EPA/600/A^93/064
DEVELOPMENT OF A FIELD TEST METHOD
FOR THE DETERMINATION OF LEAD
IN PAINT AND PAINT-CONTAMINATED DUST AND SOIL
P. M. Grohse, K. K. Luk, L L. Hodson, B. M. Wilson and W. F, Gutknecht
Research Triangle Institute, Research Triangle Park, NC 27711
S. L. Harper and M. E. Beard
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
B. S. Lim and J J. Breen, Office of Pollution Prevention and Toxics
U.S. Environmental Protection Agency, Washington, DC 20560
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I. ABSTRACT
A rapid, simple, inexpensive, and relatively accurate field test method for the
determination of lead (Pb) in paints, dusts, and soils has been developed. The method
involves the ultrasonic leaching of 0.1 g to 0.5 g of the sample in 5 ml of 25% (v/v) nitric
acid for 30 minutes, followed by colorimetric measurement with a commercially available
field test kit. A variety of actual field samples and several National Institute of Standards
and Technology (NIST) Standard Reference Materials (SRMs) were tested using the
proposed method. Results were compared with those obtained with a microwave, total
digestion method followed by inductively coupled plasma emission measurement. Lead
recovery and method precision were better than 84% and 11%, respectively, for a variety
of SRMs and field samples. No apparent interferences were encountered in the
ultrasonic/nitric acid sample extracts.
This paper has been reviewed in accordance with the U.S. Environmental
Protection Agency peer and administrative review policies and approved for presentation
and publication. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
II. BACKGROUND
The adverse health effects resulting from exposure of young children to
environmental lead have received increasing attention in recent years. The major sources
of exposure to lead in housing units are thought to be paint, dust, and soil. Lead-based
paint is currently a material of concern and a principal medium for lead contamination and
exposure. Although less consideration has been given to soil and dust, they are also
significant routes of exposure.1
Public Housing Authorities are required, by 1994, to randomly inspect all their
housing projects for lead-based paint.2 The most common test for lead in housing
employs the portable X-ray fluorescence (XRF) detector, which gives rapid results and
is non-destructive. Inconclusive XRF measurements must be confirmed with field-
collected samples in the laboratory, using a more accurate analytical method such as
atomic absorption spectrometry (AAS) or inductively coupled plasma emission
1
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spectrometry (ICP).3 Dust and soil samples collected either for risk assessment or post-
abatement clearance testing must also be returned to the laboratory for analysis. Waiting
for laboratory results, however, could result in continued exposure to hazardous levels
of lead and delay in reoccupation of a dwelling following abatement. On-site quantitative
analysis would eliminate this problem, but this would involve bringing in a mobile
laboratory, which would increase costs and require the use of highly trained personnel.
A quantitative, chemical test kit that would provide results of acceptable accuracy and
precision, and could be readily used by typical field testing personnel, would be
preferable.
In a previous study, five commercially available lead test kits were evaluated.4
These kits, which are intended principally as qualitative tools, showed a great deal of
sample dependency. The kits showed negative responses with available laboratory and
real-world samples at levels of concern (i.e., paint at > 1 mg Pb/cm2, dust at > 200 ppm,
and soil at 1000 ppm). The capability of the kits to measure approximately 1 jig of lead
in an aliquot of standard solution was demonstrated; however, because of insufficient
solubilization and/or negative interferences, positive responses were not obtained with
solid, real-world samples containing much more than 1 ng of lead. Several kits for
quantitative analysis of lead were also commercially available at the time, but these were
not evaluated because they were designed for water analysis and not solid materials.
In response to this apparent lack of a quantitative field test kit for analysis of lead
in paint, soil and dust, a study was conducted to identify or develop, if necessary, a
quantitative lead extraction procedure and a compatible measurement method.
Hi. EXPERIMENTAL
A. Extraction Studies
In the first phase of the study, a series of experiments was performed to identify
suitable lead extraction conditions for paints, dusts, and soils. Parameters studied
included extraction solution composition, sample size, agitation method, and extraction
time. Initial work was carried out on paint chips and paint dusts, on the assumption that
these would pose the greatest extraction difficulty.
