IEC Procedures for the Determination of Levels of
Procedures for the Determination of Levels of Regulated Substances in Electrotechnical
Products
IEC ACEA ad hoc Working Group
Mission of the ad hoc Working Group:
Develop a normative document that will define test procedures that will allow the electrotechnical industry to determine the concentration of the regulated substances Pb, Hg, Cd, Cr VI, PBB, PBDE (EU RoHS, China, US, Japan, etc.) in electrotechnical products on a consistent global basis
Goal of the ad hoc Working Group:
Develop a normative document for electrotechnical industry to be used by labs globally for OEMs, suppliers, NGOs, governments, etc. The normative document will be submitted as proposal for an IEC
standard.
Outline
1 Introduction (6)
2 Scope (6)
3 References (7)
4 Terms and Definitions (7)
Overview (8)
5 Test
Procedure
5.1 Test Procedure Scope (8)
5.2 Test Procedure Flow (8)
5.3 Adjustment to Material (Matrix) (10)
5.4 Qualitative and Quantitative Screening Test Procedure (10)
Procedure (10)
Test
5.5 Verification
6 Procedure for Mechanical Sample Preparation (11)
6.1 Scope, Application and Summary of Method (11)
6.2 References, Normative References, Reference Methods and Reference Materials (11)
6.3 Terms and Definitions (11)
6.4 Apparatus / Equipment and Materials (11)
6.5 Procedure (12)
6.5.1 Sample (12)
6.5.2 Cutting (12)
grinding (12)
6.5.3 Coarse
6.5.4 Homogenizing (12)
grinding (12)
6.5.5 Fine
7 Qualitative Screening by XRF Spectrometry (13)
7.1 Scope (13)
references (13)
7.2 Normative
7.3 Terms and definitions (14)
7.4 Apparatus/Equipment and Materials (15)
7.4.1 Reference
samples (16)
Procedure (17)
7.5 Test
7.5.1 Preparation of the Spectrometer (17)
7.5.2 Calibration (17)
7.5.3 Verification of Spectrometer performance (17)
7.5.4 Presentation of Sample for Measurement (18)
7.5.5 Measurement (18)
report (19)
7.5.6 Test
7.6 Method
Evaluation (19)
(Informative) (19)
7.7 Annex
7.7.1 Interpretation of results according to RoHS (19)
Effects (20)
7.7.2 Matrix
7.7.3 Sample Size and Thickness Considerations (20)
8 Quantitative Screening by XRF Spectrometry (21)
8.1 Scope (21)
references (21)
8.2 Normative
8.3 Terms and definitions (21)
8.4 Apparatus/Equipment and Materials (22)
samples (23)
8.4.1 Reference
Procedure (24)
8.5 Test
adjustment (24)
8.5.1 Spectrometer
8.5.2 Calibration (24)
test (24)
screening
8.5.3 Quantitative
report (24)
8.5.4 Test
(Informative) (25)
8.6 Annex
8.6.1 Interpretation of results according to RoHS (25)
Effects (25)
8.6.2 Matrix
8.6.3 Sample Size and Thickness Considerations (25)
9 Determination of PBB and PBDE in Polymer Materials by GC/MS (27)
9.1 Scope, Application and Summary of Method (27)
9.2 References, Normative References, Reference Methods and Reference Materials (27)
9.3 Terms and Definition (27)
9.4 Apparatus / Equipment and Materials (28)
9.4.1 Apparatus (28)
9.4.2 Equipment (28)
9.5 Reagents (28)
Preparation (29)
9.6 Sample
9.6.1 Sample
Identification (29)
9.6.2 Extraction (29)
9.6.3 Sample cleanup and purification (29)
9.7 Test
Procedure (29)
9.7.1 Calibration (29)
performance (29)
9.7.2 Instrument
9.7.3 Sample
Analysis (30)
9.7.4 Calculation of Analytical Results (30)
Report (30)
9.7.5 Test
Control (31)
9.7.6 Quality
9.8 Evaluation of the Method (31)
9.9 Annex (31)
10 Determination of PBB and PBDE in Polymer Materials by HPLC/UV (32)
10.1 Scope, Application and Summary of Method (32)
10.2 References, Normative References, Reference Methods and Reference Materials (32)
10.3 Terms and Definitions (32)
10.4 Apparatus / Equipment and Materials (32)
10.4.1 Apparatus / Equipment (32)
10.4.2 Materials (32)
10.5 Reagents (32)
10.5.1 Standard preparation / Stock solution preparation (33)
Preparation (33)
10.6 Sample
Procedure (33)
10.7 Test
10.7.1 Calibration (33)
performance (33)
10.7.2 Instrument
Analysis (33)
10.7.3 Sample
10.7.4 Calculation of Analytical Results (34)
Report (34)
10.7.5 Test
Control (34)
10.7.6 Quality
10.8 Evaluation of the Method (34)
11 Screening for Hexavalent Chromium in Colorless and Colored Chromate Coating by Spot Test.36
11.1 Scope, Application and Summary of Method (36)
11.2 References, Normative References, Reference Methods and Reference Materials (36)
11.3 Terms and Definitions (36)
11.4 Apparatus / Equipment and Materials (36)
11.5 Reagents (36)
11.6 Sample
Preparation (36)
Procedure (36)
11.7 Test
11.8 Evaluation of the Method (37)
12 Determination of Hexavalent Chromium by Colorimetric Method (38)
12.1 Scope, Application and Summary of Method (38)
12.2 References, Normative References, Reference Methods and Reference Materials (38)
12.3 Terms and Definitions (39)
12.4 Apparatus / Equipment and Materials (39)
12.4.1 Apparatus / Equipment (39)
12.4.2 Materials (40)
12.4.3 Reagents (40)
12.5 Sample
Preparation (41)
Procedure (41)
12.6 Test
12.6.1 Extraction (41)
12.6.2 Color development and measurement (41)
12.6.3 Preparation of calibration curve (42)
12.6.4 Calculation of Analytical Results (42)
Control (43)
12.6.5 Quality
12.7 Evaluation of the Method (43)
13 Determination of Mercury in Polymer Materials, Metallic Materials and Electronics by CV-AAS, AFS, and ICP-AES/MS (44)
13.1 Scope, Application and Summary of Method (44)
13.2 References, Normative References, Reference Methods and Reference Materials (44)
13.3 Terms and Definitions (45)
13.4 Apparatus / Equipment and Materials (46)
13.5 Reagents (46)
13.5.1 Contaminations: (46)
Preparation (47)
13.6 Sample
portion (47)
13.6.1 Test
13.6.2 Wet Digestion (Digestion of metal materials and electronics) (47)
13.6.3 Microwave digestion with HNO3/HBF4/H2O2 (48)
Procedure (48)
13.7 Test
