Standard Operating Procedure for the
Grinding and Extraction of Lead in Paint
Using Nitric Acid and a Rotor/Stator System
Powered by a High-Speed Motor
&EPA
United States
Environmental Protection
Agency
EPA 600/R-10/071 August 2009 www.epa.gov/ord
Office of
Research and Development
National Exposure
Research Laboratory

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EPA/600/R-10/071 August 2009 www.epa.gov/ord
Standard Operating Procedure for the Grinding and
Extraction of Lead in Paint Using Nitric Acid and a
Rotor/Stator System Powered by a High-Speed Motor
Prepared by
Kristen Sorrell, Wayne Winstead, David Binstock,
Cynthia Salmons, and William Gutknecht
Environmental and Industrial Sciences Division
RTI International
Research Triangle Park, NC 27709

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Disclaimer
The information in this document has been funded wholly or in part by the U.S. Environmental Protection
Agency (EPA) under EPA Contract No. EP-D-05-065 to Alion Science and Technology, Inc., and RTI
Subcontract No. SUB1174861RB. It has been subjected to the Agency's peer and administrative review.
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 the Work Assignment Contracting Officer's
Representative, Ms. Sharon L. Harper, National Environmental Research Laboratory, U.S. Environmental
Protection Agency, Research Triangle Park, NC.
Special acknowledgment is given to Dr. Hunter Daughtrey, Alion Science and Technology, Inc., for his
support of this effort and careful review of this document.

