c/EPA
United States
Environmental Protection
Agency
Research and Development
Atmospheric Research and Exposure
Assessment Laboratory
Research Triangle Park, NIC 27711
April 1995
EPA600/R-95/052
Standard Operating Procedure
for Solubilization of Lead on
Dust Wipes by Hotplate Acid
Digestion
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STANDARD OPERATING PROCEDURE
FOR SOLUBILIZATION OF LEAD ON DUST WIPES
BY HOTPLATE ACID DIGESTION
Prepared For:
Ms. Sharon L. Harper
Work Assignment Manager
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
EPA Contract No. 68-D1-0009
RTI Project Nos. 91U-5960-126, 91U-6960-231, 91U-6970-260
Prepared By:
D. A. Binstock, E. D. Estes, E. E. Williams, and W. F. Gutknecht
Center for Environmental Measurements and Quality Assurance
Research Triangle Institute
Research Triangle Park, NC 27709-2194
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DISCLAIMER
The information in this document has been funded wholly or in part by the
United States Environmental Protection Agency (U.S. EPA) under EPA Contract No.
68-D1-0009 to the Research Triangle Institute (RTI). It has been subjected to the
Agency's peer and administrative review, and it has been approved for publication as
an EPA document. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
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ACKNOWLEDGMENTS
This document was prepared under the direction of Ms. Sharon L. Harper,
Atmospheric Research and Exposure Assessment Laboratory (AREAL), U.S.
Environmental Protection Agency, Research Triangle Park, NC.
in
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Table of Contents
Section Page
Disclaimer ii
Acknowledgments iii
List of Tables v
1.0 PRINCIPLE AND APPLICABILITY 1
1.1 SCOPE AND APPLICATION 1
1.2 SUMMARY OF METHOD 1
2.0 APPARATUS 8
2.1 SAMPLING 8
2.2 EXTRACTION 9
2.3 PROTECTIVE EQUIPMENT 11
3.0 PROCEDURES 13
3.1 COLLECTION OF MATERIAL 13
3.2 QUALITY CONTROL SAMPLES 14
3.3 EXTRACTION PROCEDURE 15
3.4 DATA PROCESSING 17
4.0 QUALITY CONTROL 18
4.1 SAMPLE COLLECTION 18
4.2 WIPE EXTRACTION 18
4.3 QUALITY CONTROL SAMPLES 18
5.0 SAFETY 20
5.1 COLLECTION : 20
5.2 ANALYSIS 20
6.0 WASTE DISPOSAL 21
6.1 PROTECTIVE CLOTHING 21
6.2 WASH WATER 21
6.3 EXCESS DUST WIPE SAMPLES 21
6.4 SOLUTION WASTE 21
7.0 CORRECTIVE ACTION 22
8.0 REFERENCES 23
IV
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List of Tables
Table Page
1 Wipe Sampling Methods 2
2 Dust Wipe Hotplate Digestion - K-Mart Little Ones Baby Wash Cloths®
Spiked With 0.100 g Reference Material 6
3 Dust Wipe Hotplate Digestion - Wash'n Dri Moist Disposable Towelettes"
Spiked with 0.100 g Reference Material 6
4 Dust Wipe Hotplate Digestion - Nuclepore" Filters
Spiked with 0.100 g Reference Materials 7
v
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1.0 PRINCIPLE AND APPLICABILITY
1.1 SCOPE AND APPLICATION
The adverse health effects resulting from exposure of young children to
environmental lead have received increasing attention in recent years. Studies have
shown that chronic exposure even to low levels of lead can result in impairment of the
central nervous system, mental retardation, and behavioral disorders.1'2 Although
young children are at the greatest risk, adults may suffer harmful effects as well.3
As a result of the growing concern about these adverse health effects, the
identification and assessment of hazards from lead-based paint (LBP) and LBP-
containing dust and soil have become critical environmental issues. To quantify the
magnitude of these hazards and to develop and implement strategies for their
reduction, methods for measuring lead in paint, soil, and dust must be developed and
validated.
Measuring lead in dust involves collecting the dust, in most cases extracting the
lead from the dust, and finally instrumentally measuring the extracted lead. Current
methods of dust collection include vacuuming,4'5 which may result in the collection
of bulk dust or dust on filters, and surface collection using a wipe. A large number
of wipe methods have been developed, several of which are described in Table 1.
Protocols for evaluating wipes have been published, including the protocol by
Chavalitnikul and Levin.19 Procedures have been developed for measuring lead in
dust20'21 and lead in dust on air filters.22'23 This standard operating procedure (SOP)
describes a hotplate acid digestion of lead in dust collected on wipes. This procedure
is based on a method provided by Ms. Harriotte Hurley, formerly of Azimuth
Laboratories, Charleston, SC.24
1.2 SUMMARY OF METHOD
1.2.1 Sampling and Analysis
The dust wipe sample collection procedures vary considerably (See Table 1).
The basis of each method, however, is to manually move the wipe material (natural
or synthetic fabric, paper, etc.) across a fixed area of surface. The material may or
1
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TABLE 1. WIPE SAMPLING METHODS
Method/ .