13.7.1 Standard preparation / Stock solution preparation (48)
13.7.2 Calibration (48)
performance (49)
13.7.3 Instrument
parameters (49)
13.7.4 Instrument
Analysis (50)
13.7.5 Sample
13.7.6 Calculation of Analytical Results (50)
Report (50)
13.7.7 Test
Control (50)
13.7.8 Quality
13.8 Evaluation of the Method (51)
13.9 Annex (51)
14 Determination of Lead and Cadmium in Polymer Materials by ICP-AES, ICP-MS, and AAS (52)
14.1 Scope, Application and Summary of Method (52)
14.2 References, Normative References, Reference Methods and Reference Materials (52)
14.3 Terms and Definitions (52)
14.4 Apparatus/Equipment and Materials (53)
14.4.1 Apparatus/Equipment (53)
14.5 Reagents (54)
14.6 Sample
Preparation (55)
portion (55)
14.6.1 Test
14.6.2 Preparation of test solution (55)
14.6.3 Preparation of laboratory reagent blank (57)
Procedure (57)
14.7 Test
14.7.1 Preparation of calibration solution (57)
14.7.2 Development of calibration curve (57)
14.7.3 Measurement of sample (58)
14.7.4 Calculation (58)
Report (58)
14.7.5 Test
Control (58)
14.7.6 Quality
14.8 Evaluation of the Method (59)
14.9 Annex (59)
14.9.1 ICP/AES(-OES) (59)
14.9.2 ICP/MS (60)
14.9.3 AAS (60)
15 Determination of Lead and Cadmium in Metallic Materials by ICP-AES, ICP-MS, and AAS (61)
15.1 Scope, Application and Summary of Method (61)
15.2 References, Normative References, Reference Methods and Reference Materials (61)
15.3 Terms and Definitions (61)
15.4 Apparatus/Equipment and Materials (62)
15.5 Reagents (62)
15.6 Sample
Preparation (63)
portion (63)
15.6.1 Test
15.6.2 Preparation of test sample solution (63)
15.6.3 Preparation of laboratory reagent blank (64)
Procedure (64)
15.7 Test
15.7.1 Preparation of calibration standard (65)
15.7.2 Measurement of calibration standard (65)
15.7.3 Measurement of sample (66)
15.7.4 Calculation (66)
Report (66)
15.7.5 Test
Control (66)
15.7.6 Quality
15.8 Evaluation of the Method (66)
15.9 Annex (66)
15.9.1 ICP/AES(-OES) (66)
15.9.2 ICP/MS (68)
15.9.3 AAS (68)
16 Determination of Lead and Cadmium in Electronics by ICP-AES, ICP-MS, and AAS (69)
16.1 Scope, Application and Summary of Method (69)
16.2 References, Normative References, Reference Methods and Reference Materials (69)
16.3 Terms and Definitions (69)
16.4 Apparatus / Equipment and Materials (70)
16.5 Reagents (71)
Preparation (72)
16.6 Sample
portion (72)
16.6.1 Test
16.6.2 Digestion with aqua regia (72)
digestion (73)
16.6.3 Microwave
Procedure (73)
16.7 Test
16.7.1 Preparation of calibration solution (74)
preparation (74)
16.7.2 Standard
16.7.3 Calibration (75)
16.7.4 Development of calibration curve (75)
16.7.5 Measurement of sample (76)
16.7.6 Calculation of Analytical Results (76)
Report (76)
16.7.7 Test
Control (76)
16.7.8 Quality
16.8 Evaluation of the Method (76)
16.9 Annex (77)
16.9.1 ICP/AES(-OES) (77)
16.9.2 ICP/MS (78)
16.9.3 AAS (78)
17 Reference Methods and Materials (79)
1 Introduction
The widespread use of electrotechnical products has drawn increased attention to their impact on the environment. In many countries all over the world this has resulted in the adaptation of regulations affecting wastes, substances and energy use of electrotechnical products.
The use of certain substance like Lead (Pb), Mercury (Hg), Cadmium (Cd), Hexavalent Chromium (Cr VI), and some types of brominated flame retardants (like Polybrominated Biphenyls, PBB, Polybrominated Diphenyl Ethers, PBDE) in electrotechnical products is regulated in current and proposed legislation e.g in:
?European Union (EU) directive on the “Reduction of certain Hazardous Substances in electrical and electronic equipment” (RoHS)
?Chinese draft legislation on “Management Methods on the Prevention and Control of Pollution Caused by Electronic information Products”
?US (California) Electronic Waste Recycling Act of 2003 (S.B. 20) and Electronic Waste, Advanced Disposal Fees (S.B. 50)
The EU RoHS directive prohibits Lead (Pb), Mercury (Hg), Cadmium (Cd), Hexavalent Chromium (Cr VI), and two types of brominated flame retardants, Polybrominated Biphenyls (PBB) and Polybrominated Diphenyl Ethers (PBDE) from being used in electronic and electrical equipment (EEE) from 1st July 2006. The same substances are regulated in the Chinese draft legislation, adhering to the same timeline as the EU RoHS. Likewise, California restricts the same substances on the same timeline, although for a narrower set of products than the EU RoHS.
Industry is convinced of the importance of defining testing protocols for regulated substances of electrotechnical products that enter or are made available on markets, where legislation regulating the substance content of electrotechnical product is enacted. Testing may be performed for a variety of reasons including:
?As a supplement to supply chain material declarations, companies may choose to test products directly to determine compliance
?Companies may require their suppliers to perform testing as a supplement to the supplier’s material declaration
?Companies may perform “spot checks” of their suppliers to confirm compliance
?Government officials may test as basis to assess compliance
Certain test procedures to determine regulated material content already exist, but most are not appropriate for testing electrotechnical products and are not internationally recognized. Currently no procedures for compliance or enforcement of the substance restrictions have been agreed upon or mandated by countries regulating substances in electrotechnical products. Testing procedures, which are being discussed by industry associations and academia to determine presence and levels of these banned substances differ from each other.
