ASTM E2371-21a

Standard Test Method for Analysis of Titanium and Titanium Alloys by Direct Current Plasma and Inductively Coupled Plasma Atomic Emission Spectrometry (Performance-Based Test Methodology)

SIGNIFICANCE AND USE
5.1 This test method for the chemical analysis of titanium and titanium alloys is primarily intended to test material for compliance with specifications of chemical composition such as those under the jurisdiction of ASTM Committee B10. It may also be used to test compliance with other specifications that are compatible with the test method.  
5.2 It is assumed that all who use this test method will be trained analysts capable of performing common laboratory procedures skillfully and safely and that the work will be performed in a properly equipped laboratory.  
5.3 This is a performance-based test method that relies more on the demonstrated quality of the test result than on strict adherence to specific procedural steps. It is expected that laboratories using this test method will prepare their own work instructions. These work instructions will include detailed operating instructions for the specific laboratory, the specific reference materials used, and performance acceptance criteria. It is also expected that, when applicable, each laboratory will participate in proficiency test programs, such as described in Practice E2027, and that the results from the participating laboratory will be satisfactory.
SCOPE
1.1 This method describes the analysis of titanium and titanium alloys, such as specified by committee B10, by inductively coupled plasma atomic emission spectrometry (ICP-AES) and direct current plasma atomic emission spectrometry (DCP-AES) for the following elements:    
Element  
Application
Range (wt.%)  
Quantitative
Range (wt.%)  
Aluminum  
0–8  
0.009 to 8.0  
Boron  
0–0.04  
0.0008 to 0.01  
Cobalt  
0-1  
0.006 to 0.1  
Chromium  
0–5  
0.005 to 4.0  
Copper  
0–0.6  
0.004 to 0.5  
Iron  
0–3  
0.004 to 3.0  
Manganese  
0–0.04  
0.003 to 0.01  
Molybdenum  
0–8  
0.004 to 6.0  
Nickel  
0–1  
0.001 to 1.0  
Niobium  
0-6  
0.008 to 0.1  
Palladium  
0-0.3  
0.02 to 0.20  
Ruthenium  
0-0.5  
0.004 to 0.10  
Silicon  
0–0.5  
0.02 to 0.4  
Tantalum  
0-1  
0.01 to 0.10  
Tin  
0–4  
0.02 to 3.0  
Tungsten  
0-5  
0.01 to 0.10  
Vanadium  
0–15  
0.01 to 15.0  
Yttrium  
0–0.04  
0.001 to 0.004  
Zirconium  
0–5  
0.003 to 4.0  
1.2 This test method has been interlaboratory tested for the elements and ranges specified in the quantitative range part of the table in 1.1. It may be possible to extend this test method to other elements or broader mass fraction ranges as shown in the application range part of the table above provided that test method validation is performed that includes evaluation of method sensitivity, precision, and bias. Additionally, the validation study shall evaluate the acceptability of sample preparation methodology using reference materials or spike recoveries, or both. Guide E2857 provides information on validation of analytical methods for alloy analysis.  
1.3 Because of the lack of certified reference materials (CRMs) containing bismuth, hafnium, and magnesium, these elements were not included in the scope or the interlaboratory study (ILS). It may be possible to extend the scope of this test method to include these elements provided that method validation includes the evaluation of method sensitivity, precision, and bias during the development of the testing method.  
1.4 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.  
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. Specific safety hazards statements are given in Section 9.  
1.6 This international standard was developed in accordance with internationally recognized principle...

General Information

• Status: Published
• Publication Date: 30-Nov-2021
• ICS: 71.040.50 - Physicochemical methods of analysis
• ICS: 77.120.50 - Titanium and titanium alloys
• Technical Committee: E01 - Analytical Chemistry for Metals, Ores, and Related Materials
• Drafting Committee: E01.06 - Ti, Zr, W, Mo, Ta, Nb, Hf, Re

Relations

• Refers: ASTM E135-20 - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 01-Jan-2020
• Refers: ASTM E1601-19 - Standard Practice for Conducting an Interlaboratory Study to Evaluate the Performance of an Analytical Method
• Effective Date: 01-Nov-2019
• Refers: ASTM E135-19 - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 15-May-2019
• Refers: ASTM E2027-17 - Standard Practice for Conducting Proficiency Tests in the Chemical Analysis of Metals, Ores, and Related Materials
• Effective Date: 15-Nov-2017
• Refers: ASTM E50-17 - Standard Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
• Effective Date: 01-Sep-2017
• Refers: ASTM E1832-08(2017) - Standard Practice for Describing and Specifying a Direct Current Plasma Atomic Emission Spectrometer
• Effective Date: 01-May-2017
• Refers: ASTM E1479-16 - Standard Practice for Describing and Specifying Inductively Coupled Plasma Atomic Emission Spectrometers
• Effective Date: 01-Nov-2016
• Refers: ASTM E50-11(2016) - Standard Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
• Effective Date: 01-Aug-2016
• Refers: ASTM E135-16 - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 15-May-2016
• Refers: ASTM E135-15a - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 01-Jul-2015
• Refers: ASTM E135-15 - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 15-May-2015
• Refers: ASTM E135-14b - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 15-Aug-2014
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E135-14a - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 01-Apr-2014
• Refers: ASTM E135-14 - Standard Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
• Effective Date: 15-Feb-2014

Overview

ASTM E2371-21a is the Standard Test Method for Analysis of Titanium and Titanium Alloys by Direct Current Plasma and Inductively Coupled Plasma Atomic Emission Spectrometry (DCP-AES and ICP-AES). Developed by ASTM International, this performance-based standard is designed to determine the chemical composition of titanium and its alloys. The methodology supports compliance with material specifications, particularly those under ASTM Committee B10, and serves a critical function in quality control and regulatory conformance within industries using titanium materials.

This standard is widely recognized for leveraging atomic emission spectrometry to provide precise, reliable measurements essential for the control, verification, and certification of titanium alloy compositions.

Key Topics

• Scope of Analysis: The standard covers the determination of multiple key elements in titanium and titanium alloys, including but not limited to aluminum, boron, cobalt, chromium, copper, iron, manganese, molybdenum, nickel, niobium, palladium, ruthenium, silicon, tantalum, tin, tungsten, vanadium, yttrium, and zirconium. The method establishes specific quantitative ranges for each element, ensuring accuracy across typical alloy compositions.

• Performance-Based Methodology: Rather than prescribing rigid procedural steps, this standard emphasizes performance results. Laboratories are responsible for developing detailed internal work instructions, suitable reference materials, and performance acceptance criteria.

• Validation and Quality Assurance: Method validation-including sensitivity, precision, and bias-must be established by each laboratory following this standard. Participation in proficiency test programs is recommended to ensure consistent analytical quality. The approach flexibly accommodates matrix-matched calibration and encourages regular quality control practices, such as the use of control materials and periodic instrument calibration.

• Instrument Flexibility: Both DCP-AES and ICP-AES systems may be used, provided they meet the performance criteria set out in this standard.

• Safety Considerations: The method involves the use of hazardous reagents, including concentrated hydrofluoric acid. Laboratories must adhere to strict safety, health, and environmental protocols, as outlined in the associated ASTM practices.