Researcher
ASTM
ES-30-94
Georgia
Tech
HUD
Kennedy-
Krieger
(Farfel)
Lepow
(1974)
Surface
Type
Hard (floors.
windows)
Hard (floors.
windows)
Hard (floors,
windows)
Hard
Hard
Wipe Matrix
Disposable
towelette
moistened with
wetting agent
Little Ones Baby
Wash Cloths"
(K-Mart)
Commercial non-
alcohol wipes
Non-alcohol
wipes
Preweighed
adhesive labels
Area
Template 30
cm x 30 cm
(12" x 12")
measured
area
Measured
area
Template
12" x 12",
or measured
area
Template
12" x 12",
or measured
area
—
Sampling Procedure
• Wipe with "S" motion
L-R, F-B
• Fold wipe
• Repeat with "S" motion
F-B, L-R,
• Fold wipe
• Repeat with "S" motion
L «• R, F - B
• Wipe with "S" motion
F - B, L « R
• Fold wipe
• Repeat with "S" motion
F-H-B, L-R
• Fold wipe
• Repeat with "S" motion
L«.R, F-B
• Wipe with "S" motion
L «• R, F - B,
• Fold wipe inside
• Wipe with "S" motion
90° to first wipe
• Fold wipe
• Repeat with "S" motion
L «• R, F - B
• Wipe with "S" motion
L«-R, F-B,
• Fold wipe inside
• Repeat with "S" motion
F«B, L-R
• Fold wipe
• Repeat with "S" motion
L~R, F-B
—
Container
Hard-walled
container
recommended
Centrifuge
tube (50 mL)
Polypropylene
tube (50 mL)
Ziploc bags
—
Units
//g/cm2
//g/ft2
jug/ft2
A/g/ft2
PQ/9
Reference
6
7
8
9
10
(continued)
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TABLE 1. (Continued)
Method/
Researcher
Rabinowitz
LWW
NIOSH
Stark
State of
MA
State of NC
Surface
Type
Hard
Hard
Hard
Hard
Hard (floors,
windows)
Hard (floors,
windows)
Wipe Matrix
Preweighed filter
paper (Whatman
541)
3 polyethylene
filters
(preweighed) 3.8
cm x 6.35 cm
• Gauze 2" x 2"
wetted with 1-
2 mL distilled
water*
• Wash'n Dri®
(Canaan
Products, Inc.)
wipes
(individually
wrapped) or
equivalent
Prewetted cotton
gauze
Individually
wrapped alcohol
wipes (Triad
Medical, Inc.)
Johnson &
Johnson Baby
Wipes
Area
930 cm2
Template
27.3 cm x 4
cm
1 0 cm x 10
cm
disposable
template
—
Template
1ft2
Template 1
ft2 or
measured
area
Sampling Procedure
• Wipe within template with
filter 1 (moistened with
Type I water)
• Wipe within template with
filter 2 (moistened with
Type I water)*
• Wipe within template with
filter 3 (dry)
• Wipe with "S" motion 3-4
vertical strokes
• Fold wipe inside
• Wipe with "S" motion 3-4
horizontal strokes
• Fold wipe inside
• Wipe with "S" motion 3-4
vertical strokes
—
Wipe area once L -» R
• Wipe with "S" motion
• Wipe with "S" motion 90°
to first pass
Container
Resealable
polyethylene
bags
Aluminum
pouch inside
of plastic bag
Ziploc bag
...
Plastic tube
Ziploc bag
Units
A/g/wipe
^g/ft2
fjg/a
A/g/ft2
(mg/m2)
A/g/g
A*g/ft2
A/g/ft2
Reference
11
12
13
14
15
16
17
(A)
(continued)
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TABLE 1. (Continued)
Method/
Researcher
Vostal
Surface
Type
Hard
(uncarpeted)
Wipe Matrix
Disposable paper
towel (14 cm x
20cm)
moistened with
20% denatured
alcohol or 1 :1 50
benzalkonium
chloride
Area
Template
1ft2
Sampling Procedure
Container
Units
^g/ft2
. Reference
18
LEGEND:
L «» R = Left to Right, Right to Left in Overlapping "S" Motion
F -» B = Front to Back (Top to Bottom)
* American Society for Testing and Materials (ASTM) Type 1 water: resistance
16.67 megaohm-cm
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may not be pretreated with liquid solubilization or wetting agents (detergents). The
wipe is folded to enclose the collected dust and may be used to wipe a second or
even third time before being placed in a labelled container or bag.
Using the digestion method described in this SOP, the loaded dust wipe is
placed into a 250-mL beaker and digested using 30% hydrogen peroxide and
concentrated nitric acid. The digestion mixture is quantitatively transferred to a
50-mL polyethylene centrifuge tube, and the tube is filled to the mark with doubly
deionized water. The residue is separated from the supernatant by centrifugation or
simply by permitting it to settle overnight. The supernatant is analyzed for lead by
inductively coupled argon plasma (ICP) emission spectrometry, using the 220.35-nm
emission line and the optimum instrumental conditions recommended by the
manufacturer.25
1.2.2 Precision and Bias
As noted in Table 1, many different types of wipes are commercially available.