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Table of Contents
List of Figures	vi
List of Appendixes	vi
I.0	PRINCIPLE AND APPICABILITY	1
2.0 SUMMARY OF METHOD	1
2.1	Rotor/Stator Grinding and Extraction	1
2.2	Method Performance	2
3.0 DEFINITIONS, ACRONYMS, AND ABBREVIATIONS	3
4.0 HEALTH AND SAFETY WARNINGS	3
4.1	Safety with Nitric Acid	3
4.2	Use of Equipment	4
4.3	Paint Preparation	4
5.0 EQUIPMENT, SUPPLIES, AND REAGENTS	4
5.1	Apparatus	4
5.1.1	High-Speed Motor To Operate Rotor/Stator System	4
5.1.2	Rotor/Stator System	5
5.1.3	Power Timer To Control 30 s on/15 s off for Rotor/Stator Motor	5
5.1.4	Pregrinding Paint Preparation Tools	5
5.1.5	Materials and Supplies	6
5.2	Reagents	6
5.2.1	25% Trace Metal Grade Nitric Acid	6
5.2.2	Quality Control Materials	6
5.2.3	Cleaning and Rinsing	6
5.3	Safety Equipment	7
6.0 QUALITY CONTROL AND QUALITY ASSURANCE	7
7.0 PROCEDURE	7
7.1	System Setup	7
7.2	Grinding and Extraction Procedure	7
7.2.1	Paint Preparation for Extraction	7
7.2.2	Paint Extraction	8
7.3	Rotor/Stator Reuse	9
8.0 DATA CALCULATION	9
9.0 DATA AND RECORDS MANAGEMENT	10
10.0 WASTE MANAGEMENT	10
10.1	Nitric Acid	10
10.2	Wash Water	10
10.3	Lead Paint	10
II.0	REFERENCES	10
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List of Figures
Figure 1. Photograph of rotor and stator separated and combined as normally used. Also shown is
stator with 12 mm removed to work with Rotozip motor	2
Figure 2. Omni and Rotozip high-speed motors fitted with Omni rotor/stator probes and
15-mL plastic centrifuge tubes	5
List of Appendixes
Appendix 1. Results of Application of Rotor/Stator Extraction Procedure to Lead-in-Paint
Reference Materials	A-1
Appendix 2. Results of Application of Rotor/Stator Extraction Procedure to Real-World,
Lead-in-Paint Samples	A-2
Appendix 3. Results of Application of Rotor/Stator Extraction Procedure to Paint Samples That
Form a Gooey Material During the Extraction Procedure	A-4
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1.0 PRINCIPLE AND APPICABILITY
Exposure to lead (Pb) may adversely impact children's brains, nervous systems, and many organs. An
estimated 310,000 U.S. children ages 1 to 5 have elevated blood leads. In the United States, the major
exposure pathway for children to Pb is from deteriorated Pb-based paint (LBP), Pb-contaminated house
dust, and residential soil. Approximately 40% of all U.S. housing units (about 38 million homes) have
some LBP.1 The Federal regulated lead standard has been defined by the U.S. Department of Housing
and Urban Development (Title X of the Housing and Community Development Act, 1992)2 as equal to or
greater than 0.5% Pb by weight or 1.0 mg Pb/cm2. Homes built before 1978 are the most likely to contain
LBP. Each year, more than 10 million renovation activities occur in homes, child-care facilities, and
schools potentially containing LBP. To reduce the exposures to lead hazards during renovation, the U.S.
Environmental Protection Agency (EPA) promulgated the "Lead; Renovation, Repair, and Painting
Program; Final Rule" (RRP) in April 2008. The rule requires the use of inexpensive test kits. However, no
currently available commercial test kit can meet the performance requirements of no more than 5% false
negative results at levels greater than the Federal regulated level and no more than 10% false positive
results at levels less than Federal regulated level.3 Additional goals are that the test kit procedure should
be inexpensive, take less than an hour per sample, and be easy to perform.
The simple, commercially produced test kits currently available for home testing for lead in paint are very
sensitive but do not provide quantification of the lead to meet the specifications in the RRP. As noted in
Gutknecht et al., there are several field techniques already available for direct (in situ) quantitative
analysis of lead in painted surfaces, including field-portable, X-ray fluorescence and portable laser
microprobe spectrometry.4 The instrumentation for these methods is relatively expensive and requires
extensive training. Additionally, there are numerous less expensive field methods available for
quantitatively measuring lead in solution. These include electrochemical reduction/oxidation (anodic
stripping voltammetry), complexation (colorimetry), precipitation (gravimetry), orturbidimetry. However, to
apply these methods, paint first must be removed quantitatively from the surface, and Pb quantitatively
solubilized from the paint. Grinding may be needed to facilitate solubilization.
This standard operating procedure (SOP) describes a new, rapid, and relatively inexpensive one-step
procedure that grinds the paint samples removed from the substrate and simultaneously quantitatively
extracts the Pb from the paint in only one step in preparation for quantitative analysis. This method has
been applied successfully in the laboratory and is expected to perform as well in the field. It is a general
use SOP and intended to be used by trained nontechnical workers.
2.0 SUMMARY OF METHOD
2.1 Rotor/Stator Grinding and Extraction
Typically a single chip of paint 1 cm2 in area is collected from a painted surface and analyzed. Under
certain circumstances, however, the paint sample collected may be in small pieces or an irregular
chip. If the area is unknown and cannot be determined, then the sample is to be weighed to within
±0.001 g (±1 mg). Simple scales for use in the field are available for this purpose, for example, the
Gempro500 from Precision Weighing Balances, Bradford, MA. In the laboratory, a standard analytical
balance is used to weigh the paint samples. No matter the physical form, the paint sample is crushed
by hand, cut into small pieces with a scalpel or knife, or pulverized during sampling with an approach
that grinds the paint as it removes it from the surface as per EPA "Standard Operating Procedure for
Surface Paint Sample Collection Using a Modified Wood Drill Bit and Variable-Speed Portable
Electric Drill,5" prior to the grinding/extraction procedure described in this SOP.
In the method described in this SOP, the collected paint sample is placed in a 15-mL, conical bottom,
plastic centrifuge tube containing 2 mL of 25% (v/v) nitric acid (HN03). The paint in the acid is ground
using a rotor/stator system (Figure 1) powered by a high-speed (15,000- to 30,000-rpm) motor. The
paint is ground for about 3 min with 30-s on and 15-s off cycles. The rotor/stator configuration is
common in high-shear grinders and mixers. This high-shear process is at the heart of the efficiency of
this approach. When the system is operated, the small pieces of paint are drawn up into the center of
the rotor and then spun out with great force. The small pieces are caught between the rotating and
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*
\m
Figure 1. Photograph of rotor and stator separated and combined as normally used. Also shown
is stator (clear plastic piece) with 12 mm removed to work with Rotozip motor as
described below. (Rotor/stator probe shown manufactured by Omni International,
Marietta, GA).
static "blades" and are cut into smaller pieces. With continued grinding, the pieces become smaller
and smaller. The combination of small particles, 25% (v/v) HN03, and intensive mixing results in Pb
recoveries that are consistently greater than 95% for real-world paints, National Institute of Standards
and Technology's (NIST's) Standard Reference Materials (SRMs), and audit samples from the
American Industrial Hygiene Association's (AIHA) Environmental Lead Proficiency Analytical Testing
(ELPAT)6 Program.
2.2 Method Performance
The method has been evaluated using a series of reference materials and real-world paints from the
RTI repository of paint for the ELPAT program." Included were six samples of certified NIST
Research Material (RM) 8680 Paint on Fiberboard' (actually collected by RTI for EPA/NIST in the
1990s) and four standard reference paint films prepared by RTI for EPA that consist of uniform sheets
of lead-nitrate-spiked, water-based paint that were characterized by sampling and acid
extraction/inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurement.39 The
average recovery with these samples always exceeded 95%, as shown in the data presented in
Appendix 1.
Method performance also was determined as the recovery based on the amount of Pb extracted
versus that found in any undissolved residue following the rotor/stator-based grinding and extraction.
Residue analysis performed with the RTI-prepared paint films yielded a mean recovery of 97.3% ±
0.53% (0.54% RSD), while residue analysis performed with real-world paints yielded average
recoveries exceeding 95%, as demonstrated in Appendix 2.
On the basis of all the tests done with both real-world field samples and reference samples, the
rotor/stator method of grinding and extracting Pb in paint as described in this SOP consistently
produces recoveries of Pb greater than 95% from real-world paints.
[Note: Some paints form a gooey material on grinding that sticks to the rotor/stator system. The
reason for this formation remains unknown. To check the significance of this, several paint samples
that form gooey material were ground/extracted using the rotor/stator method. As demonstrated in
Appendix 3, the recovery was stiii above 95% for these samples, and, therefore, the material does not
