cincinnati, OH 45268
513-569-7253
Willison. Stuart@epa.gov
Robert Streicher, Ph.D.
Project Officer
National Institute for Occupational Safety and Health Laboratories
Alice Hamilton Laboratory
5555 Ridge Avenue
Cincinnati, OH 45213
513-841-4296
Rps3@cdc.gov
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Acknowledgments
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We would like to acknowledge the following individuals and organization for their contributions
towards the development and/or review of this method.
United States Environmental Protection Agency (EPA)
Office of Research and Development, National Homeland Security Research Center
Stuart Willison, Project Officer and Method Development
Matthew Magnuson, Reviewer
Region 5
Amy Mysz, Reviewer
National Exposure Research Laboratory
James Starr, Reviewer
Centers for Disease Control and Prevention
National Institute for Occupational Safety and Health
Jack Pretty, Laboratory Advisor
Robert Streicher, Project Officer
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Executive Summary
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The sampling and analytical method described herein was developed and tested within the same
laboratory to assess the recoveries of organophosphorus pesticides from wipe samples from
various porous (vinyl tile, painted drywall) and mostly nonporous (laminate, galvanized steel,
glass) surfaces. Performance data (method detection limits and precision and accuracy data)
were demonstrated for the fitness-for-purpose regarding the development of a method for
organophosphorus pesticides in a single laboratory. Samples were collected from surfaces using
wipes, which were then spiked with a surrogate compound and carried through extraction with
acetonitrile, sonication, and filtration steps followed by analysis using liquid chromatography
electrospray ionization-tandem mass spectrometry (LC/MS/MS). Detection limit data were
generated using wipes on a metal surface following the procedures of 40 CFR Part 136,
Appendix B, as part of U.S. Environmental Protection Agency's guidelines for determining a
method detection limit.
Gauze wipes were selected because they were found to be physically robust during the wiping
procedure, contained low background levels, produced no peaks that interfered with the target
analytes, and produced the highest percent recoveries during sample analysis. Percent recoveries
were highest for the non-porous/non-permeable surface types (laminate, metal, and glass).
Recoveries from these types of surfaces ranged from 60-107 % at the lowest tested concentration
levels for 8 of 13 of the organophosphorus (OP) pesticides analyzed in ESI positive mode. The
method resulted in low recoveries for two of the tested analytes (19-53 %), most likely due to
degradation, interference, or volatilization. The remaining three tested analytes performed
poorly and all five of the poor performers should not be considered for this method without
further evaluation to determine the cause of the poor performance; however, the data are listed
for all tested analytes. The resulting equivalent method detection limits obtained from wiping
the metal surface were 0.08 ng/cm2 for dichlorvos, 0.025 ng/cm2 disulfoton-sulfone, 0.022
ng/cm2chlorpyrifos-oxon, 0.10 ng/cm2 chlorpyrifos, 0.01 ng/cm2 fenamiphos, 0.013 ng/cm2
chlorfenvinphos, 0.01 ng/cm2 monocrotophos, 0.016 ng/cm2 methamidophos, 0.025 ng/cm2
mevinphos, 0.013 ng/cm2 disulfoton-sulfoxide, 0.047 ng/cm2 fenamiphos-sulfone, and 0.038
ng/cm2 fenamiphos-sulfoxide. The method was tested for 13 different OP pesticides or their
hazardous byproducts; however, further investigation is needed for dichlorvos, disulfoton, and
mevinphos. The wiping and analytical method for these analytes resulted in highly variable data
and/or non-detected values. Chlorpyrifos and methamidophos resulted in low or variable
recoveries and may need additional investigation. Complications are presented in Section 14.4 of
the method. Precision and accuracy data were generated from each tested surface fortified with
all analytes.
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ANALYSIS OF ORGANOPHOSPHORUS PESTICIDES FROM SURFACES USING
LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY (LC-MS/MS)
TABLE OF CONTENTS
Contents
Disclaimer ii
Acknowledgments iii
Executive Summary iv
Contents v
List of Tables v
List of Acronyms and Abbreviations vi
1. Introduction 1
2. Scope and Application 1
3. Summary of Method 3
4. Definitions 5
5. Interferences 6
6. Health and Safety 7
7. Equipment and Supplies 7
8. Reagents and Standards 9
9. Sample Collection, Preservation and Storage 12
10. Quality Control 13
11. Instrument Calibration and Standardization 18
12. Analytical Procedure 20
13. Data Analysis and Calculations 21
14. Method Performance 22
15. Pollution Prevention 23
16. Waste Management 23
17. References 24
18. Tables and Validation Data 26
19. Attachments 32
List of Tables
Table 1. Holding Time Sample Stability of Wipe Samples of Organophosphorus Pesticides in
ESI Positive (+) Mode 27
Table 2. Materials Tested for the Analysis of Wipe Samples 28
Table 3. Method Parameters for Organophosphorus Pesticides 28
Table 4. ESI (+) MRM Ion Transitions, Retention Times (RT) 29
Table 5. ESI (•) MS/MS Conditions 30
Table 6. Liquid Chromatography Gradient Conditions* 30
Table 7. Target Calibration Concentration Standards (ng/mL) 31
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List of Acronyms and Abbreviations
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AS
Analyte Stock Standard (Solution)
CAL
Calibration Standard
CAS®
Chemical Abstracts Service
ccc
Continuing Calibration Check
CDC
Centers for Disease Control and Prevention
DL
Detection Limit
DHHS
U.S. Department of Health and Human Services
DQO
Data Quality Objective
EPA
U.S. Environmental Protection Agency
ESI
Electrospray ionization
ESI(+)
Electrospray Ionization in Positive Mode
ESI (-)
Electrospray Ionization in Negative Mode
FD
Field Duplicate
IDC
Initial Demonstration of Capability
IDL
Instrument Detection Limit
LC
Liquid Chromatography
LC/MS/MS
Liquid Chromatography Coupled with Tandem Mass Spectrometry
LFB
Laboratory Fortified Blank
LFSM
Laboratory Fortified Sample Matrix
LFSMD
Laboratory Fortified Sample Matrix Duplicate
LMB
Laboratory Method Blank
MDL
Method Detection Limit
MRL
Minimum Reporting Limit
MRM
Multiple Reaction Monitoring
MS
Mass Spectrometer(try)
MS/MS
Tandem Mass Spectrometry
NHSRC
National Homeland Security Research Center
NIOSH
National Institute for Occupational Safety and Health
NIST
National Institute of Standards and Technology
OP
Organophosphorus Pesticide
ORD
Office of Research and Development (EPA)
OSHA
Occupational Safety and Health Administration
ppb
Parts per billion
ppm
Parts per million
P&A
Precision and Accuracy
QC
Quality Control
r2
Coefficient of determination
RPD
Relative Percent Difference
RSD
Relative Standard Deviation
RT
Retention Time
SAM
Selected Analytical Methods for Environmental Remediation and Recovery
SD
Standard Deviation
SDS
Safety Data Sheet
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S/N
Signal to Noise
sss
Stock Standard Solution
VOA
Volatile Organic Analysis
X
Average Percent Recovery
a
Standard Deviation
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1. Introduction
1.1. The U.S. Environmental Protection Agency (EPA) is responsible for developing tools
and methodologies which will enable the rapid characterization of indoor and outdoor
areas and water systems following an intentional or unintentional release. EPA's
National Homeland Security Research Center (NHSRC), published Selected Analytical
Methods for Environmental Remediation and Recovery (SAM), formerly referred to as
the Standardized Analytical Methods for Environmental Restoration Following
Homeland Security Events (1), which is a compendium of methods that informs sample
collection and analysis during the response to all-hazards incidents. Many chemicals
(e.g., pesticides) remain a high-priority concern because they are readily available as
commercialized products and present a potential health hazard if released.
Organophosphorus (OP) pesticides can be very dangerous because they are sufficiently
persistent and highly toxic if misused or incorrectly applied. There are hundreds of
currently available pesticides that have been commercialized for public use. If an
incident involving a contaminant release were to occur, versatile sampling procedures
would be needed to detect organophosphorus pesticides and to help determine the spread
and concentration of these chemicals in contaminated areas during site remediation.
Multiple types of contaminated surfaces from an indoor setting will need to be
extensively tested within the contaminated areas. Direct extraction may be possible;
however, the laboratory procedures can be tedious, complex, and require the destruction
of the analyzed material. Wipe sampling is a technique that can be performed quickly
and easily, and may not be destructive to the tested surface.
1.2. After sample collection, selective analytical methods should be implemented to detect
and quantify the appropriate agent and/or degradation products in an environmental
sample. To ensure that the sample maintains its integrity and that the analysis method
is applicable to the matrix of interest, the procedure should account for possible
contaminants already present within the sample, as well as other matrix complications
that may arise during analysis. Liquid chromatography-tandem mass spectrometry
(LC-MS/MS) is often the most appropriate and powerful analysis technique for polar,
nonvolatile compounds. LC-MS/MS affords laboratories an enhanced capability to
analyze specific environmental matrices for OP pesticides while avoiding
complications that may arise from derivatization, a step more commonly needed for
gas chromatography/mass spectrometry analysis. Although LC-MS analysis methods
do exist for OP pesticides in environmental matrix types (e.g., water, soils, air), very
little is currently known about wipe sample collection and analysis protocols for the
detection of OP pesticides on contaminated surfaces.
2. Scope and Application
2.1. Organophosphorus pesticides can persist at a contaminated site. This sampling and
analytical method was developed and tested in the same laboratory to investigate
persistent organophosphorus pesticides via surface wiping followed by analytical
characterization. The performance data presented help to determine the fitness-for-
purpose regarding surface analysis in a single laboratory. Surfaces (laminate, glass,
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galvanized steel, vinyl tile, and painted drywall) were wiped with cotton gauze wipes,
the wipes were sonicated and extracted with acetonitrile, and the extract was filtered.
Samples were analyzed using direct injection electrospray ionization liquid
chromatography tandem mass spectrometry (LC-MS/MS) without derivatization.
Detection limit data were generated for all analytes of interest on a laminate surface.
Accuracy and precision data were generated from each surface fortified with these
analytes. The method tested 13 analytes; however, the following 8 analytes resulted in
acceptable data:
Analyte CAS Registry Number®
Chlorfenvinphos 470-90-6
Chlorpyrifos-oxon 5598-15-2
Disulfoton-sulfone 2497-06-5
Disulfoton-sulfoxide 2497-07-6
Fenamiphos 22224-92-6
Fenamiphos-sulfone 31972-44-8
Fenamiphos-sulfoxide 31972-43-7
Monocrotophos 6923-22-4
NOTE: Further investigation is needed for method suitability for dichlorvos,
disulfoton, mevinphos, methamidophos and potentially chlorpyrifos. The wiping
and analytical procedure for these analytes resulted in highly variable data and/or
non-detect values. Performance data are included for all analytes because the
method may be, or is similar to, test methods used by responders for pesticides.
