United States
Environmental Protection
Agency
National Exposure Research
Laboratory
Research Triangle Part, NC 27711
September 1997
Research and Development
I!
EPA/600/H-95/111
xvEPA
PB5JB-136963
Standard Operating Procedure for the Laboratory
Analysis of Lead in Paint, Bulk Dust, and Soil by
Ultrasonic, Acid Digestion and Inductively Coupled
Plasma Emission Spectrometric Measurement
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STANDARD OPERATING PROCEDURE FOR THE
LABORATORY ANALYSIS OF LEAD IN PAINT, BULK
DUST, AND SOIL BY ULTRASONIC, ACID DIGESTION
AND INDUCTIVELY COUPLED PLASMA EMISSION
SPECTROMETRIC MEASUREMENT
Prepared for:
Work Assignment Manager
S. L, Harper
National Exposure Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
EPA Contract No. 68-D1-0009 and 68-D5-0040
Work Assignments 1-125, il-219, HI-256, 1-14
Prepared by:
P. M. Grohse, W.F. Gutknecht, K. K. Luk, B, M. Wilson, and C. C. Van Hise
Center for Environmental Measurements and Quality Assurance
Research Triangle Institute
Research Triangle Park, NC 27709
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* %
1. REPORT NO.
pA,-600A=-95-m
«, TIILE AND SUBTITLE
Standard Operating Procc
Analysis of Lead in Paint,
Ultrasonic, Acid Digestion
Plasma Emission Spectron
TECHNICAL BEPORf DATA
2.
idure for the Laboratory
iulk Oust, end Soil by
and Inductively Coupled
metric Measurement
7. JUJTHORtSJ
P.M. Grohse, W.F. SutJcneetit, K.K. Luk, B.M. Wilson,
and C.C. Van Hise
9. PE8PORMWG ORGANIZATION NAME AND ADDRESS
Research Triangle Institute
P.O. Box 12194
Research Triangle Park, NC 27709-2194
12. SPONSORING AGENCY NAME AND ADDRESS
National Exposure Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
^.RECIPIENT'S ACCESSION HO.
S.REPORt DME
September 1997
6.PERFORMXNS OReRNIZATIOS CODE
8. PERFORMING ORSflNIZATION REPORT NO.
10.PROGRAM ELEMENT NO.
Issue 37, E3501.B34159
11. CONTRACT/GRANT NO.
68-D5-OQ4Q, RW86937727
13.TYFB OP REPORT AND PERIOD COVERED
Project
14. SPONSORING AGENCY CODE
EPA/600/09
IS. SUPPLEMENTARY NOTES
16, ABS1RACT
The details and performance of a simplified extraction procedure and analysis for three media are
provided. Paint, bulk dust, end sell are collected using standard or referenced methods. Faint is ground
to the consistency of coarsely ground coffee or commeal and bulk dust and soil t:e sieved using a 60-
mesh (250 urn) sieve. Up to 0.25 g of paint, bulk dust, or soil is weighed out and placed in a 50-mL
centrifuge tube. Five mL of 25% (v/v) nitric acid is added and the sample is ultrasonicated for 30
minutes. Beionized water is added to a total of SO mL. Hie sample is shaken then allowed to settle. The
plasma emission spectrometer is calibrated and the samples are analyzed. Quality control samples
analyzed include blanks, duplicates, and secondary and primary reference materials. Other quality control
activities followed include checking for matrix and spectral interferences. For lead in these three media,
the typical minimum detection limit is estimated to be 10 ug/g, bias <20%, and precision <1 5% RSD.
17.
IBY WORDS AND DOCUMENT ANALYSIS
I. DESCRIPTORS b.IDENTIFIERS/ 0?EN ENDED TERMS
11. DISTRIBUTION STATEMENT
19. SECURITY CLASS (JMi Xtport)
20. SECURITY CLASS rW'JVWe)
O.COSAT!
21. NO. OF PAGES
35
32. PRICE
36
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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 Nos.
68-D1-0009 and 68-D5-0040 to 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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ACKNOWLEDGMENT
This document was prepared under the direction of Ms. Sharon L, Harper,
National Exposure Research Laboratory (NERD, U.S. Environmental Protection
Agency, Research Triangle Park, IMC,
ii
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TABLE OF CONTENTS
Disclosure , . . i
Acknowledgment . ii
Section Page
1.0 Principle and Applicability 1
1.1 Scope and Application 1
1.2 Summary of Method 2
2.0 Apparatus and Reagents 7
2.1 Sample Collection 7
2.2 Sample Extraction 8
2.3 Measurement 9
2.4 Protective Equipment 10
3.0 Procedure 11
3.1 Sample Collection 11
3.2 Sample Preparation 11
3.3 Ultrasonic Sample Extraction 15
3.4 Calibration 16
3.5 Quality Control 17
3.6 Sample Determination . 23
3.7 Waste Disposal 24
4.0 Data Processing , 25
4.1 Direct Determination .25
4.2 Calculation - Field Sample Concentration . 25
5.0 References 26
Appendix A 29
iii
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SECTION 1.0
PRINCIPLE AND APPLICABILITY
1.1 SCOPE AND APPLICATION
The adverse health effects resulting from exposure of young children to
environmental lead (Pb) has 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
The major sources of exposure to lead in housing units are thought to be paint,
dust, and soil. Food, water, and airborne lead are also potential sources but are
considered to be minor avenues of exposure. Currently, lead-based paint is receiving
emphasis as a critical area of concern and a principal medium for lead contamination
and exposure. Although less consideration has been given to soil contaminated with
lead from petroleum additives or from the leaching of exterior paint (near driphnes,
etc.), contaminated soil may be tracked into homes. Like dust, it can collect on
hands, toys, and food and be ingested. Concentrations in paint, dust, and soil must
be determined if a comprehensive approach to the problem of lead ingestion from
housing sources is to be developed.
