ASTM F3078-15(2023)

Standard Test Method for Identification and Quantification of Lead in Paint and Similar Coating Materials using Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF)

SIGNIFICANCE AND USE
5.1 This test method provides for analysis of Pb in applied paint using measurement times on the order of several minutes. It can be used to determine whether the sample of applied paint has an areal mass of Pb either substantially less than a specification limit, and therefore does not exceed it, or substantially above the specified limit, and therefore exceeds it.  
5.2 If the value obtained with this test method falls close to a specification limit, a more precise test method may be required to positively determine whether Pb content does or does not exceed the specified limit.
SCOPE
1.1 This test method describes an energy dispersive X-ray fluorescence (EDXRF) procedure for determining the areal mass of Pb in mass per unit area in paint and similar coatings on common substrates of toys and consumer products, such as plastic, wood, steel, aluminum, zinc alloys or fabric.  
1.2 This test method is applicable for homogeneous, single layer paint or similar coatings. The method does not apply to metallic coatings.  
1.3 This test method is applicable for a range of Pb mass per unit area from 0.36 μg/cm2 to approximately 10 μg/cm2 for Pb in paint and similar coatings applied on common substrates. The lower limit of this test method is between 0.36 and 0.75 μg/cm2 depending on the nature of the substrate. Based on the results obtained during the interlaboratory study (ASTM Report F40-1004), it is estimated that the applicable range of this method can be extended up to 50 μg/cm2.  
1.4 The values stated in SI units are to be regarded as standard. Values given in parentheses are for information only.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2023
• ICS: 87.040 - Paints and varnishes
• Technical Committee: F40 - Declarable Substances in Materials
• Drafting Committee: F40.01 - Test Methods

Relations

• Replaces: ASTM F3078-15 - Standard Test Method for Identification and Quantification of Lead in Paint and Similar Coating Materials using Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF)
• Effective Date: 01-Oct-2023
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D16-24 - Standard Terminology for Paint, Related Coatings, Materials, and Applications
• Effective Date: 01-Jan-2024
• Refers: ASTM D6299-23a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Dec-2023
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D16-23 - Standard Terminology for Paint, Related Coatings, Materials, and Applications
• Effective Date: 01-Aug-2023
• Refers: ASTM D6299-23e1 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Jul-2023
• Refers: ASTM D883-22 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2022
• Refers: ASTM F2576-15a - Standard Terminology Relating to Declarable Substances in Materials (Withdrawn 2024)
• Effective Date: 01-Aug-2015

Overview

ASTM F3078-15(2023) is a widely-recognized international standard that specifies a test method for the identification and quantification of lead (Pb) in paint and similar coating materials. Using energy dispersive X-ray fluorescence spectrometry (EDXRF), this standard offers a rapid, non-destructive analytical approach, allowing industry professionals to determine the areal mass of lead in coatings applied to common substrates, such as plastics, wood, steel, aluminum, zinc alloys, and fabric. This procedure is valuable for verifying compliance with regulations surrounding hazardous substances in consumer products and toys, aligning with global requirements for safety and quality assurance.

Key Topics

• Scope of Application:

  • Designed for homogeneous, single-layer paint or coatings.
  • Applicable to a wide range of substrates commonly found in consumer products.
  • Suitable for quantifying lead concentrations in the range of 0.36 μg/cm² to approximately 10 μg/cm², with possible extension up to 50 μg/cm² based on testing conditions.

• EDXRF Technique:

  • Employs calibrated EDXRF spectrometers to directly measure areal mass of Pb.
  • Measurement times are typically a few minutes, offering efficiency for screening and risk assessment.
  • Allows for screening to determine if lead content is well above or below specification limits.

• Precision and Limitations:

  • If results fall close to specification limits, more precise testing methods may be necessary for definitive classification.
  • Not applicable for metallic coatings or multi-layer, non-homogeneous coatings.
  • The user is responsible for ensuring appropriate safety, health, and environmental considerations.