In this study, three types of wipes were selected for testing the wipe extraction
procedure because (1) they were representative of the various types in use and (2)
they were used in methods provided by Federal organizations or proposed for use in
federal programs. Included were a baby wipe used in a procedure published in the
U.S. Department of Housing and Urban Development's (HUD's) Guidelines for the
Evaluation and Control of Lead-Based Paint Hazards in Housing,8 a wipe used in a
procedure proposed by the National Institute for Occupational Safety and Health
(NIOSH),13 and a Nuclepore filter used in a procedure known as the Lioy-Weisel-
Wainman (LWW) method proposed for use in the EPA National Human Exposure
Assessment Survey (NHEXAS).12-26
The three types of dust wipes (Little Ones Baby Wash Cloths",7'27 Wash'n Dri
Moist Disposable Towelettes ,13'28 and Nuclepore" filters12-29) were spiked with
standard reference materials (SRMs) and method evaluation materials (MEMs) and
digested using the hotplate procedure summarized in Section 1.2.1. The reference
materials used included National Institute of Standards and Technology (NIST) SRM
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1579, powdered lead-base paint; NIST SRM 2704, Buffalo River sediment; and two
dust MEMs from the American Industrial Hygiene Association's Environmental Lead
Proficiency Analytical (ELPAT) program.30
Accuracy as percent bias and precision as relative standard deviation (RSD)
were determined and are presented in Tables 2 through 4.31 Accuracy as percent bias
ranged from -8.7% to +3.7% and precision as RSD ranged from 2.54% to 11.7%.
The average bias was -2.9% and the pooled RSD was 7.8%.
TABLE 2. Dust Wipe Hotplate Digestion - K-Mart Little Ones Baby Wash
"
Cloths Spiked with 0.100 g Reference Material (fjglg Except
Where Noted)
Sample
NIST 1579
NIST 2704
ELPAT 3D2
ELPAT 3D4
Reference Value
11.87 ± 0.04%
161 ± 17
551 ± 55a
2210 ± 401a
Mean Value ± SD
(N = 3)
11.9 ± 0.32%
147 ± 14.1
516 ± 27.5
2150 ± 247
Accuracy
as % Bias
0
-8.7
-6.8
-2.7
RSD
%
2.69
9.60
5.33
11.5
a ELPAT program mean value of 34 reference laboratories.30
TableS. Dust Wipe Hotplate Digestion - Wash'n Dri Moist Disposable
Towelettes Spiked with 0.100 g Reference Material (//g/g Except
Where Noted)
Sample
NIST 1579
NIST 2704
ELPAT 3D2
ELPAT 3D4
Reference
Value
11.87 ± 0.04%
161 ± 17
551 ± 55a
2210 ± 401a
Mean Value ± SD
(N = 3)
11.5 ± 0.35%
167 ± 19.5
537 ± 13.6
2110 ± 222
Accuracy
as % Bias
-3.4
3.7
-2.5
-4.5
RSD
%
3.04
11.7
2.54
10.5
ELPAT program mean value of 34 reference laboratories.30
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®
TAEJLE 4. Dust Wipe Hotplate Digestion - Nuclepore" Filters Spiked with
0.100 g Reference Material (//g/g Except Where Noted)
Sample
NIST 1579
NIST 2704
ELPAT 3D3
ELPAT 3D2
Reference
Value
1 1 .87 ± 0.04%
161 ± 17
551 ± 55a
221 Ob ± 401 a
Mean Value ± SD
(N = 3)
10.9 ± 1.11%
162 ± 6.11
543 ± 45.1
2190 ± 75.8
Accuracy
as % Bias
-8.4
0.6
-1.4
-0.9
RSD
%
10.2
3.77
8.30
3.46
ELPAT program mean value of 34 reference laboratories.30
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2.0 APPARATUS
The apparatus used for sampling and analysis of the dust wipes is described
below.
NOTE: Before use, all labware should be scrupulously cleaned. The
recommended procedure is:
1. Wash with hot laboratory detergent in water or ultrasonicate 10
minutes with laboratory detergent in water.
2. Rinse and then soak a minimum of 1 hour in 50% volume/volume
(v/v) nitric acid.
3. Rinse three times with double deionized water and air dry or oven
dryat105°C.
2.1 SAMPLING
The dust collection procedures referenced in this SOP use the materials and
apparatus as follows:
2.1.1 HUD Method Using Baby Wipe7'27
2.1.1.1 Disposable baby wipe (Little Ones Baby Wash Cloths" or
equivalent).
2.1.1.2 Gloves, latex, powder-free, disposable (Fisher Scientific Catalog
No. 11-393-53 or equivalent).
2.1.1.3 Centrifuge tubes: 50-mL disposable polypropylene (Fisher
Scientific Catalog No. 05-526B or equivalent).
2.1.1.4 Template: either masking tape or reusable made of laminated
paper, metal, or plastic; typically 1 ft2 (929 cm2) to enclose the
area to be wiped.
2.1.2 NIOSH Method Using Gauze or Hand Wipe13'28
2.1.2.1 Gauze pads, 2" x 2" sterile cotton (Curity, Johnson & Johnson,
or equivalent), or Wash'n Dri Moist Disposable Towelettes or
equivalent.