Until a common agreement between governments, industry and other stakeholders is reached on how regulated substances should be measured in electrotechnical products, industry has no legal certainty that products will be found compliant if tested by national enforcement authorities or by Non Governmental Organizations (NGOs) in different countries.
The purpose of this normative document is therefore to provide test procedures that will allow the electrotechnical industry to determine the levels of the regulated substances Pb, Hg, Cd, Cr VI, PBB, PBDE (EU RoHS, China, US, Japan, etc.) in electrotechnical products on a consistent global basis.
2 Scope
This normative document provides test procedures for determining the levels of Lead (Pb), Mercury (Hg), Cadmium (Cd), hexavalent Chromium (Cr VI), and two types of brominated flame retardants, Polybrominated Biphenyls (PBB) and Polybrominated Diphenyl Ethers (PBDE) contained in electrotechnical products.
Examples of categories of electrotechnical products are:
? Large household appliances
?Small household appliances
?IT and telecommunications equipment
? Consumer equipment
? Lighting equipment
?Electrical and electronic tools (with the exception of large-scale stationary industrial tools)
?Toys, leisure and sports equipment
? Automatic dispensers
This normative document will not determine:
?Definition of a “unit” or “homogenous material” as the sample
?Disassembly procedure to get to a sample
? Assessment procedures
3 References
a) Reduction of certain Hazardous Substances in electrical and electronic equipment (RoHS)
b) Management Methods on the Prevention and Control of Pollution Caused by Electronic
information Products
c) US (California) Electronic Waste Recycling Act of 2003 (S.B. 20)
d) US (California) Electronic Waste, Advanced Disposal Fees (S.B. 50)
e) Other references are found in the reference sections of the test procedures
Definitions
4 Terms
and
The definitions of the key terms used in this document are given below
a) Electrotechnical Products: Products which are dependent on electric currents or electromagnetic
fields in order to work properly and equipment for the generation, transfer and measurement of
such currents and fields
b) Substance: Substances are chemical elements and their compounds (e.g. lead is a chemical
element and lead oxide is a compound). Registry numbers of the Chemical Abstracts System of
the American Chemical Society (CAS #) are attributed to all chemical elements and most of their
compounds and should be used for identification purposes
c) Homogenous Material: A homogenous material is made up of one or more substances that is of
uniform composition throughout that cannot be mechanically disjointed into different materials.
d) Qualitative Screening: An analytical approach with the primary goal verifying the absence or
presence of an element of interest (analyte) in tested material
e) Quantitative Screening: An analytical approach with the primary goal to quantify the concentration
of an element of interest (analyte) in tested material
f) Polymer materials: Polyethylene, polyvinyl chloride, epoxy resin, polyamide, polycarbonate ABS
resin, polystyrene, etc.
g) Metallic materials: Fe-alloys, Ni-alloys, Sn-alloys, Al-alloys, Mg-alloys, Cu-alloys, Zn-alloys,
precious metals alloys
h) Electronics (PWBs/Components): Circuit boards, wiring materials, contacts, resistors, capacitors,
cords, connectors, etc.
i) Analyte: Substance or element tested for
j) Matrix: The material or substance, form or state in which the analyte is embedded.
k)
l) Other terms and definitions are found in the terms and definition sections of the test procedures
5 Test Procedure Overview
Procedure
Scope
5.1 Test
The content of the test procedure described can be grouped in two important steps:
? Analytical test procedures
? Laboratory implementation
Analytical test procedures have to be developed and validated to make sure they are suitable and can be used for the purpose they were designed for. Subsequently they have to be made available to the public so that interested parties around the globe can implement them.
The analytical test procedures step can itself be divided into seven important points:
?Scope, application and summary of method (incl. opportunities & risks)
?References, normative references, reference methods and reference materials
?Terms and definitions
?Apparatus / Equipment and materials
? Reagents
? Sample preparation
? Test procedure
o Calibration
o Instrument performance
o Sample analysis
o Calculation of analytical results
o Test report
o Quality control
The first point includes the scope of the method, the best application and a short summary of the method. It also highlights the opportunities for the best use of the test procedure and also the risks due to the inherent limitations of the procedure. The second important point is also how the method becomes traceable to commercial reference standards and suitable calibration samples. The third point will define the terms used throughout the method procedure. The fourth point describes the apparatus and the needed equipment and materials used for the method. The fifth point describes all the reagents used when measuring using the described method procedure. The sixth important covers the sample preparation for the samples themselves. The seventh point covers the actual test procedure related to the analytical instrument used. It describes the instrument performance, the sample analysis as well as the calculation of the analytical results. Content of the test report will also be summarized. This point also covers the quality aspects directly related to the chosen analytical test procedure.
Individual test procedure descriptions will follow this seven point outline.
The laboratory implementation will not be covered in this document, as labs should be able to implement the test procedures described using procedures and standards addressed in other sources. The implementation step includes suitable quality assurance measures and a validation protocol that documents the performance of the analytical method using the instrument in the lab. Quality assurance systems such as Good Laboratory Practice (GLP) and/or accreditation to similar (inter-) national systems (e.g. ISO) are strongly encouraged.
Flow
Procedure
5.2 Test
The figure below describes the flow for the test procedure to determine the levels of regulated substances in electrotechnical products.
Figure 1: Flowchart of the Test Procedure
After obtaining the sample, a decision has to be taken, whether the screening test procedure or the verification test procedure using a variety of test methods should be used. The procedure to obtain the sample is not described in this normative document. This procedure is described in a separate guidance document in Annex N.
The screening test procedure can be carried out either qualitatively or quantitatively. The qualitative screening will indicate whether a substance is present or not, but may not give accurate information about the concentration of substance present. The quantitative screening procedure will provide results expressing the concentration of substance(s) present.
Qualitative screening can be carried out either by directly measuring the sample (non-destructive) or by going first through a mechanical sample preparation step (destructive). A screening of representative samples of many uniform materials (such as plastics, alloys, glass) can be done non-destructively, while for other, more complex samples (like a populated printed wiring board) mechanical sample preparation may be necessary.
For the quantitative screening a mechanical sample preparation is mandatory. Mechanical sample preparation is the same for both the qualitative and the quantitative screening, as well as for the verification test procedure. It consists of cutting, grinding and homogenization of the sample.