Applications

ASTM F3078-15(2023) is a critical standard across several sectors:

• Consumer Product Safety: Used extensively for screening lead in toys, furniture, and household goods to ensure compliance with safety regulations such as the Consumer Product Safety Improvement Act (CPSIA).
• Quality Assurance in Manufacturing: Manufacturers employ this method to monitor and control lead content during production, particularly in industries where painted or coated surfaces are prevalent.
• Regulatory Compliance and Enforcement: Regulatory agencies and third-party testing labs use EDXRF testing to confirm that paint and coating products meet legal limits for lead content.
• Import and Export Screening: Useful in customs and border inspection settings to verify shipments of coated consumer goods for lead safety prior to market entry.

By providing a fast and non-destructive method to analyze lead, the standard supports safer products and contributes to public health and safety.

Related Standards

To ensure comprehensive quality and safety testing, several related ASTM and international standards may be relevant when using ASTM F3078-15(2023):

• ASTM D16: Terminology for Paint, Related Coatings, Materials, and Applications.
• ASTM D1005: Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers.
• ASTM D6132: Nondestructive Measurement of Dry Film Thickness of Applied Organic Coatings Using an Ultrasonic Coating Thickness Gage.
• ASTM D7091: Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals.
• NIST Special Publication 829: Use of NIST Standard Reference Materials for Decisions on the Performance of Analytical Chemical Methods and Laboratories.
• Consumer Product Safety Improvement Act (CPSIA), Public Law 110-314: Regulatory context for lead content in child-related products.