2.2. Wipe sampling can be performed quickly, easily, and without the destruction of
the tested surface in cases where direct extraction is not feasible (e.g., walls,
posts, windows, floors and furniture). Wipe sampling will recover analyte only
from the surface, meaning that porous surfaces may have lower recoveries and
less precision because the contaminants may sorb into the material. Therefore, it
is important to understand wipe efficiencies and the materials being wiped. This
method assesses the wipe recoveries and includes performance data for several
porous and nonporous surfaces.
2.3. Method detection limit (MDL) metrics are presented using EPA conventions (2-
3). The detection limit is defined as the statistically calculated minimum
concentration that can be measured with 99% confidence that the reported value is
greater than zero (4). The MDL is compound-dependent and reliant on sample
preparation, sample matrix, concentration, and instrument performance. The
statistical procedure, utilizing the Laboratory Fortified Sample Matrix (LFSM)
samples and LFSM duplicates (LFSMDs), is used to calculate recovery.
Precision and accuracy studies are performed as an initial demonstration of
capability (IDC) and on-going demonstration of capability to perform the
procedure, including changes in instrumentation and operating conditions. These
studies evaluate whether the reporting limits and calibration standard
concentrations are appropriate.
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2.4. This method is intended for use by analysts skilled in the operation of LC-MS/MS
instrumentation and the interpretation of the associated data. Due to the inherent
complexities of LC-MS/MS analysis, including the need to relate sample
characteristics to analytical performance, laboratories should update their initial
estimates of performance and should strive to tighten their quality control limits
as more experience is gained with this particular method.
2.5. METHOD FLEXIBILITY
Many variants of liquid chromatography (LC) and Tandem Mass Spectrometry
(MS/MS) technology are currently in operation. In addition, variability exists in
the sources of wipe materials, wipe composition, and compatibility of various
wipe materials with some surfaces. This method was developed using a triple
quadrupole LC-MS/MS, with optimized LC conditions and wipe materials. The
method has been verified using only the specified equipment and conditions.
Other types of LC-MS/MS instrumentation, LC orESI-MS/MS conditions,
sample collection and processing steps, and wipe/collection materials can be used
for analysis, as long as similar performance is demonstrated and the quality
control measures outlined in Section 10 of this report are implemented.
3. Summary of Method
3.1. Wipe samples are collected from surfaces and stored at 4 °C (± 2 °C), if samples
are not extracted and analyzed within a 24-hour time period. Samples must be
extracted from wipes and analyzed within 14 days of collection. Upon sample
analysis, samples are spiked with the appropriate surrogate compounds, the
appropriate solvent volume is added, the sample solution is sonicated, it is
extracted with a syringe filter unit, then the extract is analyzed directly by LC-
MS/MS operated in positive electrospray ionization mode, (ESI+).
3.2. Each target compound is separated chromatographically and identified by
retention time. Comparison of the sample's primary multiple reaction monitoring
(MRM) transition to the known standard MRM transition from reference spectra
under identical LC-MS/MS conditions is used to identify analytes. The retention
time for the analytes of interest should fall within the retention time window of
the standard (within ± 5 %). The concentration of each analyte is determined by
the instrumentation software using external calibration. Surrogate analytes are
added to samples to monitor extraction efficiency of the method analytes from the
wipe and extraction process.
3.3. This procedure utilizes pre-packaged, sterile cotton gauze wipes, which are a
material commonly used for surface wiping. The wipes were determined to be
free from interferences with any targeted analyte, so a pre-cleaning step was not
necessary. Other wipes can be used, as long as similar performance is
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demonstrated and the quality control measures outlined in Section 10 of this
report are implemented. Surfaces were used as received.
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4. Definitions
4.1. ANALYSIS BATCH - A set of samples analyzed on the same instalment within a 24-
hour period and including no more than 20 field samples, beginning and ending with the
analysis of the appropriate continuing calibration check (CCC) standards. Additional
CCCs may be required depending on the number of samples (excluding quality control
[QC] samples) in the analysis batch and/or the number of field samples.
4.2. CALIBRATION STANDARD (CAL) - A solution prepared from the analyte stock
standard solution and the surrogate/internal standard(s). The CAL solutions are used to
calibrate the instrument response with respect to analyte concentration.
4.3. COLLISIONAL INDUCED DISSOCIATION - The process of converting the
translational energy of the precursor ion into internal energy by collisions with neutral
gas molecules to bring about dissociation into product ions.
4.4. CONTINUING CALIBRATION CHECK (CCC) - A calibration standard containing the
method analytes and surrogate standard(s). The CCC is analyzed periodically to verify
the accuracy of the existing calibration for those analytes at or near the mid-level
concentrations. Low calibration concentrations can be added, in addition to mid-level
concentrations, for further accuracy, but are not required.
4.5. DETECTION LIMIT (DL) - The minimum concentration of an analyte that can be
identified, measured, and reported with 99% confidence that the analyte concentration is
greater than zero.
4.6. EXTRACTION BATCH - A set of up to twenty field samples (excluding QC samples)
extracted together using the same solvents, surrogate(s), fortifying solutions, and
sampling devices.
4.7. FIELD DUPLICATE (FD) - Separate samples collected at the same time and place,
under identical circumstances and treated exactly the same as other field samples
throughout field and/or laboratory procedures. Analyses of FDs will give a measure of
the precision associated with sample collection, preservation, and storage, as well as
laboratory procedures.
4.8. LABORATORY FORTIFIED BLANK (LFB) - A blank matrix to which known
quantities of the method analytes are added in the laboratory. The LFB is analyzed
exactly like a sample, and its purpose is to demonstrate that the methodology is under
control and that the laboratory is capable of making accurate and precise measurements.
4.9. LABORATORY FORTIFIED SAMPLE MATRIX (LFSM) - A field sample to which
known quantities of the method analytes are added in the laboratory. The LFSM is
processed and analyzed exactly like a sample, and its purpose is to determine whether
the sample matrix contributes bias to the analytical results. The background
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concentrations of the analytes in the sample matrix should be determined in a separate
sample.
4.10. LABORATORY FORTIFIED SAMPLE MATRIX DUPLICATE (LFSMD) - A
duplicate of the field sample used to prepare the LFSM. The LFSMD is fortified and
analyzed identically to the LFSM. The LFSMD is used to assess method precision when
the observed concentrations of method analytes are low.
4.11. LABORATORY METHOD BLANK (LMB) - A blank matrix that is treated exactly the
same as a sample including exposure to all glassware, equipment, solvents and reagents
and surrogate standards that are used in the analysis batch. The LMB is used to
determine if method analytes or other interferences are present in the laboratory
environment, the reagents, or the apparatus.
4.12. MINIMUM REPORTING LEVEL (MRL) - The minimum concentration that can be
reported as a quantitated value for a method analyte in a sample following analysis. This
defined concentration can be no lower than the concentration of the lowest calibration
standard for that analyte and can be used only if acceptable QC criteria for this standard
are met.
4.13. PRECURSOR ION - For the purpose of this method, the precursor ion is the protonated
molecule ([M+H]+) or adduct ion of the method analyte. In MS/MS, the precursor ion is
mass-selected and fragmented by collisional induced dissociation to produce distinctive
product ions of lower mass.
4.14. PRODUCT ION - For the purpose of this method, a product ion is one of the fragment
ions produced in MS/MS by collisional induced dissociation of the precursor ion.
4.15. SAFETY DATA SHEET (SDS) - Written information provided by vendors concerning
a chemical's toxicity, health hazards, physical properties, fire, and reactivity data
including storage, spill, and handling precautions.
4.16. SURROGATE STANDARD - A pure chemical(s) added to a standard solution in a
known amount(s) and used to measure the relative response of other method analytes
that are components of the same solution. The surrogate standard should be a chemical
that is structurally similar to the method analytes, has no potential to be present in
samples, and is not a method analyte.
4.17. STOCK STANDARD SOLUTION (SSS) - A concentrated solution containing one or
more method analytes prepared in the laboratory using assayed reference materials or
purchased from a reputable commercial source.
5. Interferences
Procedural interferences can be caused by contaminants in solvents, reagents, glassware, and
other apparatus that lead to discrete artifacts or elevated baselines in the selected ion current
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profiles. Low recoveries may be due to surface permeability/porosity. All of these materials
should routinely be demonstrated to be free from interferences by analyzing Laboratory
Method Blanks (LMBs) (Section 10.4.2) under the same conditions as the samples (5).
Subtraction of blank values from sample results is not performed.
5.1. All reagents and solvents must be of pesticide grade purity or higher to minimize
interference problems. All glassware must be cleaned and demonstrated to be free from
interferences.
5.2. Matrix interferences can be caused by contaminants from the sample matrix, sampling
devices, or storage containers. The extent of matrix interferences will vary considerably
from sample source to sample source, depending upon variations in the sample matrix.
Wipe matrix interferences and contaminants are likely to be present and can have an
effect on the recoveries for the analytical procedure. These interferences lead to
elevated baselines and artifacts that could be mistakenly interpreted as positives. Wipes
were not pre-cleaned but were analyzed to ensure that there were no interferences
present. Any wipe materials containing interferences with the analytes of interest should
not be used.
5.3. Matrix effects are known phenomena in ESI-MS techniques. Managing the
unpredictable suppression and enhancement caused by these effects is recognized as an
integral part of the performance and verification of an ESI-MS procedure. The data
presented in this method were designed to demonstrate that the method is capable of
functioning with realistic samples. Each analyst is encouraged to observe appropriate
precautions and follow the described QC procedures to help minimize the influence of
ESI-MS matrix effects on the data reported. Matrix effects include ion
suppression/enhancement, high background and improper ion ratios.
6. Health and Safety
The toxicity and carcinogenicity of each reagent used in this method are defined in the safety
data sheets (SDS). Each chemical compound must be treated as a health hazard. Exposure to
these chemicals should be reduced to the lowest possible level and proper protective
equipment should be worn for skin, eyes, etc. Each laboratory is responsible for maintaining
an awareness of Occupational Safety and Health Administration (OSHA) regulations
regarding the safe handling of chemicals used in this method. A reference file of SDSs that
address the safe handling of the chemicals should be made available to all personnel involved
in the chemical analyses or subject to potential exposure. Additional references are available
(6-9).
7. Equipment and Supplies
References to specific brands of equipment and catalog numbers are provided solely as
examples and do not constitute an endorsement of the use of such products or suppliers.
Materials tested for the wipe analysis of organophosphorus pesticides are described in
Section 18.
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7.1 LC-MS/MS APPARATUS
7.1.1 LIQUID CHROMATOGRAPHY (LC) SYSTEM - An analytical system
complete with a temperature programmable liquid chromatograph with a
solvent mixer (Waters, Milford, MA - Acquity™ or equivalent able to
perform the analyses as described) and all required accessories including
syringes, solvent degasser, and autosampler.