Both the qualitative and the quantitative screening of a sample is performed using either an EDXRF (Energy Dispersive X-Ray Fluorescence) or a WDXRF (Wavelength Dispersive X-Ray Fluorescence) device. It must be noted that the screening test procedure should be performed under controlled conditions, as either EDXRF or WDXRF have limitations to its use and the applicability of the results obtained, although its fast and resource efficient way of analysis has its merits particularly for the demands of the electrotechnical industry.
After the screening test procedure it can be decided if the sample meets the limits based on the entity’s criteria for regulated substances or if further testing is required.
The verification test procedure is performed after a mechanical sample preparation using a variety of analytical procedures tailored to the regulated substances and the material of the sample, which can be either polymer materials, metallic materials or electronics(in form of populated PWBs or components). The
intent of using a particular verification test procedure is to ensure the most accurate results possible; however, it most likely will take more resources to carry out.
After the verification test procedure it can be decided if the sample meets the limits based on the entity’s criteria for regulated substances.
5.3 Adjustment to Material (Matrix)
Analytical procedures for regulated substances that are present at relatively low levels amongst other chemical elements or compounds at relatively high concentrations or representing the major constituent of the sample are very often material or matrix dependent. Therefore the test procedures have to be adjusted to the materials to be tested, either by introducing the appropriate blanks and matrix adjusted calibration samples or by a preparation step that separates the analyte from the adherent materials or the main matrix. The main material types (or matrices) in electronic equipment are polymer materials, mostly technical polymers with a whole series of additives that can moreover be painted; metallic materials as well as alloys of different types; and electronics such as (populated) printed wiring boards (PWBs) and electrical and electronic components.
5.4 Qualitative and Quantitative Screening Test Procedure
Both the qualitative and the quantitative screening of a sample is performed using either an EDXRF (Energy Dispersive X-Ray Fluorescence) or a WDXRF (Wavelength Dispersive X-Ray Fluorescence) device, which x-rays the content of the sample. Both handheld and desktop types of equipment are suitable. It must be noted that the screening test procedure should be performed under controlled conditions, as the use of XRF has limitations to its use and the applicability of the results obtained, although its fast and resource efficient way of analysis has its merits particularly for the demands of the electrotechnical industry.
5.5 Verification Test Procedure
The verification test procedure of a sample is done using a variety of analytical methods tailored to the regulated substances and the material of the sample, which can be either plastics, metals or electronics in form of populated PWBs or components. The use of the verification test procedures will ensure results with less error, however taking more resources to carry out.
Table 1: Overview of the content of the verification test procedure
Steps
Substances Polymer Materials Metal Materials Electronics (PWBs/Components) Sample preparation Direct measurement,
Grinding
Microwave digestion
Acid digestion
Dry Ashing
Solvent extraction
Direct measurement, Grinding, Acid digestion Grinding Microwave digestion Acid digestion Solvent extraction PBB/PBDE Cr VI
Hg
Analytical technique definition (incl. typical margins of errors) Pb/Cd
See Table 2 References (material, methods) for comparison BCR-680, BCR-681
In-house references
Commercial Solid Metal Standards None commercially available, In-house references Limitations &
Information delivered
Table 2: Details of the of the verification test procedure
Substance Polymer Materials Metal Materials Electronics (PWBs/Components)
Analytical technique
definition (incl. typical PBB/PBDE GC/MS (including FT-
IR) NA GC/MS (including FT-IR) HPLC/UV
margins of errors)
HPLC/UV
NA
Cr VI NA Spot test (ISO 3613)
Alkaline Digestion &
Colorimetric Method
(EPA 3060A)
Hg ICP-AES
ICP-MS
CV AAS
AFS
Pb/Cd ICP-AES
AAS
ICP-MS
Bold: Preferred Method
Normal: Acceptable Method
6 Procedure for Mechanical Sample Preparation
6.1 Scope, Application and Summary of Method
The purpose of this document is to provide practical guidance for the mechanical sample preparation step using the procedures described in the IEC ACEA ad hoc Working Group document.
This document is limited to providing general guidance for a practical approach toward the mechanical sample preparation of electrotechnical products. Due to the vast number and diverse nature of electronic products, it is not possible to cover all electrotechnical product sample in detail in this document. If detailed guidance is needed by product type or product family, such guidance should be developed by the individual industry sector TCs that manufacture the products.
In order to allow reproducible screening results the sample material should be as homogeneous as possible (in case of non-homogeneous materials) and show a consistent grain size distribution and density of the sample (for homogeneous materials).
6.2 References, Normative References, Reference Methods and Reference Materials
a) EN 13346:2000 Characterization of sludges – Determination of trace elements and phosphorus –
Aqua regia extraction methods
b) EPA method 3052:1996 Microwave assisted acid digestion of siliceous and organically based
matrices.
c) EPA method 3050B:1996 Rev. 2 Acid digestion of sediments, sludges and soils
d) ASTM D 4004-93:2002-Total digestion with alkali fusion
e) EN 1122:2001 Plastics – Determination of cadmium – Wet decomposition method
f) ISO 247: 1990: Rubber – Determination of ash
g) ISO 3696 : 1987 – water specification
h) ISO 40 and JIS 40 – specification of hydrofluoric acid
6.3 Terms and Definitions
a) n.a.
6.4 Apparatus / Equipment and Materials
a) Cutting mill with 4 and 1 mm stainless steel bottom sieve (Retsch SM2000 or similar)
b) Centrifugal mill with 25μm tungsten carbide (WC) coated steel sieve, 6-fold WC coated rotor, (for
homogenous plastic material a 1 mm steel sieve is appropriate) (Retsch ZM100 or similar)
In order to avoid any risks of impurities during milling a 1 mm titan sieve and a steel/titan sieve
rotor should be used
c) Vibratory Feeder (Retsch DR100 or similar)
d) Mixer (Turbula T2F or similar)
e) Analytical balance: Capable of accurate weighing to 0.0001 g
f) Brushes (different sizes)
g) Paper
h) Scissors, Heavy Plate Shears
i) 250 ml Glass Beaker
j) Liquid Nitrogen (N2)
k) Powder Funnel
l) Gloves
m) Safety glasses
6.5 Procedure
6.5.1 Sample
The sample to be analyzed should be a homogenous material, e.g. a polymer material, a metallic material or electronics. Guidance on how to get to this sample should be developed by the entity, the individual industry sector that manufactures the product or by TCs of the product group.