ASTM F3078-15(2023) reliably supports lead content analysis in paint and coatings, enhancing product stewardship and regulatory compliance in global markets.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3078 − 15 (Reapproved 2023)
Standard Test Method for
Identification and Quantification of Lead in Paint and Similar
Coating Materials using Energy Dispersive X-ray
Fluorescence Spectrometry (EDXRF)
This standard is issued under the fixed designation F3078; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method describes an energy dispersive X-ray
fluorescence (EDXRF) procedure for determining the areal D16 Terminology for Paint, Related Coatings, Materials, and
Applications
mass of Pb in mass per unit area in paint and similar coatings
on common substrates of toys and consumer products, such as D883 Terminology Relating to Plastics
D1005 Test Method for Measurement of Dry-Film Thick-
plastic, wood, steel, aluminum, zinc alloys or fabric.
ness of Organic Coatings Using Micrometers
1.2 This test method is applicable for homogeneous, single
D6132 Test Method for Nondestructive Measurement of Dry
layer paint or similar coatings. The method does not apply to
Film Thickness of Applied Organic Coatings Using an
metallic coatings.
Ultrasonic Coating Thickness Gage
1.3 This test method is applicable for a range of Pb mass per
D6299 Practice for Applying Statistical Quality Assurance
2 2
unit area from 0.36 μg/cm to approximately 10 μg/cm for Pb
and Control Charting Techniques to Evaluate Analytical
in paint and similar coatings applied on common substrates.
Measurement System Performance
The lower limit of this test method is between 0.36 and 0.75
D7091 Practice for Nondestructive Measurement of Dry
μg/cm depending on the nature of the substrate. Based on the
Film Thickness of Nonmagnetic Coatings Applied to
results obtained during the interlaboratory study (ASTM Re-
Ferrous Metals and Nonmagnetic, Nonconductive Coat-
port F40-1004), it is estimated that the applicable range of this
ings Applied to Non-Ferrous Metals
method can be extended up to 50 μg/cm .
E135 Terminology Relating to Analytical Chemistry for
Metals, Ores, and Related Materials
1.4 The values stated in SI units are to be regarded as
E177 Practice for Use of the Terms Precision and Bias in
standard. Values given in parentheses are for information only.
ASTM Test Methods
1.5 This standard does not purport to address all of the
E691 Practice for Conducting an Interlaboratory Study to
safety concerns, if any, associated with its use. It is the
Determine the Precision of a Test Method
responsibility of the user of this standard to establish appro-
C693 Test Method for Density of Glass by Buoyancy
priate safety, health, and environmental practices and deter-
F2576 Terminology Relating to Declarable Substances in
mine the applicability of regulatory limitations prior to use.
Materials
1.6 This international standard was developed in accor-
2.2 Other Standards:
dance with internationally recognized principles on standard-
Consumer Products Safety Improvement Act of 2008 (CP-
ization established in the Decision on Principles for the
SIA), Public Law 110-314, August 14, 2008
Development of International Standards, Guides and Recom-
SSPC-PA2 Paint Application Standard No. 2, Measurement
mendations issued by the World Trade Organization Technical
of Dry Coating Thickness with Magnetic Gauges
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
This test method is under the jurisdiction of ASTM Committee F40 on Standards volume information, refer to the standard’s Document Summary page on
Declarable Substances in Materials and is the direct responsibility of Subcommittee the ASTM website.
F40.01 on Test Methods. Full text is available on the Consumer Products Safety Commission website:
Current edition approved Oct. 1, 2023. Published November 2023. Originally http://www.cpsc.gov//PageFiles/113865/cpsia.pdf.
approved in 2015. Last previous edition approved in 2015 as F3078 – 15. DOI: Available from Society for Protective Coatings (SSPC), 40 24th St., 6th Floor,
10.1520/F3078-15R23. Pittsburgh, PA 15222, http://www.sspc.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3078 − 15 (2023)
NIST Special Publication 829 Use of NIST Standard Refer- 3.1.8 Rayleigh scatter, n—the elastic scattering of an X-ray
ence Materials for Decisions on Performance of Analyti- photon through its interaction with the bound electrons of an
cal Chemical Methods and Laboratories atom; this process is also referred to as coherent scatter.
3.1.8.1 Discussion—The measured count rate of Compton
and Rayleigh scattered radiation varies depending upon speci-
3. Terminology men composition. The measured count rate of the Compton
and Rayleigh scattered radiation or the ratio of Compton/
3.1 Definitions:
Rayleigh scatter may be used to compensate for matrix effects
3.1.1 Definitions of terms applying to X-ray fluorescence
specific to XRF analysis.
(XRF) spectrometry, plastics and declarable substances appear
3.1.9 screening, n—screening is an analytical test procedure