Under Section 302 of the Lead-Based Paint Poisoning Prevention Act, as
amended, Public Housing Authorities (PHAs) are required to randomly inspect ail their
housing projects for lead-based paint.4 Currently, the device most frequently used
for testing in housing is the portable X-ray fluorescence (XRR spectrometer, which
gives rapid results and is nondestructive. However, uncertainty as to the accuracy
and precision of XRF measurements is a major problem, especially near and below the
abatement level for paint {i.e., 5,000 figlg or 1 mg/cm2).6 inconclusive XRF
measurements must be confirmed in the laboratory using a more accurate method
such as microwave or hotplate digestion followed by atomic absorption spectrometry
(AAS) or inductively coupled plasma (ICP> emission spectrometry.6 This standard
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operating procedure describes use of a third lead solubilization method applicable to
paint, bulk dust, and soil consisting of an ultrasonic extraction with dilute nitric acid
followed by ICP analysis.6'7
1.2 SUMMARY OF METHOD
1.2.1 Sampling and Measurement
Samples are collected in the field according to the Department of Housing and
Urban Development (HUD) guidelines.5
Following a suitable sample homogenization procedure,8 the sample is extracted
using 25% {v/v} nitric acid for 30 minutes in a centrifuge tube placed in an ultrasonic
bath. After dilution to a fixed volume with thorough mixing and separation of soiids,
the lead content is measured by ICP emission spectrometry using the 220.35-nm
emission iine and the optimum instrumental conditions recommended by the
manufacturer.
1.2.2 Quant'ttation Range. Sensitivity, and Minimum Dejection Limit
1.2.2.1 Quantitation Range —
For paint samples, the typical range is 50 to 100,000 ng Pb/g (O.OOS to 10
percent) assuming {1} the instrument is linear up to 200 ^g/mL, (2) a sample mass
of 0.1 g was used, and (3) the final extract volume was SO ml. The range is 2O to
40,000 (*g Pb/g (0.002 to 4 percent) with a 0.25-g sample.
For dust and soil samples, the typical range is 20 to 40,000 ng Pb/g (0.002 to
4 percent) assuming instrument linearity up to 200 jug/mL, a final extract volume of
50 ml, and a sample mass of 0.25 g.
1.2.2.2 Sensitivity --
!CP sensitivity is a function of the photo current integration time as well as
other instrumental parameters. However, an indication of ICP sensitivity at a given
wavelength is the ratio of net analyte intensity to background analyte intensity, ln/lb.
For the 220.35-nm line, a reasonable value for this ratio is 50 to 100, which would
result in a detection limit of approximately 0.050 ttglml (50 ppb).9
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Many ICPs manufactured in the last five years employ torches arranged in an
axial configuration as compared to the radial torch configuration used to collect the
data for this SOP, These axial systems are considerably more sensitive (at least an
order of magnitude) and would be expected to provide correspondingly lower
detection limits.
1.2.2.3 Minimum Detection Limit (MDL) --
The typical MDL for lead in paint, bulk dusts, and soils Is estimated to be 10
M9/9 (0.0010 percent), with the MDL defined as 3 times the standard deviation of
replicate (n = 5 to 15) analyses of low-level samples. This value is based on
conditions described in Section 1.2.2.1 (0.25-g sample).10
Detection limits using ICPs with axial torches may be expected to be
considerably lower (see Section 1.2.2.2).
1.2.3 Interferences
Interferences for ICP can be manufacturer and model specific.9
1.2.3.1 Spectrallnterference--
The efficient excitation of sample constituents at high temperature results in
the possibility of spectral overlap interferences. A mathematical correction can be
applied for the interference if the interfering element and the magnitude of the
interference are determined. As an alternative, an interference-free line may be
chosen if the line exhibits an adequate detection limit. Background shifts due to stray
light, line broadening, and recombination continuum and other less well-defined
sources require correction by background measurement near the analysis line. This
correction normally is done dynamically within the instrument,
1.2.3.2 Physical Interferences -
Paint, dust end soil extracts may contain unknown species that effect the
efficiency of their nebulization relative to standards, thereby making matrix matching
of sample extracts and standards essentially impossible. The existence of these
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physical interferences may be checked for by: 1 ) analyzing a post-extraction spike
and determining the recovery of that spike; or, 2} analyzing serial dilutions of the
original sample extract and determining if an increase in concentration (after the
appropriate dilution factor has been applied) over the original extract of greater than
10% is observed. These effects may be compensated for using either: (1) the
method of standard additions; (2) sample dilution; or (3) internal standardization.
1.2.3,3 Chemical Interferences --
Chemical interferences, that is, interactions between molecular and/or ionic
species during the emission process, are insignificant for ICP because of the
completeness of sample destruction by the high energy of the plasma,
1.2.4 precision and Bias
In a laboratory evaluation of the method, homogenized real-world paint,, bulk
dust, and soil samples were analyzed along with the National Institute for Standards
and Technology (NtST) Standard Reference Materials (SRMs) using both the subject
method and a referee method, microwave acid extraction, and measurement using
ICP.7'11 The accuracy (as percent bias) and precision (relative standard addition
[RSD]) achieved are presented in Tables 1 and 2.