2.1.2.2 Bags, plastic, scalable (for example, with attached wire, tape, or
zip-type seal); (Ziploc 1-quart freezer bags or equivalent).
2.1.2.3 Gloves, latex, powder-free, disposable (Fisher Scientific - see
Section 2.1.1.2 or equivalent).
8
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2.1.2.4 Template, plastic, 10 cm x 10 cm or other standard size to
enclose the area to be wiped.
2.1.2.5 Water, distilled, ASTM Type 1, in plastic squeeze bottle.
2.1.3 LWW Method Using Nuclepore® Filter12'29
2.1.3.1 Nuclepore" filter preweighed and stored in folded aluminum foil
pouch (Nuclepore8 Catalog No. 232300, Costar Corp., Cambridge,
MA 02140).
2.1.3.2 Wipe sampler template with sampling area of 27.3 cm x 4 cm.
2.1.3.3 Wipe sampler movable plate-filter retainer consisting of two
sections: 1) a 4-cm square block that is 7-mm thick and 2) a
5.1-cm x 4.7-cm frame.
2.1.3.4 Gloves, latex, powder-free, disposable (Fisher Scientific - See
Section 2.1.1.2 or equivalent).
2.1.3.5 Bags, plastic, scalable (for example, with attached wire, tape, or
zip-type seal); (Ziploc 1-quart freezer bags or equivalent).
2.2 EXTRACTION
The applicability of this method has been tested with three of the most
commonly used lead-in-dust collection wipes (Section 1.2.2) Applicability of this
method to other types of wipes will be verifiable through quality control (QC) activities
(sections 3.2 and 4.0). The apparatus and reagents used in this procedure are as
follows:
2.2.1 Hotplate with temperature control from 70° to 200° Celsius (Corning
6795, Fisher Scientific Catalog No. 11-495-52A or equivalent).
2.2.2 Beakers, 250-mL (borosilicate glass, Fisher Scientific Catalog No. 02-
540K or equivalent).
2.2.3 Disposable wipes for preparation of laboratory control standards (LCS).
These wipes are to be selected at random from the set to be used for sample
collection.
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2.2.4 Electronic top-loading balance for preparation of LCSs (Mettler AJ 100
balance, Mettler Instruments Corp., P.O. Box 71, Highstown, NJ 08520, or
equivalent).
2.2.5 Pipetter, 200- to 1000-/;L (Oxford Benchmate, Fisher Scientific Catalog
No. 21-229 or equivalent).
2.2.6 Glass (4-mm) rod to push wipe into beaker.
2.2.7 Forceps, Nalgene polypropylene scissor-type (Fisher Scientific Catalog
No. 10-309 or equivalent).
2.2.8 Hydrogen peroxide: 30% H202, volume/volume, ACS reagent grade.
2.2.9 Nitric acid: Concentrated, ACS spectrographic grade.
2.2.10 Watch glass, ribbed, borosilicate glass (Fisher Scientific Catalog No. 02-
613B or equivalent).
2.2.11 Centrifuge tubes: 50-mL disposable polypropylene (Fisher Scientific
Catalog No. 05-526B or equivalent).
2.2.12 Centrifuge (International Equipment Company Model CL or equivalent).
2.2.13 Deionized water in dropper or squirt bottle: Unless otherwise indicated,
references to deionized water shall be understood to mean reagent water as defined
by Type 1 of ASTM Specification D 119332 (ASTM Type 1 Water: minimum
resistance of 16.67 megohm-cm or equivalent).
2.2.14 NIST Traceable Secondary Reference Materials for LCS. If these are not
10
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available, use a NIST SRM such as NIST SRM 1648 (Urban particulate matter); SRM
2583 (Lead in dust); SRM 2704 (Buffalo River sediment); or SRM 1 579 or 2582 (Lead
in paint).
2.2.15 Automatic pipettor: 10-mL capacity, 0.1-mL subdivision (Universal
Repipet Dispenser, VWR Scientific, 1230 Kennestone Circle, Marietta, GA 30066,
Catalog No. 53528-168, or equivalent).
2.2.16 Two- and three-mL Class A volumetric pipettes.
2.2.17 Chemical fume hood, Kewaunee Scientific Equipment Corp., Adrian, Ml
49221, Airflow Supreme Model.
2.3 PROTECTIVE EQUIPMENT
Safety equipment to be used for protection from both lead and biological
contamination during dust collection and wipe extraction is as follows:
2.3.1 If significant airborne dust is present or being generated by the
collection activity, wear a fitted respirator (Occupational Safety and Health
Administration (OSHA) Standard 29 CFR 1910.134) for dust collection (half-mask
respirator, Fisher Scientific Catalog No. 17-632 [size], and high-efficiency particulate
air (HEPA) filter/cartridge, Fisher Scientific Catalog No. 17-635-7, or equivalent).
2.3.2 Disposable booties, coveralls, and head covers for dust collection in
high-lead environment (coveralls with shirt collar, tacked-on hood, elasticized wrists,
bound seams, Fisher Scientific Catalog No. 01-361-51 [size], or equivalent).