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Leachates resulting from the extraction studies were initially subjected to
inductively coupled plasma emission (ICP) measurement using a Leeman Labs Plasma
Spec I sequential ICP. To correct for any unanticipated differences between standards
and samples (and between samples), the use of internal standards and the method of
additions were employed. For a comparison check on the ICP measurements, leachates
were also measured by direct aspiration atomic absorption spectrometry (AAS).
When the lead concentrations of the test samples were not known, the extraction
efficiencies of the candidate methods were determined by analyzing the residue remaining
after the extractions. This analysis was performed using a microwave "total digestion"
method incorporating nitric (HN03), hydrofluoric (HF) and hydrochloric (HCI) acids.5
Methods for agitating the leaching solution include manual and automatic shaking,
static leaching, and uftrasonication. Automated shaking was ruled out because the
equipment is too cumbersome for field applications. Manual shaking is labor-intensive,
and was rejected because of low throughput. Therefore, static leaching and two Fisher
Scientific ultrasonic baths (the 2.8 L, 100-watt and the 1.06 L, 53-watt models) were used.
The majority of the extractions were performed with the larger unit.
In the initial tests, HN03 solutions ranging from 1 to 50% (v/v) were tested with
National Institute of Standards and Technology (NIST) Standard Reference Material
(SRM) 1579 (lead-in-paint). Extraction times ranged between 1 and 24 hours for static
leaching, and between 15 and 60 minutes for ultrasonication. Alternative or
supplementary extraction media (addition of an HCI extraction step and pretreatment of
the samples with alkaline solution) also were evaluated with the goal of improving either
(1) the extractability of the sample prior to leaching or (2) the solubilization of the lead
compound itself.
The effect of the sample preparation method was tested using oil-based paint films
spiked with known levels of lead nitrate or white lead. Paint film samples were leached
in one of three configurations: (1) 1 cm2 intact samples, (2) 1 cm2 samples cut into 1/16"
squares, and (3) ground samples crushed to pass 60-80 mesh. These tests were
repeated on actual real-world paint chips. Initially, between 0.05 g and 0.10 g of paint
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samples were used for the extraction studies. The maximum allowable volume of
required extraction solution was also determined.
Once leaching solution and time conditions and sample preparation methods had
been established, the maximum amount of sample to be used for extraction was
determined. Following the identification of the most promising candidate extraction
method, tests were carried out on well-ground and homogenized paint a"hd dust samples.
NIST sediment SRMs 2704 and 1645 were used as test soils. Finally, real-world paint
chip samples were subjected to the candidate method.
B. Measurement Studies
In the second part of this study, lead measurement methods that were potentially
compatible with the proposed extraction procedure were identified and tested. Because
we had determined that ultrasonic leaching produced a usable solution of lead extracted
from paint, dust and soil samples, we were now able to consider measurement methods
designed for lead in water. A measurement method was considered an acceptable
candidate if it was:
1) portable
2) selective for lead (i.e., interferences were not significant)
3) sensitive (should detect solution concentrations of less than 10 ng Pb/l)
4) rapid
5) inexpensive
6) simple (not requiring high level of education/technical background)
7) compatible with the leachate from the extraction study candidate method
8) chemically safe to use (i.e., minimum use of hazardous reagents).
Several different measurement methods were considered, including the lead ion
selective electrode, field portable anodic stripping vottammetry, and colorimetric methods.
Preliminary tests with a lead ion selective electrode indicated good response for aqueous
solutions, but little or no response to lead extracted from paint and dust samples. Anodic
stripping voltammetry was rejected because of its complexity.
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Although many colorimetric methods for lead are available in the literature, we
decided that a commercially available colorimetric lead test kit would be most desirable
since it would be immediately available to testers. A commercial colorimetric analysis
system would eliminate the need to purchase and prepare reagents and to purchase a
colorimeter. Three quantitative test kits designed to measure lead in water were
purchased for testing: LEADTRAK from Hach,6 Octet Comparator from LaMotte
Chemical,7 and Lead Test from Chemetries.* The latter two utilized a visual color
comparison for quantification, but when they were tested with aqueous standards and
paint and dust sample extracts, the color of the sample extracts did not match the color
(chroma) of the standards. Therefore, an intensity comparison could not be made.