in Terminology E135, Terminology D883 and Terminology
to determine the presence or absence of a substance (such as
F2576, respectively. Definitions of terms applying to Paint
Pb) or compound in the representative part or section of a
appear in Terminology D16.
product, relative to the value or values accepted as the criterion
3.1.2 areal mass (or mass per unit area), n—mass of
for such decision.
substance (element) contained in a unit area of surface over
3.1.9.1 Discussion—The value or values accepted as the
which substance (element) is uniformly spread.
criterion for decision shall be within the applicable range and
3.1.2.1 Discussion—This way of expressing the mass of a
above the limit of detection of the method. If the screening test
substance is typical and useful when material is present in a
produces values that are not conclusive, then additional analy-
form of thin layer rather than bulk volume. The term is used not
sis or other follow-up actions may be necessary to make a final
only in XRF analysis but also in a variety of coating industry
presence/absence decision.
applications. Areal mass is related to mass fraction through the
thickness and density of the layer (see X1 for an example).
3.1.10 thin sample, n—applied paints and similar coatings
represent a type of sample which is markedly different from a
3.1.3 Compton scatter, n—the inelastic scattering of an
bulk sample of infinite thickness. The absorption and enhance-
X-ray photon through its interaction with the bound electrons
ment phenomena typical of XRF analysis of bulk materials are
of an atom; this process is also referred to as incoherent scatter.
minimized by the fact that layer of paint is “thin”. A layer of
3.1.4 empirical method, n—a method for calibration of
paint is considered “thin” for XRF purposes if it fulfills the
X-ray fluorescence response of an analyzer using well
following criterion :
characterized, representative samples (calibrants).
m·μ # 0.1 (1)
3.1.5 fundamental parameters (FP) method, n—a method
for calibration of X-ray fluorescence response of an analyzer,
where:
which includes the correction of matrix effects based on the
μ = a mass absorption coefficient of the sample for exciting
theory describing the physical processes of the interactions of
radiation and characteristic X radiation of excited ele-
X rays with matter. 2
ment in cm /g, and
3.1.6 homogeneous coating, n—the coatings such as paints m = mass per unit area of the sample (areal mass) in g/cm .
or similar types are considered homogeneous for purposes of
3.2 Acronyms:
XRF analysis when their elemental composition is independent
3.2.1 EDXRF—energy dispersive X-ray fluorescence
with respect to the measured location on the specimen and
3.2.2 FP—fundamental parameters
among separate specimens obtained from the same material.
3.1.7 infinite thickness, n—the thickness of a specimen
4. Summary of Test Method
above which no measurable count rate increase is observed for
4.1 An EDXRF analyzer that has been calibrated using
any analyte is referred to as ‘infinite thickness’.
either a fundamental parameters approach or an empirical
3.1.7.1 Discussion—Bulk materials with a matrix of low
approach is used to directly measure the areal mass of Pb in
atomic number elements, such as polymers or wood, exhibit
paint applied on any of the common substrates described in 1.1
relatively low X-ray absorption. This leads to a requirement
by placing the painted surface of the object to be tested over the
that for the best quantitative analysis the specimens must be
measuring aperture (window) of the analyzer and initiating the
thick, generally in excess of several millimeters, depending on
measurement. Alternatively, when using a handheld XRF
the X-ray energies to be measured and the actual composition
analyzer, its measuring aperture (window) should be placed
of the matrix. In general, more accurate and precise results can
flush against the painted area of the object. The analyzer can be
be obtained when the reference materials and the unknown
calibrated either by the manufacturer or by the user.
samples are of infinite thickness or if thicknesses of the
4.2 The test sample for this method should be a single,
reference materials and unknown samples are at least within
10 % relative of each other. Typical substrates on which paint homogenous layer of dry, solid paint or similar coating applied
over substrate material.
is applied may often be considered to be of infinite thickness
for the purpose of XRF analysis.
Rhodes J.R., Stout J.A., Schindler S.S. and Piorek S., “Portable X-ray Survey
Meters for In-Situ Trace Element Monitoring of Air Particulates,” in Toxic Materials
Available from National Institute of Standards and Technology (NIST), 100 in The Atmosphere: Sampling and Analysis, ASTM STP 786, ASTM International,
Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov. 1981, pp. 70–82.
F3078 − 15 (2023)
4.3 The test sample should cover the measuring aperture of 6.3 Substrate Interferences—Elements in the substrate may