2.3.3 Safety glasses with side shields for wipe extraction.
2.3.4 Laboratory gloves (See Section 2.1.1.2) and coat for wipe extraction.
11
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2.3.5 Dust mask to be worn while handling dust wipes (mask for dusts and
mists, NIOSH/OSHA TC-21C-132; Fisher Scientific Catalog 17-653 or equivalent).
2.3.6 Heavy-duty plastic bags (6-mil or greater) for disposal of personal
protection products and dust collection waste (IPCO, Inc., Catalog No. R3350BP,
IPCO, Inc., Norcross, GA 30091, or equivalent).
2.3.7 Detergent (heavy-duty cleaner with sodium metasilicate; Bondex
International, Inc., St. Louis, MO 63122, or equivalent) and wet wipes for cleanup
®
(Wash 'n Dri , Softsoap Enterprises, Inc., Chasha, MN 55318, or equivalent).
2.3.8 Filter for waste water filtration: 20-/;m pore size (Spectra/Mesh Nylon;
Fisher Scientific Catalog No. 08-670-204 or equivalent).
12
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3.0 PROCEDURES
3.1 COLLECTION OF MATERIAL
As stated earlier (Section 1.1), a variety of wipe methods is described for
collection of dust on surfaces. Check the references for complete descriptions of
operating procedures. Three methods chosen for testing are described below:
3.1.1 HUD Method Using Baby Wipes8 - The HUD method uses a disposable
wipe material meeting the following criteria: a) low lead background (less than 5
/yg/wipe14); b) a single thickness; c) durable; d) does not contain aloe or alcohol; e) can
be digested in the laboratory; f) yields 80-120% spike recovery rates; and g) remains
moist during the sampling process. A template of paper, metal, or plastic, typically
with a sampling area of 1 ft2, is placed on the surface to be sampled.
The wipe is placed at one corner of the template and wiped side to side with
as many horizontal "S" strokes as necessary to cover the entire template area. The
wipe is folded in half with the contaminated side facing in and placed in the template
top corner, and the wiping is repeated but in a top-to-bottom direction. Finally, the
side- to-side wiping is repeated. When all the visible dust is removed, the wipe is
inserted into a labelled centrifuge tube.
3.1.2 NIOSH Method Using Gauze or Hand Wipe13 - The NIOSH method uses
®
a 2" x 2" gauze pad or a Wash'n Dri towelette and a plastic template with a sampling
area of 10 cm x 10 cm. The template is placed over the area to be sampled, and the
surface is wiped using three to four vertical "S" strokes. The wipe is folded with the
exposed side in, and the area is again wiped with three to four horizontal "S" strokes.
Finally, the wipe is folded once more and the area wiped with three to four vertical
"S" strokes. The wipe is then folded with the exposed sides in and placed into a
labelled plastic bag.
3.1.3 LWW Method Using Nuclepore® Filter12'26 - The LWW method is a new
dust wipe sampling technique utilizing the LWW sampler. The sampler consists of
two sections constructed from Delrin : (1) a movable plate-filter retainer consisting
13
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of a 4-cm square block 7 mm thick and a 5.1 -cm x 4.7-cm frame that holds the 4-cm
block; and (2) a template 3 mm thick with a sampling area of 27.3 cm x 4 cm. The
frame plus block traces the rectangular opening within the template.
For sampling, a Nuclepore" filter cut into a rectangle of 3.8 cm x 6.35 cm is
preweighed, folded, and placed into the sample frame so that the filter edges are
touching the frame sides. The 4-cm square block is inserted into the frame to hold
the filter in place. The filter is wetted with deionized water and slid across the length
of the template. It is passed back and forth three times, removed from the plate-filter
retainer, and placed into an aluminum foil pouch.
3.2 QUALITY CONTROL SAMPLES
3.2.1 Blank - If a blank wipe was not submitted from the field, initiate a
laboratory blank by placing a clean, unused wipe in a clean, labelled 250-mL glass
beaker. The filter should come from the same lot as those used to collect the
samples. Record the sample number in the laboratory notebook.
3.2.2 Quality Control Check - Initiate a QC check by placing a wipe spiked
with 250 fjg of lead in a clean, 250-mL beaker.
Prepare the spiked wipe as follows:
3.2.2.1 — Place an unused, clean wipe in a clean 250-mL glass beaker.
3.2.2.2 - Using a 500-//L micropipette, measure 250 //L of commercial
1000-/;g/mL Pb standard onto the wipe.
3.2.2.3 -- Allow the wipe to air dry.
3.2.3 Laboratory Control Standard - Initiate an LCS by using the calibrated
Mettler balance to carefully weigh out an NIST-traceable reference material (Section
2.2.1.4) on a piece of clean glassine weighing paper. Record the exact weight.
Quantitatively transfer the entire amount into a clean, unused dust wipe. Fold the
dust wipe so that all the weighed material is contained, and place it in a clean, labelled
250-mL beaker. Record the sample number in the laboratory notebook. For example,
14
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to prepare a 1000 /yg Pb LCS, 0.1 527 g of a 6550 fjg/g reference material would be
used.
3.3 EXTRACTION PROCEDURE
The extraction process should be conducted in a chemical fume hood.