These two kits also used potentially hazardous reagents such as cyanide and carbon
tetrachloride.
The LEADTRAK system uses a proprietary colorimetric reaction with lead ion that
reaches maximum color intensity at 477 nm. This kit was judged the most suitable and
was used exactly as the manufacturer recommended. Several colorimeters are available
for the LEADTRAK system. Tested here were the DR/100 with analog meter readout and
the DR/700 with digital readout. The quoted concentration range for both colorimeter
systems is 0 to 150 u.g/L in drinking water. The method is summarized in Figure 1.
To ensure that the chemistry of the Hach LEADTRACK kit was compatible with the
extraction leachates, and specifically to determine the lowest test sample pH tolerated by
the test kit, the same standard (50 ng Pb/L) was analyzed in dilute HNO3 solutions
ranging from 0 to 0.3%. A linearity check was performed by analyzing a series of
standards throughout the stated analytical range of the colorimeters.
Using the ultrasonic/25% nitric acid leaching method developed in the first part of
the study, we used both Hach colorimeters to analyze the paint and dust method test
samples and SRMs previously measured using ICP and AAS. Three different analysts
performed the determinations. Two analysts used both colorimeters to analyze the
leachates. Five replicate extractions were performed for each sample. Overall method
(extraction/measurement) precision and accuracy were calculated, in addition to operator
variability.
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IV. RESULTS AND DISCUSSION
A. Extraction Study
Both static and ultrasonic leaching were tested over a variety of extraction times
and HNO3 concentrations. Approximately 0.1 g paint samples were used for these
determinations. For the static extraction method, acceptable extraction efficiency (>90%)
was achieved after approximately three hours with two out of five samples of NIST SRM
1579 using 25% (v/v) HNO3. Using the 100-watt ultrasonic bath, greater than 85%
efficiency was achieved with only 10% (v/v) HNO3 after 30 minutes for all samples, and
greater than 95% efficiency was achieved with 25% (v/v) HNO3. Assuming that most
paint samples would be in the chip form, it appeared unlikely that the static extraction
technique would be adequately efficient. Therefore, the remaining studies focused on the
ultrasonic extraction method. At this time in the study, 10% HNO3 appeared to be the
most suitable leaching media for subsequent work because (1) It provided close to 90%
lead recovery for samples tested, (2) it is highly desirable to minimize strength of acid
solutions used in the field, and (3) extracts having minimum acidity would have the
greatest chance of being compatible with the method(s) of measurement ultimately
selected.
Using the 10% (v/v) HNO3 extraction method, the need for a grinding procedure
prior to the extraction was evaluated. Latex paint film samples were prepared in-house
and extracted in the three configurations described in Section IIIA. Results using the 10%
(v/v) HNO3 extraction (30 minutes) and ICP measurement showed no difference in
recovery between intact and ground paint chips. All sample aliquots were in the 0.1 g
range. There also appeared to be no difference in efficiency when using 2.5 ml or 15
mL of extraction solution (10% HNO3). However, when the grinding procedure was
evaluated using real-world, old paint chips, there was an average increase of 13% in the
measured lead levels for ground chips over chips that had been extracted intact.
In an effort to improve the extraction procedure, 1.0 N sodium hydroxide was
evaluated as a paint chip "softening" agent (prior to extraction); in a separate experiment,
concentrated HCI was added after the 10% HNO3 extraction step. Results in both cases
indicated no improvement in the extraction efficiency for the real-world old paint chip
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samples. Ultimately, effective recovery was deemed to be more important than avoiding
the use of relatively strong acid in the field or compatibility with potential measurement
methods. Therefore, we decided to use 25% (v/v) HNO3 because this reagent gave
better than 95% recovery with the samples tested.
The maximum sample weight for extraction for each matrix that resulted in greater
than 90% lead recovery was then determined. Although 0.5 g aliquots appeared to be
quantitatively extracted for most samples of each matrix type, some paint samples
showed a decline in recovery even above 0.1 g (Table 1). Consequently, a maximum
weight of 0.1 g was chosen for paint samples, while 0.25 to 0.5 g was found to be
acceptable for dusts and sediments.