an analyzer. interfere with determination of Pb in a layer of paint. For
example, if both substrate and paint contain Pb, the composite
NOTE 1—Increased quantitative error may result if the coated sample
Pb signal will include contributions from both sources and
area does not cover the measuring aperture of the analyzer. Correction
effectively may result in a significant positive bias of Pb mass
schemes may be available to adjust the measurements of such samples.
These schemes have not been evaluated for this method. Refer to the per unit area. For example, a plastic substrate containing 100
analyzers manufacturer’s instructions for guidance.
mg/kg of Pb may produce apparent areal Pb concentration of
30 μg/cm , even if paint on such substrate does not contain Pb.
4.4 The test sample is irradiated by an X-ray source, and the
resulting characteristic X rays of Pb and other elements present
7. Apparatus
in the sample are measured. A value of the Pb mass per unit
area of the paint sample is calculated and compared to the
7.1 EDXRF Spectrometer, designed for X-ray fluorescence
specification limit against which the sample is being evaluated.
analysis of materials with energy dispersive selection of
radiation. Any EDXRF spectrometer can be used if its design
5. Significance and Use
incorporates the following features.
7.1.1 A means of repeatable sample presentation for
5.1 This test method provides for analysis of Pb in applied
analysis—For hand-held spectrometers this is usually a small,
paint using measurement times on the order of several minutes.
flat plane with round, oval or rectangular aperture that comes
It can be used to determine whether the sample of applied paint
into direct contact with the sample and through which X rays
has an areal mass of Pb either substantially less than a
can reach the sample under test. Laboratory embodiments of
specification limit, and therefore does not exceed it, or sub-
analyzer design may have specimen holders and a specimen
stantially above the specified limit, and therefore exceeds it.
chamber.
5.2 If the value obtained with this test method falls close to
7.1.2 Source of X-ray Excitation, typically an X-ray tube,
a specification limit, a more precise test method may be
capable of exciting the Pb L -M (Lβ ) line (secondary line: Pb
2 4 1
required to positively determine whether Pb content does or
L -M (Lα )).
3 4,5 1,2
does not exceed the specified limit.
7.1.3 X-ray Detector, with energy resolution sufficient to
resolve the recommended Pb L -M (Lβ ) line from X-ray
2 4 1
6. Interferences
lines of other elements present in sample. An energy resolution
6.1 Spectral Interferences—Spectral interferences in XRF of better than 250 eV at the energy of Mn K-L (Kα) has been
2,3
found suitable for the purpose of Pb analysis.
analysis manifest themselves as overlaps of spectral peaks
representing lines of different X-ray energies. These overlaps
7.1.4 Signal conditioning and data handling electronics,
are the result of limited energy resolution of detectors. For
that include the functions of X-ray counting and peak/spectrum
example, the As Kα peak overlaps completely the Pb Lα peak.
processing.
Interactions of photons with the detector and limitations of
7.1.5 Data Processing Software, for calculating elemental
associated electronics give rise to additional peaks in a
composition of sample from measured X-ray intensities using
spectrum known as escape peaks and sum peaks. For example,
one of calibration methods.
high content of iron in a paint or substrate may produce a sum
7.2 The following spectrometer features and accessories are
peak that will overlap with the Pb Lβ line. Fundamental
optional.
Parameters equations require that the measured net count rates
7.2.1 Beam Filters—Used to make the excitation more
be free from line overlap effects. Some empirical approaches
selective and to reduce background count rates.
incorporate line overlap corrections in their equations. The
7.2.2 Secondary Targets—Used to produce semi-
software used for spectrum treatment must compensate for line
monochromatic radiation enhancing sensitivity for selected
overlaps. Manufacturers’ software typically provides tools to
X-ray lines and to reduce spectral background for improved
compensate for peak overlaps, escape peaks and sum peaks in
detection limits. The use of monochromatic radiation also
spectra.
allows the simplification of FP calculations.
6.2 Matrix Interferences—Interelement effects, also called
7.2.3 Specimen Spinner—Used to reduce the effect of sur-
matrix effects, exist among all elements as the result of
face irregularities of the specimen.
absorption of fluorescent X rays (secondary X rays) by atoms
7.2.4 Built-in Camera—Used to capture and record an
in the specimen. Absorption reduces the apparent sensitivity
image of the tested area/object.
for the element. In contrast, the atom that absorbs the X rays
may in turn emit a fluorescent X ray, increasing the apparent 7.3 Drift Correction Monitors—Due to potential instability
sensitivity for the element it represents. Mathematical methods of the measurement system, the sensitivity and background of