7.1.2 ANALYTICAL COLUMN - Atlantis® - dC 18, 150 mm x 2.1 mm, 3 \im
particle size (Waters, Milford, MA, Catalog # 186001299), or equivalent.
7.1.3 TANDEM MASS SPECTROMETER (MS/MS) SYSTEM - An MS/MS
instrument (Waters TQD™ or similar instrument) can be used for analysis of
the target analytes. A mass spectrometer capable of MRM analysis with the
capability to obtain at least 10 scans over a peak with adequate sensitivity is
required.
7.1.4 DATA SYSTEM - Waters MassLynx™ software (Waters, Milford, MA) (or
similar software) interfaced to the LC/MS that allows the continuous
acquisition and storage on machine-readable media of all mass spectra
obtained throughout the duration of the chromatographic program. Waters
QuanLynx™ (or similar software) is used for all quantitative analysis for
data generated from the LC-MS unit.
7.2 EXTRACTION DEVICE
7.2.1 SONICATOR (Fisher Scientific Catalog # 15-335-112) or equivalent.
7.3 GLASSWARE AND MISCELLANEOUS SUPPLIES
7.3.1 AUTOSAMPLER VIALS - Amber 2-mL autosampler vials with pre-slit
Teflon®-lined screw tops (Waters Corp., Milford, MA), or equivalent.
7.3.2 DISPOSABLE STERILE SYRINGES - 10.0 mL ± 1% accuracy BD Safety-
Lok™ syringes (Catalog No. 14-829-32, Fisher Scientific, Pittsburgh, PA),
or equivalent.
7.3.3 AUTO PIPETTES - 10.0 mL, 1000 \iL, 100 [j,L and 10 [xL ± 1% accuracy.
7.3.4 DESOLVATION GAS - Nitrogen gas generator or equivalent nitrogen gas
supply. Aids in the generation of an aerosol of the ESI liquid spray and
should meet or exceed instrument manufacturer's specifications.
7.3.5 COLLISION GAS - Argon gas used in the collision cell in MS/MS
instruments and should meet or exceed instrument manufacturer's
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specifications.
7.3.6 ANALYTICAL BALANCE - accurate to 0.1 mg; reference weights traceable
to Class S or S-l weights.
7.3.7 National Institute of Standards and Technology (NIST)-traceable
thermometer.
7.3.8 STANDARD SOLUTION FLASKS - Class A volumetric glassware
7.3.9 SYRINGE FILTER - Millex® GV Syringe-driven polyvinylidene fluoride 13
mm filter unit, 0.22 |j,m (Millipore Corporation, Billerica, MA, Catalog #
SLGV013NL).
7.3.10 WIPES - Dukal™, 2" x 2" - 12-ply sterile cotton gauze pads, two wipes per
package (Fisher Scientific, Pittsburgh, PA, Catalog # 17986468).
7.3.11 SURFACE MATERIALS - Coupons were purchased from various vendors.
The surface materials were not pre-cleaned and were used as received. Glass
coupons (Carolina Glass Co.) were purchased from Lowe's Home
Improvement (Cincinnati, OH). Vinyl tile (Armstrong® commercial flooring,
pattern 51858, sandrift white), Laminate (Wilsonart® white countertop with
matte finish), latex paint (BEHRR Premium Plus, interior flat enamel, paint
and primer in one) and standard drywall (1/2 inch thickness) were purchased
from Home Depot (Cincinnati, OH). Galvanized steel metal was purchased
from McMaster-Carr (Robbinsville, NJ).
7.3.12 SAMPLE COLLECTION CONTAINERS - Clean 40 mL amber Volatile
Organic Analysis (VOA) vials with screw caps (Fisher Scientific™,
Pittsburgh, PA, Catalog # 05-719-127), or equivalent.
8. Reagents and Standards
8.1 REAGENTS AND STANDARDS
When compound purity is assayed to be 98% or greater, the weight may be used
without correction to calculate the concentration of the stock standard. Expiration
times for prepared solutions are suggested below, but laboratories should follow
standard QC procedures to determine when the standards should be replaced.
Label all standards and verify the correct grade of solvents. Traceability of
standards is established by the manufacturer's specifications provided at time of
purchase.
8.1.1 SOLVENTS, REAGENTS and GASES - Acetonitrile (Chemical Abstracts
Service® [CAS®] # 75-05-8); Methanol (CAS® # 67-56-1); and LC-MS grade
Water (CAS® # 7732-18-5), High performance liquid chromatography
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(HPLC) mass spectrometry pesticide grade or equivalent, demonstrated to be
free of analytes and interferences. Formic Acid (CAS # 64-18-6). Nitrogen is
used for the generation of aerosol of the ESI liquid spray, and purity should
meet instrument manufacturer's specifications. Argon is used as the collision
gas in MS/MS applications, and purity should meet instrument manufacturer's
specifications.
8.1.2 MOBILE PHASE A - Solution A consists of 10 mM ammonium formate and
0.2% of formic acid. To prepare 0.5 L, add 0.315 g of ammonium formate and
1 mL of formic acid and dilute to 0.5 L mark with water. This solvent system
is prone to some microbial growth and must be replaced daily.
8.1.3 MOBILE PHASE B - Solution B is comprised of acetonitrile and 0.2% formic
acid. To prepare 0.5 L, dilute 1 mL of formic acid to 0.5 L mark with
acetonitrile.
8.1.4 TARGET ANALYTES - Disulfoton (Catalog #: 50-803-00), disulfoton-
sulfoxide (Catalog #: 50-778-52), disulfoton-sulfone (Catalog #: 50-776-91),
monocrotophos (Catalog #: 50-805-82), methamidophos (Catalog #: 50-712-
05), chlorfenvinphos (Catalog #: 50-799-52), chlorpyrifos (Catalog #: 50-799-
97), chlorpyrifos-oxon (Catalog #: NC9569833), mevinphos (Catalog #: 50-
805-78), dichlorvos (Catalog #: 50-734-37), fenamiphos (Catalog #: 50-803-
56), fenamiphos-sulfone (Catalog #: 50-709-71), and fenamiphos-sulfoxide
(Catalog #: 50-709-73) were purchased from Fisher Scientific (Pittsburgh,
PA).
8.1.5 SURROGATE ANALYTES - Chlorpyrifos-dio (Catalog #: 50-799-99),
disulfoton-dio (Catalog #: 50-803-02), dichlorvos-d6 (Catalog #: 50-734-38),
and methamidophos-d6 (Catalog #: 50-805-41) were purchased from Fisher
Scientific (Pittsburgh, PA).
8.2 STANDARD SOLUTIONS
When compound purity is assayed to be at least 98% or greater, the weight can be
used without correction to calculate the concentration of the stock standard.
Stock standards and all subsequent solutions must be replaced when analyzed
solution concentrations deviate more than ± 20% from the prepared concentration.
Standards are stored protected from light (amber flasks) and at 4 °C (± 2 °C).
Standards are estimated to be stable for at least a month as long as water is not
present. Degradation can occur, thus, requiring storage at lower temperatures (-
20 °C). Although stability times are suggested, laboratories should utilize QC
practices to determine when standards should be replaced.
8.2.1 SURROGATE STOCK STANDARD SOLUTION (Surrogate SSS) (10-1000
Hg/mL)
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A standard solution must be prepared from certified commercially available
solutions or neat compounds. Isotopically-labeled surrogates, chlorpyrifos-dio
and methamidophos-d6, were purchased as acetone solutions. Disulfoton-dio
was purchased as a cyclohexane solution and dichlorvos-d6 was purchased as
a neat standard. Surrogates are added to a 10 mL volumetric flask to achieve a
concentration of 2.5, 10, and 15 ppm for methamidophos-d6, chlorpyrifos-dio,
disulfoton-dio, and dichlorvos-d6, respectively (i.e., 250 |j,L of
methamidophos-d6 of a 100 ppm solution, 1000 |j,L of 100 ppm solutions of
chlorpyrifos-dio, disulfoton-dio, and 150 |j,L of a 1000 ppm solution of
dichlorvos-d6 were added to a 10 mL volumetric flask and diluted to the mark
with acetonitrile). Surrogate stock standard solutions are stable for at least a
two weeks when stored at 4 °C.
(NOTE: Although the isotopically-labeled analytes were used as surrogates in
this method, they potentially could be used as internal standards for
quantitation purposes. Further evaluation would be necessary to ensure that
they are viable internal standards and meet QC requirements.)
8.2.2 ANALYTE STOCK STANDARD SOLUTION (AS)
Standard solutions must be prepared from certified commercially available
neat compounds. Dichlorvos, disulfoton-sulfone, and chlorpyrifos-oxon were
purchased as neat materials. Chlorpyrifos, fenamiphos, chlorfenvinphos,
disulfoton, monocrotophos, methamidophos, mevinphos were purchased as
acetonitrile solutions. Disulfoton-sulfoxide was purchased as an acetone
solution. Fenamiphos-sulfone and fenamiphos-sulfoxide were purchased as
hexane: acetone (4:1) solutions. All thirteen analytes were used to make the
analyte stock standard acetonitrile solution (four times calibration level 8).
The standard acetonitrile solution (with a concentration of 1 ng/mL [ppm] for
methamidophos, disulfoton-sulfoxide, monocrotophos, and fenamiphos, 2
Hg/mL [ppm] for mevinphos and chlorfenvinphos, 4 |j,g/mL [ppm] for
chlorpyrifos, chlorpyrifos-oxon, disulfoton, disulfoton-sulfone, fenamiphos-
sulfone, and fenamiphos-sulfoxide, and 6 |j,g/mL [ppm] for dichlorvos) was
made in a 25 mL volumetric flask (i.e., 2.5 mL of methamidophos, 25 |j,L of
disulfoton-sulfoxide, 250 |j,L of monocrotophos and fenamiphos, 500 |j,L of
mevinphos and chlorfenvinphos, 1000 |j,L of chlorpyrifos and disulfoton, 100
|j,L of disulfoton-sulfone, chlorpyrifos-oxon, fenamiphos-sulfone, and
fenamiphos-sulfoxide, and 30 |j,L of dichlorvos are each added to a 25 mL
volumetric flask and diluted to the mark with acetonitrile). The calibration
standards and spike solutions are made from the appropriate dilution of this
analyte stock standard. The analyte stock standard solution is stable for at
least 2 weeks when stored at 4 °C.