The combined extraction-analysis RSDs are summarized as follows:
Paint
RSD0>1 „ = 2% to 10% at Pb concentrations of O.02% to 1 1 .9%
RSD0.25o = 3% to 9% at Pb concentrations of O.O2% to 11.9%
RSD02BB = 3% to 14% at Pb concentrations of 0.01% to 0,45% H04 to 4,550
SM
RSD0.26g = 1 % to 4% at Pb concentrations of 0.06% to 0,26% (581 to 2,690
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Table 1. ICP Measurement of Ultrasonic Extracts of Paint Samples - Comparison
to Referee Method Values
Sample
ELPAT SP2
MEM Low
Paint
ELPAT 4P2
ELPAT 6P2
ELPAT 5P1
ELPAT 5P3
NIST SRM
1579
Aliquot Size
(fll
0.10
0.25
0.10
0.25
0.10
0.25
0.10
0.25
0.10
0,25
0.10
0.25
0.10
0.25
Mean Value, %
Pb{N)
0.0185 (31
0.0169(12)
0.154 ± 0.016
(51
0.157 ± 0.015
(5)
0.478 18)
0.50i (41
0.856 ± 0.039
(5)
0.779 ± 0.016
(5)
1.79 (5)
1.73 m
4.51 (3)
4.43 (5)
11.613)
11. 6 {6)
%
RSD
10.3
6.5
10.5
9.4
5.4
8.7
4.6
2.1
3.2
2.9
2.0
3.8
3.0
4.8
Ref. Value
%Pb
0.022 ± 0.003'
0.169 ± 0.063"
0.526 ± 0,039*
0.899 ± 0.082'
1.76 ± 0.17*
4.40 ± 0.58*
11.87 ± 0.02
Accuracy
as%
Bias
-16.7
-23.9
-8.8
-7.1
-9.2
-4.0
-5.0
-13.4
1.7
-1.7
2.5
0.7
-2.6
-2.6
Based on the hot plate and microwave acid digestion and atomic absorption and emission
spectrometric analysis performed by over 30 reference laboratories in the AIHA/ELPAT
laboratory accreditation program.12
Based on hotplate and microwave acid digestion and atomic absorption and emission
spectrometric analysis by over 25 laboratories in a round robin study.8
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Table 2. fCP Measurement of Ultrasonic Extracts of Bulk Oust and Soil Samples
Comparison to Referee Method Values
Sample
MEM Low Dust
ELPAT 3D3 Dust
MEM High Dust
Aliquot
Size (g)
0.25
0.25
0.25
Mean Value,
MO/8 Pb (N)
88.6 (6)
540 (9)
4,820 {61
%RSD
13.9
7.0
2.9
Ref. Value
ng/g Pb
104 ± &
551 ± 55"
4,550 ± 120*
Accuracy
as % Bias
-14.8
•2.0
6.0
ELPAT 5S3 Soil
ELPAT 6S3 Soil
ELPAT 4S2 Soil
NIST SRM 271 1
{Montana Soil)
0.25
0.25
0.25
0.25
560 (10)
735 (6)
2,390 (9)
991 (6)
4.0
3.3
3.3
1.4
581 ± 38"
790 ± 52b
2,690 ± 170"
1,162 ± 31
-3.6
-7.0
-11.2
-14.7
Based on hotplate and microwave digestion and atomic absorption and emission spectrometric
analysis by over 25 laboratories in a round robin study.8
Based on the hot plate and microwave acid digestion and atomic absorption and emission
spectrometric analysis performed by over 20 reference laboratories in the AIHA/ELPAT
laboratory accreditation program.13
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SECTION 2.0
APPARATUS AND REAGENTS
MOTE: Before use, all apparatus should be scrupulously cleaned. The
recommended procedure is:
1. Wash with warm laboratory detergent solution or ultrasonicate 10 minutes with
laboratory detergent.
2. Rinse and then soak a minimum of 1 hour in 50% fv/v) nitric acid.
3, Rinse three times with doubly deionized water and air dry.
2.1 SAMPLE COLLECTION
2.1.1 Paint
A paint sample collection procedure is described in Chapter 5 of the HUD
Guidelines.5
2.1.2 Bulk Dust
A standard method for collection of lead-contaminated bulk dust from carpets
has been developed by the American Society for Testing and Materials (ASTM).14
One research device to be considered for bulk dust collection from hard surfaces is
the HVS-3 vacuum sampler as modified by the Kennedy-Krieger Institute.15
2.1.3 Soil
A standard procedure for collection of soil samples was used in the EPA Urban
Soil Lead Abatement Demonstration Project.18
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2.2 SAMPLE EXTRACTION
The following apparatus and reagents are used in this procedure:
2.2.1 Polypropylene centrifuge tubes with screw caps; 50 mL (PGC Scientifics Corp,
No. 000-2090-STR (ELKAY), or equivalent).
2.2.2 Glass rods: 1/4 to 3/8 inch diame^., 6 to 8 inches long, tapered at one end
to conform to shape of bottom of centrifuge tube (Pyrex glass, or equivalent),
2.2.3 Sieves: 10 mm and 250 ^m (Nalgene #4233-0012 U.S. Standard HOPE sieves,
or equivalent), plus collection tray, rubber mallet to tap sieves, and nylon brush
and some form of moist wipe to clean sieves.
2.2.4 Glass Mortar and pestle (optional apparatus for sample grinding),
2.2.5 Analytical balance; reliable to ±0.001 g {Denver instrument Co., Mode) 400O,
XE Series, or equivalent).
2.2.6 Ultrasonic bath; 53 W or greater, 2-1/4-pt capacity {Fisher Model FSi,
equivalent or larger). Operation of ultrasonic bath must be confirmed prior to
use following one of the procedures given in Appendix A.
NOTE: The centrifuge tubes placed in the ultrasonic bath must be kept in an upright
position, with the bath water about 1 inch above the level of liquid in the centrifuge
tubes. This can be done by placing the tubes in a rack that will fit into the ultrasonic
bath. A rack to hold six centrifuge tubes in the Fisher FS5 ultrasonic bath can be
obtained by cutting a section from a larger plastic rack (Fisher Scientific Catalog No.
14-809-30, or equivalent). The bottom of the tubes should be kept from touching the
metal bottom of the bath to maximize transfer of ultrasonic energy. The cover of the
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bath or some other weight, such as a block of polyethylene or Teflon, must be placed
on top of the tubes to keep them immersed in the water in the bath.
2.2.7 Sample riffler (Carpco, Inc. Model SS-16-3 Microsplitter, or equivalent).
2.2,8 Deionized water: Unless otherwise indicated, references to deioni/ed water
shall be understood to mean reagent water as defined by Type 1 of ASTM
Specification D1193." {ASTM Type \ Water: Minimum resistance of 16.67 megohm-
cm, or equivalent).
2.2.9 Extraction solution (25% v/v HN03): To a 1-liter volumetric flask, add 50 mL
of deionized water. Cautiously add 250 ml of nitric acid (Baker Instranaiyzed, or
equivalent) and dilute to volume with deionized water.
CAimON: Nitric acid fumes are toxic. Prepare in a well-ventilated fume hood while
wearing safety glasses.
-.2.10 Nitric acid cleaning solution (50% v/v HN03): Prepare by diluting American
Chemical Society (ACS) reagent-grade HNO3 1:1 with deionized water.
2.2.11 Nitric acid rinsing solution (10% v/v HNQ3): Prepare by diluting ACS reagent-
grade HNO3 1:10 with deionized water.
2.2.12 Chemical fume hood (Kewaunee Scientific Equipment Corp., Adrian, Ml.
43221, Airflow Supreme Model or equivalent).
2.3 MEASUREMENT
2.3.1 Inductively Coupled Argon Plasma Emission Spectrometer
Computer-controlled plasma emission spectrometer with background correction
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and radio frequency plasma generator. The Lee man Labs Plasma Spec I ICP (or
equivalent) may be used.
2.3.1.1 Argon Gas Supply -
Ensure that adequate argon, water, and electrical power are available. Liquid
argon is the most desirable source of argon, especially for daily use, from a cost and
labor perspective. If gas is used, ensure adequate purity.