may be used to compensate for matrix effects. A number of the spectrometer may drift with time. Drift correction monitors
mathematical correction procedures are commonly utilized may be used to correct for this drift. The optimum drift
including full FP treatments and mathematical models based on correction monitor specimens are permanent materials that
influence coefficient algorithms. remain stable with time and repeated exposure to X rays. Drift
F3078 − 15 (2023)
TABLE 1 Recommended Lead Contents in Paint Calibrants
correction monitors may be permanently installed inside the
spectrometer and exposed only for diagnostic measurement Pb (μg/cm )
Paint Film
(see the note below)
when necessary.
Film 1 < 0.4
Film 2 0.4 to 1.0
8. Reagents and Materials
Film 3 1.4 to 2.6
Film 4 5.0 to 10.0
8.1 Purity of Reagents —Reagent grade chemicals shall be
Film 5 >10.0
used in all tests. Unless otherwise indicated, it is intended that
all reagents conform to the specifications of the Committee on
Analytical Reagents of the American Chemical Society (ACS)
where such specifications are available. Other grades may be
fractions of Pb in remaining paint films should be in the range
used provided it is first ascertained that the reagent is of
of 50 mg/kg to 1200 mg/kg.
sufficiently high purity to permit its use without lessening the
NOTE 2—A preferable form of standard paint film is paint film
accuracy of the determination. Reagents used include all
deposited on polyester foil so that it may be placed for measurement over
materials used for the preparation of reference materials and
any substrate. Polyester foil is made of polyethylene terephthalate (PET)
for cleaning of specimens and parts of the analyzer which come
resin. Such foil has been found to be mechanically strong and durable and
in direct contact with tested samples.
yet thin enough to not interfere with XRF analysis. A 50 μm thick
polyester foil absorbs less than 1 % of Pb Lβ X rays and less than 2 % of
8.2 Reference Materials:
Pb Lα X rays. Other film materials of equivalent or better than PET’s
8.2.1 The user of this test method shall obtain applicable
properties may be used as substrates for standard paint films.
reference materials available from sources such as the National
8.3 Quality Control Samples:
Institute of Standards and Technology or from reputable
8.3.1 To ensure the quality of results, analyze quality
commercial vendors.
control (QC) samples at the beginning and at the end of each
8.2.2 Reference materials can be prepared by adding known
batch of specimens or after a fixed number of specimens, but at
amounts of pure compounds or additives (or both), to an
least once each day of operation. Each QC sample shall be a
appropriate base paint material, mixing, and depositing the
homogeneous layer of paint deposited on polyester film with a
homogenized mixture uniformly on a flat substrate.
minimum thickness of 50 μm (2 mil). The areal mass of Pb,
8.2.2.1 Thorough mixing of ingredients is required for
mass fraction of Pb in paint, thickness of paint layer as well as
optimum homogeneity.
its density must be known and consistent with the requirements
8.2.2.2 Element concentrations can be calculated from the
in 8.2.2.5 for each QC sample. The QC samples must be stable
concentrations and molecular formulae of the compounds and
under the anticipated storage and use conditions. The QC
additives used.
samples must be handled with care. The surface of a QC
8.2.2.3 The elemental compositions of user-prepared refer-
sample must not be scratched or contaminated by foreign
ence materials must be confirmed by one or more independent
substances. They should be stored at room temperature, away
analytical methods.
from direct exposure to UV radiation.
8.2.2.4 The preferred form of a reference material is a
standard paint film, that is paint film deposited as a layer of
9. Hazards
uniform thickness onto a polyester foil so that the whole
9.1 Occupational Health and Safety standards for X rays
assembly may be placed for test over any substrate.
and ionizing radiation shall be observed. It is recommended
8.2.2.5 The Pb levels in the standard paint films (CRMs)
that proper practices be followed as presented by most manu-
shall be based on the appropriate specifications against which
facturers’ documentation. Guidelines for safe operating proce-
the samples of lead containing paint are anticipated to be
dures are also given in current handbooks and publications
measured. Such paint films may be used for instrument
from original equipment manufacturers, and the National
calibrations or method validation. Preferably, for the purpose
Institute of Standards and Technology (NIST). For more
of this test method, the paint films shall be as shown in Table
information, see ANSI-NIST Handbook 114 or similar hand-
1.
books on radiation safety.
8.2.2.6 In addition, the layer thickness, density of paint
9.2 Warning—Appropriate precautions are recommended
layer and mass fraction of Pb in the paint layer shall be known