Extraction efficiency was evaluated by sonicating crushed real-world paint chip
samples in 25% (v/v) HNO3 for 30 minutes in the 100-watt ultrasonic bath, followed by
digestion of the undissolved residue using a more complete microwave method employing
HNO3, HCI and HF acids. Both the leachate and residue digestate were analyzed by ICP.
For every sample, extraction efficiency was greater than 95% (Table 2). Using the same
conditions, the smaller, 53-watt ultrasonic bath was used to extract samples of the same
real-world paint. Extractions with this less powerful unit also yielded recoveries in excess
of 95%. Finally, using the larger bath and 25% HNO3, extraction efficiences for four "real-
world" dust samples and two sediment/soil SRMs were determined, using the same
"residue analysis" approach. As shown in Table 2, extraction efficiencies exceeded 94%
for dust samples and 91% for sediments.
The extraction method was then tested on three real-world method evaluation paint
samples and two dust samples. The preparation and round-robin analyses of these
samples were presented in another paper.9 Rve replicate extractions were performed for
each sample. Extracts were measured for lead by ICP and AAS. Extraction recoveries
for all paints were 93.3% or better. Recovery for one dust sample was 84.3%. The lead
level in the other dust sample was too low for an accurate recovery determination.
Extraction results were compared to data from the total digestion (HNO3, HCI, HF) of
these samples (Table 3). A statistical parrwise comparison was made of each of the
three methods for each sample.10 Despite the significant differences among samples
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(Table 4), the averages of the ultrasonic/ICP and uftrasonic/AAS values differed by less
than 5% from total digestion values for the three paint samples and the paint SRM. The
difference was 16% for the dust sample. After review of these and earlier test results,
a final extraction procedure (Figure 2) was formulated.
B. Measurement Study
Initial tests of the Hach lead test kit (LEADTRACK), a system designed for analysis
of lead in drinking water, involved measurement of standard lead solutions and
comparison of the results obtained by using both the kit colorimeter and a laboratory
scale UV/Visibie spectrophotometer. Results agreed within 10%, demonstrating the
potential accuracy of the test kit measurements. Tests were then performed using NIST
SRM 1579 paint extracts to determine the maximum allowable volume of test solution that
could be used with the Hach kit. With a final (diluted) nitric acid concentration of 2,5%,
a maximum of 3 ml of the final extract could be used before the buffering capacity of the
Hach system was exceeded.
Using a series of aqueous standards, the linearity of the colorimeters was tested.
These tests showed the Hach system to yield a linear response over the range of 0 to
150 u.g/L. Using a 1 ng/L standard, a series of eleven replicate determinations were
made to obtain an estimate of the detection limit. A value of 2.5 ng/L was obtained using
three times the standard deviation of these measurements.
Following the preliminary measurements, two different models of Hach colorimeters
were used to measure lead concentrations in extracts acquired using the proposed
method. Dust and paint samples that had been sieved and homogenized in-house were
used. Three operators performed the measurements. Five separate aliquots of each
sample were subjected to the ultrasonic extraction method and measurement using the
Hach kit. Data from all operators and replicates for each sample and each colorimeter
were pooled and the mean calculated. These data are compared to the pooled ICP and
flame AAS measurements of the same leachates (Table 5). All Hach values were within
10% of the atomic spectroscopy values.
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A statistical, pairwise comparison was made of each of the three measurement
methods for each sample. The Hach results for PAINT-2, PAINT-3 and the SRM are
biased low relative to the atomic spectroscopic results (Table 6), whereas the results are
variable for the dust and the other paint. Table 7 presents a breakdown of data from
each Hach operator. These data are compared to "total digestionVICP results (n=3 for
each sample). The total digestion used microwave heating in the presence of HN03, HF,
and HCI. Therefore, Table 7 also represents a preliminary measure of the overall field
method accuracy and precision. Average recoveries for the Hach kit field method
calculated relative to the "Reference Values" exceeded 90% for paints and 82% for the
dust sample. In only one instance did the precision over the five replicates of a given
sample exceed 10% RSD (10.2%), and generally it was considerably better. A statistical,
pairwise comparison of the operator results showed only one difference at the 95%
confidence level (the difference between operators 1 and 2 for PAINT-2).