8.2.3 CALIBRATION STANDARD SOLUTION (CAL)
Dilution of the analyte stock standard solution can be used to obtain a
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calibration level 8 solution in acetonitrile. A calibration stock standard
solution (Level 8) is prepared from the Analyte Stock Standard Solution (AS)
and SSS by adding, 2.5 mL of AS, and 1 mL of the SSS (i.e., 2.5 mL of the
AS containing dichlorvos, disulfoton-sulfone, chlorpyrifos-oxon, chlorpyrifos,
fenamiphos, chlorfenvinphos, disulfoton, monocrotophos, methamidophos,
mevinphos, disulfoton-sulfoxide, fenamiphos-sulfone, and fenamiphos-
sulfoxide and 1 mL of the SSS are added to a 10 mL volumetric flask and
diluted to the mark with acetonitrile). From Level 8, further dilutions are
performed with acetonitrile to prepare Levels 7 through 1, as shown in Section
18.
9. Sample Collection, Preservation and Storage
9.1 SAMPLE COLLECTION
9.1.1 VOA vials were used for sample collection in this method. Other vessels may
be used as long as they are tested and verified to ensure they do not contain
any interfering compounds. As an example for field samples, the field
samplers would collect samples with the appropriate wetted wipe and place
the wipes in a VOA vial, seal the vial with a screw cap, and ship the vial
containing the sample to the laboratory.
9.1.2 The wipe is wetted with 1 mL of acetonitrile, sufficient to wet the wipe. The
surface is wiped in a Z-like pattern horizontally across a defined surface (100
cm2), then around the perimeter of the surface (Attachment 19.3), and placed
in a VOA vial. A second wetted wipe is used to wipe the same surface in a Z-
like pattern vertically across a defined surface (100 cm2), then around the
perimeter of the surface, and is placed into the same 40 mL VOA vial.
Surrogates (100 |j,L of the SSS) and LC-MS grade acetonitrile (5 mL) are
added to the vial after surface wiping is completed and capped. Field and/or
matrix blanks are needed, according to conventional sampling practices;
therefore, one wiped blank sample coupon (surface wipe blank) and one wipe
blank (unsampled wipe) must be analyzed in every sample extraction batch
(Section 10.4). Wetting solvent and surrogates are added to field and matrix
blanks.
9.2 SAMPLE STORAGE AND HOLDING TIMES
9.2.1 Wipe samples should be extracted as soon as possible after collection. If not
immediately extracted, they must be extracted and analyzed within 14 days of
collection. Samples not immediately analyzed from a particular site must be
carefully characterized to ensure there is no interaction with the wipe or a
specific surface to cause interferences or degradation of the analytes. An
LFSM must be generated for the appropriate time period to verify such an
occurrence. Samples can be stored up to 14 days prior to extraction (Table 1)
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at 4 °C (± 2 °C). Further evaluation is needed to confirm holding times longer
than 14 days for certain analytes. Matrix enhancement/suppression effects
resulted in high recoveries for some of the analytes past 14 days (Table 1).
10. Quality Control
10.1 QC requirements include the performance of an initial demonstration of capability
(IDC) and ongoing QC requirements that must be met to generate data of
acceptable quality when preparing and analyzing samples. This section describes
the QC parameters, their required frequencies and performance criteria on the
tested surfaces (Table 2). A precision and accuracy study (as shown in section
19.2) as well as a Detection Limit (DL) study (Table 3 and section 19.1) must be
performed to demonstrate laboratory capability. Laboratories are encouraged to
institute additional QC practices to meet their specific needs.
10.2 INITIAL DEMONSTRATION OF CAPABILITY (IDC)
The IDC must be performed successfully prior to the initiation of analysis of field
samples. Prior to conducting an IDC, an acceptable Initial Calibration must be
generated as outlined in Section 11.2.
10.2.1 INITIAL DEMONSTRATION OF LOW SYSTEM BACKGROUND
Any time a new lot of solvents, reagents, filters, and autosampler vials are
used, the LMB must be demonstrated to be reasonably free of contamination
(i.e., that the criteria are met as stipulated in Section 10.4.2). The LMB is
used to ensure that analytes of interest or other interferences are not present in
the laboratory environment, the solvent, or the apparatus.
NOTE: Good laboratory practices indicate the use of a blank before and after
analyzing a calibration curve for an instrument to ensure that no carryover will
occur. If the required criteria are not met and samples were not free of
contamination, then the source of the contamination must be identified and
eliminated before the performance of any analysis.
10.2.2 INITIAL DEMONSTRATION OF PRECISION AND ACCURACY
NOTE: Because porosity of the wiped surface will inevitably have an effect on
analyte recovery from the surface, accuracy results between calculated values
and true values may differ from surface to surface. The precision and accuracy
results are based on the wipe used on the metal (McMaster-Carr, Robbinsville,
NJ) surface because (1) the metal surface has been shown to be free of
contamination, (2) this surface results in minimal surface interaction between the
chemical and the surface, and (3) the metal is a nonporous/non permeable
surface.
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For a precision and accuracy demonstration, prepare a check standard
containing dichlorvos, disulfoton-sulfone, chlorpyrifos-oxon, chlorpyrifos,
fenamiphos, chlorfenvinphos, disulfoton, monocrotophos, methamidophos,
mevinphos, disulfoton-sulfoxide, fenamiphos-sulfone, and fenamiphos-
sulfoxide near or below the midpoint concentration of the calibration range.
This check standard should be analyzed using a minimum of four replicates.
For this study, three different concentrations are chosen with seven samples
each. The check samples are analyzed according to Section 12.
10.2.3 The average percent recovery (X), standard deviations (a) and the percent
relative standard deviation (% RSD) of the recoveries are calculated for each
analyte. The relative percent difference (% RPD) limit of < 30% should be
applied to all replicate analyses.
10.2.4 MINIMUM REPORTING LEVEL (MRL)
Establish a target concentration for the MRL based on the intended use of the
method. Establish an Initial Calibration (Section 11.2). The lowest CAL
standard used to establish the initial calibration should be at or below the
MRL concentration. If the MRL concentration is too low, ongoing QC
requirements may fail repeatedly, and the MRL should be determined again at
a higher concentration.
10.2.5 CALIBRATION VERIFICATION
Mid-level and low-level samples from the calibration curve must be analyzed
to confirm the accuracy of the fit of the calibration curve/standards after the
end of sample batches.
3 METHOD DETECTION LIMITS (MDL)
The procedure for the determination of the laboratory detection and quantitation
limits for the EPA approach follows 40 CFR Part 136, Appendix B. The MDLs
represent the minimum concentration at which there is a high degree of statistical
confidence that, when the method reports that an analyte is present, that analyte is
actually present (i.e., a low risk of false positives).
10.3.1 DETERMINATION OF LABORATORY INSTRUMENT DETECTION
LIMITS (IDLs)
The laboratory instrument detection limit (IDL) can be used to establish an
estimate of the initial spiking concentration used for determination of the
MDL, although other approaches for determining the initial spiking
concentration may be used. The laboratory IDL is determined for each analyte
as a concentration that produces an average signal-to-noise (S/N) ratio in the
range of 3:1 - 5:1 for at least three replicate injections. For example,
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successively lower concentrations of the analytes are injected until the S/N
ratio is in the range of 3:1 -5:1. Replicates are then injected at that target
concentration to ensure that the average S/N of the replicates was within the
3:1 -5:1 range. Note that since linearity of S/N ratio with increasing or
decreasing concentration cannot be assumed, the concentrations determined
via this procedure are necessarily approximate.
10.3.2 DETERMINATION OF LABORATORY METHOD DETECTION LIMIT
(MDL)
Method Detection Limits (MDLs) represent the optimal detection achieved by
a laboratory in a matrix of interest. The analyte spiking solution, containing
all thirteen analytes, was added to the metal surface (section 19.3). The
solution on the surface was allowed to completely dry (60-90 minutes) and
wiped using a wetted-cotton gauze wipe. Wipe extracts from the metal
coupons are used for the determination of the MDL for surface samples. The
40 CFR Part 136, Appendix B procedure is followed, particularly with regard
to spike levels used. Replicate reference matrix samples are spiked at a level
between 1-5 times the estimated detection level (e.g., suggested by the IDL
procedure in 10.3.1). The resulting MDL should be within 10 times the spike
level used, or the MDL determination would be repeated using a more
appropriate spike level. Full method sample preparation procedures to
prepare and analyze at least seven replicates of the spiked matrix of interest
are used. Apply the following equation to the analytical results (Student's t-
factor is dependent on the number of replicates used; the value 3.14 assumes
seven replicates):
MDL — t (n-l, 1-
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An LFB is required with each extraction batch to confirm that potential
background contaminants are not interfering with identification or quantitation
of the target analytes. If there is a contaminant within the retention time
window preventing the determination of the target analyte, the source of the
contamination should be determined and eliminated before processing
samples. LFBs include cotton gauze wipes wetted with acetonitrile.
10.4.2 LABORATORY METHOD BLANK (LMB)
An LMB is prepared and analyzed with each extraction batch, using LC-MS
grade acetonitrile, for confirmation that there are no background contaminants
interfering with the identification or quantitation of the target analytes. If
there is a contaminant within the retention time window preventing the
determination of the target analyte, the source of the contamination should be
determined and eliminated before processing samples. LMBs include the
extracted wipe used to wipe the surface coupon.
10.4.3 CONTINUING CALIBRATION CHECK (CCC)
CCC standards are analyzed at the beginning and end of each analysis batch.
The CCC is analyzed periodically to verify the accuracy of the existing
calibration for analytes near the midpoint of the calibration range and/or near
the MRL (low concentrations observed in the calibration curve). The CCC
standards can rotate between the two values suggested above. CCC values
should be specified by the sample submitter's Data Quality Objectives
(DQOs) or fulfill other QC requirements, such as LFSM acceptance).
10.4.4 LABORATORY FORTIFIED SAMPLE MATRIX (LFSM)
A LFSM is analyzed to determine that spike accuracy for a particular sample
matrix is not adversely affected by chemical interactions between target
analytes and experimental matrices (i.e., coupon/wipe materials). If a variety
of sample matrices are analyzed, performance must be established for each
surface.
4.4.1 Within each analysis batch, an LFSM is prepared and analyzed at a
frequency of one sample matrix for every twenty samples. The LFSM is
prepared by spiking a sample with the appropriate amount of AS (Section
8.2.2). Select a spiking concentration that is greater than or equal to the matrix
background concentration, if known. Records are maintained of the surface
target compound spike analyses, and the average percent recovery (X), and the
standard deviation of the percent recovery (a) are calculated. Analyte
recoveries may exhibit bias for certain matrices. Acceptable recoveries are 50-
150%, if a low-level concentration near or at the MRL (within a factor of 3) is
used. If the recovery does not fall within this range, check with a CCC or
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prepare a fresh AS solution for analysis. If the recovery of any analyte still falls
outside the designated range and the laboratory performance for that analyte is
shown to be in control in the CCCs, the recovery is judged to be matrix biased.
The result for that analyte in the unfortified sample is labeled suspect/matrix to
inform the data user that the results are suspect due to matrix effects.