Applications

• Material Compliance Testing: Essential for verifying that titanium and titanium alloys meet chemical composition specifications referenced in ASTM and other international standards.
• Quality Control in Manufacturing: Commonly used in the aerospace, medical device, chemical processing, and automotive industries to ensure consistent alloy quality and performance.
• Research and Development: Enables precise elemental analysis in alloy development and comparative studies.
• Regulatory and Trade Documentation: Supports certification and traceability of titanium materials during trade, procurement, and supply chain validation.

Related Standards

ASTM E2371-21a cites and aligns with several other international standards and guidelines, including:

• ASTM E50 - Practices for apparatus, reagents, and safety considerations for chemical analysis of metals, ores, and related materials.
• ASTM E1097 - Guide for determination of various elements by direct current plasma atomic emission spectrometry.
• ASTM E1479 - Practice for specifying inductively coupled plasma atomic emission spectrometers.
• ASTM E2027 - Practice for conducting proficiency tests in chemical analysis of metals.
• ASTM E2857 - Guide for validating analytical methods.
• ISO Guide 98-3 - Guide to the expression of uncertainty in measurement.

Practical Value

By following ASTM E2371-21a, laboratories can ensure their chemical analyses of titanium alloys are robust, traceable, and consistent with global market and regulatory expectations. The performance-based approach gives laboratories the flexibility to adapt test conditions to their unique setups while maintaining required levels of data quality. This ensures the integrity, safety, and reliability of titanium products supplied to critical sectors.

Keywords: ASTM E2371-21a, titanium alloys, chemical analysis, ICP-AES, DCP-AES, performance-based standard, atomic emission spectrometry, material compliance, quality control, laboratory validation, spectrochemical analysis, alloy certification.