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negatively affect the recovery of these real-world paints. Because the cleaning method effectively
removes the gooey material, it should be used to prepare the rotor/stator for reuse. The potential for
gooey material formation requires that several rotor/stator systems be available for efficient work with
multiple samples.]
3.0 DEFINITIONS, ACRONYMS, AND ABBREVIATIONS
A number of acronyms and abbreviations are used in this SOP. These acronyms and their meanings
are shown below.
•	AIHA - American Industrial Hygiene Association
•	ELPAT - Environmental Lead Proficiency Analytical Testing Program
•	EPA - U.S. Environmental Protection Agency
•	ICP-AES - inductively coupled plasma atomic emission spectroscopy
•	LBP - lead-based paint
•	NIST - National Institute of Standards and Technology
•	Pb - elemental or ionic lead
•	RM - NIST Reference Material
•	RRP - Lead; Renovation, Repair, and Painting Program; Final Rule
•	RTI - RTI International
•	SOP - standard operating procedure
•	SRM - NIST Standard Reference Material
•	v/v - volume-to-volume ratio
4.0 HEALTH AND SAFETY WARNINGS
4.1 Safety with Nitric Acid
The component of this procedure requiring the greatest care is HN03, which is a strong, corrosive,
oxidizing agent that requires protection of the eyes, skin, and clothing. The diluted acid (25%, v/v)
used with the method is less harmful than concentrated nitric acid but still requires full protection,
especially of the eyes. Items to be worn during use of this reagent include those that follow.
•	Safety goggles (or safety glasses with side shields)
•	Acid-resistant gloves
•	A protective garment such as a laboratory apron. Nitric acid spilled on clothing will destroy the
fabric and result in a hole; contact with the skin underneath will result in a chemical burn.
It is also essential that an eye wash bottle be available during performance of this method. This is a
bottle with a spout that covers the eye. If acid or any other corrosive gets into the eye, the water in
this bottle is squirted onto the eye to wash out the harmful material. Eye washing should be
performed immediately after exposure with the eye wash bottle or with large amounts of water from
another source if available. Medical help should be sought immediately after washing. If nitric acid is
spilled onto the skin, wash immediately with large amounts of water. Medical attention is not required
unless the burn appears to be significant. Even after washing and drying, the nitric acid may leave the
skin slightly brown in color. This will heal and fade with time.
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4.2	Use of Equipment
The equipment used in this method does not present any major hazard to the user. However, using
the rotor/stator does require several precautions to avoid personal injury or equipment damage.
•	Be sure the high-speed motor is fastened securely to the holding device.
•	The rotor/stator probe may warp slightly if it overheats; do not touch when still hot. When
warping occurs, this indicates a need to insert a new rotor/stator probe and discard the warped
one.
•	Be sure the rotor/stator probe is secure and centered in the test tube so that it does not contact
the sides of the test tube.
4.3	Paint Preparation
•	If the paint chips are cut into small pieces using a knife or scalpel, caution is required to avoid
cutting oneself.
•	If the paint is ground using the modified drill bit sampling method, care must be taken to avoid
any inhalation of this dust.
•	Any lead-based paint or paint dust must be washed from the hands before eating or drinking.
5.0 EQUIPMENT, SUPPLIES, AND REAGENTS
5.1 Apparatus
5.1.1 High-Speed Motor To Operate Rotor/Stator System
Motors currently identified are the Rotozip spiral saw system by Bosch and the Omni tissue
homogenizer by Omni International; either motor may be used. Other suitable motors also may
be available and equivalent.
in
5.1.1.1	Rotozip RZ10 Spiral Saw System by Bosch
•	Variable Speed (15,000 to 30,000 rpm)
•	Modification of the Omni rotor/stator probe required to fit Rotozip chuck. Stator must be
reduced in length 12 mm at top and held in place by separate clamp.
•	Rotozip tool can be set up on a timer (see below) that runs 30 s on and then 15 s off
for a total time of 3 min.
•	System to hold motor, rotor/stator probe, and sample preparation tube in place during
grinding such as a ring stand with appropriate clamps as shown in Figure 2. The
components of this support system for the Rotozip motor include the following four
items.
(1)	Ring stand, VWR 60010-105, or equivalent
(2)	Chain clamp, VWR 21573-275, or equivalent
(3)	Two clamp holders, VWR 21572-501, or equivalent
(4)	Two miniature three-prong clamps, VWR 21572-805, or equivalent
5.1.1.2	Omni Tissue Homogenizer Model TH115 by Omni International11
•	Speed is variable from 5,000 to 35,000 rpm.
•	Chuck provides for mounting of both Omni rotor and stator.
•	Homogenizer can be set up on a timer (see below) that runs 30 s on and then 15 s off
for a total time of 3 min.
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Figure 2. Omni (left) and Rotozip (right) high-speed motors fitted with Omni rotor/stator probes
and 15-mL plastic centrifuge tubes. [Note: Clamp not needed to hold statorwhen using
Omni motor.]
•	The manufacturer of that motor offers a support stand specifically made for the Omni
motor.
5.1.2	Rotor/Stator System
5.1.2.1	Omni Inc.—Hard Tissue Omni Tips (7x110 mm) Model 30750H—includes rotor and
stator.
•	See Figure 1.
•	The rotor and stator typically can be used 10 times before they need to be replaced.
5.1.2.2	Omni-supplied chuck to hold stator and rotor or chuck to fit in another motor to hold
rotor with another device such as a clamp on a ring stand to hold the stator.
[Note: As noted above, 12 mm of the top of the stator purchased from Omni must be cut off
using a hacksaw or equivalent if the Omni rotor/stator probe is to be used in a Rotozip motor
(see Figure 1). The stator then is supported with a clamp as shown in Figure 2b because the
chuck on the Rotozip tool only allows insertion of the rotor.]
5.1.3	Power Timer To Control 30 s on/15 s off for Rotor/Stator Motor
• VWR Controller/Timer, VWR 23609-188, or equivalent
5.1.4	Pregrinding Paint Preparation Tools
If EPA "Standard Operating Procedure for Surface Paint Sample Collection Using a Modified
Wood Driil Bit and Variable-Speed Portable Electric Driii"5 is not used to collect/pregrind the paint
materials, obtain the following supplies.
5.1.4.1	Field scale balance with readability of ±0.001 g, GemproSOO from Precision Weighing
Balances, Bradford, MA, or equivalent
5.1.4.2	Small cutting board that can be washed between samples: 8.5 x 11 in (22 x 28 cm),
Chefmate white poly kitchen cutting board, Target or equivalent
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5.1.4.3	Weighing paper for sample handling and crushing, VWR WL565223-1 OA, or
equivalent
5.1.4.4	Scalpel or knife for cutting up rubbery samples, VWR 25853-003, or equivalent
5.1.5 Materials and Supplies
5.1.5.1	One 500-mL plastic beaker to serve as wash basin for cleaning rotors and stators,
VWR 13917-550, or equivalent
5.1.5.2	Two 1 -L polyethylene bottles—one for storage of 25% v/v nitric acid and the other for
storage of 2% trisodium phosphate solution for cleaning the rotor/stator probe, VWR 83009-
063, or equivalent
5.1.5.3	Squirt bottle for rinsing down rotor/stator during withdrawal from the centrifuge tube,
VWR 16651-143, or equivalent
5.1.5.4	Small brush for cleaning rotors and stators, if required, VWR 17080-004, or equivalent
5.1.5.5	Three wide-mouth, 5-L, polyethylene carboys—one for acid waste, one for wash and
rinse water waste, and one for storage of soapy water for washing, VWR 80094-464, or
equivalent
5.1.5.6	Indelible marker to label centrifuge tubes and containers used to collect waste
5.1.5.7	Notebook (VWR 28196-346, or equivalent) or bound forms prepared specifically for
this SOP
5.1.5.8	Volumetric pipette to deliver 2.0 mL of HN03 into 15-mL centrifuge tube, VWR 89003-
490, or equivalent, plus manual, 2-mL pipette pump, VWR 53502-222, or equivalent
5.1.5.9	Labeled 15-mL plastic centrifuge tubes, VWR Catalog No. 21008-918, or equivalent
5.2 Reagents
5.2.1	25% (v/v), Trace Metal Grade Nitric Acid
Pour three parts deionized water into a narrow-mouth, 1-L polyethylene container that can be
capped. Carefully and slowly add one part concentrated, reagent grade, nitric acid. Allow the
mixture to cool, cap the bottle, and mix thoroughly by rotating the container. Label the container
with the name of the contents, the date of preparation, and the name of the preparer.
5.2.1.1	Concentrated, reagent grade nitric acid, VWR EM-NX 0409-2, or equivalent
5.2.1.2	Deionized or distilled water
5.2.2	Quality Control Materials
•	NIST SRMs 2580,12 2581,13 and/or 2582.14 Order online:
www.srmors.nist.aov/orderinaSRMs.cfm.
•	ELPAT samples. Order from American Industrial Hygiene Association, 2700 Prosperity
Ave., Suite 250, Fairfax, VA.
5.2.3	Cleaning and Rinsing
5.2.3.1	100-mL plastic beaker for rotor/stator cleaning, VWR 25384-152, or equivalent
5.2.3.2	Laboratory detergent, Alconox, VWR 21835-032, or equivalent. Prepare wash water
in 5-L carboy following instructions on detergent container.
5.2.3.3	Trisodium phosphate for rotor/stator cleaning, VWR AAAL15052-36, or equivalent