6.5.2 Cutting
Samples are precut to a size of no more than 2×10×10 cm3.
Electronics: Samples are precut to a size of 4x4 cm using heavy plate shears
Polymer Materials: Samples are precut to a size of 5x5 mm using heavy plate shears or/and scissors. Thin polymer foils are to be cut into small pieces with a shear.
6.5.3 Coarse
grinding
Cool the samples if needed with the liquid nitrogen. For organic samples without metal content cryogenic milling is recommended. Then grind samples in mill using 4 mm stainless steel bottom sieve. Carefully sweep out and collect all particles. Refit mill with pre-weighed 1.0 mm stainless steel bottom sieve and reprocess the 4 mm material. Carefully sweep out mill and collect all particles. There is a 5 minutes cooling periods between grinding cycles.
6.5.4 Homogenizing
The resulting coarse powder is homogenized in the mixer prior to further size reduction in the centrifugal mill. Use a container with double capacity of the amount of powder to be mixed. Set mixer on middle speed setting by adjusting drive belts to the center of the drive pulleys. Mix powder for 45 minutes.
grinding
6.5.5 Fine
Cool the sample powder with the liquid nitrogen if needed. For organic samples without metal content cryogenic milling is recommended. Be careful not to allow the liquid nitrogen to directly contact the powder to avoid spattering and sample loss. Mill the sample powder with centrifugal mill. Carefully sweep out centrifugal mill and collect all powder for assay.
7 Qualitative Screening by XRF Spectrometry
7.1 Scope
This document describes the procedure for the qualitative screening of regulated substances found in electrotechnical products using X-ray fluorescence (XRF). It covers parts and all material types such as polymers, metals and electronics.
Qualitative screening can be carried out either by directly measuring the sample (non-destructive) or by going through a mechanical sample preparation step (destructive). A screening of representative samples or uniform materials (such as plastics) can be done non-destructively, while for other samples (like a populated printed wiring board) mechanical sample preparation may be necessary.
The sample is irradiated by the beam emitted from an X-ray source. The resultant, characteristic X-rays of elements present in the sample tested are measured and converted to mass percent concentrations of elements.
Qualitative screening with X-ray fluorescence spectrometric analysis employs a qualitative analytic method to identify presence of regulated substances. Compared to other analytical procedures this test method offers high throughput, minimal or no sample preparation and wide dynamic range of measured concentrations. The equipment specified is in most cases less expensive than that required for alternative methods. Depending on the acceptance criteria in place for the controlled substances and performance of the analyzer used this test may or may not be conclusive. Should the latter be the case, this test must be followed either by quantitative screening analysis or by another verification test procedure that determine the presence and the concentration of controlled substance in the sample.
It must be noted that X-ray fluorescence spectrometric analysis only provides information on the presence of regulated substances in their elemental form. Special attention is needed e.g. for Chromium and Bromine, where the result will reflect the determination of presence of total Chromium and total Bromine, and not that for the regulated hexavalent chromium and PBB and PBDE. Therefore, the absence or presence of hexavalent chromium, PBB or PBDE must be confirmed with verification test procedure, if the presence of Chromium or Bromine is detected. On the other hand it must be noted that the presence of hexavalent chromium, PBB and PBDE is not possible if chromium and bromine are not detected in elemental form.
Since XRF Spectrometry is a comparative technique, its performance depends on the quality of calibration, which in turn depends on the accuracy of the standards used to establish instrument calibration. XRF Analysis is very much matrix sensitive. This means that spectral as well as matrix interferences (such as absorption and enhancement phenomena) must be taken into account during analysis, especially of such diverse and complex samples as polymers and electronic components.
XRF utilizes radiation, which is dangerous to humans. Therefore all radiation producing instruments should always be operated in accordance with safety instructions provided by manufacturer and in agreement with local regulations. In addition, the personnel using the equipment should be properly trained in pertinent safety matters.
references
7.2 Normative
The following referenced documents may be helpful for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
a) ASTM C 982 Guide for Selecting Components for Energy-Dispersive X-Ray Fluorescence
Systems, Annual Book of ASTM Standards, Vol. 12.01
b) C1118-89(2000) Standard Guide for Selecting Components for Wavelenght-Dispersive X-Ray
Fluorescence Systems
c) Bertin, E.P. “Principles and Practices of X-Ray Spectrometric Analysis” ed 2 Plenum Press N.Y.
d) Buhrke V.E. , Jenkins, R., Smith D.K., “A Practical Guide for the Preparation of Specimens for X-
ray Fluorescence and X-ray Diffraction Analysis” Wiley-VCH
e) ISO 20847:2004, Petroleum products – Determination of the sulfur content of automotive fuels –
Energy-dispersive X-ray fluorescence spectrometry
f) ISO 8754:2003, Petroleum products – Determination of the sulfur content – Energy-dispersive X-
ray fluorescence spectrometry
g) ISO 14596:1998, Petroleum products – Determination of the sulfur content – Wavelength-
dispersive X-ray fluorescence spectrometry
h) van Grieken R. “Handbook of X-Ray Spectrometry” Marcel Dekker Inc.
i) VDA Reference Material No 001 through 004, Institute for Reference Materials and
Measurements (IRMM), Geel, June 1993.
j) Certified Reference Materials BCR-680, and BCR-681, Trace Elements in Polyethylene, European Commission, Community Bureau of Reference – BCR, Brussels, January 2000.