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: E2371 − 21a
Standard Test Method for
Analysis of Titanium and Titanium Alloys by Direct Current
Plasma and Inductively Coupled Plasma Atomic Emission
Spectrometry (Performance-Based Test Methodology)
This standard is issued under the fixed designation E2371; 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 1.3 Because of the lack of certified reference materials
(CRMs) containing bismuth, hafnium, and magnesium, these
1.1 This method describes the analysis of titanium and
elements were not included in the scope or the interlaboratory
titanium alloys, such as specified by committee B10, by
study (ILS). It may be possible to extend the scope of this test
inductively coupled plasma atomic emission spectrometry
method to include these elements provided that method vali-
(ICP-AES) and direct current plasma atomic emission spec-
dation includes the evaluation of method sensitivity, precision,
trometry (DCP-AES) for the following elements:
and bias during the development of the testing method.
Application Quantitative
Element
1.4 Units—The values stated in SI units are to be regarded
Range (wt.%) Range (wt.%)
Aluminum 0–8 0.009 to 8.0
as the standard. No other units of measurement are included in
Boron 0–0.04 0.0008 to 0.01
this standard.
Cobalt 0-1 0.006 to 0.1
Chromium 0–5 0.005 to 4.0
1.5 This standard does not purport to address all of the
Copper 0–0.6 0.004 to 0.5
safety concerns, if any, associated with its use. It is the
Iron 0–3 0.004 to 3.0
responsibility of the user of this standard to establish appro-
Manganese 0–0.04 0.003 to 0.01
Molybdenum 0–8 0.004 to 6.0
priate safety, health, and environmental practices and deter-
Nickel 0–1 0.001 to 1.0
mine the applicability of regulatory limitations prior to use.
Niobium 0-6 0.008 to 0.1
Specific safety hazards statements are given in Section 9.
Palladium 0-0.3 0.02 to 0.20
Ruthenium 0-0.5 0.004 to 0.10
1.6 This international standard was developed in accor-
Silicon 0–0.5 0.02 to 0.4
dance with internationally recognized principles on standard-
Tantalum 0-1 0.01 to 0.10
ization established in the Decision on Principles for the
Tin 0–4 0.02 to 3.0
Tungsten 0-5 0.01 to 0.10
Development of International Standards, Guides and Recom-
Vanadium 0–15 0.01 to 15.0
mendations issued by the World Trade Organization Technical
Yttrium 0–0.04 0.001 to 0.004
Barriers to Trade (TBT) Committee.
Zirconium 0–5 0.003 to 4.0
1.2 This test method has been interlaboratory tested for the
2. Referenced Documents
elements and ranges specified in the quantitative range part of
2.1 ASTM Standards:
the table in 1.1. It may be possible to extend this test method
D1193 Specification for Reagent Water
to other elements or broader mass fraction ranges as shown in
E50 Practices for Apparatus, Reagents, and Safety Consid-
the application range part of the table above provided that test
erations for Chemical Analysis of Metals, Ores, and
method validation is performed that includes evaluation of
Related Materials
method sensitivity, precision, and bias. Additionally, the vali-
E135 Terminology Relating to Analytical Chemistry for
dation study shall evaluate the acceptability of sample prepa-
Metals, Ores, and Related Materials
ration methodology using reference materials or spike
E177 Practice for Use of the Terms Precision and Bias in
recoveries, or both. Guide E2857 provides information on
ASTM Test Methods
validation of analytical methods for alloy analysis.
E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
This test method is under the jurisdiction of ASTM Committee E01 on
Analytical Chemistry for Metals, Ores, and Related Materials and is the direct
responsibility of Subcommittee E01.06 on Ti, Zr, W, Mo, Ta, Nb, Hf, Re. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2021. Published January 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2004. Last previous edition approved in 2021 as E2371 – 21. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E2371-21A. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2371 − 21a
E1097 Guide for Determination of Various Elements by Practice E2027, and that the results from the participating
Direct Current Plasma Atomic Emission Spectrometry laboratory will be satisfactory.
E1329 Practice forVerification and Use of Control Charts in
3 6. Interferences
Spectrochemical Analysis (Withdrawn 2019)
E1479 Practice for Describing and Specifying Inductively 6.1 In Practice E1479, the typical interferences encountered
Coupled Plasma Atomic Emission Spectrometers during ICP emission analysis of metal alloys are described. In
E1601 Practice for Conducting an Interlaboratory Study to Guide E1097, the typical interferences encountered during
DCP emission spectrometric analysis of metal alloys are
Evaluate the Performance of an Analytical Method
E1763 Guide for Interpretation and Use of Results from described. The user is responsible for ensuring the absence of,
or compensating for, interferences that may bias test results
Interlaboratory Testing of Chemical Analysis Methods
(Withdrawn 2015) obtained using their particular spectrometer.
E1832 Practice for Describing and Specifying a Direct
6.2 The use of an internal standard may compensate for the
Current Plasma Atomic Emission Spectrometer
physical interferences resulting from differences between
E2027 Practice for Conducting Proficiency Tests in the
sample and calibration solutions transport efficiencies.
ChemicalAnalysis of Metals, Ores, and Related Materials
6.3 Shifts in background intensity levels because of recom-
E2857 Guide for Validating Analytical Methods
4 bination effects or molecular band contributions, or both, may
2.2 ISO Standard:
be corrected by the use of an appropriate background correc-
ISO Guide 98-3 Uncertainty of Measurement Part 3: Guide
tion technique. Direct spectral overlaps are best addressed by
to the Expression of Uncertainty in Measurement (GUM:
selecting alternative wavelengths. Spectral interference studies
1995)–First Edition
should be conducted on all new matrices to determine the
interference correction factor(s) that shall be applied to con-
3. Terminology
centrations obtained from certain spectral line intensities to
3.1 For definitions of terms used in this test method, refer to
minimize biases. Some instrument manufacturers offer soft-
Terminology E135.
ware options that mathematically correct for direct spectral
overlaps, but the user is cautioned to evaluate carefully this
4. Summary of Test Method
approach to spectral correction.
4.1 Amineralacidsolutionofthesampleisaspiratedintoan
6.4 Modern instruments have software that allows compari-
inductively coupled plasma (ICP) or direct current plasma
son of a sample spectrum to the spectrum obtained from a
(DCP) spectrometer. The intensities of emission lines from the
blank solution. The user of this test method shall examine this
spectra of the analytes are measured and compared with
information to ascertain the need for background correction
calibration curves obtained from solutions containing known
and the correct placement of background points.
amounts of pure elements.
6.5 In Table 1, wavelengths that may be used for analysis of
5. Significance and Use
titanium alloys are suggested. Each line was used by at least
5.1 This test method for the chemical analysis of titanium
one laboratory during the interlaboratory phase of test method
and titanium alloys is primarily intended to test material for
developmentandprovidedstatisticallyvalidresults.Additional
compliance with specifications of chemical composition such
elements and wavelengths may be added if proficiency is
as those under the jurisdiction of ASTM Committee B10. It
demonstrated. Information for the suggested analytical wave-
may also be used to test compliance with other specifications
lengths was collected from each laboratory and has been
that are compatible with the test method.
converted to wavelengths as annotated in the NIST Atomic
Spectra Database. In this database, wavelengths of less than
5.2 It is assumed that all who use this test method will be
200 nm were measured in vacuum and wavelengths greater
trained analysts capable of performing common laboratory
than or equal to 200 nm were measured in air.Additionally, the
procedures skillfully and safely and that the work will be
MIT Wavelength Tables were used. Tables for individual
performed in a properly equipped laboratory.
instruments may list wavelengths somewhat differently, as
5.3 Thisisaperformance-basedtestmethodthatreliesmore
instrument optical path atmospheric conditions may vary.
on the demonstrated quality of the test result than on strict
6.6 Information on potential spectral interfering elements
adherence to specific procedural steps. It is expected that
was provided by the laboratories participating in the interlabo-
laboratories using this test method will prepare their own work
ratory study (ILS) and may have originated from sources such
instructions. These work instructions will include detailed
as recognized wavelength reference tables, instrument manu-
operating instructions for the specific laboratory, the specific
facturer’s software wavelength tables, an individual laborato-
reference materials used, and performance acceptance criteria.
ry’s wavelength research studies, or a combination of these.
It is also expected that, when applicable, each laboratory will
participate in proficiency test programs, such as described in
Ralchenko,Yu., Kramida,A. E., Reader, J., and NISTASDTeam, NIST Atomic