5.2.3.4	2% trisodium phosphate rotor/stator cleaning solution. Mix 20 g trisodium phosphate
in 1 L of deionized water in a plastic bottle.
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5.2.3.5	Deionized water for rinsing down rotor and stator as they are withdrawn from the
centrifuge tube and corresponding sample dilution if required for the follow-up measurement
method
5.2.3.6	Laboratory wipe, Kimwipe, VWR 21905-026, or equivalent
5.3 Safety Equipment
Safety equipment is required for protection from harm from nitric acid. Items to be used include
•	safety goggles, VWR 10837-120, or equivalent
•	eye wash bottle, VWR 56611-060, or equivalent
•	acid resistant gloves, VWR 40101 (extra small to extra large), or equivalent
•	laboratory apron, VWR 32891-268, or equivalent
6.0 QUALITY CONTROL AND QUALITY ASSURANCE
Quality control activities to be practiced during the performance of this method include those that follow.
•	Use only clean, 15-mL plastic centrifuge tubes and rotor/stator systems. If a rotor and stator are not
clean, they must be thoroughly washed in soapy water, rinsed thoroughly in deionized water, and
then air dried or blotted dry with a laboratory wipe before use.
•	Use only a clean cutting board for each sample; cutting boards are to be washed and dried
between samples or wiped clean with a laboratory wipe.
•	Use only reagent grade nitric acid.
•	A blank should be prepared for analysis about every 20th sample. This consists of running acid
alone with the rotor/stator system.
•	A quality control sample should be prepared about every 20th sample. This will consist of nominally
0.1 g of a NIST paint reference material such as NIST SRM's 2580 at nominally 4% Pb,12 2581 at
nominally 0.5%,13 or 2582 at nominally 200 mg/kg.14 Alternatively, excess ELPAT materials may be
purchased from the AIHA15 for this purpose.
•	Carefully record the sample tube label number on a sampling log and/or in a laboratory notebook.
Adequately describe the sample collection location and characteristics of the paint, such as
estimated thickness, color, and number of layers.
7.0 PROCEDURE
7.1	System Setup
7.1.1	Secure a rotor/stator probe in the Omni motor chuck (or the Rotozip motor or some
equivalent chuck and stator clamp), so that the clear and blue bottom ends or the rotor and stator,
respectively, are flush with each other. When the Rotozip is used, 12 mm of the top of the stator
has to be cut off, so that the bottom of the rotor and stator are aligned horizontally.
7.1.2	Be sure that the rotor and stator are aligned vertically to avoid any physical contact
between them; such contact will generate heat and the eventual failure of the rotor/stator system.
7.2	Grinding and Extraction Procedure
7.2.1 Paint Preparation for Extraction
Paint samples collected for analysis will be whole chips of a known area, small pieces of paint,
and/or powdered paint. If a whole paint chip is relatively thick (>1mm), the mass of the sample
may exceed the capacity of the 2 mL of 25% (v/v) of nitric acid to yield 95+% recovery of Pb. If
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this situation is suspected, it's advisable to crush the sample into millimeter-sized particles on
weighing paper placed on the cutting board and to weigh out a portion that is no more than 0.1 g.
Simple scales for use in the field are available for this purpose, for example, the Gempro500 from
Precision Weighing Balances, Bradford, MA.
7.2.1.1	Large mass paint samples
(1)	Place a piece of weighing paper on the scale and determine the weight as per the
manufacturer's instructions.
(2)	Place the paint on the paper and weigh again. The weight of paper plus paint minus
weight of the paper is the weight of the paint.
(3)	Alternatively, cut a large chip into smaller chips of measurable area and use one of
these for the rotor/stator extraction process. [Note: The risk of using a smaller sample
is that it will be less representative of the true average value of the source.]
7.2.1.2	Small mass paint samples
(1)	If a paint sample is intact or consists of several pieces, place it on a weighing paper,
being sure to not lose any of the sample during the transfer.
(2)	Fold the paper and crumble the paint sample in the folded paper as much as possible
using your fingers, taking care to not touch the paint with your hands. If the paint is
rubbery and unable to be crushed, carefully cut up the paint sample on a clean glass,
polypropylene, Teflon, or equivalent cutting board (to approximately the size of grains
of rice) using a scalpel. Take care not to lose any of the paint during the cutting
process.
7.2.1.3	If the paint sample has been ground as part of the sample collection method, then it is
transferred directly without further pretreatment to the 15-mL, grinding/extraction tube.
7.2.1.4	If the surface area of the paint sample is unknown and cannot be determined, then
the sample is to be weighed to within ±0.001 g (±1 mg). Simple scales for use in the field are
available for this purpose, for example, the Gempro500 from Precision Weighing Balances,
Bradford, MA.
(1)	Place a piece of weighing paper on the scale and determine the weight as per the
manufacturer's instructions.
(2)	Place the paint on the paper and weigh again.
(3)	The weight of paper plus paint minus weight of the paper is the weight of the paint.
This weight will yield the final value in percent Pb.
7.2.2 Paint Extraction
7.2.2.1	Place pieces of, or "pour", ground paint chip sample carefully into a labeled, 15-mL,
plastic centrifuge tube.
7.2.2.2	Tap the bottom of the tube lightly on a hard surface to bring all the particles of paint to
the bottom of the tube.
7.2.2.3	Using the volumetric pipette or pipette pump, transfer 2.0 mL of the 25% (v/v) HN03
into the centrifuge tube.
7.2.2.4	Secure the tube with a clamp at the base of the motor holder.
7.2.2.5	Raise the tube containing the sample onto the rotor/stator such that the separation
between the inner bottom of the centrifuge tube and the bottom of the rotor/stator is about 1
to 2 mm; be sure that the rotor/stator is centered in the tube.
7.2.2.6	Turn on the motor on top speed (30,000 rpm) and allow it to run its timed course of 30
s on, 15 s off for approximately 3 min. This on-and-off process controlled by a suitable power
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timer allows the particles to settle and then be pulled back up into the vortex and thus
sheared. The resultant mixture will be cloudy.
7.2.2.7	Partially lower the centrifuge tube containing the paint extract, trying to keep any
remaining paint residue in the solution.
7.2.2.8	With the rotor/stator above the liquid, rinse the rotor/stator with 1 to 2 mL of deionized
water.
7.2.2.9	Lower the centrifuge tube away from the rotor/stator.
7.2.2.10	Carefully add deionized water to bring the total volume to 5 mL. [Note: Add water
until the bottom of the meniscus is at the 5-mL mark on the tube.]
7.2.2.11	Cap the labeled centrifuge tube and place it in a secure container for lead analysis.
[Note: If the lead concentration is to be determined using the EPA "Standard Operating
Procedure for the Turbidimetric Determination of Lead in Paint Extracts"16 or some other test
method that requires the maximum concentration of lead in the extract, then do not rinse the
rotor/stator. Instead, with the rotor/stator just above the liquid, tap the rotor/stator lightly to
shake off any remaining droplets of solution. Then fully lower the centrifuge tube. Finally, cap
the labeled centrifuge tube and place it in a secure container for lead analysis.]
7.3 Rotor/Stator Reuse
Experience has shown that the rotor/stator probe can be used 10 to 12 times before the components
become worn to the point of not efficiently grinding the paint, or that the components become warped
such that the rotor and stator come in contact during grinding, and excessive heating occurs.
As noted earlier, some paints form a gooey mass during the extraction process that is very difficult to
remove from the rotor/stator by simple washing with soap and water. The method for cleaning is
described below.
7.3.1	Use a laboratory wipe to remove as much goo as possible.
7.3.2	With the rotor/stator probe mounted in the motor, immerse the probe in about 50 mL of 2%
trisodium phosphate solution in a 100-mL beaker; the probe should extend about 8 cm into the
cleaning solution.
7.3.3	Operate the motor at 30,000 rpm for 1 min.
7.3.4	Lower the beaker, rinse the probe with deionized water, and wipe the probe lightly with a
paper towel.
7.3.5	Rinse the rotor/stator probe with deionized water a second time.
8.0 DATA CALCULATION
This SOP describes a method for grinding and extracting lead from a known amount of paint. The
collected paint sample may be measured by its area (cm2) or by its mass or weight (g). The analysis
following this grinding and extraction will yield a value of total micrograms or milligrams of Pb in the
extract. To calculate the concentration in weight per unit area, divide the total value for the Pb measured
by the area of the paint sample. For example,
mg Pb/cm2 = mg Pb measured/area of paint sample in cm2.
To calculate the concentration in percent, divide the total micrograms or milligrams of lead measured by
the mass of the paint sample and multiply by 100. For example,
% Pb = 100 x (mg Pb measured/mg of paint sample extracted).
9