for each paint film. The thickness of paint films should be in the when working with the element and compounds of Pb.
range 25 μm to 75 μm (1 mil to 3 mil), and density should be
3 3
10. Sample Preparation
in the range 1.1 g/cm to 1.8 g/cm . Specifically, at least one
paint film standard shall have thickness between 35 and 45 μm
10.1 The user of this test method must define the sample
and Pb mass fraction between 80 mg/kg and 110 mg/kg. Mass
using documented work instructions. These instructions should
at minimum address the following items:
10.1.1 Ensure that the tested sample is within the measure-
ment aperture of the analyzer. In addition, the measurement
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
aperture must not include adjacent materials which may be of
listed by the American Chemical Society, see Analar Standards for Laboratory
different compositions than the measured sample.
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
10.1.2 The sample within the measurement aperture must be
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. uniform.
F3078 − 15 (2023)
extension of measurement time. Therefore, the reduction of error obtained
10.1.3 The sample must be clean and free of foreign
at 200 s measurement time by a factor of two would require a measure-
elements such as stickers or markings.
ment time of 800 s, which would significantly reduce the number of
10.1.4 If feasible, the sample should be tested in multiple
samples that could be measured.
locations of similar composition.
12. Calibration
11. Preparation of Apparatus
12.1 Empirical Calibration—Obtain a set of calibration
11.1 Turn on the analyzer and allow it to warm up and
standards that cover the range of areal mass of Pb prepared in
stabilize in accordance with the manufacturer’s recommenda-
the matrix typical of natural paints. Standard paint films
tion.
recommended in 8.2 may be used for instrument calibration. It
is important to have available several standards when using an
11.2 Follow the manufacturer’s recommendation to set the
optimum current and voltage for analysis of Pb-bearing paint empirical calibration. For Pb areal mass up to 100 μg/cm the
relation between count rate of Pb X-rays and Pb mass per unit
or select the appropriate manufacturer supplied or laboratory
prepared calibration. area is linear; therefore, a small number of standards (at least
three) may be sufficient to determine the slope and the intercept
11.3 Determine a minimum measurement time resulting in a
of the calibration curve.
maximum counting statistical error (CSE) at one sigma of 10 %
12.1.1 Place each standard specimen on the appropriate
relative for a specimen containing Pb at a level close to the
substrate and then into the X-ray beam of analyzer and measure
specification limit. This shall be performed for each anticipated
the count rate of Pb using the measurement conditions chosen
substrate type.
in Section 11. Measure each standard at least twice.
11.3.1 The required measurement time can be calculated by
12.1.2 Follow the manufacturer’s instructions to obtain net
using Eq 2:
count rates of Pb X rays and to perform a regression of net
2 2
100 1 100 BGD
count rate of Pb X rays versus Pb mass per unit area.
t $ · 1 · (2)
S D S D 2
CSE% R CSE% R
12.1.3 As an option, the net count rates may first be divided
by the Compton scatter count rate for the specimen.
where:
12.1.4 If the spectrum processing options of the instrument
R = net count rate of Pb X rays in counts per second
do not include corrections for peak overlaps, corrections must
(cps) measured for time, t,
be included in the regression model.
t = counting time in seconds, s,
12.1.5 Repeat the calibration procedure for each typical
BGD = count rate of background under the Pb peak in cps,
substrate expected to be analyzed.
measured for time, t, and
CSE = relative error of counting statistics, (%).
NOTE 4—With some instruments it may be possible to generate a single
(global) calibration curve which will be valid for more than one type of
11.3.1.1 When background count rate, BGD, is much less
substrate.
than the net count rate, R, the second term in Eq 2 may be
12.2 FP Calibration and Manufacturer Pre-calibrated
omitted, then the product of R and t equals the total number of
Instruments—Matrix correction procedures by FP are based on
net counts accumulated under the Pb peak in EDXRF mea-
mathematical descriptions of physical interactions between
surements. This time corresponds to a measuring time resulting
X-ray photons and matter. Calibration with FP can be accom-
in collection of > 100 counts after accounting for background.
plished using very few standards, and depending on the
11.3.2 In cases of instruments pre-calibrated by the
mathematical formalism chosen, with multielement or pure,
manufacturer, measure specimens containing Pb at levels close
single element ones. This is because the corrections for
to the specification limit for as long as it takes the measurement
interelement effects (such as absorption and enhancement) are
error reported by the instrument at one sigma level to be <