®
3.3.1 Carefully remove the field sample wipe from its container using Teflon
tipped tweezers or clean, gloved fingers.
3.3.2 Place the wipe in a clean, labelled 250-mL glass beaker and push down
with an acid-washed glass rod.
3.3.3 Using a volumetric pipette, add 3 ml of 30% hydrogen peroxide.
3.3.4 Add 20 ml_ of concentrated nitric acid using the automatic pipettor.
Use the glass rod to mix and agitate the wipe and extraction reagents until the wipe
is thoroughly wetted. Withdraw the glass rod, rinsing it with about 1 ml of deionized
water. Allow the sample to sit until any visible reaction ceases.
3.3.5 Place the beaker on a hotplate and cover with a ribbed watch glass.
3.3.6 Turn on the hotplate to the level necessary to achieve a slow reflux.
The temperature setting required to achieve a slow reflux will depend upon the type
of wipe being extracted, the temperature of the laboratory, and the model of the
hotplate. Do not allow the extraction solution to boil.
3.3.7 After 20 minutes, cautiously add 2 ml of 30% hydrogen peroxide.
3.3.8 Continue to reflux until the volume has decreased and the sample is
nearly dry. Do not allow to evaporate completely. There must be some liquid left to
ensure that the Pb is not lost through splattering or formation and loss of aerosols.
15
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3.3.9 Add 5 ml of concentrated nitric acid and repeat the reflux step to near
dryness.
3.3.10 Carefully remove the beaker from the hotplate and allow to cool.
3.3.11 Using a volumetric pipette, add 5 ml_ of concentrated nitric acid to the
sample beaker.
3.3.12 Using a squirt bottle or dropper, rinse the watch glass with 3 - 5 ml_ of
deionized water, being careful to catch all the rinsate in the sample beaker.
3.3.13 Carefully pour the sample liquid into a clean, labelled, 50-mL
polyethylene centrifuge tube. If any undissolved material remains in the beaker, press
the wipe material down using a clean glass rod to extract as much solution as
possible.
3.3.14 Using a squirt bottle or dropper and small quantities of deionized water,
carefully rinse all interior surfaces of the beaker and pour the rinsate into the same
centrifuge tube that contains the sample. Repeat the rinse step at least three times,
but do not exceed a final volume of 50 ml_.
3.3.15 Dilute to the mark on the centrifuge tube with deionized water to
achieve a final volume of 50 ml_. This dilution results in a nitric acid concentration of
approximately 10%.
3.3.16 Allow any undissolved particulate matter to settle out overnight, if
necessary, or centrifuge at 2500 rpm for 25 minutes. If the extract is not to be
analyzed immediately, decant the solution into a separate clean, labelled centrifuge
tube.
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3.3.17 The sample is now ready for lead analysis using the selected
instrumental technique, atomic absorption spectroscopy (AAS) or ICP.21'25
3.4 DATA PROCESSING
AAS or ICP analysis will result in values of /yg Pb/mL for the extracts. To
convert from fjg Pb/mL to //g Pb/wipe, use this formula:
/yg Pb/wipe = /vg/mL measured x DF1 x 50 mL/wipe
where DF1 = any dilution performed prior to analysis due to high lead
concentrations.
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4.0 QUALITY CONTROL
4.1 SAMPLE COLLECTION
Check original references for details of QC procedures for sample collection.
General procedures to be applied include the following:
4.1.1 Only use wipes that are uniform from one to another in size, thickness,
and appearance.
4.1.2 Only use wipes that, from wipe to wipe, appear to have similar loadings
of solubilization or wetting agents.
4.1.3 Avoid contamination of wipes before and after use.
4.1.4 Make all reasonable attempts to maintain constant and uniform pressure
while using an individual wipe and from wipe to wipe.
4.1.5 Maintain uniform wiping motions from wipe to wipe.
4.1.6 Place wipes in labelled containers.
4.2 WIPE EXTRACTION
4.2.1 Remove used wipes from containers carefully and deliberately to avoid
dust sample loss.
4.2.2 Immerse each wipe as completely as possible in extraction reagents.
4.2.3 Do not allow extraction solution to boil as this may result in splattering
and sample loss.
4.3 QUALITY CONTROL SAMPLES
Preparation of the QC samples is described in Section 3.2. Criteria for the
extraction procedure being under control are as follows:
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4.3.1 Blank - The blank wipe shall contain < 5 jjg Pb. If a higher level is
measured, repeat the blank analysis. If this blank is also > 5 //g Pb per wipe, either
identify a new source of wipes that have blank values < 5 fjg Pb per wipe and discard
the current batch, or make replicate measurements of the blank (n = 5 to 7) and
calculate an average blank value. Report this value with the field sample results.
4.3.2 Quality Control Check - The QC check shall yield a recovery of > 90%.
If the recovery is < 90%, repeat the test. If the repeat value is also < 90%, identify
the source(s) of error, including, for example, overheating of the digestion beaker or
miscalibration of the measurement instrument, and make appropriate corrections.