2,3,1.2 Cooling Water --
Recirculating or fresh water that meets flow rate and temperature
specifications'
2.3.2 Reagents - Measurement
Master Stock solution: 1,000 fig Pb/mL. Commercial standard; alternatively,
weigh out 1.5985 g ACS reagent-grade Pb(NO3)2 that has been dried for 2 hours at
11O° C and dissolve in 200 ml water in a 1-L volumetric flask. Add 25 mL
concentrated HN03 and dilute to volume with water. Store in a linear polyethylene
or Teflon bottle. Stable - 1 year.
Nitric acid diluent: 2.5% v/v nitric acid. Place about 100 mL deionized water
in a 1-L volumetric flask. Add 25 mL concentrated HN03 and dilute to volume with
deionized water. Mix well and store in a linear polyethylene or Teflon bottle.
2.4 Protective Equipment
Safety equipment to be used for protection from both lead and nitric acid
during sample extraction and measurement is as follows:
1. Safety glasses with side shields
2. Laboratory gloves, latex, powder-free, disposable (Fisher Scientific
Catalog No. 11-393-52 or Equivalent)
3, Laboratory coat
10
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SECTION 2.0
PROCEDURE
3.1 SAMPLE COLLECTION
Samples will be collected as described in Section 2.1.
3.2 SAMPLE PREPARATION
The precision and bias values presented in Section 1,2.4 are based on analyses
of paint samples mechanically ground to < 120 //m and dust and soil samples sieved
to <150 fjm. Because real-world samples of these materials tend to be relatively
non-homogeneous, the quality of the results will depend upon sample preparation.
More thorough preparation (e.g., more thorough grinding, sieving, mixing) will
improve the quality of the analytical results but will also increase the costs of the
analysis.
3.2.1 fiaint
Collected paint may be in the form of a chip or chips lifted or scraped off a
surface, chips swept off a floor, or small pieces of paint swept, for example, off a
window sill. A standardized collection method may be found in the 1995 HUD
guidelines.5 The paint must be ground to a small particle size (equivalent to coarsely
ground coffee or cornmeal) to maximize extraction efficiency.
3.2.1.1 Preliminary Treatment --
The first step taken is to remove by hand any foreign objects in the sample,
including pieces of wood, plaster, or other debris.
The second step is to weigh the paint sample. If the cleaned or initial sample
is less than or equal to about 0,25-g, the entire sample is analyzed; otherwise, only
a portion is analyzed.
11
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The third step is to grind the chip{s) in a 50-mL centrifuge tube, beaker, or
mortar to particles equivalent to coarsely ground coffee or cornmeal using a glass rod
or pestle. If the sample is less than about 2 g, the entire sample is to be ground, if
the sample is more than 2 g, use a mechanical riffler {Carpco, Inc. Model SS-16-3
Microsplitter, or equivalent) to split the sample. The sample is split until a final
portion of about 1 g is obtained. Alternatively, 1 g may be obtained from the crushed
bulk sample by grabbing four to six small portions from different locations in the bulk
material using a spatula. The grabbed samples are placed together in the grinding
vessel.
3.2.1.2 Grinding -
Weigh and record the weight of a 50 mL centrifuge tube. Place the total
original sample {if < 2 g) or sample portion in the tube. Proceed to grind the paint
in the tube using a Pyrex glass rod that has been tapered at one end to conform to
the bottom shape of the centrifuge tube. The rod should be moved in a rotary
manner similar to that used with a pestle in a mortar. Grind until a particle size
equivalent to coarsely ground coffee or cornmeal is achieved. This may require 3 to
i minutes of grinding. Upon withdrawing the glass rod from the tube, tap it gently
on the inside of the tube to knock off any particles of paint. Weigh the tube plus
contents and record the weight. Take the difference between the empty tube and the
tube plus paint to determine the weight of the paint. If the sample is less than or
about equal to 0.25 g, the entire sample is analyzed; if the sample is greater than
0.25 g, weigh out between 0,1 and 0.25 g of the ground paint into a second,
preweighed, labeled centrifuge tube for analysis.
An alternative to grinding in a centrifuge tube is to use a mortar and pestle.
This device will permit preparation of a finer powder. However, the mortar and pestle
must be thoroughly cleaned between each sample. This is best done using a brush
and a moist wipe to remove all particles. The wipes are placed in a plastic bag as
waste. The mortar and pestle are then rinsed in 10% nitric acid (v/v) and deionized
12
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water and thoroughly dried. The mortar and pestle should be constructed of a
material (such as glass) with low lead content.
: Latex paint or layers of latex paint on oil-based paint will not grind well, The
latex paint can be ground into small chips 1-2 mm in diameter, but these pieces
stretch like rubber rather than break into a powder, if the latex-containing sample
collected must be altquoted before extracting, then attempts must be made to grind
the latex as finely as possible through several extra minutes of grinding; also, efforts
must be made to take an aliquot that Is representative of the whole, i.e., includes a
representative portion o* the latex material. Alternatively, the latex-containing paint
can be cryogenically ground. Manual cryogenic grinding is performed by placing the
50-mL centrifuge tube with the paint sample into a small, wide-mouth dewar
containing crushed Dry Ice for several minutes to chill the paint, and then proceeding
to grind the paint with a glass rod while the tube remains in the Dry Ice.18 The tube
should be capped both before grinding and after grinding to minimize condensation
of water vapor into the sample. The paint sample can also be ground using a
commerciaily available cryo-mill (Spex Mode! 6700 Freezer/Mill, or equivalent}19 that
takes 1 to 2 g of sample and produces a fine powder with several minutes of grinding
at liquid nitrogen temperature. The paint is ground in a tube that is a component of
the device; the tube must be cleaned between samples.
3.2,2 Bulk Dust
Bulk dust may be swept from a surface or collected using a vacuum cleaner
{Section 2.1.2). The dust may be mixed with large amounts of other materials
including lint, hair, etc., and other large debris which must be separated from the dust
through sieving.
White wearing gloves and a dust mask, remove large foreign objects from the
dust with a tweezer. Then stack the 60-mesh (250-//m> sieve on the collection pan.
Transfer the dust to the sieve and proceed to gently tap the side of the sieve with a
rubber mallet for about 30 seconds. Stir the dust and repeat the tapping process.
13
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Repeat the stirring and tapping process three more times. Then transfer the dust
collected in the pan to a preweighed, labeled centrifuge tube and weigh the tube
again. The material remaining in the sieve may be saved in another container for
further study or emptied into a plastic bag for later disposal. The centrifuge tube is
capped and then rotated (pitch and yaw) for about 15 seconds and then rolled for 15
seconds. If the sample is less than or about equal to 0.25 g, the entire sample is
analyzed; if the sample Is greater than 0.25 g, weigh out 0.25 g of the sieved dust
into a second, preweighed, labeled centrifuge tube for analysis.