Spectra Database (version 3.1.5), 2008, online. Available: http://physics.nist.gov/
The last approved version of this historical standard is referenced on asd3 [2008, October 28]. National Institute of Standards and Technology,
www.astm.org. Gaithersburg,MD.
4 6
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St., Harrison, G. R., MIT Wavelength Tables, John Wiley & Sons, New York, New
4th Floor, New York, NY 10036, http://www.ansi.org. York, 1969, https://mitpress.mit.edu/books.
E2371 − 21a
TABLE 1 Analytical Lines and Potential Interferences
either specify this information or reference instrument pro-
Wavelength Potential grams that include this information in their laboratory analysis
Element
(nm) Interference
procedures.
Aluminum 176.639
Aluminum 394.400
7. Apparatus
Bismuth (see 1.3) 190.241
Boron 182.579 Molybdenum, cobalt,
7.1 DCP-AES used in this test method may conform to the
chromium
specifications given in Practice E1832. A differently designed
Boron 249.678 Tin, chromium, iron
Boron 208.893
instrument may provide equivalent measurements. Suitability
Cobalt 230.786
for use is determined by comparing the results obtained with
Cobalt 231.160 Antimony, nickel
the precision and bias statements contained in this method.
Cobalt 235.342
Cobalt 237.863 Iron
7.2 ICP-AES used in this test method may conform to the
Cobalt 238.892
Copper 224.701 specifications given in Practice E1479. A differently designed
Copper 327.396
instrument may provide equivalent measurements. Suitability
Chromium 267.716
for use is determined by comparing the results obtained with
Chromium 206.553 Tungsten
Chromium 266.602 Cobalt the precision and bias statements contained in this test method.
Chromium 275.072 Iron, molybdenum
7.3 The sample introduction system shall be constructed of
Hafnium (see 1.3) 277.336
Hafnium (see 1.3) 232.247
materials resistant to all mineral acids including hydrofluoric
Iron 261.187
acid (HF).
Iron 259.940
Magnesium (see 1.3) 280.270
7.4 Each instrument shall be set up according to the manu-
Manganese 257.611 Cerium, cobalt,
facturer’s instructions.
tungsten
Manganese 260.568
7.5 Machine tools capable of removing surface oxides and
Molybdenum 201.510
other contamination from the as-received sample may be used
Molybdenum 202.030
Nickel 231.604
to produce uncontaminated and chemically representative
Niobium 288.318
chips or millings for analysis.
Niobium 295.088 Hafnium
Palladium 340.458
Palladium 355.308
8. Reagents and Materials
Palladium 360.955
Ruthenium 240.272 8.1 Reagents:
Ruthenium 245.553
8.1.1 Purity of Reagents—Reagent-grade chemicals shall be
Silicon 251.611 Hafnium, molybdenum
used in all tests. Unless otherwise indicated, it is intended that
Silicon 288.160 Chromium
Tantalum 240.062 Iron all reagents conform to the specifications of the Committee on
Tin 175.791
Analytical Reagents of theAmerican Chemical Society, where
Tin 242.949
such specifications are available. Other grades may be used,
Titanium Internal 191.391
Standard provided it is first ascertained that the reagent is of sufficiently
Titanium Internal 247.417
high purity to permit its use without lessening the accuracy of
Standard
the determination.
Titanium Internal 326.369
Standard
8.1.2 Purity of Water—Unless otherwise indicated, refer-
Titanium Internal 348.966
ences to water shall mean reagent water sufficiently purified to
Standard
meet the requirements of Type II of Specification D1193 or
Titanium Internal 358.713
Standard
equivalent. Equivalency is defined as water quality that does
Titanium Internal 372.459
not adversely affect test results. Laboratories shall establish
Standard
and document water quality requirements. The water purifica-
Titanium Internal 431.506
Standard
tionmethodusedshallbecapableofremovalofallelementsin
Tungsten 207.911
concentrations that might bias the test results.
Vanadium 292.402 Iron, molybdenum
8.1.3 Internal Standard—The use of an internal standard is
Vanadium 326.770
Vanadium 354.519 Niobium. tungsten
optional. However, the use of an internal standard may
Vanadium 359.202
compensate for the physical interferences resulting from dif-
Yttrium 360.073 Molybdenum
ferences in sample and calibration solutions transport effi-
Zirconium 343.823 Nickel
ciency. It also helps compensate for daily instrumental drift as
a result of changes in temperature and other parameters.
8.2 Calibration Solutions:
6.7 The user shall verify that the selected wavelength
performs acceptably in their laboratory, preferably during
method validation (see Section 15). The user also may choose
Reagent Chemicals, American Chemical Society Specifications, American
to use multiple wavelengths to help verify that line selection is
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
optimized for the particular alloy being determined. It is
listed by the American Chemical Society, see the United States Pharmacopeia and
recommended that when wavelengths and appropriate spectral
National Formulary,U.S.PharmacopeialConvention,Inc.(USPC),Rockville,MD,
corrections are determined, the user of this test method should www.chemistry.org and www.usp.org
E2371 − 21a
8.2.1 In this test method, calibration is based on laboratory 8.2.4.2 Use caution when boiling solutions for the analysis
prepared, alloy matrix-matched, calibration solutions. Alloy of boron and silicon with HF as volatile fluorides may be lost.
matrix-matched calibration solutions are solutions that contain The reaction rate should be moderated with the addition of
approximate amounts of the major alloying elements, such as water to the sample before the addition of HF, or a sealed
aluminum, tin, vanadium, and zirconium found in typical digestion bomb may be used where method validation dictates
sample solutions. These additions are intended to model the their use.
physical behavior of sample solutions in the plasma. The 8.2.5 In the tables in Appendix X1, the calibration formu-
matrix solutions are prepared with starting materials of rela- lations used in ILS No. 0537 are illustrated.
tively pure materials, certified reference materials (CRMs), or
8.3 Other Materials:
both. Reference materials may be either digested solid mate-
8.3.1 Argon—The purity of the argon shall meet or exceed
rials or purchased single or multi-element standard solutions.
the specifications of the instrument manufacturer.
The solution can be spiked with aliquots of single or multi-
8.3.2 Purge Gases—The purity of the purge gases shall
element CRM solutions that contain the analytes to be quan-
meet or exceed the specifications of the instrument manufac-
tified if not present in the reference materials or a pure metal
turer.
form. It may be possible to analyze different alloys using
8.3.3 Control Materials:
common matrix-matched calibration solutions provided
8.3.3.1 A laboratory may choose to procure, produce, or
method validation studies demonstrate acceptable data. Care
have manufactured a chip material containing analyte contents
shall be exercised in the selection of commercial CRM
in the range of typical samples to be used as a control material.
solutions. Solutions designed for use in atomic absorption
These chips should be homogenous and well blended. When-
techniques, for example, may not contain sufficient purity for
ever possible, users of this test method are discouraged from
DCP or ICP-AES use. Take care when using reference mate-
using CRMs as routine control materials to preserve limited
rials designated for atomic absorption techniques.
material supplies.
8.2.2 Calculate the nominal amounts of titanium and alloy-
8.3.3.2 A laboratory may find it difficult to procure or have
ing metals present in the samples to be analyzed, based on
manufactured the materials described in 8.3.3.1 for all of the
specimen mass and final dilution volume.
necessary analytes or alloys. If so, then it is acceptable to
8.2.2.1 TransferappropriatevolumesoftheCRMsormatrix
develop control solutions by preparing equivalent reference
metals into a HF-resistant volumetric flask. Matrix metals
material solutions using the procedure described in 8.2.
solutions may be from CRM or solid metal digestions.
9. Hazards
8.2.2.2 If an internal standard is used, pipette the predeter-
mined amount into each volumetric flask. Alternatively, tita-
9.1 This test method involves the use of concentrated HF.
nium can be used as an internal standard.
Read and follow label precautions, material safety data sheets
8.2.2.3 The solutions used to prepare the matrix solutions
(MSDS) information, and Practices E50 for HF handling
may contain analyte elements as residual elements in signifi-
precautions, as well. For precautions to be observed in the use
cantconcentrations.Usersmayneedtocalculatetheamountof
of certain other reagents in this test method, refer to Practices
residual elements contained in each matrix solution addition.
E50.
The amount of relevant analyte from these sources should be
totaled and used to adjust the stated concentration of each
10. Sampling, Test Specimens, and Test Units
calibration solution accordingly.
10.1 Laboratories shall follow written practices for sam-
8.2.3 Add the needed amount of single-element or multi
pling and preparation of test samples.
element CRM solutions into the flasks, ensuring to leave one
10.2 Test specimens may be obtained by milling or drilling
analyte free for use as a blank. Maintain the acidity necessary
chips or shearing pieces that are clean and of sufficient size to
to assure solution stability. The acidity given on the solution
allow the weighing of the appropriate specimen for dissolution
CRM certificate of analysis will provide guidance on the