4.3.3 Laboratory Control Standard - The LCS shall yield a recovery between 80
and 120% relative to that which would be achieved with direct HN03/H202 digestion
of the reference material. If the recovery is outside these limits, repeat the test. If
the recovery remains outside the 80 to 120% window, either (1) identify the source(s)
of error and make appropriate corrections, or (2) make replicate measurements of the
LCS (n = 5 to 7) and calculate an average recovery value. Report this value with the
field sample results.
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5.0 SAFETY
5.1 COLLECTION
Appropriate safety procedures must be followed during collection of dust
material from paint abatement sites or other sites that might have high airborne lead
levels. Collection from areas where paint chips and dust could contaminate a person
requires full-body protection to protect the worker and to prevent take-home lead
contamination. This includes wearing disposable booties, coveralls, head cover, and
gloves during collection. A respirator and safety glasses with side shields or goggles
must also be worn. At the end of the collection period, remove the disposable safety
wear in a relatively clean area and place it in a plastic bag for disposal (Section 6.0).
After collecting the dust samples, take a shower as soon as is practically possible.
If worker contamination is not a potential problem, gloves still need to be used
to prevent contamination of the samples. In some cases, the use of booties may also
be needed.
5.2 ANALYSIS
Take normal laboratory precautions when digesting the dust wipe samples.
Wear gloves, a laboratory coat, and safety glasses with side shields when performing
acid-based extractions. Also, follow the manufacturer's instructions for safe usage
of the ICP or AAS.
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6.0 WASTE DISPOSAL
6.1 PROTECTIVE CLOTHING
Disposable protective clothing including dust masks and spent respirator dust
filter cartridges will generally not be categorized as hazardous waste because they
typically pass the EPA Toxicity Characteristic Leaching Procedure (TCLP).33 If there
is any uncertainty about the characterization of these materials, subject them to the
TCLP. This procedure involves an extraction in an aqueous solution at constant pH
in a closed vessel for 18 ± 2 hours followed by analysis of the solution for lead. If
the extracted lead exceeds 5 mg/L, consider the material a hazardous waste, and
place it in a State-licensed or -permitted hazardous waste landfill. If this level is not
exceeded, place the material in a municipal landfill.
6.2 WASH WATER
Filter wash water using a 20-/;m pore size filter (Section 2.3.8) and allow to
drain into a sanitary sewer system. A coarse screen may be used as a prefilter.
6.3 EXCESS DUST WIPE SAMPLES
Subject excess dust wipe samples to the TCLP and treat them as hazardous
waste should the extract exceed the allowed limit of 5 mg/L.
6.4 SOLUTION WASTE
Pour all leftover extract solutions, reagent wastes, and rinse water into a plastic
carboy. Rinse with water any centrifuge tubes or other vessels containing nitric acid
as one of the reagents before putting them into a plastic bag for disposal or reuse
after cleaning. Dispose of waste solutions according to applicable regulations.
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7.0 CORRECTIVE ACTION
See Section 4.3 for corrective actions in response to unacceptable QC sample
analysis results.
Corrective action for the measurement of lead is described in the "Standard
Operating Procedure for Lead in Paint by Hotplate- or Microwave-Based Acid Digestion
and Atomic Absorption of Inductively Coupled Plasma Emission Spectrometry."25
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8.0 REFERENCES
1. Agency for Toxic Substances and Disease Registry. "The Nature and Extent
of Lead Poisoning in Children in the United States: A Report to Congress."
U.S. Department of Health and Human Services, 1988.
2. Grand, L.D., and J.M. Davis. "Effects of Low Level Lead Exposure on Pediatric
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An International Assessment. Kluwer Academic Publishers: London, pp. 49-
115, 1989.
3. Goyer, R.A. "Toxic Effects of Metals." In: Klassen, C.D., M.O. Amdur, and
J. Doull, eds. Casarett and Doull's Toxicology, Third Edition, Macmillan: New
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4. Que Hee, S.S., B. Peace, C.S. Clark, J.R. Boyle, R.L. Bornshein, and P.B.
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5. Roberts, J.W., W.T. Budd, M.G. Ruby, A.E. Bond, R.G. Lewis, R.W. Weiner,
and D.E. Camann. "Development and field testing of a high volume sampler for
pesticides and toxics in dust." Journal of Exposure Analysis and Environmental
Epidemiology. 1 (2) 143-155, 1991.
6. ASTM ES 30-94. "Emergency Standard Practice for the Field Collection of
Dust Samples Using Wipe Sampling Methods for Lead Determination by Atomic
Spectrometry Techniques." ASTM Standards on Lead-Based Paint Abatement
in Buildings: Am. Soc. Test. Mat., Philadelphia, PA 19103. 1994.
7. Georgia Technical Research Institute. "Georgia Technical Research Institute
Wipe Sampling Procedures: Inspecting for Lead Hazards and Lead-Based Paint
Risk Assessment." 1993.
8. Office of Public and Indian Housing, Department of Housing and Urban
Development. "HUD wipe sampling procedure." In: Lead-Based Paint: Interim
Guidelines for Hazard Identification and Abatement in Public and Indian
Housing. U.S. Government Printing Office, Washington, DC, 1990.
9. Farfel, M.R., and J.J. Chisolm. "Health and environmental outcomes of
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children." Environmental Health Perspectives. 99: 1974.