The sieve and collection pan must be thoroughly cleaned between samples.
First, brush the sieve with a soft nylon brush. This should be done in an area where
the cleaning process wili not contaminate other samples. Then wipe both the sieve
and pan with moist wipes. The wipes are placed in a plastic bag as waste. The pan
and sieve are allowed to air dry and then inspected visually for any residue. The
cleaning process is to be repeated if residue is observed.
3.2.3 Soil
Soil samples are typically scooped from the surface or collected with an auger
type of device. The first step is to manually remove large objects such as stones,
pebbles, and sticks from the soil.
The next concern is moisture. Samples that are too wet will not sieve properly.
Also, analysis of wet samples would add uncertainty to the analysis since percent
moisture is unknown. Therefore, some form of drying is recommended. The samples
are spread in pans such as aluminum pie tins and allowed to air dry for 8 hours or
overnight. The samples in the pan should be mixed occasionally to facilitate drying.
The pans should be placed in an area where the samples could not be accidentally
contaminated by other operations in progress or by airborne dust.
When the samples appear dry, they are sieved. Place the 60-mesh {250-//m>
sieve on the collection pan and the 10-mm sieve on the 250-^/rn sieve. Place the soil
in the 10-mm sieve and, using a gloved hand, gentfy rub the soil round and round to
break up clumps and facilitate sieving. Continue the process until no more material
14
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passes through the 10-mm sieve. Remove the 10-mm sieve and discard the material
in the 10-mrn sieve.
Next, proceed to manually rub the soil in the 250-i/m sieve until it appears that
no more material is breaking up into smaller pieces or passing through the sieve.
Separate the 250-j/m sieve from the coilection pan, discard the material left in
the 250-//m sieve and transfer the material in the collection pan to a preweighed,
labeled 50-mL centrifuge tube and weigh the tube again. Proceed to mix the soil as
described in Section 3.2.2 for bulk dusk. If the sample is less than or about equal to
0.25 g, the entire sample is analyzed; if the sample is greater than 0.25 g, weigh out
0.25 g of the sieved soil Into a second, preweighed, labeled centrifuge tube for
analysis. Clean the sieving apparatus as described in Section 3.2.2 for bulk dust.
3.3 ULTRASONIC SAMPLE EXTRACTION
WARNING: Safety glasses, a laboratory coat, and gloves are to be worn when
performing the extractions with nitric acid. It is recommended that they also be worn
during performance of the analysis procedure.
3.3.1 Bulk Samples - Paint
The extraction procedure for powdered paints is as follows:
3.3.1.1 Weigh out 0.1 to 0.25 g (nearest milligram) of sample into a graduated 50-
mL centrifuge tube (if not already done under Section 3.2,1.2).
3.3.1.2 With a pipet, add 5 mL of extracting acid (25% v/v HNO3, Section 2.2.9)
and then cap the centrifuge tube.
3.3.1.3 Using an ultrasonic bath that has been tested for acceptable operation (see
Appendix A}, place the centrifuge tubes in the ultrasonic bath (Section 2.2.6) so that
the bath water is about 1 inch above the level of liquid in the tubes, and sonicate the
samples for 30 minutes following the manufacturer's instructions.
15
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3.3.1.4 Following sonication, allow the samples to cool and add deionized water
(Section 2.2.8) to the 5O-mL mark.
3.3.1.5 Shake the tube briefly {5-10 seconds) and allow to settle for 15 minutes.
The clear solution (supernatant) above the solid residue is now ready for analysis.
3.3.2 Bulk Samples - Dust
Weigh out a maximum of 0.25 g (nearest milligram) of sample into a graduated
50-mL centrifuge tube (if not already done under Section 3.2.2). Proceed with the
extraction as in Section 3.3,1.2.
3.3.3 Bulk Samples - Soil
Weigh out a maximum of 0.25 g (nearest milligram) of sample into a graduated
50-mL centrifuge tube (if not already done under Section 3.2.3). Proceed with the
extraction as in Section 3.3.1.2.
CAUTION: Sample aliquots greater than 0.25 g for paints, dust, and soils may result
in lower extraction efficiency and therefore a negative bias.6
3.4 CALIBRATION.
3.4.1 Working Standard. 100 uq/ml
Prepare by diluting 10 mL of the 1,000 /zg/mL master stock solution to 100 mL
in 2.5% HNO3. The working standard should be prepared at least weekly; daily
preparation is preferred.
16
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3.4.2 Calibration Standards
Normally two to five standards are used for ICP calibration. Typical
concentrations are shown in the following table. Prepare daily by diluting the working
standard as indicated.
Volume of 1 00 fig
Pb/mL working
standard, ml
0
1.0
3.0
10,0
30.0
100.0
Final volume, mL
100
200
100
100
100
100
Concentration,
^g Pb/mL
0
0.5
3.0
10.0
30.0
100.0
Higher lead concentrations may be used as tang as the linearity of response is
verified.
3.4.3 Calibration Curve
The calibration curve (integrated photocurrent [or equivalent] vs. concentration)
will be calibrated automatically. When first calibrating ths system or after any
significant change to or work on the instrument, a manually plotted standard curve
should be prepared and then compared to the standard curve calculated by the
system. Any difference In the curves of more than 10 percent needs to be
investigated and corrective action taken.
3.3 QUALITY CONTROL
Quality control is necessary to ensure that resulting data are of adequate
quality. These are described in the following sections.
17
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3.5.1 Blank Check
Laboratory or reagent blanks are analyzed to determine the background or
contamination levels. Contamination levels above the detection limit must be
accounted for and eliminated, if possible, before proceeding with sample analysis.
3.5.2 Duplicates
It is recommended that one duplicate sample be analyzed for every 20 samples.
A duplicate (split) sample is one brought through the whole sample preparation and
measurement process. The duplicate analysis gives a measure of overall precision,
which is a combination of the precision of sample preparation (grinding, sieving,
mixing), sample extraction, dilution (if necessary), and analysis.