and analysis.
necessary acid concentrations required. Typically, if these
solutions are to match samples prepared using1gof alloy
11. Preparation of Apparatus
diluted to 100 mL, the quantity of acids used in 8.2.4 will be
sufficient to hold all analytes in solution. 11.1 Analytical instrumentation and sample preparation
equipment shall be installed and operated in a manner consis-
8.2.4 Laboratories must determine acid mixtures that will
tent with manufacturer’s recommendations.
dissolve the metals used in the matrix-matched calibration
solutions and the alloys to be analyzed using this method.Acid
12. Calibration
mixtures shall be documented within laboratory quality sys-
tems documentation.
12.1 Laboratories must establish that the instrument being
8.2.4.1 A mixture of HF+HNO (2+1), HCl+HF+HNO used can demonstrate acceptable sensitivity and precision for
3 3
(1.5+2+1) or HCl+HF+HNO (15+2+1) are examples of acid the elements being analyzed. Once completed, it is not neces-
matrices that will dissolve many types of titanium alloys. sary to evaluate sensitivity and precision routinely. Methods to
Moderate the reaction with the addition of reagent water. For evaluate equipment sensitivity and precision are described in
alloys containing molybdenum, palladium, or ruthenium, first 12.1.1 and 12.1.2. Other methods to evaluate sensitivity and
addconcentratedHClbeforetheadditionofH OorHF/HNO . precision are acceptable. A description of the evaluation
2 3
E2371 − 21a
methodandresultsshallbedocumentedwithinthelaboratory’s include calculation of a linear function using a calculated
quality documentation. Refer to Section 14 (Control) for intercept, calculation of a linear function while forcing the
routine drift control. intercept through zero, and calculation of a linear function
using concentration weighting. Method validation per Section
12.1.1 Sensitivity—Sensitivity can be evaluated by first
15 may help the laboratory in selecting an appropriate calibra-
establishing a calibration curve for each element being deter-
tion algorithm.
mined using calibration solutions prepared as described in 8.2.
12.2.5 Theuserofthistestmethodshallverifythequalityof
At a minimum, the calibration curve will contain two points.
the calibration fit. Typical instrument software will calculate a
After thorough rinsing, the blank solution is analyzed ten
correlation coefficient for each calibration. It is acceptable to
times. Calculate three times the standard deviation of this
rely upon the correlation coefficient as a demonstration of
determination as an approximation of the limit of detection
calibrationfit.Ideally,thiscoefficientshouldbe0.995to1.000.
(LOD). Calculate ten times the standard deviation to approxi-
The user of this test method may choose other methods to
mate the limit of quantification (LOQ). If the instrument/
judge the quality of a calibration fit such as checking the
parameter selection does not produce an estimated LOD equal
residuals for trends and calculating a lack of fit parameter.
to or better than the lower scope limit for the element(s) being
determined, then it is probable the method will be unable to
13. Procedure
meet the lower scope limit. If the instrument/parameter selec-
13.1 Weigh a specimen, consistent with the specimen size
tion does not produce a LOQ equal to or better than the lower
selected for use in preparing the calibration solutions, to the
scope limit for the element(s) being determined, then it is
nearest 0.001 g and place it into a HF-resistant vessel.
possible the method user will be unable to meet consistently
the method’s lower scope limit.
13.2 Add to the specimen an appropriate volume of the
12.1.2 Precision—The short-term precision shall be deter-
same acid mixture used to prepare the calibration solutions
mined as follows. Using the same calibration generated in
(8.2) and cover.
12.1.1,analyzethehighcalibrationsolutiontentimesusingthe
13.2.1 Ifnecessary,heatthevesselgentlyuntilthespecimen
selected instrument/parameters. Calculate the % relative stan-
is dissolved.
dard deviation (% RSD) as follows:
13.3 Make any other necessary acid volume adjustments so
100s
that the acidity of the samples matches the acidity of the
%RSD 5 (1)
¯
calibration solutions, such that the specimen mass to final
C
solution volume is consistent with that of the calibration
where:
solutions.
s = estimated standard deviation, and
13.4 Add an internal standard if used in the calibration
¯
C = average of the ten results for the measured
solutions. Alternatively, titanium can be used as an internal
concentration.
standard.
12.1.2.1 As concentrations decrease or as intensities ap-
13.5 Transfer and dilute to volume and mix well.
proach detector saturation, % RSD may tend to increase, while
13.6 Analyze the sample solution according to the instru-
not necessarily affecting the quality of the reported result.
ment manufacturer’s instructions and the laboratory’s standard
During the ILS, % RSD values were typically approximately 1
operating procedure, using the calibration generated in Section
%, although some values approached 5 %. The user of this test
12.
method shall decide if precision is adequate for meeting data
quality objectives. In Practice E1479, limited guidance regard-
13.7 Analyze a control sample periodically throughout the
ing the parameters that may have an effect on instrument
run of the batch and at the end of the run. Use the control
precision is given. Manuals provided by the manufacturer of
sample to evaluate the need for recalibration and reanalysis of
the equipment may also provide guidance for optimizing
samples. Refer to Section 14 for specific information on
performance for the specific instrument being used.
control sample analysis.
12.2 Calibration:
14. Control
12.2.1 Set up the instrument for calibration in a manner
14.1 Thelaboratorywillestablishproceduresforcalibration
consistent with the manufacturer’s recommendations.
drift control. One suggested method involves the use of a
12.2.2 Specify calibration units consistent with the concen-
control chart to monitor drift. Monitor each control sample.
trations of the calibration solutions prepared in 8.2. The user
Refer to Practice E1329 for guidance on use of control charts.
may choose to specify units in the instrument software as a
Users of this test method are strongly discouraged from using
mass fraction such as % or mg/kg to simplify calculation and
CRMs as routine control materials.
reporting of final results.
14.2 Most instrument manufacturer’s software allows the
12.2.3 Define the number of replicate measurements to be
use of programmable control sample tolerances. It is accept-
made and averaged for a single reported result. Typically, a
able to calculate control limits and to use these as limits in the
minimum of two replicates is specified.
instrument software.
12.2.4 Calibrate the instrument using the calibration solu-
tions. Calibration for ICP-AES are generally linear over 14.3 The individual laboratories’ analysis procedures will
several orders of magnitude. Typical calibration methods specifythedriftcontrolacceptabilityandreanalysisprocedures
E2371 − 21a
of affected samples if control samples indicate that the calibra- 18. Precision and Bias
tion is no longer valid.
18.1 Precision—Originally, seven laboratories cooperated
in testing this test method. In Tables 2-15, summaries of this
15. Method Validation
precision information are presented. The interlaboratory data
15.1 A laboratory using this test method for the first time
were evaluated in accordance with Practice E1601 and Guide
shall provide additional method validation data to demonstrate E1763; the details are given in ASTM Research Report No.
that the test method as applied in their laboratory is yielding
E01-1112.
unbiased, repeatable results.
18.2 A new study was performed in 2011 to demonstrate
15.2 Initially, the laboratory shall prepare and analyze solid
method precision and bias for an expanded scope. Additional
CRMs or reference materials (RMs), or both, using this test
analytes included cobalt, lead, niobium, palladium, ruthenium,
method to obtain these data. If there are no solid CRMs or
tantalum, and tungsten. In Tables 16-21, the summaries of data
RM’s available for the alloys or analytes being determined,
for this additional study are presented. Eight laboratories were
then spike recovery studies using alloy samples may be part of
asked to report triplicate results, for six elements, obtained
the validation process.The precision and bias data obtained for from five different titanium alloy samples. One laboratory
thesematerialsshallbecomparedtotheprecisionandbiasdata
reportedthreesetsofdatausingoneICPandtwodifferentDCP
stated in this test method or compared to laboratory measure- spectrometers. These three sets of data all used independent
ment quality objectives.
sample preparations and calibration materials. A total of
thirteen sets of data were reported. Every “test result” reported
15.3 Any laboratory demonstrating precision and bias data
represents an individual determination. Practice E691 was
outside of the laboratory’s measurement quality objectives
followed for the design and analysis of the data; the details are
should attempt to identify and correct any problems associated
given in ASTM Research Report No. E01-1120.
with their application of this test method.
18.2.1 Repeatability Limit (r)—Two test results obtained
15.4 The user of this test method shall weigh customer
within one laboratory shall be judged not equivalent if they