7.3 Terms and definitions
For the purpose of this International Standard, the following terms and definitions apply.
a) X-ray fluorescence spectrometry: A comparative analytical technique in which sample of material
is irradiated under strictly controlled conditions by a beam of x-rays or low energy gamma rays in
order to induce the emission of characteristic X-rays by the elements in the sample. The energy
of these characteristic X-rays is specific to each element while their intensity is a direct measure
of the element concentration in sample. The process of emission of the characteristic X-rays is
called X-Ray Fluorescence, or XRF. There are two practical realization of the XRF Spectrometry:
o WDXRF spectrometry (Wavelength dispersive): Spectrometry in which X-rays emanated from sample are sorted according to their wavelengths rather than energy by dispersing
element such as crystal or multilayer, and then only detected by (typically) gas-filled or
scintillation detector.
o EDXRF spectrometry (Energy dispersive): Spectrometry in which X-rays from sample are sorted according to their energy in a detector which plays a double role; of the dispersive
device and of the detector itself at the same time.
b) Excitation X-rays: X-rays emitted by spectrometer’s x-ray source and directed at a sample to
induce X-ray fluorescence of the elements in a sample. Excitation X-rays can be generated by an X-ray tube or by an appropriate radioisotope source.
c) Secondary target method: For selective or more effective excitation of the element(s) in a sample
X-rays emitted from a source are first directed at a target of appropriate pure metal, whose
characteristic X-rays are then used to induce the X-ray fluorescence of sample elements. It is
used mainly in the energy dispersive XRF spectrometers.
d) Primary beam filter: A thin foil (usually but not always made of pure metal) placed in the beam of
excitation X-rays, between the excitation source and specimen, to change the spectral
distribution of the excitation X-rays. Typically, this filter would have thickness selected in such a
way that it would be opaque for lower energy X-rays and transparent for higher energy X-rays
emitted by the source.
e) Synthetic multilayer film: Two or more layers of materials stratified for use as X-ray dispersive
element.
f) Detector of X-ray radiation: Device used to detect the X-ray photon and convert its energy into
electric pulse of amplitude proportional to energy of the photon. Examples are proportional
counter (gas flow type and sealed type) and scintillation counter for wavelength dispersive X-ray
fluorescence spectrometer (WDXRF). For energy dispersive X-ray fluorescence spectrometer
(EDXRF) usually solid state, semiconductor detectors are used such as Si(Li) or silicon p-i-n
diode.
g) Energy Resolution of Detector: A critical parameter of detector of radiation that reflects its ability
to separate X-rays of adjacent energies. For detectors used in XRF Spectrometry this parameter
is expressed as the Full Width at Half Maximum (FWHM) of the peak of the manganese K-alpha
line irradiated directly at the detector at total count rate in spectrum not exceeding 1000 counts
per second. For solid state detectors the FWHM is expressed in units of energy, electron-Volts,
while for gas-filled proportional detectors it is expressed in percent as a ratio of FWHM to energy
of the Mn K-alpha peak.
h) Calibration samples: Set of samples with very well known compositions used to develop or
update the calibration curve(s) for the element(s) of interest.
i) Standardization sample: A sample used to confirm proper operation of the instrument. This
sample is measured always under the same conditions and the results of its analysis including
analytical errors must be within an a priori specified acceptance range in order for the instrument to be used for quantitative analysis of an unknown material. This sample must not change its
composition over time, and its composition should be as similar to the unknown material tested
as practically possible. This sample is often referred to as “Check Sample” or “Reference
Sample”.
j) Analytical Background: The intensity of radiation measured from spectrum of a sample in the region specific to the element of interest (analyte) when this element is not present in sample.
Modern XRF Spectrometers automatically account for the background.
k) Escape peak: This is a companion peak observed on X-ray spectrum at an energy lower than the energy of the parent, characteristic X-ray peak by energy of the characteristic X-rays of the
detector material. For silicon detectors escape peak occurs at 1.74 keV left off the parent peak,
while for argon gas-filled detector it will show at 2.96 keV left off the parent peak. Typical
intensity of this peak is about 1% of the parent peak. The smaller the detector the more likely the occurrence of escape peak. Modern XRF Spectrometers automatically eliminate escape peaks
from the spectra.
l) Sum peak: An artificial peak on X-ray spectrum occurring at an energy which is a multiple (usually the double) of an energy of a characteristic X-ray peak. This phenomenon is the result of the spectrometer inability to distinguish two consecutive photons when they occur within a very
short time (typically within few hundred nanoseconds). This phenomenon is observed at higher
count rates that challenge resolution time of the spectrometer. Modern XRF Spectrometers
automatically correct for this spectral artifact.
m) Statistical error of counting: Fluctuation in counts (or count rate) observed during repeated measurements of X-ray intensity of the element in sample, which is due solely to the random
nature of interaction of X-rays with matter. This fluctuation has Poisson distribution and therefore, its measure can be expressed as the square root of counts.
Materials
7.4 Apparatus/Equipment
and
a) X-ray fluorescence spectrometer (XRF): Any X-Ray Fluorescence Analyzer (Spectrometer) may
be used if its design incorporates, as a minimum, the following features:
o Source of excitation X-rays. X-ray source capable of generating x-rays of energies up to and above 35 keV. An X-ray tube or radioisotope is commonly used as source of X-ray
excitation.
Warning: If a radioactive source is used, it must be well shielded to international standard requirements and, therefore, not present any safety hazard. Attention to the source is only to be carried out by a fully trained, competent and authorized person using the correct shielding techniques. Operation of analyzers using X-ray tube sources must be conducted in accordance with the manufacturer’s safety instructions and local regulations.
o Means of sample presentation for analysis. An analyzer must have the provision to present sample for analysis in a consistent and repeatable manner. This may be a sample
holding mechanism, a sample table or a sample cup holder (in case when liquid or
powdered material is amnalyzed) - as is typical in a laboratory type instruments, or a
specially configured flat, external surface with the window that is pressed directly against
the measured sample- a feature typical for the hand-held portable instruments.
o X-ray detector. A detector of X-rays with sufficient sensitivity within the energy range from
2 to 35 keV, with energy resolution not worse than 220 eV. Solid state detectors such as
liquid nitrogen cooled Si(Li) detectors or “room temperature” thermoelectrically cooled p-i-
n silicon diodes are suitable for the task of X-ray detection and counting.
o Filters or other means of modifying or optimizing the primary X-ray radiation in order to improve analytical performance of the instrument.
o Signal conditioning and data handling electronics and software that include the functions of X-ray intensity counting, spectrum processing and alghoritms to convert the measured
intensities (count rates) of elements into their mass concentration of sample..
o Display, printer or other means of communication with the operator to report the results of analysis and accept operator’s feedback.
There are two types of X-ray fluorescence spectrometers - wavelength dispersive X-ray fluorescence spectrometer (WDXRF) and energy dispersive X-ray fluorescence spectrometer (EDXRF). Both can be used for qualitative screening. Independent from the X-ray fluorescence spectrometer which is used, the equipment needs to be able to distinguish between materials that contain regulated substances below or above the limits given in Table 3.