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9.0 DATA AND RECORDS MANAGEMENT
Keeping accurate and complete records will help assure that the final results of the testing can be used to
make decisions about risk and the need for lead-in-paint treatment. Activities to be performed include
those that follow.
•	Maintain all records in a bound notebook or on a form prepared specifically for recording
information pertinent to this SOP. The forms shall be maintained in a binder.
•	Each paint sample shall be given an identifying name or number that is recorded along with a
description of the sample. This description shall indicate the source of the paint and its physical
attributes (color, estimated number of layers, estimated thickness, and brittleness).
•	The label placed on the 15-mL extraction tube shall be the same as the name or number of the
paint sample. If the tube is given a different label, an accurate record must be maintained that
relates the tube label to the name or number of the paint sample placed in the tube.
•	The date and time of the extraction shall be recorded in the notebook or on the form.
•	The person performing the grinding and extraction shall be identified in the notebook or on the
form.
•	Records are to be maintained of unusual occurrences such as the formation of the goo, unusual
amounts of residue, or unusual extract color.
10.0 WASTE MANAGEMENT
There are several forms of waste generated during the operation of this SOP. Each is discussed in the
following subsections.
10.1	Nitric Acid
If nitric acid waste or waste extract is generated, carefully pour this material into a wide mouth,
polyethylene carboy that is carefully labeled with a description of the contents. When the carboy is
about three-fourths full, it should be delivered to a commercial firm that specializes in removal of
hazardous waste.
10.2	Wash Water
The wash water from cleaning the rotor and stator is to be poured into a 5-L, polyethylene carboy that
is carefully labeled with a description of the contents or can simply be poured down the drain since
the Pb and acid content of the wash water will be minimal. Trisodium phosphate solution used to
remove paint goo from a rotor/stator probe is to be poured into this vessel also.
10.3	Lead Paint
Excess paint chips or paint powders that are no longer needed are to be placed in a resealable
plastic bag. The bag is to be labeled with a description of the contents, the source(s) of the paint, and
the name of the person who has placed these materials in the bag. This waste paint shall be
delivered to a commercial firm that specializes in removal of hazardous waste.
11.0 REFERENCES
(1)	Jacobs, D.E., R.P. Clickner, J.Y. Zhou, S.M. Viet, D.A. Marker, J.W. Rodgers, D.C. Zeldin, P.
Broene, and W. Friedman. 2002. The prevalence of lead-based paint hazards in U.S. housing.
Environmental Health Perspectives, 110(10):A599-A606.
(2)	Title X of the Housing and Community Development Act, Residential Lead-Based Paint Hazard
Reduction Program Act of 1992. Public Law 102-550.
10