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11. Rabinowitz, M., A. Leviton, H. Needleman, D. Bellinger, and C. Waternaux.
"Environmental correlates of infant blood levels in Boston." Environmental
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12. Lioy, P.J., T. Wainman, and C. Weisel. "A wipe sampler for the quantitative
measurement of dust on smooth surfaces: Laboratory performance studies."
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13. Eller, P.M. Lead in Surface Wipe Samples, Method 9100. National Institute for
Occupational Safety and Health (NIOSH) In: NIOSH Manual of Analytical
Methods. Fourth Edition, 1994.
14. Millson, M., P.M. Eller, and K. Ashley, "Evaluation of Wipe Sampling Materials
for Lead in Surface Dust." Am. Ind. Hyg. Assoc. J.. 55: 339-342 (1994).
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16. Timperi, R. Dust collection protocol. Department of Public Health, Health and
Human Services, Commonwealth of Massachusetts, Boston, MA. 1992.
17. Hayes, J. Dust sampling protocol. Environmental Health Services Section,
State of North Carolina, P.O. Box 27687, Raleigh, NC. 1992.
18. Vostal, J.J., E. Taves, J.W. Sayre, and E. Charney. Lead analysis of house
dust: A method for the detection of another source of lead exposure in inner
city children. Environ. Health Perspec.,7: 91, 1974.
19. Chavalitnikul, C. and L. Levin. "A laboratory evaluation of wipe testing based
on lead oxide surface contamination." Am. Ind. Hyg. Assoc. J., 45: 311,
1984.
20. Williams, E.E., D.A. Binstock, J.A. O'Rourke, P.M. Grohse, and W.F.
Gutknecht. "Evaluation of Hotplate- and Microwave-Based Methods for
Extracting Lead in Paint, Dust, and Soil with Measurement by Atomic
Absorption Spectrometry and Inductively Coupled Plasma Emission
Spectrometry." EPA 600/R-94/147, U.S. Environmental Protection Agency,
Research Triangle Park, NC, 1994.
21. ASTM, ES 36-94. Emergency Standard Practice for Hotplate Digestion of Dust
Wipe Samples for Determination of Lead by Atomic Spectroscopy. ASTM
Standards on Lead-Based Paint Abatement in Buildings: Am. Soc. Test. Mat.,
Philadelphia, PA, 19103. 1994.
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22. Eller, P.M. Lead on Air Filters, Method 7105. National Institute of
Occupational Safety and Health (NIOSH). NIOSH Manual of Analytical
Methods, Fourth Edition, 1994.
23. ASTM, ES 33-94. Emergency Standard Practice for Preparation of Airborne
Particulate Lead Samples Collected During Abatement and Construction
Activities for Subsequent Analysis by Atomic Spectrometry. ASTM Standards
on Lead-Based Paint Abatement in Buildings: Am. Soc. Test. Mat.,
Philadelphia, PA 19103. 1994.
24. Azimuth Laboratories. "Azimuth Method No. Az-M-105, Revision No. 2:
Preparation Procedure for Lead (Pb) Analysis - Dust Wipe Samples." Analytical
Methods Manual. October 1992.
25. Binstock, D.A., D.L. Hardison, P.M. Grohse, and W.F. Gutknecht. "Standard
Operating Procedure for Lead in Paint by Hotplate- or Microwave-Based Acid
Digestion and Atomic Absorption or Inductively Coupled Plasma Emission
Spectrometry." EPA 600/8-91/213, U.S. Environmental Protection Agency,
Research Triangle Park, NC, 1991, 19 pp. Available from NTIS, Springfield,
VA; NTIS PB92-114172.
26. "The National Human Exposure Assessment Survey (NHEXAS): A Workshop
to Identify Optimal Dermal Exposure Sampling Methodologies." January 10-11,
1994; EPA Contract 68-D1-0009. U.S. Environmental Protection Agency,
Research Triangle Park, NC.
27. Little Ones Baby Wash Cloths®, K-Mart Corporation, Troy, Ml 48084.
28. Wash'n Dri Moist Disposable Towelettes", Softsoap Enterprises Inc., Chaska,
MN 55318.
29. Nuclepore Filtration Products. Costar Corporation, Cambridge, MA 02140,
CAT #232300.
30. American Industrial Hygiene Association (AIHA) Environmental Lead Proficiency
Analytical Testing (ELPAT) Program, 2700 Prosperity Avenue, Suite 250,
Fairfax, VA 22031.
31. Binstock, D.A., E.D. Estes, E.E. Williams, J.D. Neefus, and W.F. Gutknecht.
"Development and Evaluation of a Procedure for Determination of Lead on Dust
Wipes by Hotplate Acid Digestion." EPA Contract 68-D1-0009, U.S.
Environmental Protection Agency, Research Triangle Park, NC, 1995.
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32. American Society for Testing and Materials. "Standard Specification for
Reagent Water, Designation D 1193-77 (Reapproved 1983)." 1991 Annual
Book of ASTM Standards. Vol. 11.03, 1991. 3 pp.
33. Toxicity Characteristic Leaching Procedure. Federal Register, Vol. 55, No. 126,
Friday, June 29, 1990.
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