requirements and the laboratory’s data quality objectives and
differ by more than the “r” value for that material; “r”isthe
justify acceptance of the validation data.
interval representing the critical difference between two test
15.5 The test method validation study shall be documented.
results for the same material obtained by the same operator
using the same equipment on the same day in the same
16. Calculation
laboratory.
18.2.1.1 Repeatability limits are listed in Tables 16-21.
16.1 If the user chooses to specify units in the instrument
18.2.2 Reproducibility Limit (R)—Two test results obtained
software to express the amount of analyte contained in the
by different laboratories shall be judged not equivalent if they
sampleasamassfraction,thennoothercalculationsotherthan
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2371 − 21 E2371 − 21a
Standard Test Method for
Analysis of Titanium and Titanium Alloys by Direct Current
Plasma and Inductively Coupled Plasma Atomic Emission
Spectrometry (Performance-Based Test Methodology)
This standard is issued under the fixed designation E2371; 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
1.1 This method describes the analysis of titanium and titanium alloys, such as specified by committee B10, by inductively
coupled plasma atomic emission spectrometry (ICP-AES) and direct current plasma atomic emission spectrometry (DCP-AES) for
the following elements:
Application Quantitative
Element
Range (wt.%) Range (wt.%)
Aluminum 0–8 0.009 to 8.0
Boron 0–0.04 0.0008 to 0.01
Cobalt 0-1 0.006 to 0.1
Chromium 0–5 0.005 to 4.0
Copper 0–0.6 0.004 to 0.5
Iron 0–3 0.004 to 3.0
Manganese 0–0.04 0.003 to 0.01
Molybdenum 0–8 0.004 to 6.0
Nickel 0–1 0.001 to 1.0
Niobium 0-6 0.008 to 0.1
Palladium 0-0.3 0.02 to 0.20
Ruthenium 0-0.5 0.004 to 0.10
Silicon 0–0.5 0.02 to 0.4
Tantalum 0-1 0.01 to 0.10
Tin 0–4 0.02 to 3.0
Tungsten 0-5 0.01 to 0.10
Vanadium 0–15 0.01 to 15.0
Yttrium 0–0.04 0.001 to 0.004
Zirconium 0–5 0.003 to 4.0
1.2 This test method has been interlaboratory tested for the elements and ranges specified in the quantitative range part of the table
in 1.1. It may be possible to extend this test method to other elements or broader mass fraction ranges as shown in the application
range part of the table above provided that test method validation is performed that includes evaluation of method sensitivity,
precision, and bias. Additionally, the validation study shall evaluate the acceptability of sample preparation methodology using
reference materials or spike recoveries, or both. Guide E2857 provides information on validation of analytical methods for alloy
analysis.
1.3 Because of the lack of certified reference materials (CRMs) containing bismuth, hafnium, and magnesium, these elements
This test method is under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and is the direct responsibility of
Subcommittee E01.06 on Ti, Zr, W, Mo, Ta, Nb, Hf, Re.
Current edition approved Aug. 1, 2021Dec. 1, 2021. Published August 2021January 2022. Originally approved in 2004. Last previous edition approved in 20132021 as
E2371 – 13.21. DOI: 10.1520/E2371-21.10.1520/E2371-21A.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2371 − 21a
were not included in the scope or the interlaboratory study (ILS). It may be possible to extend the scope of this test method to
include these elements provided that method validation includes the evaluation of method sensitivity, precision, and bias during
the development of the testing method.
1.4 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this
standard.
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. Specific safety hazards statements are given in Section 9.
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.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
E50 Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
E135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1097 Guide for Determination of Various Elements by Direct Current Plasma Atomic Emission Spectrometry
E1329 Practice for Verification and Use of Control Charts in Spectrochemical Analysis (Withdrawn 2019)
E1479 Practice for Describing and Specifying Inductively Coupled Plasma Atomic Emission Spectrometers
E1601 Practice for Conducting an Interlaboratory Study to Evaluate the Performance of an Analytical Method
E1763 Guide for Interpretation and Use of Results from Interlaboratory Testing of Chemical Analysis Methods (Withdrawn
2015)
E1832 Practice for Describing and Specifying a Direct Current Plasma Atomic Emission Spectrometer
E2027 Practice for Conducting Proficiency Tests in the Chemical Analysis of Metals, Ores, and Related Materials
E2857 Guide for Validating Analytical Methods
2.2 ISO Standard:
ISO Guide 98-3 Uncertainty of Measurement Part 3: Guide to the Expression of Uncertainty in Measurement (GUM:
1995)–First Edition
3. Terminology
3.1 For definitions of terms used in this test method, refer to Terminology E135.
4. Summary of Test Method
4.1 A mineral acid solution of the sample is aspirated into an inductively coupled plasma (ICP) or direct current plasma (DCP)
spectrometer. The intensities of emission lines from the spectra of the analytes are measured and compared with calibration curves
obtained from solutions containing known amounts of pure elements.
5. Significance and Use
5.1 This test method for the chemical analysis of titanium and titanium alloys is primarily intended to test material for compliance
with specifications of chemical composition such as those under the jurisdiction of ASTM Committee B10. It may also be used
to test compliance with other specifications that are compatible with the test method.
5.2 It is assumed that all who use this test method will be trained analysts capable of performing common laboratory procedures
skillfully and safely and that the work will be performed in a properly equipped laboratory.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
E2371 − 21a
5.3 This is a performance-based test method that relies more on the demonstrated quality of the test result than on strict adherence
to specific procedural steps. It is expected that laboratories using this test method will prepare their own work instructions. These
work instructions will include detailed operating instructions for the specific laboratory, the specific reference materials used, and
performance acceptance criteria. It is also expected that, when applicable, each laboratory will participate in proficiency test
programs, such as described in Practice E2027, and that the results from the participating laboratory will be satisfactory.
6. Interferences
6.1 In Practice E1479, the typical interferences encountered during ICP spectrometricemission analysis of metal alloys are
described. In Guide E1097, the typical interferences encountered during DCP emission spectrometric analysis of metal alloys are
described. The user is responsible for ensuring the absence of, or compensating for, interferences that may bias test results obtained
using their particular spectrometer.
6.2 The use of an internal standard may compensate for the physical interferences resulting from differences between sample and
calibration solutions transport efficiencies.
6.3 Shifts in background intensity levels because of recombination effects or molecular band contributions, or both, may be
corrected by the use of an appropriate background correction technique. Direct spectral overlaps are best addressed by selecting
alternative wavelengths. Spectral interference studies should be conducted on all new matrices to determine the interference
correction factor(s) that shall be applied to concentrations obtained from certain spectral line intensities to minimize biases. Some
instrument manufacturers offer software options that mathematically correct for direct spectral overlaps, but the user is cautioned
to evaluate carefully this approach to spectral correction.
6.4 Modern instruments have software that allows comparison of a sample spectrum to the spectrum obtained from a blank
solution. The user of this test method shall examine this information to ascertain the need for background correction and the correct
placement of background points.
6.5 In Table 1, wavelengths that may be used for analysis of titanium alloys are suggested. Each line was used by at least one
laboratory during the interlaboratory phase of test method development and provided statistically valid results. Additional elements
and wavelengths may be added if proficiency is demonstrated. Information for the suggested analytical wavelengths was collected
from each laboratory and has been converted to wavelengths as annotated in the NIST Atomic Spectra Database. In this database,
wavelengths of less than 200 nm were measured in vacuum and wavelengths greater than or equal to 200 nm were measured in
air. Additionally, the MIT Wavelength Tables were used. Tables for individual instruments may list wavelengths somewhat
differently, as instrument optical path atmospheric conditions may vary.
6.6 Information on potential spectral interfering elements was provided by the laboratories participating in the interlaboratory
study (ILS) and may have originated from sources such as recognized wavelength reference tables, instrument manufacturer’s
software wavelength tables, an individual laboratory’s wavelength research studies, or a combination of these.
6.7 The user shall verify that the selected wavelength performs acceptably in their laboratory, preferably during method validation