10.4.5 SURROGATE STANDARD
All samples (CCCs, LFBs, LMBs, LFSMs, LFSMDs, FDs, and CAL
standards) are spiked with surrogate standard spiking solution as described in
Section 8.2.1. An average percent recovery of the surrogate compound and
the standard deviation of the percent recovery are calculated and updated
regularly.
10.4.6 FIELD DUPLICATE (FD) OR LABORATORY FORTIFIED SAMPLE
MATRIX DUPLICATE (LFSMD)
Within each analysis batch, a minimum of one FD or LFSMD should be
analyzed for every twenty samples. Target compound spike accuracy in the
sample matrix is monitored and updated regularly. Duplicates check the
precision associated with sample collection, storage, and laboratory
procedures. Records are maintained of spiked matrix analyses and the
average percent recovery (X) and corresponding standard deviation (a) are
calculated. FD/LFSMD samples must be incorporated into the field sampling
plan. If the laboratory did not receive FD samples for determination of site-
specific precision and accuracy, the laboratory will evaluate the site data
quality based on the LFSM data, if there is sufficient sample in the site
samples to conduct an analysis. FD/LFSMD recovery results will be used for
site-specific precision and accuracy data. LFSM data are used as FD/LFSMD
sample data for this study. RPD values should be < 30% for FD/LFSMD
samples.
10.4.6.1 Calculate the relative percent difference (RPD) for duplicate
measurements (FDi and FD2) using the equation:
Ifd, -fdJ
RPD = ^—x 100
(FD1+FD2)/2
RPDs for Field Duplicates should be < 30% for each analyte. Greater
variability may be observed when Field Duplicates have analyte
concentrations at or near the MRL (within a factor of two times the MRL
concentration). At these concentrations, FDs should have RPDs that are <
50%). If the RPD of an analyte falls outside the designated range and the
laboratory performance for the analyte is shown to be in control in the
CCC and in the LFB, the precision is judged matrix influenced. Report
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the result for the corresponding analyte in the unfortified sample as
"suspect/matrix."
10.4.6.2 If an LFSMD is analyzed instead of an FD, calculate the RPD for
the LFSM and LFSMD using the equation:
Ilfsm-lfsmdI
RPD = ^x 100
(LFSM + LFSMD)/2
RPDs for duplicate LFSMs should be < 30% for each analyte. Greater
variability may be observed when the matrix is fortified at analyte
concentrations at or near the MRL (within a factor of two times the MRL
concentration). LFSMs at these concentrations should have RPDs that
are < 50%. If the RPD of an analyte falls outside the designated range
and the laboratory performance for the analyte is shown to be in control
in the CCC and in the LFB, the precision is judged matrix influenced.
Report the result for the corresponding analyte in the unfortified sample
as "suspect/matrix" to inform the data user that the results are suspect due
to matrix complications.
11. Instrument Calibration and Standardization
All laboratory equipment must be calibrated according to manufacturer's protocols.
Demonstration and documentation of acceptable mass spectrometer (MS) tuning and initial
calibration is necessary prior to sample analysis. Verification of the tuning of the MS must
be repeated each time instrument modification/maintenance is performed and prior to analyte
calibration. After initial calibration is successful, a CCC (at the appropriate concentration
described in section 10.4.2) must be performed at the beginning and end of each analysis
batch.
11.1 CALIBRATION OF MASS SPECTROMETER
Calibrate the mass scale of the mass spectrometer as prescribed by the
manufacturer. The mass calibration file is saved in the mass spectrometer
software file folder (MassLynx™ or similar software). The mass calibration
solution used in this method is a mixture of NaCsI provided by the manufacturer.
Other calibration solutions can also be used per instrument manufacturer's
specifications.
11.2 INITIAL CALIBRATION FOR ANALYTES
11.2.1 ESI positive mode is the preferred choice for this method due to the
optimal conditions and advantages (e.g., greater peak intensity, few
interferences, and lower background).
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11.2.2 Optimize the [M-H]+ ion in ESI positive mode for each analyte by
infusing an appropriate calibration solution at a flow rate similar to the
flow rate used for the LC separation. Adjust MS parameters (voltages,
temperatures, gas flows, etc.) until optimal analyte responses are achieved.
Optimize the product ion by following the same procedures as for the [M-
H]+ ion. Ensure that there are at least 10 scans across the peak to optimize
precision. ESI-MS and MS/MS parameters utilized during development
of this method are presented in Tables 4 and 5.
11.2.3 Establish LC operating conditions that will optimize peak resolution and
shape. Suggested LC conditions (listed in Table 6) may not be optimal for
all LC systems.
11.2.4 The initial calibration contains an eight-point curve using the analyte
concentrations prepared in section 8.2.3 and shown in Table 7. The lowest
calibration curve standard should be at the MRL. The calibration curve
and all samples should be analyzed in a low to high concentration
regimen, so carryover is less of a concern in case the LC cleaning cycle
does not clean the system adequately between injections. Verify that all
analytes have been properly identified and quantified using software
programs. Integrate manually, if necessary, in accordance with laboratory
quality assurance plans. Depending on the instrument, sensitivity and
calibration curve responses may vary. At a minimum, a five-point linear or
a six-point quadratic calibration curve will be utilized for all analytes. If
the polynomial type excludes the point of origin, use a fit weighting of 1/X
to give more weighting to the lower concentrations. The coefficient of
determination (r2) of the linear fit should be greater than or equal to 0.98.
If one of the calibration standards other than the high or low standard
causes the r2 to be < 0.98, this point should be re-injected or a new
calibration curve should be analyzed. If the low and/or high point is
excluded, a seven or six-point curve is acceptable but the calibration range
and reporting limits should be modified to reflect this change. The r2 of
the quadratic curve should be greater than or equal to 0.99. If one of the
calibration standards other than the high or low standards causes the r2 to
be < 0.99, follow the same procedure given above for a linear fit. A
calibration curve and an instrument blank will be analyzed at the
beginning of each batch or daily to ensure instrument stability (9). In
addition to the r2 values, when quantitated, each calibration point for each
analyte should calculate to be within 70-130 % of its true value as a check
to ensure results are valid. The lowest CAL standard must calculate to be
within 50-150 % of its true value. A new curve will be generated daily.
The calibration method is used to quantify all samples.
11.3 QUANTITATION OF ANALYTES
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The quantitation of the target analytes is accomplished with quantitation software
as it relates to each specific instrument (9, 10). An external calibration is used
along with monitoring methamidophos-d6, chlorpyrifos-dio, disulfoton-dio, and
dichlorvos-d6 surrogate recoveries. Refer to Table 4 for the MRM transitions and
retention times utilized during the development of this method.
12. Analytical Procedure
12.1 SAMPLE PREPARATION
12.1.1 Samples must be collected and stored as described in Section 9.
Surrogates (methamidophos-d6, chlorpyrifos-dio, disulfoton-dio, and
dichlorvos-de) are added to wipe samples in the collection vessels, then
LC-MS grade acetonitrile (5 mL) is added to the jar and capped. Samples
are stored as described in Section 9. Wipes samples should be extracted
within 14 days of collection. Sonicate each jar containing the solution for
approximately 15 minutes in a water bath at room temperature.
12.1.2 After sonication, decant the extraction solvent into a 10 cc lock-tip sterile
fitted syringe and filter using a Millex® GV syringe driven filter unit,
polyvinylidene fluoride filter (0.22 |j,m).
12.1.3 Transfer solution (via pipette) to a standard 2 mL sample vial.
NOTE: Calibration standards are not filtered through the syringe-driven filter
units because no particulates are present. The filters and syringes used in this
study were shown not to affect analyte concentrations. If alternate filtering is
incorporated, the filters should be subjected to QC requirements to ensure they
do not introduce interferences or retain the target analytes.
12.2 SAMPLE ANALYSIS/ANALYTICAL SEQUENCE
12.2.1 Use the same LC-MS conditions established per guidance described in
Section 11 and summarized in Tables 4, 5, and 6.
12.2.2 Prepare an analytical batch that includes all QC samples and surface
samples. The first sample to be analyzed is a 10 [j.L injection of a blank
(LC-MS grade acetonitrile) on column, followed by the calibration curve.
12.2.3 Update the calibration file and archive (or print) a calibration report.
Review the report for calibration outliers and make area corrections by
manual integration, if necessary and appropriate. If corrections have been
made, update the calibration file, noting the changes, and regenerate a
calibration report. Alternatively, re-analyze "nonconforming" calibration
level(s) and repeat the above procedures.
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12.2.4 The first sample analyzed after the calibration curve is an additional blank
(LC-MS grade acetonitrile) to ensure there is no carryover (11). If the
initial calibration data are acceptable, begin analyzing samples, including
QC and blank samples, at their appropriate frequency injecting the same
size aliquots (10 |j,L) under the same conditions used to analyze CAL
standards. The ending CCC should have each analyte concentration
within 30% of the calculated true concentration, or the affected analytes
from that run should be qualified as estimates or the samples should be re-
analyzed with passing criteria to remove the qualification.
12.2.5 If the absolute amount of a target compound exceeds the working range of
the LC-MS system (see Level 8 in Table 7), the prepared sample is diluted
with acetonitrile and re-analyzed along with additional samples that may
have run after the sample known to exceed the calibration range, because
of the possibility of carryover. Care should be taken to ensure that there is
no carryover of the analyte that has exceeded the calibration range. If the
amount of analyte exceeds the calibration range, a blank sample should be
analyzed afterward to demonstrate no carryover has occurred.
12.2.6 At the conclusion of the data acquisition, use the same software that is
used in the calibration procedure to identify peaks of interest from the
predetermined retention time windows. Use the data software to examine
the ion abundances of the peaks in the chromatogram to identify and
compare retention times in the sample chromatogram with the retention
time of the corresponding analyte peak in an analyte standard.
13. Data Analysis and Calculations
13.1 QUALITATIVE AND QUANTITATIVE ANALYSIS
13.1.1 An external calibration is used when monitoring the MRM transitions of
each analyte. Quantitation software is utilized to conduct the quantitation
of the target analytes and surrogate standards. The MRM transitions of
each analyte are used for quantitation and confirmation. The MRM
transition serves as a confirmation by isolating the precursor ion,
fragmenting the precursor ion to the product ion, and relating the transition
to the retention time in the calibration standard (9).
13.1.2 Computer programs used for analysis of data include instrumentation and
quantitation software. Manual integration may be necessary for some
peak areas if the peak area is not integrated properly {i.e., the integration
for the peak is not fully performed by the instrument's software, which
will be noticeable by visual inspection of each peak). Inspect all
integrated peaks for visible integration errors and manually integrate as
necessary to ensure consistent integration of other peaks and/or known
calibration peaks. Any manual integration should be carried out by a
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qualified analyst, noted, and checked against quality control procedures
(sections 10 and 11.3).