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(3)	USEPA. 2008. Lead; Renovation, Repair, and Painting Program; Final Rule. Federal Register. April
22. (pp.21691-21769). U.S. EPA, 40 CFR Part 745, EPA-HQ-2005-0049.
(4)	Gutknecht, W.F., S.L. Harper, W. Winstead, K. Sorrell, D.A. Binstock, C.A. Salmons, C. Haas, M.
McCombs, W. Studabaker, C. Wall, and C. Moore. 2007. Rapid new methods for paint collection and
lead extraction. Journal of Environmental Monitoring, 11:166-174.
(5)	Winstead, W., K. Sorrell, D. Binstock, C. Salmons, and W. Gutknecht. 2009. "Standard Operating
Procedure for Surface Paint Sample Collection Using a Modified Wood Drill Bit with a Variable-
Speed Portable Electric Drill." Work assignment 3-23, RTI Subcontract No. SUB1174861RB, USEPA
Contract. EP-D-05-065, National Exposure Research Laboratory, U.S. Environmental Protection
Agency, August, 2009.
(6)	ELPAT. 2007. http://www.aiha.org/Content/LQAP/PT/ELPAT.htm Environmental Lead Proficiency
Analytical Testing Program, American Industrial Hygiene Association: Fairfax, VA. Web site visit-
09/21/07.
(7)	NIST. 1997. Certificate of Analysis. Research Material 8680 Lead-Based Paint on Fiberboard.
National Institute of Standards and Technology: Gaithersburg, MD.
(8)	Wlliams, E.E., D.A. Binstock, and W.F. Gutknecht. Preparation of Lead-Containing Paint and Dust
Method Evaluation Materials and Verification of the Preparation Protocol by Round-Robin Analysis.
EPA 600/R-93/235, U.S. EPA: Research Triangle Park, NC, 1993. Available from NTIS (NTIS
#PB94-141165).
(9)	Binstock, D.A., E.E. Wlliams, J.D. Neefus, and W.F. Gutknecht. 1994. Standard Operating
Procedure for Preparation of Method Evaluation Materials for Lead in Paint. EPA 600/R-94/132, U.S.
EPA: Research Triangle Park, NC. Available from NTIS (NTIS #PB95-174090).
(10)	Rotozip. Robert Bosch Tool Cooperation, a Division of Robert Bosch GmbH, based in Stuttgart,
Germany. (May be purchased at Home Depot or Lowes.)
(11)	Omni Model TH Miniature Grinder, Omni International, based in Marietta, GA. (May be purchased
from manufacturer.)
(12)	NIST. 1996. Certificate of Analysis. Standard Reference Materials 2580, Powdered Paint, Nominal
4% Lead. National Institute of Standards and Technology: Gaithersburg, MD.
(13)	NIST. 1997. Certificate of Analysis. Standard Reference Materials 2581, Powdered Paint, Nominal
0.5% Lead. National Institute of Standards and Technology: Gaithersburg, MD.
(14)	NIST. 1996. Certificate of Analysis. Standard Reference Materials 2582, Powdered Paint, Nominal
200mg/kg Lead. National Institute of Standards and Technology: Gaithersburg, MD.
(15)	American Industrial Hygiene Association, 2700 Prosperity Ave., Suite 250, Fairfax, VA 22031.
(16)	Studabaker, W., K. Sorrell, M. McCombs, C. Salmons, and W. Gutknecht. 2009. "Standard
Operating Procedure for the Turbidimetric Determination of Lead in Paint Extracts." Work
Assignment 3-23, RTI Subcontract No. SUB1174861 RB, USEPA Contract. EP-D-05-065, National
Exposure Research Laboratory, U.S. Environmental Protection Agency, August, 2009.
11