A suitable method for evaluating the acceptability of the results of a duplicate
analysis is through calculation of the maximum acceptable Relative Percent Difference
(RPD) between the individuals in a duplicate pair. The RPD is calculated as
X2}/2]
where X, and X2 are values of the individuals of a duplicate pair. The maximum
acceptable RPD will vary with the proximity of the analytical result to the MDL, the
precision of the method, and the acceptable probability of a false positive wherein a
"false positive" would be failing the QC check when, in fact, the true precision
(unknown) is at an acceptable level. On the basis of laboratory tests and limited field
use, the true relative standard deviation (o) of the method used in the field is
estimated to be 100% at 0 to 2 times the MDL, 15% at 2 to 10 times the MDL and
7% at >10 times the MDL.6 A reasonable probability for a false positive is 5%.
Under these limitations, maximum allowable RPDs, which are calculated as 2.770,20
are as follows:
18
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Average Analyte Concentration
(Multiples of Minimum
Detection Limit MDL)
0-2
2-10
>10
Maximum Acceptable Relative
Percent Difference, RPD
277%
42%
19%
The procedure is to choose a sample for duplicate analysis. It is preferable for
the lead level to be >2 x MDL. Perform the duplicate analysis and calculate the RPD.
If the calculated RPD value exceeds the maximum acceptable value given above,
corrective action is to be taken including review of ail original data and calculations,
and possible analysis of a second duplicate sample.
3,5.3 Reference Materials
Depending on the matrix, it is recommended that a secondary reference
material be analyzed once per sample batch or, at a minimum, once per day to check
the entire extraction/analysis procedure. Environmental Lead Proficiency Analytical
Testing (ELPAT) materials, which are available from the American Industrial Hygiene
Association, Fairfax, VA, may be used as secondary reference materials, or such
materials may be purchased from commercial suppliers of reference materials.
It is recommended that a primary reference material (SRM) be analyzed once
per week. Lead recovery should be within 80 to 120 percent of the known value.
Appropriate SRMs for paint, which are currently available from the National Institute
for Standards and Technology (MIST), Gaithersburg, MD, include NIST 2S80 {nominal
4% Pb), 2581 (nominal 0.5% Pb}, 2582 {nominal 200 mg Pb/kg) and 2589 (nominal
10% Pb). Suggested SRMs for dust are NIST 2583 (nominal 90 mg Pb/kg); and
2584 (nominal 1 % Pb} and suggested SRMs for soil are NIST 2709 (Agricultural Soil,
18.9 ± O.B //g Pb/g), 2711 (Montana Soil II, 1162 ± 31 IIQ Pb/g), 2710 (Montana
Soil I, 5532 ± 80 ng Pb/g), 2586 (500 mg Pb/kg) and 2587 (3000 mg Pb/kg). If the
19
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sample is out of contra!, sources of error must be identified and appropriate corrective
action taken.
3.5.4 Matrix Interferences
It has been observed that the high concentrations of dissolved materials in
paints, soils and dusts depress the values measured by ICP.7 Testing for physical
interferences may be performed by either {1} spiking the sample extract with lead
solution and determining the recovery of the spike or (2) performing serial dilution(s)
of the extract and determining if there is a significant increase (> 10%) in the lead
value from the analysts of the diluted sample(s) compared to the analysis of the
original extract. These checks as well as compensation techniques are described
below.
3.S.4.1 Method of Addition {Extract Spike) Check -
Aliquots of extracts representing each source of paint, dust ?nd soil samples
are spiked with Jead solution after initial analysis to approximately double the original
extract concentration, and then analyzed. The spike recovery must be within 80 to
120 percent of the expected value. The spike addition should produce a minimum
level of 10 times and a maximum of 100 times the instrumental detection limit. If the
spike is not recovered within the specified limits, a matrix interference/suppression
is likely. The use of a standard-addition analysts, such as the Method of Standard
Addition (MSA) procedure can usually compensate for this effect.
CAUTION: The standard-addition technique does not detect coincident spectral
overlap. If suspected, use of computerized compensation, an alternate wavelength,
or comparison with an alternate method is recommended.
3.5.4.2 Dilution Check --
Matrix suppressions in the nebulizer can also be tested for by analyzing a set
of serial dilutions of the original extract (e.g. 1:9, 1:24, 1:99). An increase in the
20
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lead value of more than 10% (properly corrected for the dilution} indicates a matrix
effect. Such a dilution test should be performed for each new matrix type. The final
dilution ratio used will be limited by the lead concentration, which should be at least
1 vg/mL and within the linear range of the calibration curve. If ail samples in the
analysis batch are sufficiently high in lead content, then sample dilution may be used
to compensate for this type of suppression. This technique should not be applied to
sample extracts with a lead content < 100 times the instrument detection limit.
3.5.4.3 Matrix Interference Compensation by Internal Standardization --
A fairly simple and effective means of compensating for matrix effects while
allowing for determinations near the detection limit is internal standardization.
Internal standardization (I.S.) allows the analyst to correct the signal without
compromising the detection limit. Most instrumentation manufactured in the past five
years provides the analyst with automated I.S. correction through the instrument
software. The analyst spikes all standards, field samples, and QC sample digests
with an element not likely to be present in detectable quantities in the sample
background (such as yttrium [Y])» ensuring that the I.S. concentration is identical for
alt standards and samples. The signal from both lead and the I.S. is then measured
by ICP. Any suppression of signal should be equivaiently proportionai for both
elements. The instrument software then recalculates the lead concentration based
on the ratio of the I.S. concentration in the sample to the I.S. concentration in the
standard. For example, using a 5 ^g Y/mL final known concentration in ail standards
and samples, it is found that the measured yttrium signal in the sample is 4.5 fig/mi.
or a 10% suppression. The instrument software then automatically corrects
(increases) the lead signal in the sample by a factor of 5/4.5 or 1.111 to compensate
for the matrix effect. This technique compensates for subtle differences in both
sample and acid matrix in the sample digest. If added to the digest prior to dilution
to volume, this approach will also correct for slight errors in sample dilution.
Consult the ICP operator's manual for more detailed instructions.
21
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3.5.5 Spectral Interferences
When lead is being measured by ICP, It is important to be aware of the
potential for spectral Interferoppea due to the existence of potentially high ievels of
interferences {e.g., Ti, Al, Cr). it is important to periodically analyze interfering
e)errjgpt fihach; samples that contain known high levels {200-1,000 M9/mt_) of each
suspected interfering element. Such solutions are available from a variety of vendors.
Once the solutions are analyzed, the data must be evaluated to determine the
existence of false lead values that are more than 2 times the solution detection limit.