Table 3: Qualitative screening detection limits in mg/kg (ppm) for regulated substances in various matrices Substance Polymer
Materials
Metallic
Materials
Electronics Cd 50 100 100 Pb 100 200 200 Hg 100 200 200 Br 50 100 Cr 100 200 200
As these limits are to be seen as limits of quantification, the analyzer should be capable of achieving detection limits (LOD) at a level of a third of the screening limits. This requirement is listed in table 4, where the detection limit is calculated following the IUPAC definition of:
00
N C
U
3 LOD ?
?
= where:
U: Background intensity (counts)
C0: Concentration of sample (close to LOD) (ug/g)
N0: Net pulse intensity (counts)
Table 4: Desired detection limits in mg /kg (ppm) to fulfill the qualitative screening detection limits for different substances in various matrices
Element Polymer Material Metallic Material Electronics
Cd153030
Pb306060
Hg306060
Br1530
Cr306030
Note: These detection limits should be determined based on measurements of appropriate Certified Reference Materials (CRMs), for example such as BCR-680 and BCR 681 or equivalent if available. Otherwise, well characterized samples might be used.
7.4.1 Reference
samples
Commercially Available
There exist a variety of commercially available reference materials, mainly in polymeric and metallic matrices, but also, to a lesser degree, in glass and ceramic matrices. These materials have been specially formulated (doped) with the five elements of concern (Pb, Cd, Hg, Cr and Br), possibly with other elements present as well. These doped materials were then analyzed using a variety of wet chemistry methods, at a number of testing laboratories, to determine the concentration of these elements.
In XRF analysis, the semi-quantitative programming of the instrument can be modified, or corrected, using the reference material(s). The software used by the instrument determines the concentration of each element in each material(s). The concentrations are then corrected (i.e., the known values from the certified reference material replace the values obtained by the instrument), creating a standard reference material. This material can then be used in the analysis of unknown materials.
In-House Reference Materials
Where commercially available materials do not exist, laboratory specific reference samples may be created. The process for creating these materials is the same as above, although the verification process will not be as complete, as multiple laboratories will not be conducting the analysis. The in-house reference material must be documented for all analyses conducted using the reference.
Creation of New Certified Reference Material
In the interest of uniformity, it is desirable to create certified reference materials for all matrices, including both the upper and lower concentration levels. The steps to creating a certified reference material are as follows:
a) Determine the concentration levels for each of the elements of concern. Contract with a
manufacturer of the desired matrix (polymer, metal, glass, ceramic, etc.) to prepare samples to
the previously identified specifications.
b) Provide samples of this material to multiple laboratories for analysis. Analytical methods that may
be used include atomic absorption spectrometry; inductively coupled plasma spectrometry;
inductively coupled plasma optical emission spectrometry; instrumental neutron activation
analysis; instrumental photon activation analysis; titration; and others as appropriate.
c) The results of the inter-laboratory tests are to be analyzed and a variance determined. If the
variance between laboratories is deemed acceptable, the average concentration level obtained
will become the certified value for that element.
Procedure
7.5 Test
7.5.1 Preparation of the Spectrometer
a) Power on the instrument according to the operation manual of instrument. Let the instrument
warm up and stabilize as per the manufacturer’s guidelines.
b) To assure measurement stability, stability of the detector should be achieved, as specified by the
manufacturer's guidelines.
7.5.2 Calibration
a) If the instrument calibration is not required, proceed to 7.5.3. This is often the case with
instruments which use so called fundamental parameter method approach.
b) If the instrument requires calibration, it should be performed by following the guidelines in the
instrument’s users manual. There are two typical approaches to instrument calibration: empirical and fundamental parameters based.
o Empirical calibration involves measurement of set of calibration samples. Samples used for calibration should resemble in composition as close as possible the unknown material.
Concentrations of analytes in calibration samples should be well known and should
bracket the expected concentrations in the unknown material, and should not be obtained
by dilution. Since typically at least 5 samples of different concentration is required per
analyte to calibrate the instrument as many as 25 or more samples may be required. After
samples are measured, the X-ray intensities of each analyte are correlated via multiple
linear regression equation with concentration data for the analyte.
o In fundamental parameter calibration approach one may need only one calibration sample per sample matrix type. If the fundamental parameter calibration is to be performed by the
user at all, the details of such procedure will be given in users manual.
o Regardless of the type of calibration employed in the instrument, its performance must be verified after each calibration or calibration update as per Section 7.5.3.
7.5.3 Verification of Spectrometer performance
Whether or not the apparatus to be used meets the required performance criteria must be determined by measuring standard reference material or comparable reference sample. The elements contained in such sample must be present at concentrations levels that are not greater than 3 to 5 times the screening limits for elements tested (see Table 3). The results obtained from reference sample must agree within the error
of measurement with accepted concentration values for that sample. Only then the apparatus may be used for analysis of the unknown material. Some manufacturers may provide with instrument a Standard Operating Procedure (SOP) as well as an appropriate reference sample. Following the recommendation contained in such document assures the operator of the best possible quality of analytical results.
7.5.4 Presentation of Sample for Measurement
a) If a section including the specimen to be measured can be placed inside the specimen chamber of
the desk top X-ray fluorescence spectrometer in such a way that the specimen itself can be
properly placed in measuring position, measurement is conducted accordingly. If the specimen
does not fit properly in the chamber, it must be cut to appropriate size for measurement.
Specimens that are too small or very thin may violate the condition of minimum sample thickness or mass that must be present in order for the results to be valid. In such instances a number of
small objects of the same kind (for example small screws) should be placed in a sample cup and then only analyzed. Similarly, thin samples of the same kind should be stacked in the pile thick
enough to fulfill the minimum sample thickness criterion and analyzed accordingly. As a general
rule all samples must completely cover the measuring window of the spectrometer, and should be at least 5 mm thick in case of polymers and light alloys such as Al, Mg or Ti, minimum of 15 mm
thick in case of liquids and about 1 mm thick for all other alloys. However, due to individual
variations by instrument of the required sample size the operator of the spectrometer is advised to always consult the instrument manual or manufacturer for requirements on minimum
size/mass/thickness conditions of the sample.
b) If the measurement is to be performed with a portable, hand held XRF analyzer, care must be
taken to make sure that the analyzer measuring window can be placed against the sample tested, in direct contact with it. Small and very thin samples must be presented for analysis as described in section a) above. Then, the analysis is performed with help of an additional accessory (if such is made available with the analyzer) that allows hand held analyzer to measure samples in sample cups. All provisions about minimum sample size/mass/thickness apply also to portable analyzers.
c) If the specimen is in liquid, powder or pellet form or if it is a very small component, it is measured
in the disposable sample cup fitted with disposable window film which should not be reused.