V. Summary and Conclusion
Due to the current lack of a comprehensive and quantitative lead test kit for paints,
dusts, and soils, a field method has been developed that combines a simple extraction
technique with a commercially available colorimetric test kit for lead in water. The method
is relatively rapid. Weighing and grinding of paint requires about 5 minutes per sample.
Setting up for ultrasonication requires 1 to 2 minutes per sample. The ultrasonicated
samples can be allowed to settle for 30 minutes, which does not require any labor, or
they can be centrifuged, which requires about 5 minutes per sample. Finally,
measurement with the Hach kit requires about 15 minutes per sample. A number of
samples can be processed simultaneously, depending on the capacity of the ultrasonic
bath.
The method is capable of detecting 50 ng/g in paint and 20 ^/g in sediments and
dusts. Extraction recovery is greater than 85% and measurement values are within 10%
of atomic spectroscopic values. Overall method precision is generally better than 10%
RSD. The estimated cost for materials is approximately $5 per analysis (1992); initial
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outlay for the Hach kit varies, depending on the colorimeter purchased, from
approximately $250 for a kit with an analog device to $800 for a kit with a digital device.
Some pretreatment of paint chips appears necessary; a simple 30-second crushing
operation with a glass or plastic rod appears to be adequate. Quality control operations
are critical. Check samples should be analyzed periodically to verify calibration curve
accuracy and compensate for instrument drift and variations in operator performance.
Digital colorimeter units such as the Hach DR/700 are preferable to the'analog units due
to the potential variations in "style" in reading the meter. Based on the existing data, it
appears that 0.1 g aliquots are most suitable for paint chips and powdered paint, while
as much as 0.25 g may be used for house bulk dusts and sediments. The measurement
system has a range limited to extracts with between 10 and 150 jig Pb/L For some
samples this may be beneficial due to the "diluting out" of any potential matrix or
interference effects.
Although the method appears suitable for paints, bulk dusts and soils, work needs
to be performed for dust wipes. In addition, the method should be evaluated for actual
field soil samples. The sediments tested in this study were SRMs that were well
homogenized and of very small (and easily extractable) particle size. In order to further
define the precision and accuracy of the method, it must be tested through a round-robin
study, preferably performed in a field environment.
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VI. REFERENCES
1. Elwood, P. C., "The Sources of Lead in Blood: A Critical Review." The Science of
the Total Environment. 52:1-23, 1986.
2. Lead-Based Paint Poisoning Prevention Act, 42, U.S.C. 4:22 (d)(2)(A), 1971.
3. Lead-Based Paint: Interim Guidelines for Hazard Identification and Abatement in
Public and Indian Housing. Department of Housing and Urban Development,
September 1990.
4. Luk, K. K., Hodson, L L., Smith, D. S., O'Rourke, J. A., and Gutknecht, W. F.,
"Evaluation of Lead Test KHs for Analysis of Paint, Soil and Dust," Presented at
AWMA/EPA International Symposium on Measurement of Toxic and Related Air
Pollutants, Durham, NC, May 30, 1992.
5. Bao-hou, Li, Zhong-quan, Yu, and Kai, Han, "Determination of Si, Al, Mg, Fe, Ti, Mn,
Cu, Co and Ni in Vanadium-Titanium Ore by Microwave Oven Digestion, ICP, AA and
Chemical Analysis Methods,* Institute of Chemical Industry and Metallurgy, The
Academy of Sciences of China, Beijing, China, June 1988.
6. Hach Company, 100 Dayton Ave., P. O. Box 907, Ames, IA 50010.
7. LaMotte Chemical Products Co., P. O. Box 329, Chestertown, MD 21620.
8. Chemetrics, Rt. 28, Calverton, VA 22016-0214.
9. Williams, E. E., Binstock, D. A., Estes. E. D., Neefus, J. D., Gutknecht, W. F., Lim,
B. S., Breen, J. J., Harper, S. L., and Beard, M. E., "Preparation and Evaluation of
Lead-in-paint and Lead-in-dust Reference Materials," In: Proceedings of Symposium,
204th ACS National Meeting, Washington, DC, August 23-27, 1992. In press,
1993.