If the false values do exceed this criterion, an interfering element correction factor
(FIEC) must be determined as follows:
False analyte signal
FIEC = '
Concentration of interferant
For example, 1,000 #g/mL of aluminum causes a false lead signal of
approximately 0.250 ttg/mL (7 x DL^) for many optical systems. Therefore,
FIEC = (0.25/1000) - 0.00025. This value is then used to correct lead data in the
presence of high aluminum. The interfering element identified in the above manner
is therefore added to the analytical program. This procedure must be applied to all
potential interfering elements. The presence and magnitude of interferences will vary
by instrument due to differences is optical designs. Follow the operator's manual to
establish automated interfering element correction through the instrument software,
3.5.6 Calibration Check Samples
High and low independently prepared check samples are to be run alternately
after every 10 samples to determine that calibration has not drifted. If a change of
more than 1O percent is measured, the system must be recalibrated and all samples
run since the fast calibration check must be reanalyzed.
-------
The results should be plotted on a control chart at the end of each sample
analysis session, although real-time checking is preferred.21 The analysis is concluded
to be out of control if any one or more of the following criteria is met.
1. One or more points outside of the control limits.
2. A run of at least eight points, where the type of run could be either a run
up or down, a nm above or below the center line, or a run above or below
the median.
3. Two of three consecutive points outside the 2-sigma warning limits but still
inside the control limits.
4. Four of five consecutive points beyond the 1-sigma limits.
5. An unusual or nonrandom pattern in the data.
3.6 SAMPLE DETERMINATION
3.6.1 ICP
1. Ensure that adequate argon, water, and electrical power are available.
Liquid argon is the most desirable source of argon, especially for daily use,
from a cost and labor perspective. If gas is used, ensure adequate purity.
2. Adjustment of Nebulizer Spray - See operator's manual for procedure.
3. Ignition of Torch - Check that argon supply is on.
4. After startup, be sure plasma does not flicker or present an orange corona
around torch. If the plasma flickers, be sure the spray chamber is draining
properly, if the orange corona is observed, make sure that the nebulizer
argon is on. Otherwise some residual salt may be present in the nebulizer
spray that must be flushed out or the entire spray chamber assembly must
be cleaned.
5. Warmup - Allow the instrument to warm up at least 30 minutes to permit
the standard readings to stabilize and allow analyses to begin.
6. Optical Calibration/Torch Alignment Procedures - Before analytical
calibration procedures are performed, (t is important to perform the optical
calibration procedures and the torch alignment operation. Each of these is
described in the operator's manual.
23
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7. Select a program that includes wavelength, integration time, number of
replicate readings, sample uptake time, and rinse time. Consult the
instrument operator's manual for other parameters, such as plasma forward
power, gas pressures and flow rates, etc.
8. Aspirate the calibration standards and establish a calibration curve.
9. Run a calibration check sample as described in Section 3.5.6.
10. Aspirate a sample solution and obtain the concentration readout.
11. Analyze a calibration blank at least every ten (101 samples. This result must
be less than three {3} times the instrument detection limit. If not, sample
carryover due to an insufficient rinse time setting is likely. Correct the
problem and reanalyze ail samples measured since the last successful
calibration blank analysis.
12. Analyze a check sample (Section 3.5.6) every ten (10) samples to evaluate
instrument drift. This result should be within 10 percent of the expected
value. If not, recalibrate the instrument and reanalyze all samples measured
since the last successful check sample analysis.
13. Analyze the Interfering Element Check Sample I s^. (See Section 3.5.5) to
ensure that the "false" lead signal is less than three times the instrument
detection limit.
14. Conclude the ICP measurement run with successful calibration blank and
check sample analyses.
3.7 WASTE DISPOSAL
All leftover extract solutions, reagent wastes, and rinse water are poured into
a carboy for waste containment. Any centrifuge tubes or other vessels containing
nitric acid as one of the reagents are to be rinsed with water before being placed in
a plastic bag for disposal or reuse after cleaning. The waste collected in the carboy
is disposed of according to applicable regulations.
24
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SECTION 4.0
DATA PROCESSING
4.1 DIRECT DETERMINATION
For direct determination, read the element value
-------
SECTION 5.0
REFERENCES
1. Agency for Toxic Substances and Disease Registry (ATSDRJ, The Nature and
Extent of Lead Poisoning in the United States: A Report to Congress. Agency
for Toxic Substances and Disease Registry, Atlanta, GA, 1988.
2, Centers for Disease Control (CDC). Preventing Lead Poisoning in Young
Children. A Statement by the Centers for Disease Control, U.S. Department
of Health and Human Services, Public Health Service, Atlanta, GA, 1985.
3. Goyer, R. A. Toxic Effects of Metals, in." Casarett and Douli's Toxicology,
Third Edition. Klassen, C, D., Amdur, M. 0., and Doull, J., eds. Macmillan,
New York, 1986.
4. Lead-Based Paint Poisoning Prevention Act, 42 U.S.C.(dH2HA)» 1971.
Amended 1991.
5. U.S. Department of Housing and Urban Development. Office of Lead-based
Paint Abatement and Poisoning Prevention. Guidelines for the Evaluation and
Control of Lead-Based Paint Hazards in Housing. U.S. Government Printing
Office, Washington, DC, June 1995.
6. Grohse, P. M., K. K. Luk, L. L. Hodson, B. M. Wilson, W. F, Gutknecht, S. L.
Harper, and M. E. Beard. Development of a Field Test Method for the
Determination of Lead in Paint and Paint Contaminated Dust and Soil. In:
Proceedings of the Symposium, "Lead Poisoning in Children: Exposure,
Abatement and Program Issues." American Chemical Society 204th National
Meeting, Washington, DC, August, 1992. Breen, J. J. and Stroup, C. R., Eds.,
Lewis Publishers, Ann Arbor, Ml, 1995.
7. Binstock, D. A., D. L. Hardison, P. M. Grohser and W. F. Gutknecht. Standard
Operating Procedures for Lead in Paint by Hotplate- or Microwave-based Acid
Digestions and Atomic Absorption or Inductively Coupied Plasma Emission
Spectrometry. EPA 600/R-91/213. U.S. Environmental Protection Agency,
Research Triangle Park, NC, 1991, 19 pp. 'Available from NTIS, Springfield,
VA; NTISPB92-114172.
8. Williams, 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.
Environmental Protection Agency, Research Triangle Park, NC, 1993.
•Available from NTIS, Springfield, VA; NTIS PB94-141165.