When handling the window film, attention must be paid not to contaminate its surface by touching it.
7.5.5 Measurement
a) To analyze the specimen follow the instructions provided in the operating manual of the
instrument which, as minimum, should include the following basic steps:
o Place the sample in the measurement position (chamber) and perform measurement in compliance with instructions in users’ manual. In case of portable instrument, place the
measuring window of the analyzer against the surface of the sample and perform
measurement by initiating the spectrum acquisition of a sample for a predetermined
measurement time.
o At the conclusion of the measurement the instrument should typically provide the measured concentration(s) of analyte(s), or a numerical value related to the
concentrations of the elements in sample.
o If the instrument does not store the results automatically, record the results and any pertinent information. Continue with measurements.
o Every few unknown samples perform measurement of the reference sample as in Section
7.5.3. It is recommended that either the SOP supplied by manufacturer is followed or the
user’s own SOP (if such exists) is followed as to how often the reference sample must be
measured to maintain integrity of the results.
b) In order to assure sufficient analytical performance for each measured element, the measurement
conditions of the instrument should be optimized by proper selection of excitation parameters
(such as type of isotope or X-ray tube High Voltage, current and primary beam filter, as well as
measurement time per sample). These conditions are instrument specific and typically, this
information is found in analyzer’s instruction manual. As a general guidance the user of this
method is advised that spectral interferences existing between elements and matrix composition
variations from sample to sample, significantly affect the accuracy, precision and minimum
detection limit of each analyte. For example, it is feasible to achieve a 15 mg/kg Detection Limit
for Cd in pure polyethylene, but not when 10% Br-compound and/or 2% of antimony are present.
Following, table 5 shows characteristic X-ray lines intensities, which are recommended for
individual analytes:
Table 5: Characteristic X-ray lines intensities for individual analytes.
Analyte Primary Line Secondary Line
Cadmium, Cd Kα
Lead, Pb LαLβ
Mercury, Hg Lα
Chromium, Cr Kα
Bromine, Br KαKβ
c) Measurement time per sample necessary for detecting controlled substance varies with
instruments and matrix and has to be chosen to fulfill the criteria from 7.4. Typical measurement
times may vary from 30 to 300 sec per sample, depending on analyte, sample type and
instrument model.
report
7.5.6 Test
The work carried out by the testing laboratory shall be covered by a report which accurately, clearly and unambiguously presents the test results and other relevant information. Each test report shall include at least the following information:
a) Name, address and location of any laboratory involved in the analysis
b) Unique identification of report (such as serial number) and of each page and total number of
pages of the report
c) Description and identification of the sample
d) Date of receipt of sample and date(s) of performance of test
e) A reference to this IEC standard
f) Which processes, procedures and apparatus were used
g) Any details not specified in this standard which are optional, and any other factors which may
have affected the results.
Corrections or additions to a test report after issue shall be made only y a further document suitably marked, e.g. “Amendment/Addendum to test report serial number (or as otherwise identified)”, and shall meet the relevant requirements of the preceding paragraphs.
7.6 Method
Evaluation
Precision and Bias of the method will be evaluated in a qualified round robin test.
(Informative)
7.7 Annex
7.7.1 Interpretation of results according to RoHS
a) If the qualitative analysis gives a result for all elements, which is lower than the lower limit than
listed in table 3, the sample is tested ok according to RoHS.
b) If the qualitative analysis gives a result for any element, which is higher than the higher limit than
listed in table 3, the sample is tested not ok according to RoHS.
7.7.2 Matrix
Effects
a) The intensity of characteristic radiation of the element in the sample is adversely influenced by the
process of scattering of the excitation radiation, which contributes to the spectral background. In addition two major effects take place:
b) Absorption of excitation radiation and subsequent emission of fluorescence radiation by the
analyte and by the other elements (matrix) in the sample.
c) Secondary excitation (enhancement) of the analyte by other elements in the sample:
o Plastic materials: In plastics samples the matrix influence on the analyte characteristic x-ray intensity comes from:
?the scattering (mainly incoherent) of the primary radiation, which contributes
heavily to the spectral background
?the absorption of the fluorescence radiation mainly by Cl in PVC, by additive
elements like Ca, Ti, Zn, Sn,… and by such elements as Br and Sb, which
originate in flame retardants
?the secondary excitation by elements like Sb, Sn, and Br
o Metals: In metals samples the scattering of the primary radiation does not play an important role. The matrix effect is mainly caused by absorption and secondary excitation
effects. These will be different for each metal matrix. The following table shows some
typical elements in the various matrices:
?Fe alloys: Fe, Cr, Ni, Nb, Mo, W, …
?Al alloys: Al, Mg, Si, Cu, Zn, …
?Cu alloys: Cu, Zn, Sn, Pb, Mn, Ni, Co, …
?Solder alloys: Pb, Cu, Zn, Sn, Sb, Bi, Ag, ...
?Zn alloys: Zn, Al, …
?Precious metals alloys: Rh, Pd, Ag, Ir, Pt, Au, Cu, Zn, …
o Electronic components and printed wiring boards: In principle all effects, which are described for polymers and metals.
7.7.3 Sample Size and Thickness Considerations
Specimens that are too small or very thin may violate the condition of minimum sample thickness or mass that must be present in order for the results to be valid. In such instances a number of small objects of the same kind (for example small screws) should be placed in a sample cup and then only analyzed. Similarly, thin samples of the same kind should be stacked in the pile thick enough to fulfill the minimum sample thickness criterion and analyzed accordingly. As a general rule all samples must completely cover the measuring window of the spectrometer, and should be at least 5 mm thick in case of polymers and light alloys such as Al, Mg or Ti, minimum of 15 mm thick in case of liquids and about 1 mm thick for all other alloys. However, due to individual variations by instrument of the required sample size the operator of the spectrometer is advised to always consult the instrument manual or manufacturer for requirements on minimum size/mass/thickness conditions of the sample.