10. Natrella, M. G., Experimental Statistics. National Bureau of Standards Handbook 91,
October 1966, pp. 3-23 - 3-30.
11
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Figure 1. Measurement Method (Highlights)
Hach DR 100/700
Dilute sample extract diluted to 100 ml with deionized H20
Add 1 ml preservative (Hach pPb-1 Acid Preservative Solution) and swirl to mix
Add 1 ml fixer (Hach pPb-2 Fixer Solution) and swirl to mix
Pass sample through Hach Fast Column Extractor column to retain Pb
Elute Pb from column using Hach pPb-3 Eluant Solution
Adjust pH of eluent using Hach pPb-4 Neutralizer Solution
Add color agent (Hach pPb-5 Indicator Powder Pillow)
Decolorize 1/2 of above solution as blank using Hach pPb-6 Decolorizer Solution
Measure sample and blank by colorimetry at 477 nm
12
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Table 1. Effect of Variation In Sample Extraction Weights
Sample
Sample
Aliquot Weight
(9)
Ultrasonic Leach/
ICP Measurement
{% Pb)
DUST-1
PAINT-1
PAINT-2
PAINT-3
NIST 2704
Buffalo River Sediment
(0,0161)a
NIST 1645
River Sediment
(0.0714)a
0.25
0.50
0.25
0.50
0.10
0.25
0.50
0.10
0.25
0.50
0.10
0.25
0.50
0.25
0.50
0.414
0.429
0.148
0.147
0.635
0.634
0.431
3.51
3.41
1.15
0.0157
0.0162
0.0143
0.0664
0.0694
Certified values in %
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Table 2. Determination of Extraction Efficiency
Through Extract Residue Analysis
(n.1)
Extractable Residual Extraction
Sample Lead Lead Efficiency
(ug/g) Oig/g)a
Paint
P711
P254
P273
P268
P355
P719
40,400
2160
7889
52,400
71,800
288,000
330
59
25
1400
600
5900
Dust
Sediment
99.2
97.3
96.9
97.4
99.2
98.0
D116 548 14 97.5
D120 1240 34 97.3
D121 1710 8 99.5
D122 850 52 94.2
NIST2704 160 1 99.4
NIST 1645 653 61 91.4
Calculated relative to original sample weight.
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Table 3. Comparison of Total Digestion and
Uitrasonication Analysis Results1
(% Pb + Std. Dev.)
Sample
Total Digestion/ICP US/ICPC
US/AASC
DUST-1
0.496 + 0.041 0.414 + 0.017 0.418 + 0.009
PAINT-1
0.162 + 0.004 0.160 + 0.008 0.178 + 0.012
PAINT-2
0.645 + 0.023 0.635 + 0.013 0.642 + 0.005
PAINT-3
3.60 + 0.12
3.51+0.12
3.36 + 0.30
NIST 1579
(11.87%)
11.87 + 0.15
11.40 + 0.20
12.10 + 0.30
b Ultrasonic extraction/ICP measurement
c Ultrasonic extraction/Flame AAS measurement
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Table 4. Pairwise Comparisons of Methods.
Test Samples for Which Results Differed at the 95% Confidence Level
RT1 Total
Digestion US/ICP3 US/AASb
RT1 Total
Digestion
US/ICP DUST-1
NIST 1579
US/AA DUST-1 PAINT-1
PAINT-1 NIST 1579
aUltrasonic extraction/ICP measurement
bUltrasonic extraction/Flame AAS measurement
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Figure 2. Extraction Method
• Weigh 0.1 g paint (0.25 g sediment or dust) in a 50 ml graduated centrifuge tube
» Pipet 5 ml of 25% (v/v) HNO3 into centrifuge tube and cap
• Sonicate for 30 minutes (solution will heat to approximately 45 °C)
» Remove from bath, allow to coo!, and dilute to 50 ml with DI H2O
• Centrifuge for 5 minutes at 2,000 rpm or allow to settle for approximately 30
minutes
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Table S. Comparison of Atomic Spectroscopic
and Hach Measurements of Paint
and Dust Leachates
(% Pb ± Std. Dev.)