13.2 Prior to reporting data, the chromatogram should be reviewed for any incorrect peak
identifications. The retention time window of the MRM transitions should be within
5 % of the retention time of the analyte standard. If this is not true, the calibration
curve needs to be re-analyzed to see if there was a shift in retention times during the
analysis and if the sample needs to be re-injected. If the retention time is still
incorrect in the sample, the analyte is referred to as an unknown. If peaks need to be
manually adjusted due to incorrect integration by the program, clarification of where
professional judgment was used to alter the peaks should be documented during the
data reduction and verification process.
14. Method Performance
14.1 PRECISION, ACCURACY AND DETECTION LIMITS
14.1.1 Tables for precision, accuracy and detection limit results for a single
laboratory study are presented in Sections 19.1 and 19.2 and Table 3.
14.2 RECOVERIES AND PRECISION FOR SURFACE TYPES
14.2.1 Section 19.2 lists recoveries and precision of target analytes for a variety
of surfaces. Recoveries from non-porous/non-permeable surfaces are
better (70-130 %) than from porous/permeable surfaces. The differences
between the surface types should be noted when interpreting recovery
results.
14.3 WIPE STORAGE STABILITY STUDY
14.3.1 Extract storage was conducted on the metal surface fortified with the
targeted method analytes. Precision and accuracy (n = 7) of the extracts
were analyzed on days 0, 2, 7, 14, 21, and 31 days and are reported in
Table 1.
14.4 PROBLEM ANALYTES AND SURFACES
14.4.1 TARGET ANALYTES ON UNCLEANED SURFACES
Dichlorvos, disulfoton, mevinphos, methamidophos, and chlorpyrifos
recoveries may be problematic due to the volatility, interferents, surface
interaction, or rapid decomposition of these specific compounds (12, 13, 14).
Analysts should be aware that these specific compounds may be present
within the tested sample matrix and plan accordingly. Furthermore, ESI (+)
analysis results may be problematic for certain compounds (e.g., chlorpyrifos)
due to possible electrospray enhancement/suppression effects. Detection limits
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are based on ESI (+) data. Although porosity/permeability of the surface is
likely the culprit for low recoveries, further analysis should be performed to
determine definitive reasons for poor recoveries from the surface. Other
causes include suppression in the ESI source due to co-eluting substances.
Direct extraction of the analytes from porous surfaces could be used to
elucidate whether or not chemical interactions are occurring between target
analytes and compounds found in such a matrix.
15. Pollution Prevention
15.1 This method utilizes small volumes of organic solvent and small quantities of pure
analytes, thereby minimizing the potential hazards to both analyst and environment.
15.2 For information about pollution prevention that may be applicable to laboratory
operations, consult "Less is Better: Laboratory Chemical Management for Waste
Reduction" available from the American Chemical Society's Department of
Government Relations and Science Policy, 1155 16th Street N.W., Washington,
D.C., 20036 or on-line at
http://www.acs.org/content/dam/acsorg/about/governance/committees/chemicalsafet
v/publications/less-is-better.pdf (accessed April 15, 2017).
16. Waste Management
16.1 The analytical procedures described in this method generate relatively small
amounts of waste because only small amounts of reagents and solvents are used.
Laboratory waste management practices should be conducted consistent with all
applicable rules and regulations, and laboratories should protect the air, water, and
land by minimizing and controlling all releases from fume hoods and bench
operations. Also, compliance with any sewage discharge permits and regulations is
required, particularly the hazardous waste identification rules and land disposal
restrictions.
16.2 Each laboratory should determine with federal and local officials how to safely
dispose of field and QC samples. Waste containers should be properly labeled to
identify the contents. Remember to attach the appropriate chemical waste label,
date the beginning of collection before using the container and follow all
appropriate federal and local waste disposal requirements.
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17. References
1. U.S. Environmental Protection Agency (EPA), 2012. Selected Analytical Methods for
Environmental Restoration Following Homeland Security Events (SAM). EPA/600/R-
12/555 July 2012. Cincinnati, Ohio: United States Environmental Protection Agency,
Office of Research and Development, National Homeland Security Research Center.
2. Code of Federal Regulations, 40 CFR Part 136, Appendix B. Definition and Procedure
for the Determination of the Method Detection Limit - Revision 1.11.
3. Federal Advisory Committee on Detection and Quantitation Approaches and Uses in
Clean Water Act Programs. Final Report. (Submitted to U.S. Environmental
Protection Agency.) December 28, 2007.
4. Glaser, J.A., Foerst, D.L., McKee, G.D., Quave, S.A., Budde, W.L., "Trace Analyses
for Wastewaters." Environ. Sci. Technol. 1981, 15, 1426-1435.
5. Standard Practices for Preparation of Sample Containers andfor Preservation of
Organic Constituents, ASTM Annual Book of Standards, Part 31, D3694-78.
Philadelphia: American Society for Testing and Materials.
6. OSHA Safety and Health Standards, General Industry (29CRF1910). Occupational
Safety and Health Administration, OSHA 2206 (Revised, July 1, 2001).
7. Carcinogens-Working with Carcinogens, Publication No. 77-206. Atlanta, Georgia:
Department of Health, Education, and Welfare, Public Health Service, Center for
Disease Control, National Institute of Occupational Safety and Health, August 1977.
8. Safety in Academic Chemistry Laboratories, American Chemical Society Publication,
Committee on Chemical Safety, 7th Edition.
9. "Prudent Practices in the Laboratory: Handling and Disposal of Chemicals," National
Academies Press (1995), available at http://www.nap.edu (accessed April 17, 2017).
10. Winslow, S.D., Pepich, B.V., Martin, J.J., Hallberg, G.R., Munch, D.J., Frebis, C.P.,
Hedrick, E.J., Krop, R.A. "Statistical Procedures for Determination and Verification of
Minimum Reporting Levels for Drinking Water Methods." Environ. Sci. Technol.
2006, 40, 281-288.
11. Peters, F.T.; Drummer, O.H.; Musshoff, F. "Validation of New Methods", Forensic
Science International 2007, 165 (2): 216-224.
12. "Toxicological Profile for Chlorpyrifos," U.S. Department of Health and Human
Services, Public Health Service Agency for Toxic Substances and Disease Registry,
September 1997.
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13. "Public Health Statement for Dichlorvos," U.S. Department of Health and Human
Services, Public Health Service Agency for Toxic Substances and Disease Registry,
September 1997.
14. "Addendum to the Toxicological Profile for Disulfoton," U.S. Department of Health
and Human Services, Public Health Service Agency for Toxic Substances and Disease
Registry, September 2011.
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18. Tables and Validation Data
Item Title
Table 1. Holding Time Sample Stability of Wipe Samples of Organophosphorus Pesticides in ESI Positive (+) Mode 27
Table 2. Materials Tested for the Analysis of Wipe Samples 28
Table 3. Method Parameters for Organophosphorus Pesticides 28
Table 4. ESI (+) MRM Ion Transitions, Retention Times (RT) 29
Table 5. ESI (•) MS/MS Conditions 30
Table 6. Liquid Chromatography Gradient Conditions* 30
Table 7. Target Calibration Concentration Standards (ng/mL) 31
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Table 1. Holding Time Sample Stability of Wipe Samples of Organophosphorus Pesticides in ESI Positive (+) Mode
ESI (+) Mode
Holding Time (days)
0
2
7
14
21
31
Analyte
(concentration - ng/mL)
Average* %
Recovery ±
% RSD
Average* %
Recovery ±
% RSD
Average* %
Recovery ±
% RSD
Average* %
Recovery ±
% RSD
Average* %
Recovery ±
% RSD
Average* %
Recovery ±
% RSD
Chlorfenvinphos (50)
95 ±4
102 ±6
105 ±7
106 ± 10
116 ± 16
89 ± 8
Chlorpyrifos (100)
95 ±27
116 ±29
101 ±8
89 ±21
146 ±21
82 ± 12
Chlorpyrifos-oxon (100)
84 ±5
81 ±3
97 ±5
89 ±7
83 ± 11
90 ±6
Dichlorvos (150)
100 ± 14
133 ± 14
116 ± 11
135 ±25
82 ±330
77 ±28
Disulfoton (100)
161 ± 18
145 ± 16
177 ± 12
183 ± 16
319 ± 32
118 ± 13
Disulfoton sulfone (100)
90 ± 8
89 ± 8
95 ±9
102 ±4
97 ± 16
71 ± 6
Disulfoton sulfoxide (25)
86 ±6
90 ±7
102 ±8
92 ± 11
102 ±11
88 ±5
Fenamiphos (25)
88 ±7
97 ±6
102 ±4
95 ±9
125 ± 15
91 ± 7
Fenamiphos sulfone (100)
94 ± 11
86 ±9
109 ±8
93 ± 10
115 ± 11
91 ± 9
Fenamiphos sulfoxide (100)
89 ±6
76 ±6
91 ±9
90 ±6
104 ±7
102 ±3
Methamidophos (25)
153 ±21
123 ± 13
179 ±11
109 ±28
46 ± 190
87 ±39
Mevinphos (50)
86 ± 8
77 ±6
96 ±6
94 ± 12
102 ±11
104 ±6
Monocrotophos (25)
100 ±11
94 ±2
114 ± 8
117 ± 6
234 ±6
148 ±6
*Average recovery of 7 samples. RSD, relative standard deviation
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Table 2. Materials Tested for the Analysis of Wipe Samples
of Organophosphorus Pesl
ticides
Material
Manufacturer/Vendor*
Glass
Carolina Glass Co./Lowe's
Vinyl Tile
Armstrong/Home Depot
Laminate
Wilsonart® Laminate/Home Depot
Galvanized steel
McMaster-Carr
Painted Drywall (BEHR® latex paint)
BEHR/Home Depot
*Material vendor information is listed in Section 7.3.11
Table 3. Method Parameters for Organophosphorus Pesticides
METAL SURFACE
Analyte
MDL
MRL
ng/cm2
ng/mL
ng/mL
Chlorfenvinphos
0.013
1.3
4
Chlorpyrifos-oxon
0.022
2.2
7
Disulfoton sulfone
0.025
2.5
26
Disulfoton sulfoxide
0.013
1.3
8
Fenamiphos
0.010
1.0
3
Fenamiphos sulfone
0.047
4.7
15
Fenamiphos sulfoxide
0.038
3.8
12
Monocrotophos
0.010
1.0
2
Analytes Requiring Further Testing
Chlorpyrifos
0.10
10
33
Dichlorvos*
0.075
7.5
75
Disulfoton*
0.050
5.0
50
Methamidophos
0.016
1.6
5
Mevinphos*
0.025
2.5
25
*The lowest calibration level is presented as the MDL value because recoveries were non-detect or below acceptable
recovery levels at the tested concentration. ESI+ ionization mode provided the method detection limit (MDL) and
minimum reporting level (MRL) values. MRL levels are conservative and the lowest calibration level may suffice.