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APPENDIX 1
Results of Application of Rotor/Stator Extraction Procedure to
Lead-in-Paint Reference Materials
The paint samples were removed from the certified NIST RM 8680 Paint on Fiberboard7 pieces using the
modified drill bit method5 described in the aforementioned SOP, and these samples were then
ground/extracted using the rotor/stator method. The RTI reference paint films were rubbery when made,
but they have become somewhat brittle over approximately 10 years of storage.8 9 When these "imbrittled"
samples were hand crushed and put through the rotor/stator process, well-ground samples were
produced. Results are shown in Table A-1, along with results for several ELPAT materials and samples of
NIST SRM 2581 powdered paint.13
Table A-1. Results of Rotor/Stator Grinding/Extraction and ICP-AES Analysis of Six NIST RM 8680
Reference Materials, Two RTI-Prepared Paint Films, and Six Reference Materials
NIST Fiber Board,
RM 8680a
ICP-AES Pb Cone."
(mg/cm2)
NIST Value
(mg/cm2)
Recovery Based on
Expected Value (%)
KB2
1.20 ±0.12
1.25 ±0.35
96.0
TD5
1.48 ±0.05
1.21 ±0.38
122
DG2
1.13 ± 0.07
1.14 ±0.32
99.1
HA3
1.28 ±0.36
1.31 ±0.34
97.7
MD2
1.09 ±0.09
1.10 ± 0.30
99.1
JH1
1.57 ±0.09
1.29 ±0.40
122