Sample
Atomic
Spectroscopy
(n=10)
Hach with DR/
100
Colorimeter
(n-15)
Hath with DR/
700
Colorimeter
DUST-1
PAINT-1
PAlNT-2
PAINT-3
0.416 ±0.013
0.169 ±0.010
0.639 ± 0.009
3.44 + 0.21
NIST1579 11.8 ±0.3
(11.87 ±0.04%)
0.409 ± 0.024
0.182 ±0.014
0.624 ± 0.023
3.24 + 0.20
10.7 + 0.5
0.439 ± 0.027
0.179 ±0.014
0.613 ±0.030
3.24 + 0.19
10.9 + 0.6
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Table 6. Palrwlse Comparison of Methods.
Test Samples for Which Results Differed
at the 95% Confidence Level
Atomic
Spectroscopy
Hach with
DR/100
Colorimeter
Hach with
DR/700
Colorimeter
Atomic
Spectroscopy
Hach with
DR/100
Colorimeter
PAINT-1
PAINT-2
PAINT-3
NIST 1579
Hach with
DR/700
Colorimeter
DUST-1
PAINT-2
PAiNT-3
NIST 1579
DUST-1
19
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Table 7. Comparison of Field Method Results
with Reference Values
(% Pb * Std. Dev.)
Field Method13
Sample Ret. Value8 Operator 1 Operator 2 Operator 3
DUST-1 0.496 ±0.041 0.419 ±0.030 0.389 ±0.017 0.420 ±0.025
PAINT-1 0.162 ±0.004 0.182 ±0.014 0.184 ±0.012 0.179 ±0.017
PAINT-2 0.646-1-0.023 0.604 + 0.016 0.646 + 0.021 0.622 + 0.032
PAINT-3
3.60 + 0.03 3.27 + 0.14
3.26 + 0,33° 3.21+0.13
NIST 1579 11.9 + 0.2
10.5 + 0.8
10.7 + 0.4
10.7 + 0.3
n=3
C%RSD=10.2
20
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TECHNICAL REPORT DATA
1. REPORT NO. 2.
EPA/600/A-93/064
4. TITLE AND SUBTITLE
Development of a Field Test Method for the
Determination of Lead in Paint, and Paint
Contaminated Dust and Soil
7. AUTHOR(S)
P. M. Grohse, K. K. Luk, L. L. Hodson, B. M. Wilson,
W. F. Gutknecht, S. L. Harper, M. E. Beard,
B. S. Lim, and J. J. Breen
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Research Triangle Institute
P.O. Box 12194
Research Triangle Park, NC 27709-2194
12. SPONSORING AGENCY NAME AND ADDRESS
U. S. EPA
AREAL
Research Triangle Park, NC 27711
3.
5. REPORT DATE
6. PERFORMING ORGANIZATION CODE
8.PERFORMING ORGANIZATION REPORT
NO.
10.PROGRAM ELEMENT NO.
J01/01
1 1 . CONTRACT/GRANT NO.
68-01-0009
13. TYPE OF REPORT AND PERIOD COVERED
Symposium Proceedings
14. SPONSORING AGENCY CODE
EPA/600/09
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A rapid, simple, inexpensive, and relatively accurate field test method for the
determination of lead (Pb) in paints, dusts, and soils has been developed. The
method involves the ultrasonic leaching of O.lg - 0.5g of the sample in 5 mL of 25%
(v/v) nitric acid for 30 minutes followed by colormetric measurement with a
commercially available field test kit. A variety of actual field samples and
several National Institute of Standards and Technology (NIST) Standard Reference
Materials (SRMs} were tested using the proposed method. Results were compared with
those obtained employing a microwave, total digestion method followed by
inductively coupled plasma emission measurement. Lead recovery and method
precision were better than 84% and 11%, respectively, for a variety of SRMs and
field samples. No species encountered in the samples were found to interfere in
the measurement.
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