(see Section 15). The user also may choose to use multiple wavelengths to help verify that line selection is optimized for the
particular alloy being determined. It is recommended that when wavelengths and appropriate spectral corrections are determined,
the user of this test method should either specify this information or reference instrument programs that include this information
in their laboratory analysis procedures.
7. Apparatus
7.1 DCP-AES used in this test method may conform to the specifications given in Practice E1832. A differently designed
instrument may provide equivalent measurements. Suitability for use is determined by comparing the results obtained with the
precision and bias statements contained in this method.
Ralchenko, Yu., Kramida, A. E., Reader, J., and NIST ASD Team, NIST Atomic Spectra Database (version 3.1.5), 2008, online. Available: http://physics.nist.gov/asd3
[2008, October 28]. National Institute of Standards and Technology, Gaithersburg, MD.
Harrison, G. R., MIT Wavelength Tables, John Wiley & Sons, New York, New York, 1969, https://mitpress.mit.edu/books.
E2371 − 21a
TABLE 1 Analytical Lines and Potential Interferences
Wavelength Potential
Element
(nm) Interference
Aluminum 176.639
Aluminum 394.400
Bismuth (see 1.3) 190.241
Boron 182.579 Molybdenum, cobalt,
chromium
Boron 249.678 Tin, chromium, iron
Boron 208.893
Cobalt 230.786
Cobalt 231.160 Antimony, nickel
Cobalt 235.342
Cobalt 237.863 Iron
Cobalt 238.892
Copper 224.701
Copper 327.396
Chromium 267.716
Chromium 206.553 Tungsten
Chromium 266.602 Cobalt
Chromium 275.072 Iron, molybdenum
Hafnium (see 1.3) 277.336
Hafnium (see 1.3) 232.247
Iron 261.187
Iron 259.940
Magnesium (see 1.3) 280.270
Manganese 257.611 Cerium, cobalt,
tungsten
Manganese 260.568
Molybdenum 201.510
Molybdenum 202.030
Nickel 231.604
Niobium 288.318
Niobium 295.088 Hafnium
Palladium 340.458
Palladium 355.308
Palladium 360.955
Ruthenium 240.272
Ruthenium 245.553
Silicon 251.611 Hafnium, molybdenum
Silicon 288.160 Chromium
Tantalum 240.062 Iron
Tin 175.791
Tin 242.949
Titanium Internal 191.391
Standard
Titanium Internal 247.417
Standard
Titanium Internal 326.369
Standard
Titanium Internal 348.966
Standard
Titanium Internal 358.713
Standard
Titanium Internal 372.459
Standard
Titanium Internal 431.506
Standard
Tungsten 207.911
Vanadium 292.402 Iron, molybdenum
Vanadium 326.770
Vanadium 354.519 Niobium. tungsten
Vanadium 359.202
Yttrium 360.073 Molybdenum
Zirconium 343.823 Nickel
7.2 ICP-AES used in this test method may conform to the specifications given in Practice E1479. A differently designed instrument
may provide equivalent measurements. Suitability for use is determined by comparing the results obtained with the precision and
bias statements contained in this test method.
7.3 The sample introduction system shall be constructed of materials resistant to all mineral acids including hydrofluoric acid
(HF).
E2371 − 21a
7.4 Each instrument shall be set up according to the manufacturer’s instructions.
7.5 Machine tools capable of removing surface oxides and other contamination from the as-received sample may be used to
produce uncontaminated and chemically representative chips or millings for analysis.
8. Reagents and Materials
8.1 Reagents:
8.1.1 Purity of Reagents—Reagent-grade chemicals shall be 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, where such
specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity
to permit its use without lessening the accuracy of the determination.
8.1.2 Purity of Water—Unless otherwise indicated, references to water shall mean reagent water sufficiently purified to meet the
requirements of Type II of Specification D1193 or equivalent. Equivalency is defined as water quality that does not adversely affect
test results. Laboratories shall establish and document water quality requirements. The water purification method used shall be
capable of removal of all elements in concentrations that might bias the test results.
8.1.3 Internal Standard—The use of an internal standard is optional. However, the use of an internal standard may compensate
for the physical interferences resulting from differences in sample and calibration solutions transport efficiency. It also helps
compensate for daily instrumental drift as a result of changes in temperature and other parameters.
8.2 Calibration Solutions:
8.2.1 In this test method, calibration is based on laboratory prepared, alloy matrix-matched, calibration solutions. Alloy
matrix-matched calibration solutions are solutions that contain approximate amounts of the major alloying elements, such as
aluminum, tin, vanadium, and zirconium found in typical sample solutions. These additions are intended to model the physical
behavior of sample solutions in the plasma. The matrix solutions are prepared with starting materials of relatively pure materials,
certified reference materials (CRMs), or both. Reference materials may be either digested solid materials or purchased single or
multi-element standard solutions. The solution can be spiked with aliquots of single or multi-element CRM solutions that contain
the analytes to be quantified if not present in the reference materials or a pure metal form. It may be possible to analyze different
alloys using common matrix-matched calibration solutions provided method validation studies demonstrate acceptable data. Care
shall be exercised in the selection of commercial CRM solutions. Solutions designed for use in atomic absorption techniques, for
example, may not contain sufficient purity for DCP or ICP-AES use. Take care when using reference materials designated for
atomic absorption techniques.
8.2.2 Calculate the nominal amounts of titanium and alloying metals present in the samples to be analyzed, based on specimen
mass and final dilution volume.
8.2.2.1 Transfer appropriate volumes of the CRMs or matrix metals into a HF-resistant volumetric flask. Matrix metals solutions
may be from CRM or solid metal digestions.
8.2.2.2 If an internal standard is used, pipette the predetermined amount into each volumetric flask. Alternatively, titanium can be
used as an internal standard.
8.2.2.3 The solutions used to prepare the matrix solutions may contain analyte elements as residual elements in significant
concentrations. Users may need to calculate the amount of residual elements contained in each matrix solution addition. The
amount of relevant analyte from these sources should be totaled and used to adjust the stated concentration of each calibration
solution accordingly.
8.2.3 Add the needed amount of single-element or multi element CRM solutions into the flasks, ensuring to leave one analyte free
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD,
www.chemistry.org and www.usp.org
E2371 − 21a
for use as a blank. Maintain the acidity necessary to assure solution stability. The acidity given on the solution CRM certificate
of analysis will provide guidance on the necessary acid concentrations required. Typically, if these solutions are to match samples
prepared using 1 g of alloy diluted to 100 mL, the quantity of acids used in 8.2.4 will be sufficient to hold all analytes in solution.
8.2.4 Laboratories must determine acid mixtures that will dissolve the metals used in the matrix-matched calibration solutions and
the alloys to be analyzed using this method. Acid mixtures shall be documented within laboratory quality systems documentation.
8.2.4.1 A mixture of HF+HNO (2+1), HCl+HF+HNO (1.5+2+1) or HCl+HF+HNO (15+2+1) are examples of acid matrices
3 3 3
that will dissolve many types of titanium alloys. Moderate the reaction with the addition of reagent water. For alloys containing
molybdenum, palladium, or ruthenium, first add concentrated HCl before the addition of H O or HF/HNO .
2 3
8.2.4.2 Use caution when boiling solutions for the analysis of boron and silicon with HF as volatile fluorides may be lost. The
reaction rate should be moderated with the addition of water to the sample before the addition of HF, or a sealed digestion bomb
may be used where method validation dictates their use.
8.2.5 In the tables in Appendix X1, the calibration formulations used in ILS No. 0537 are illustrated.
8.3 Other Materials:
8.3.1 Argon—The purity of the argon shall meet or exceed the specifications of the instrument manufacturer.
8.3.2 Purge Gases—The purity of the purge gases shall meet or exceed the specifications of the instrument manufacturer.
8.3.3 Control Materials:
8.3.3.1 A laboratory may choose to procure, produce, or have manufactured a chip material containing analyte contents in the
range of typical samples to be used as a control material. These chips should be homogenous and well blended. Whenever possible,
users of this test method are discouraged from using CRMs as routine control materials to preserve limited material supplies.
8.3.3.2 A laboratory may find it difficult to procure or have manufactured the materials described in 8.3.3.1 for all of the necessary
analytes or alloys. If so, then it is acceptable to develop control solutions by preparing equivalent reference material solutions using
the procedure described in 8.2.
9. Hazards
9.1 This test method involves the use of concentrated HF. Read and follow label precautions, material safety data sheets (MSDS)
information, and Practices E50 for HF handling precautions, as well. For precautions to be observed in the use of certain other
reagents in this test method, refer to Practices E50.
10. Sampling, Test Specimens, and Test Units
10.1 Laboratories shall follow written practices for sampling and preparation of test samples.