Av 106 ±12 (11%)
aPaint samples preground with wood drill bit during sample collection prior to rotor/stator grinding.
bConc. = concentration
RTI-Made
Reference Film0
ICP-AES Pb Cone.
(mg/cm2)
Expected Value
(mg/cm2)
Recovery Based on
Expected Value (%)
RTI-49-A1-B
0.36
0.30
120
RTI-49-A1-B
0.36
0.30
120
RTI-35-A6-T
0.57
0.60
95
RTI-35-A6-T
0.52
0.60
86.7



Av 105 ±17 (16%)
cPaint samples prepared by hand crushing prior to rotor/stator grinding.
Reference
Materials'1
ICP-AES Pb
Cone. (%)
Expected Value
(%)
Recovery Based on
Expected Value (%)
ELPAT 51P1
2.18
2.22 ±0.13
97.8
ELPAT 51P2
1.47
1.51 ±0.11
96.1
ELPAT 39P3
0.53
0.558 ± 0.039
98
ELPAT 40P2
0.50
0.506 ± 0.032
109
ELPAT 51P3
0.48
0.461 ± 0.035
102
SRM 2581
0.43
0.449 ±0.011
95.6
SRM 2581
0.44
0.449 ±0.011
98.0



Av 99.5 ±4.7 (4.7%)
Paint samples in powdered form prior to rotor/stator grinding.
A-1

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APPENDIX 2
Results of Application of Rotor/Stator Extraction Procedure to
Real-World, Lead-in-Paint Samples
Extraction efficiency was determined by using ICP-AES to separately analyze the extract solution
and any remaining residue following rotor/stator extraction; these two phases were separated using
centrifugation. The microwave/aqua regia digestion method, which is used for preparing ELPAT paint
materials,5 was used to digest the solid residue remaining in the 15-mL centrifuge tube following
extraction and centrifugation of the rotor/stator paint extract. The recovery in the extract, which was
calculated as the amount measured in the extract divided by the total of the amounts in the extract
and the residue, was found to be in the range of 92% to 96% as demonstrated in Table A-2 below.
Table A-2. Determination of Lead Recovery from Real-World Paint Samples with the Rotor/Stator
Grinding/Extraction Procedure as Determined by Comparison of the Lead in the Extract
and Lead in Digested/Extracted Residue
Paint Material
Mixer/
Pb in Liquid
Pb in
Pb Recovery in Lquid
Identifier
Grinder
Extract (|jg)
Residue (|jg)
Extract (%)
TEST 1
"0.3% Pb"
Omni
153
4.38
97.2
"0.3% Pb"
Omni
151
4.30
97.2
LGS
Omni
534
18.2
96.7
LGS
Omni
389
14.8
96.3




Av 96.9 ± 4.4 (4.5%)
TEST 2
"0.3% Pb"
RotoZip
133
5.00
96.4
"0.3% Pb"
RotoZip
181
6.08
96.8
"0.3% Pb"
RotoZip
147
4.56
97.0





LGS
RotoZip
402
15.7
96.2
LGS
RotoZip
430
18.3
95.9
LGS
RotoZip
405
15.4
96.3




Av 96.4 ± 4.0 (4.2%)
A-2

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Table A-2. Determination of Lead Recovery from Real-World Paint Samples with the Rotor/Stator
Grinding/Extraction Procedure as Determined by Comparison of the Lead in the
Extract and Lead in Digested/Extracted Residue (cont'd.)
Paint Material
Mixer/
Pb in Liquid
Pb in
Pb Recovery in Liquid
Identifier
Grinder
Extract (|jg)
Residue (|jg)
Extract (%)
TEST 3
"0.3% Pb"
RotoZip
173
5.01
97.2
"0.3% Pb"
RotoZip
179
5.38
97.1





LGS
RotoZip
325
14.5
95.7
LGS
RotoZip
392
16.8
95.9





DorDix
RotoZip
211
4.67
97.8
DorDix
RotoZip
585
19.2
96.8





P926
RotoZip
72.5
1.65
97.8
P926
RotoZip
104
2.72
97.5




Av 97.0 ± 0.8 (0.8%)
TEST 4
"0.3% Pb"
RotoZip
194
10.9
94.7
"0.3% Pb"
RotoZip
166
4.67
97.3





LGS-74B
RotoZip
447
15.2
96.7
LGS-74B
RotoZip
387
16.9
95.8





DorDix-P1108
RotoZip
802
18.7
97.7
DorDix-P1108
RotoZip
689
19.2
97.3





OH-P926
RotoZip
36.0
0.41
98.9
OH-P926
RotoZip
77.4
2.02
97.5




Av 96.9 ± 1.3 (1.3%)
A-3

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APPENDIX 3
Results of Application of Rotor/Stator Extraction Procedure to
Paint Samples That Form a Gooey Material During the
Extraction Procedure
Some paints form a gooey material on grinding that sticks to the rotor/stator system. The reason for this
formation remains unknown. To check the significance of this, several paint samples that form gooey
material were ground/extracted using the rotor/stator method. Because the material sticks to the
rotor/stator, the gooey material from each sample was scraped carefully and washed from the rotor/stator
using a small spatula, small brush, and soap and water, which break up and apparently dissolve the goo.
The wash water was quantitatively collected in a beaker. The solutions that were collected in this manner
were then extracted using microwave/aqua regia digestion and analyzed for Pb by ICP-AES for the
measurement. As demonstrated in Table A-3, the recovery remains above 95% with these types of
samples, and it is apparent that the gooey material does not negatively affect the recovery of these real-
world paints.
Table A-3. Results of Analysis of Paint Samples That Form Gooey Material
RTI Repository
Paint Material
Weight
(g)
Amount Wash
Water Used (mL)
Liquid Extract,
Lead, Pb (pg)
Rotor/Stator
Wash Water,
Pb (Mg)
Pb in Wash
Water (%)
P728
0.100
18
43,126.60
1,053
2.38
P1149
0.108
24.5
40,389.90
300
0.74
PB-5
0.100
20.5
32,335.70
192
0.59
A-4

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