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where applicable, as the MRL value. See section 19.1 for complete DL data.
¦fng/cm2 was calculated by dividing the concentration spiked onto the surface by coupon test area (100 cm2).
Table 4. ESI (+) MRM Ion Transitions, Retention Times (RT) and Variable Mass
Spectrometer Parameters
Analyte
Cone
voltage
MRM mass transition
(parent —~ product)
Collision
energy
(eV)
RT*
(minutes)
Chlorfenvinphos
32
361.16 > 155.07
14
6.4
Chlorpyrifos
32
352.03 > 199.89
24
9.7
Chlorpyrifos-oxon
32
336.11 >279.82
24
5.6
Dichlorvos
38
221.16 > 108.94
26
2.9
Disulfoton
12
275.22 >88.97
16
8.1
Disulfoton sulfone
30
307.14 > 153.40
14
4.5
Disulfoton sulfoxide
22
291.22 >212.99
12
3.1
Fenamiphos
44
304.27 >216.98
28
4.8
Fenamiphos sulfone
46
336.39 > 108.02
40
2.6
Fenamiphos sulfoxide
44
320.46 >233.30
30
1.9
Methamidophos
26
142.10 >93.92
10
1.4
Mevinphos
24
225.22 > 126.96
20
1.9
Monocrotophos
30
224.22 > 192.99
6
1.5
Chlorpyrifos-dio
32
362.11 >98.86
32
9.6
Dichlorvos-d6
38
227.16 > 114.99
20
2.8
Disulfoton-dio
28
285.29 >89.04
16
8.0
Methamidophos-d6
32
148.10 >96.92
14
1.4
'Retention times should fall within 5% of the given value; otherwise re-analysis may be necessary.
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Table 5. ESI (+) MS/MS Conditions
MS Parameter
Setting
Capillary Voltage
4.0 kV
Cone Voltage
See Table 4
Extractor
3 Volts
RF Lens
0.2 Volts
Source Temperature
Ux
o
o
O
Desolvation Temperature
350 °C
Desolvation Gas Flow
600 L/hr
Cone Gas Flow
50 L/hr
Low Mass Resolution 1
2.7
High Mass Resolution 1
14.3
Ion Energy 1
0.6
Entrance Energy
50
Collision Energy
See Table 4
Exit Energy
50
Low Mass Resolution 2
12.0
High Mass resolution 2
15.0
Ion Energy 2
1.8
Multiplier
-553
Gas Cell Pirani Gauge
3.0 x 10"3Torr
Inter-Channel Delay
0.005 seconds
Inter-Scan Delay
0.005 seconds
Repeats
1
Span
0.1 Daltons
Dwell
0.05 Seconds
Table 6. Liquid Chromatography Gradient Cont
itions*
Time
(min)
Flow
(M,L/min)
%
Solution A+
%
Solution B++
0
300
50
50
7
300
20
80
9
300
20
80
10
300
50
50
13
300
50
50
*Autosampler Temperature: 15 °C
Equilibration time: 3 minutes
Injection volume -10 |iL (recommended)
Column: 150 mm x 2.1 mm, 3|_im particle size
Column Temperature: 30 ° C
+A: 10 mM Ammonium Formate in water (0.2% Formic Acid)
++B: Acetonitrile (0.2%Fonnic Acid)
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Table 7. Target Calibration Concentration Standards (ng/mL) Used for Method
Development
Analyte/Surrogate
Level
1
Level
2
Level
3
Level
4
Level
5
Level
6
Level
7
Level
8
Chlorfenvinphos
2.5
5
10
25
50
100
250
500
Chlorpyrifos
5
10
20
50
100
200
500
1000
Chlorpyrifos-oxon
5
10
20
50
100
200
500
1000
Dichlorvos
7.5
15
30
75
150
300
750
1500
Disulfoton
5
10
20
50
100
200
500
1000
Disulfoton sulfone
5
10
20
50
100
200
500
1000
Disulfoton sulfoxide
1.25
2.5
5
12.5
25
50
125
250
Fenamiphos
1.25
2.5
5
12.5
25
50
125
250
Fenamiphos sulfone
5
10
20
50
100
200
500
1000
Fenamiphos sulfoxide
5
10
20
50
100
200
500
1000
Methamidophos
1.25
2.5
5
12.5
25
50
125
250
Mevinphos
2.5
5
10
25
50
100
250
500
Monocrotophos
1.25
2.5
5
12.5
25
50
125
250
Chlorpyrifos-dio
5
10
20
50
100
200
500
1000
Dichlorvos-d6
7.5
15
30
75
150
300
750
1500
Disulfoton-dio
5
10
20
50
100
200
500
1000
Methamidophos-d6
1.25
2.5
5
12.5
25
50
125
250
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19. Attachments
19.1 Method Detection Limit Data and Calculations
19.2 Preci si on and Accuracy
19.3 Illustration depicting the wiping pattern on a 100 cm2 surface
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19.1 METHOD DETECTION LIMIT (MDL) DATA AND CALCULATIONS
MDL Data for Seven Replicates for Organophosphorus Pesticides
Analyte
Metal in ESI (+) mode
Concentration 1*
Average Recovery
(ng/mL)
Average Recovery
(ng/cm2)t
%
Recovery
%
RSD
Chlorfenvinphos
10
0.1
82
4
Chlorpyrifos-oxon
19
0.19
75
4
Disulfoton sulfone
21
0.21
85
4
Disulfoton sulfoxide
6
0.06
99
7
Fenamiphos
5
0.05
72
7
Fenamiphos sulfone
20
0.2
81
8
Fenamiphos sulfoxide
20
0.2
81
6
Monocrotophos
5
0.05
77
4
Method Currently Unsuitable for These Analytes
Chlorpyrifos+
8
0.08
32
41
Dichlorvos+
ND
ND
-
-
Disulfoton+
2
0.02
9
120
Methamidophos+
3
0.03
53
14
Mevinphos+
ND
ND
-
-
Concentration 1 correlates to the following analyte concentrations: 12.5 ng/inL for fenamiphos, disulfoton-
sulfoxide, monocrotophos, and metliainidophos, 25 ng/inL for chlorfenvinphos and mevinphos, 50 ng/inL for
clilorpyrifos, clilorpyrifos-oxon, disulfoton-sulfone, disulfoton fenamiphos-sulfone, and fenamiphos-sulfoxide, and
75 ng/inL for diclilorvos.
+Dichlorvos, disulfoton, metliainidophos, clilorpyrifos, and mevinphos recoveries were lower than expected (not
quantitative) and may not be applicable for this method. Clilorpyrifos and metliainidophos recoveries are low and
may be considered for further evaluation. Nevertheless, data are presented for these analytes with the understanding
that further evaluation is still needed and values are representative of expected recoveries. The values reported in
Table 3 represent the lowest calibration (Level 1).
¦f ng/cm2 calculation was performed by dividing the recovered surface concentration by the test area of the coupon
(100 cm2).
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MDL Calculation for Seven Replicates for Organophosphorus Pesticides
Metal in ESI (+) mode
Analyte
MDL
MRL
ng/cm2f
ng/mL
ng/mL
Chlorfenvinphos
0.013
1.3
4
Chlorpyrifos-oxon
0.022
2.2
7
Disulfoton sulfone
0.025
2.5
26
Disulfoton sulfoxide
0.013
1.3
8
Fenamiphos
0.010
1.0
3
Fenamiphos sulfone
0.047
4.7
15
Fenamiphos sulfoxide
0.038
3.8
12
Monocrotophos
0.010
1.0
2
Method Currently Unsuitable for These Analytes
Chlorpyrifos
0.10
10
33
Dichlorvos*
0.075
7.5
75
Disulfoton*
0.050
5.0
50
Methamidophos
0.016
1.6
5
Mevinphos*
0.025
2.5
25
MDL, method detection limit; MRL, minimum reporting limit; *Lowest calibration level 1 is listed. MRL levels are
conservative and the lowest calibration level may suffice, where applicable, as the MRL value.
¦f ng/cm2 calculation was performed by dividing the recovered surface concentration by the test area of the coupon
(100 cm2).
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19.2 PRECISION AND ACCURACY
Concentration levels correspond to the following final surface concentrations: Concentration 1 is
calibration concentration level 4; Concentration 2 is calibration concentration level 5;
Concentration 3 calibration concentration level 6. Isotopically-labelled surrogates were spiked at
the following concentration for all samples: 100 ng/ml-chlorpyrifos-dio and disulfoton-dio, 150
ng/mL for dichlorvos-d6, and 25 ng/ml for methamidophos-d6. Average concentrations represent
seven samples at each concentration. For surface concentrations, ng/cm2 calculation was
performed by dividing the concentration spiked onto the surface by the test area of the coupon
(100 cm2). Recoveries from non-porous/non-permeable surfaces are better (70-130 %) than from
porous/permeable surfaces. The differences between the surface types should be noted when
interpreting recovery results.
• Table A. Precision and Accuracy Data for Wipe Analysis of Organophosphorus
Pesticides Analytes on Laminate Surfaces in ESI (+) Mode
• Table B. Precision and Accuracy Data for Wipe Analysis of Organophosphorus
Pesticides Analytes on Galvanized Steel Surfaces in ESI (+) Mode
• Table C. Precision and Accuracy Data for Wipe Analysis of Organophosphorus
Pesticides Analytes on Glass Surfaces in ESI (+) Mode
• Table D. Precision and Accuracy Data for Wipe Analysis of Organophosphorus
Pesticides Analytes on Painted Drywall Surfaces in ESI (+) Mode
• Table E. Precision and Accuracy Data for Wipe Analysis of Organophosphorus
Pesticides Analytes on Vinyl Tile Surfaces in ESI (+) Mode
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Precision and accuracy data for wipe analysis of organophosphorus pesticides analytes on surfaces.