done entirely from theory. For instruments that are pre-
10 % relative to the value measured. The measurement time
calibrated at the factory either using an FP approach, or using
thus determined shall be used for subsequent tests.
procedures specific to the analytical software employed in a
11.4 Verify the limit of detection. The limit of detection (L )
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given instrument, follow exactly the calibration procedure
shall be estimated for each combination of sample
supplied by the manufacturer.
presentation, substrate and measurement conditions by the use
12.2.1 If applicable, follow the manufacturer’s instructions
of Eq 3:
to perform a regression of net count rate of Pb versus Pb mass
L 5 3·s (3)
per unit area.
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12.2.2 If the spectrum processing options do not include
where:
corrections for peak overlaps, corrections must be included in
s = the standard deviation of a set of at least seven measure-
the regression model. FP approaches are predicated on the
ments of a Pb-free paint film presented on a substrate.
assumption that the count rate data has already been processed
11.4.1 For optimum results the L should be less than 30 %
to remove background and spectral interferences.
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of the specification limit or of the laboratory’s action limit,
12.2.3 As an option, the inclusion of the count rate of
whichever is less.
Compton scattered radiation (or the ratio of Compton and
Rayleigh scattered radiation) in the FP algorithm may be used
NOTE 3—Longer measurement time may be necessary for some
to compensate for matrix effects caused by sample elements
instruments to achieve performance stipulated in 11.3 and 11.4. Relative
error of measurement in EDXRF decreases twofold for each fourfold that cannot be measured directly.
F3078 − 15 (2023)
12.2.4 Unless specifically instructed otherwise, repeat the 13.2 Measure the unknown test sample prepared according
calibration procedure for each type of substrate expected to be to the work instructions in Section 10 using the analyzer as
analyzed. calibrated, prepared and verified in Sections 11 and 12.
12.3 Verification of Calibration: 13.3 Measure the sample for at least the time calculated in
12.3.1 Verify the calibration by analyzing one or more 11.3.
reference materials. Measure the reference materials immedi-
13.4 If applicable, measure also an uncoated area of sample
ately after completing calibration of the instrument.
to verify that the substrate does not contain Pb.
12.3.2 When using a pre-calibrated system for which user
calibration is not available, verify the calibration by running
14. Calculation
the reference materials before measuring unknown samples for
14.1 Allow the analyzer to calculate the areal mass of Pb in
the first time.
μg/cm .
12.3.3 Measure areal mass of Pb in one or more reference
materials. The areal masses of Pb from these measurements 14.2 Record the result.
must be in agreement with the known (certified) values for Pb
14.3 Some combinations of extremely thin layer of paint
in the measured reference materials samples to within agreed
and substrate may result in measurements which produce
precision and bias of this test method, inclusive of uncertainty
results less than the limit of detection, L , of the instrument. In
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reported for known (certified) values for Pb in these samples.
such instances, always report the actual limit of detection
All measurements must be performed on samples placed over
reported or applicable for the specific test, not the symbol ND.
appropriate substrates. If a bias is detected, an investigation
14.4 Approaches to interpretation of results or decisions
must be carried out to find the root cause.
based on them are discussed in Annex A1.
12.4 Drift Monitors and Quality Control Samples:
12.4.1 When using drift correction, measure the count rates
15. Report
of the drift correction monitors in the same manner as the
15.1 Report the following information:
calibrants with the exception of counting times. The monitors’
15.1.1 A unique sample identification.
compositions and the count time for measurement of a monitor
15.1.2 The date and time of the test.
shall be optimised to achieve a minimum of 2,500 counts for
15.1.3 Numerical results of the test, inclusive of less than
each element for CSE = 2 %.
L results, to the second decimal place (that is to the nearest
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12.4.2 In many contemporary instruments, drift correction
0.01 μg/cm ).
is accomplished with monitors which are integral parts of the
15.1.4 Reference to this standard test method (F40, F3078).
analyzer (external or internal). In such a case, follow
15.1.5 Identification of the substrate on which the paint film
manufacturer-provided procedures, and monitor for drift cor-
was measured.
rection.
15.1.6 Information on sample p
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