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9. Winge, R. K., V. A. Fassel, V. J. Peterson, and M. A. Floyd. Inductively
Coupled Plasma-Atomic Emission Spectroscopy. Elsevier, New York, p. 276,
1985.
10, Binstock, D, A., D. L. Hardison, J. White, P. M, Grohse, and VV. F. Gutknecht.
Evaluation of Atomic Spectroscopic Methods for Determination of Lead in
Paint, Soil, and Dust. Contract No. 68-02-4550. U.S. Environmental
Protection Agency, Research Triangle Park, NC, September 1991.
11. Luk, K.K., C.C. Van Hise, P.M. Grohse, and W.F. Gutknecht. Evaluation of the
Applicability of Ultrasonic Acid Digestion and Colorimetric Measurement to
Determination of Lead in Paint, Soil and Bulk, Vacuum and Wiped Dust. U.S.
Environmental Protection Agency, Contract 68-D1-0009, Report in Preparation,
12. Williams, E.E., C.C. Van Hise, and W.F. Gutknecht. Evaluation of the
Performance of Reflectance and Electrochemical Technologies for the
Measurement of Lead is Characterized Paints, Buik Ousts and Soils. EPA
600/R-91/093. U.S. Environmental Protection Agency, Research Triangle Park,
NC, 1996.
13. Environmental Lead Proficiency Analytical Testing Program (ELPAT), American
industrial Hygiene Association, Fairfax, VA. ELPAT Reports for Rounds 2-6,
1993-1994.
14. American Society for Testing and Materials. Standard Practice for Collection
of Dust from Carpeted Floors for Chemical Analysis. ASTM Designation D
5438-93. 20 pp.
15. Farfel, M., and B. S. Lim. The Lead Paint Abatement and Repair and
Maintenance Study in Baltimore. Lead in Paint, Soil, and Dust; Health Risk,
Exposure Studies, Control Measures, Measurement Methods, and Quality
Assurance, ASTM STP 1226, Michael E. Beard and S. D. Allen Iske, eds.,
American Society for Testing and Materials, Philadelphia, PA, 1994.
16. U.S. Environmental Protection Agency. Urban Soil Lead Abatement
Demonstration Project. Office of Hsaith and Environmental Assessment,
Environmental Criteria and Assessment Office. EPA Report No. EPA/600/AP-
93/001, Volumes 1-4. Research Triangle Park, NC, 1993.
17, American Society for Testing and Materials. Standard Specification for
Reagent Water, Designation D 193-77 (Reapproved 1983). 1991 Annual Book
of ASTM Standards, Vol. 11.03, 1991. 3 pp.
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18. DeWalt, G. Quality Assurance for Project Plan; Comparative Field Study of
Methodologies Used to Detect Lead in Paint. EPA Contract 68-DO-0137, Work
Assignment 111-57. Midwest Research institute, Kansas City, MO, July, 1993.
19. Spex Industries, 3880 Park Ave., Edison, NJ 08820.
20. Walpole, R.E, and R.H. Myers. Probability and Statistics for Engineers and
Scientists. 3rd edition, MacMillan Publishing Co., NY, 1985.
21. Montgomery, D. C. introduction to Statistical Quality Control. 2nd ed. John
Wiley & Sons, 1991,
28
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APPENDIX A
PROCEDURES FOR TESTING
OPERATION OF
ULTRASONIC BATH
29
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Procedure for Testing Operation of Ultrasonic Bath
The test is performed using apparatus available from;
Blackstone Ultrasonics
P.O. Box 220
Jamestown, NY 14702-0220
The apparatus is sold as a Performance Kit, Part No. 4050114. The general
procedure is to place a set of ceramic rings coated with pencil iead into the
ultrasonic bath. The bath is operated for a set period of time and the amount of
pencil lead removed is taken as an indication of acceptable or unacceptable
operation. The Performance Kit consists of the following items.
» Qty (5) Ceramic Rings
« Qty (5) Pencils
• Qty (1) Bottle of Water Wetter
The procedure to follow is:
1. Fill the ultrasonic tank with water to a depth of 12 inches and add two
ounces of Water Wetter.
2. Bring the water temperature to 100°F.
3. Using a pencil supplied with the kit, coat the smooth side of each of the
5 ceramic rings with pencil lead. At least 95% of each ring's surface
should be covered.
4. Place the rings, face up, in an "X" pattern in the cleaning basket. One
ring should be in the center of the basket and the others approximately
1 inch from each corner.
5. De-gas the liquid in the tank by operating the ultrasonics continuously
for 10 minutes.
6. Turn OFF the ultrasonics and allow the system to settle for 30 seconds.
7. Turn ON the ultrasonics and lower the basket into the tank. Start timing
as soon as the ceramic rings are immersed in the liquid.
8. Gently move the basket up and down approximately ¥2 inch for thirty
seconds.
30
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9. After 30 seconds, turn the ultrasonics OFF and remove the basket.
10. Compare each ring with the comparator chart provided in the kit. (The
chart shows ten rings ranging from essentially no removal of pencil lead
[score of 11 to essentially total removal of the pencil lead [score of 101).
From the chart, grade the rings accordingly.
11. Add the five scores together. A total of 30 is acceptable.
Alternative Procedure for Testing Operation of Ultrasonic Bath
This alternative procedure has been provided by Mr. Lee Seaman, formerly
of Pace Environs, Inc., and now of J and L Environmental Services, Elfers, FL.:
1. Obtain any standard "household" aluminum foil. Standard foil rather
than "freezer thickness" foil should be used. Cut a piece of the foil
large enough to cover % to 3/4 of the tank bottom. Since there are
differences in foil manufacturing, try to buy enough foil at one time to
keep as a working standard,
2. Fill tank with warm water (approximately 120° F} with a known amount
of wetting agent. Three drops of a dishwashing detergent will be
sufficient.
3. Run bath for 5 minutes to properly degas the solution.
4. Turn ultrasonics off and lower foil Into the tank at an angle to avoid air
getting trapped under the foil. Foil should end up almost parallel and
centered to bottom.
5. Turn ultrasonics on for 45 seconds. Turn off machine and remove foil.
6. Examine the piece of foil. Notice a peening effect and/or perforations
on the foil. The location and size of these peening and/or perforation
patterns indicate the cleaning intensity and uniformity of the ultrasonic
sound waves throughout the tank. If the foil appears unchanged
following this process, the unit most likely needs repair,
7. Date and save foils in a protective box. If foils show a sudden decline
In the magnitude of the peening effect and/or perforations, the unit may
need to be repaired.
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