Table A. Precision and Accuracy Data for Wipe Analysis of Organophosphorus Pesticides on Laminate Surfaces in ESI (+) Mode
Laminate in ESI (+) Mode
Analyte
Concentration 1
Concentration 2
Concentration 3
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Chlorfenvinphos
8
67
6
21
85
7
43
86
6
Chlorpyrifos-oxon
16
62
10
26
51
6
63
63
4
Disulfoton sulfone
18
70
5
35
70
5
77
77
15
Disulfoton sulfoxide
7
107
9
17
138
4
21
84
6
Fenamiphos
4
68
8
8
65
8
21
85
4
Fenamiphos sulfone
18
74
10
45
90
5
96
96
7
Fenamiphos sulfoxide
23
90
6
44
87
3
86
86
10
Monocrotophos
4
67
8
13
101
4
23
92
14
Chlorpyrifos-dio
62
62
9
89
89
15
97
97
11
Dichlorvos-d6
120
82
12
163
109
9
131
88
21
Disulfoton-dio
59
59
13
103
103
12
172
172
13
Methamidophos-d6
18
70
6
35
138
4
33
131
14
Method Currently Unsuitable for These Analytes
Chlorpyrifos+
5
19
39
6
12
32
39
39
21
Dichlorvos+
3
9
59
6
4
40
ND
-
-
Disulfoton+
ND
-
-
ND
-
-
34
34
88
Methamidophos+
3
40
18
5
21
20
8
33
32
Mevinphos+
1
9
57
2
4
10
7
14
30
* (n = 7 samples at each concentration.) Concentration 1 is calibration level 4; Concentration 2 is calibration level 5; Concentration 3 calibration level 6; RSD is
relative standard deviation; ND is non-detect; Isotopically-labelled surrogates were spiked at the following concentration for all samples: 100 ng/ml-chlorpyrifos-
dio and disulfoton-dio, 150 ng/mL for dichlorvos-d6, and 25 ng/ml for methamidophos-cU.
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+ Dichlorvos, disulfoton, chlorpyrifos, methamidophos, and mevinphos recoveries were lower than expected, not quantitative, and may not be applicable for this
method. Data are still presented with the understanding that further evaluation is still needed and values are representative of expected recoveries.
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Table B. Precision and Accuracy Data for Wipe Analysis of Organophosphorus Pesticides Analytes on Metal Surfaces in ESI (+) Mode
Metal in ESI (+) Mode
Analyte
Concentration 1
Concentration 2
Concentration 3
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Chlorfenvinphos
10
82
4
23
92
3
50
99
10
Chlorpyrifos-oxon
19
75
4
36
72
4
78
78
10
Disulfoton sulfone
21
85
4
44
87
7
76
76
14
Disulfoton sulfoxide
6
99
7
22
178
7
35
140
6
Fenamiphos
5
72
7
10
81
6
22
89
8
Fenamiphos sulfone
20
81
8
50
101
5
91
91
11
Fenamiphos sulfoxide
20
81
6
47
95
7
92
92
4
Monocrotophos
5
77
4
13
105
5
29
116
6
Chlorpyrifos-dio
74
74
10
99
99
7
122
122
6
Dichlorvos-d6
130
84
8
155
103
6
179
120
19
Disulfoton-dio
64
64
11
101
101
17
221
221
9
Methamidophos-d6
21
82
3
35
140
6
42
169
7
Method Currently Unsuitable for These Analytes
Chlorpyrifos+
8
32
41
25
50
26
18
18
45
Dichlorvos+
ND
-
-
ND
-
-
ND
-
-
Disulfoton+
2
9
120
15
30
73
28
28
43
Methamidophos+
3
53
14
7
27
44
8
33
35
Mevinphos+
ND
-
-
ND
-
-
5
10
42
* (n = 7 samples at each concentration.) Concentration 1 is calibration level 4; Concentration 2 is calibration level 5; Concentration 3 calibration level 6; RSD is
relative standard deviation; ND is non-detect; Isotopically-labelled surrogates were spiked at the following concentration for all samples: 100 ng/ml-chlorpyrifos-
dio and disulfoton-dio, 150 ng/mL for dichlorvos-d6, and 25 ng/ml for methamidophos-d6.
+Dichlorvos, disulfoton, and mevinphos were lower than expected, not quantitative, and may not be applicable for this method. Data are still presented with the
understanding that further evaluation is still needed and values are representative of expected recoveries. Chlorpyrifos and methamidophos recoveries are low
and should be considered for further evaluation.
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NHSRC
Revision Date: 12/16
Page 39 of 43
Table C. Precision and Accuracy Data for Wipe Analysis of Organophosphorus Pesticides on Glass Surfaces in ESI (+) Mode
Glass in ESI (+) Mode
Analyte
Concentration 1
Concentration 2
Concentration 3
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Chlorfenvinphos
10
78
5
21
85
5
43
86
13
Chlorpyrifos-oxon
15
60
10
28
55
27
44
44
24
Disulfoton sulfone
19
75
7
42
85
6
69
69
23
Disulfoton sulfoxide
6
99
5
13
99
8
28
111
8
Fenamiphos
5
78
7
10
83
5
23
94
12
Fenamiphos sulfone
22
87
3
47
94
1
88
88
8
Fenamiphos sulfoxide
23
91
4
48
95
4
86
86
12
Monocrotophos
5
83
6
13
104
5
30
118
12
Chlorpyrifos-dio
71
71
7
103
103
8
100
100
16
Dichlorvos-d6
136
91
9
169
112
10
174
116
22
Disulfoton-dio
65
65
11
116
116
13
187
187
10
Methamidophos-d6
20
81
6
32
128
6
40
158
10
Method Currently Unsuitable for These Analytes
Chlorpyrifos+
7
27
49
14
27
42
17
17
104
Dichlorvos+
ND
-
-
4
2.3
33
75
43
5
Disulfoton+
ND
-
-
ND
-
-
18
13
35
Methamidophos+
2
28
31
2
8.3
37
4
11
65
Mevinphos+
ND
-
-
1
2.7
7
3
6.5
30
* (n = 7 samples at each concentration.) Concentration 1 is calibration level 4; Concentration 2 is calibration level 5; Concentration 3 calibration level 6; RSD is
relative standard deviation; ND is non-detect; Isotopically-labelled surrogates were spiked at the following concentration for all samples: 100 ng/ml-chlorpyrifos-
dio and disulfoton-dio, 150 ng/mL for dichlorvos-d6, and 25 ng/ml for methamidophos-d6.
+ Dichlorvos, disulfoton and mevinphos were lower than expected, not quantitative, and should not be considered for this method. Data are still presented with
the understanding that further evaluation is still needed and values are representative of expected recoveries. Chlorpyrifos and methamidophos recoveries are low
and should be considered for further evaluation.
39
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NHSRC
Revision Date: 12/16
Page 40 of 43
Table D. Precision and Accuracy Data for Wipe Analysis of Organophosphorus Pesticides on Painted Drywall Surfaces in ESI (+) Mode
Painted Drywall in ESI (+) Mode
Analyte
Concentration 1
Concentration 2
Concentration 3
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Chlorfenvinphos
2
14
9
3
13
13
28
55
14
Chlorpyrifos-oxon
3
13
10
5
11
15
41
41
11
Disulfoton sulfone
5
19
22
8
16
18
65
65
20
Disulfoton sulfoxide
1
21
14
3.0
24
16
23
92
15
Fenamiphos
1
14
20
2
15
21
25
100
8
Fenamiphos sulfone
6
25
15
15
29
18
82
82
15
Fenamiphos sulfoxide
8
32
11
18
36
14
134
134
12
Monocrotophos
3
40
9
5.2
41
15
78
314
19
Chlorpyrifos-dio
69
69
8
89
89
11
192
192
10
Dichlorvos-d6
189
126
6
226
151
8
469
313
34
Disulfoton-dio
33
33
18
70
70
13
587
587
7
Methamidophos-d6
25
102
11
69
278
6
162
647
20
Method Currently Unsuitable for These Analytes
Chlorpyrifos+
4
15
13
4
8
41
21
21
21
Dichlorvos+
10
26
16
ND
-
-
ND
-
-
Disulfoton+
13
51
15
27
54
24
220
220
17
Methamidophos+
3
43
20
15
60
54
43
124
17
Mevinphos+
3
23
16
6.5
13
19
39
78
31
* (n = 7 samples at each concentration.) Concentration 1 is calibration level 4; Concentration 2 is calibration level 5; Concentration 3 calibration level 6; RSD is
relative standard deviation; ND is non-detect; Isotopically-labelled surrogates were spiked at the following concentration for all samples: 100 ng/ml-chlorpyrifos-
dio and disulfoton-dio, 150 ng/mL for dichlorvos-d6, and 25 ng/ml for methamidophos-d6.
+ Dichlorvos, disulfoton and mevinphos were lower than expected, not quantitative, and should not be considered for this method. Data are still presented with
the understanding that further evaluation is still needed and values are representative of expected recoveries.
40
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NHSRC
Revision Date: 12/16
Page 41 of 43
Table E. Precision and Accuracy Data for Wipe Analysis of Organophosphorus Pesticides on Vinyl Tile Surfaces in ESI (+) Mode
Vinyl Tile in ESI (+) Mode
Analyte
Concentration 1
Concentration 2
Concentration 3
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Average
Recovery
(ng/mL)*
%
Recovery
%
RSD
Chlorfenvinphos
2
15
13
3
12
13
41
82
8
Chlorpyrifos-oxon
3
13
14
4
8
20
87
87
9
Disulfoton sulfone
4
17
16
6
12
20
73
73
15
Disulfoton sulfoxide
1
18
17
2
13
14
20
79
8
Fenamiphos
1
13
19
1
11
19
22
89
14
Fenamiphos sulfone
4
15
12
8
16
13
71
71
16
Fenamiphos sulfoxide
4
15
14
7
15
12
75
75
7
Monocrotophos
1
16
10
3
20
12
28
112
14
Chlorpyrifos-dio
75
75
6
85
85
29
181
181
14
Dichlorvos-d6
141
94
11
114
103
41
171
114
39
Disulfoton-dio
59
59
10
85
85
39
516
516
11
Methamidophos-d6
21
86
3
33
125
19
45
479
23
Method Currently Unsuitable for These Analytes
Chlorpyrifos+
5
20
24
3
6
39
55
55
19
Dichlorvos+
8
21
52
4
3
75
ND
-
-
Disulfoton+
5
18
19
5
9
44
174
174
16
Methamidophos+
1
15
26
3
12
16
43
171
15
Mevinphos+
2
6
14
3
7
14
23
46
10
* (n = 7 samples at each concentration.) Concentration 1 is calibration level 4; Concentration 2 is calibration level 5; Concentration 3 calibration level 6; RSD is
relative standard deviation; ND is non-detect; Isotopically-labelled surrogates were spiked at the following concentration for all samples: 100 ng/ml-chlorpyrifos-
dio and disulfoton-dio, 150 ng/mL for dichlorvos-d6, and 25 ng/ml for methamidophos-d6.
+Dichlorvos, disulfoton, and mevinphos were lower than expected, not quantitative, and should not be considered for this method. Data are presented with the
understanding that further evaluation is still needed and values are representative of expected recoveries.
41
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NHSRC
Revision Date: 12/16
Page 42 of 43
19.3 Illustration of wiping pattern on 100 cm2 surface
The analyte spike solution was added to the surface as shown in 19.3, allowed to dry completely
(approximately 60-90 minutes depending on droplet size), and wiped using wetted-cotton gauze
wipes. After wiping in the horizontal and vertical directions, the surface perimeter was also
wiped with each wipe and placed in the same sampling container for processing.
42
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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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