10.2 Test specimens may be obtained by milling or drilling chips or shearing pieces that are clean and of sufficient size to allow
the weighing of the appropriate specimen for dissolution and analysis.
11. Preparation of Apparatus
11.1 Analytical instrumentation and sample preparation equipment shall be installed and operated in a manner consistent with
manufacturer’s recommendations.
12. Calibration
12.1 Laboratories must establish that the instrument being used can demonstrate acceptable sensitivity and precision for the
elements being analyzed. Once completed, it is not necessary to evaluate sensitivity and precision routinely. Methods to evaluate
equipment sensitivity and precision are described in 12.1.1 and 12.1.2. Other methods to evaluate sensitivity and precision are
acceptable. A description of the evaluation method and results shall be documented within the laboratory’s quality documentation.
Refer to Section 14 (Control) for routine drift control.
E2371 − 21a
12.1.1 Sensitivity—Sensitivity can be evaluated by first establishing a calibration curve for each element being determined using
calibration solutions prepared as described in 8.2. At a minimum, the calibration curve will contain two points. After thorough
rinsing, the blank solution is analyzed ten times. Calculate three times the standard deviation of this determination as an
approximation of the limit of detection (LOD). Calculate ten times the standard deviation to approximate the limit of quantification
(LOQ). If the instrument/parameter selection does not produce an estimated LOD equal to or better than the lower scope limit for
the element(s) being determined, then it is probable the method will be unable to meet the lower scope limit. If the
instrument/parameter selection does not produce a LOQ equal to or better than the lower scope limit for the element(s) being
determined, then it is possible the method user will be unable to meet consistently the method’s lower scope limit.
12.1.2 Precision—The short-term precision shall be determined as follows. Using the same calibration generated in 12.1.1, analyze
the high calibration solution ten times using the selected instrument/parameters. Calculate the % relative standard deviation (%
RSD) as follows:
100s
%RSD 5 (1)
¯
C
where:
s = estimated standard deviation, and
C¯ = average of the ten results for the measured concentration.
12.1.2.1 As concentrations decrease or as intensities approach detector saturation, % RSD may tend to increase, while not
necessarily affecting the quality of the reported result. During the ILS, % RSD values were typically approximately 1 %, although
some values approached 5 %. The user of this test method shall decide if precision is adequate for meeting data quality objectives.
In Practice E1479, limited guidance regarding the parameters that may have an effect on instrument precision is given. Instrument
troubleshooting manuals Manuals provided by the manufacturer of the equipment may also provide guidance for optimizing
performance for the specific instrument being used.
12.2 Calibration:
12.2.1 Set up the instrument for calibration in a manner consistent with the manufacturer’s recommendations.
12.2.2 Specify calibration units consistent with the concentrations of the calibration solutions prepared in 8.2. The user may
choose to specify units in the instrument software as a mass fraction such as % or mg/kg to simplify calculation and reporting of
final results.
12.2.3 Define the number of replicate measurements to be made and averaged for a single reported result. Typically, a minimum
of two replicates is specified.
12.2.4 Calibrate the instrument using the calibration solutions. Calibration curves for ICP-AES are generally linear over several
orders of magnitude. Typical calibration methods include calculation of a linear function using a calculated intercept, calculation
of a linear function while forcing the intercept through zero, and calculation of a linear function using concentration weighting.
Method validation per Section 15 may help the laboratory in selecting an appropriate calibration algorithm.
12.2.5 The user of this test method shall verify the quality of the calibration fit. Typical instrument software will calculate a
correlation coefficient for each calibration curve. calibration. It is acceptable to rely upon the correlation coefficient as a
demonstration of calibration fit. Ideally, this coefficient should be 0.995 or better.to 1.000. The user of this test method may choose
other methods to judge the quality of a calibration fit such as checking the residuals for trends and calculating a lack of fit
parameter.
13. Procedure
13.1 Weigh a specimen, consistent with the specimen size selected for use in preparing the calibration solutions, to the nearest
0.001 g and place it into a HF-resistant vessel.
13.2 Add to the specimen an appropriate volume of the same acid mixture used to prepare the calibration solutions (8.2) and cover.
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13.2.1 If necessary, heat the vessel gently until the specimen is dissolved.
13.3 Make any other necessary acid volume adjustments so that the acidity of the samples matches the acidity of the calibration
solutions, such that the specimen mass to final solution volume is consistent with that of the calibration solutions.
13.4 Add an internal standard if used in the calibration solutions. Alternatively, titanium can be used as an internal standard.
13.5 Transfer and dilute to volume and mix well.
NOTE 1—If sample preparation methods other than those specified are used, a validation study as specified in Section 15 should be used to evaluate the
validity of the sample preparation method. Caution should be used when boiling solutions for the analysis of boron and silicon with HF as volatile
fluorides may be lost. The reaction rate should be moderated with the addition of H O to the sample before the addition of HF, or a sealed digestion bomb
may be used where method validation dictates their use.
13.6 Analyze the sample solution according to the instrument manufacturer’s instructions and the laboratory’s standard operating
procedure, using the calibration generated in Section 12.
13.7 Analyze a control sample periodically throughout the run of the batch and at the end of the run. Use the control sample to
evaluate the need for recalibration and reanalysis of samples. Refer to Section 14 for specific information on control sample
analysis.
14. Control
14.1 The laboratory will establish procedures for calibration curve drift control. One suggested method involves the use of a
control chart to monitor drift. Monitor each control sample. Refer to Practice E1329 for guidance on use of control charts. Users
of this test method are strongly discouraged from using CRMs as routine control materials.
14.2 Most instrument manufacturer’s software allows the use of programmable control sample tolerances. It is acceptable to
calculate control limits and to use these as limits in the instrument software.
14.3 The individual laboratories’ analysis procedures will specify the drift control acceptability and reanalysis procedures of
affected samples if control samples indicate that the calibration is no longer valid.
15. Method Validation
15.1 A laboratory using this test method for the first time shall provide additional method validation data to demonstrate that the
test method as applied in their laboratory is yielding unbiased, repeatable results.
15.2 Initially, the laboratory shall prepare and analyze solid CRMs or reference materials (RMs), or both, using this test method
to obtain these data. If there are no solid CRMs or RM’s available for the alloys or analytes being determined, then spike recovery
studies using alloy samples may be part of the validation process. The precision and bias data obtained for these materials shall
be compared to the precision and bias data stated in this test method or compared to laboratory measurement quality objectives.
15.3 Any laboratory demonstrating precision and bias data outside of the laboratory’s measurement quality objectives should
attempt to identify and correct any problems associated with their application of this test method.
15.4 The user of this test method shall weigh customer requirements and the laboratory’s data quality objectives and justify
acceptance of the validation data.
15.5 The test method validation study shall be documented.
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16. Calculation
16.1 If the user chooses to specify units in the instrument software to express the concentrationamount of analyte contained in the
sample as a mass fraction, then no other calculations other than sample weightmass correction will be necessary. Results may be
taken directly from the instrument readout.
16.2 If the user specified analyte concentration as a volume fraction into the software, it will be necessary to convert the analyte
volume fraction concentrations obtained for the sample solution into analyte mass fractions contained in the sample. For example,
if the sample is prepared as 1 g of sample diluted to a final volume of 100-mL solution, an analyte volume fraction of 1.00-mg
analyte/L of solution corresponds to a mass fraction of 0.010 % analyte in the sample.
17. Report
17.1 Results shall be reported in a manner consistent with customer requirements. When uncertainty estimates are required, results
should be reported in accordance with the guidance provided in ISO Guide 98-3. In this test method, it is explained that the analyst
shall obtain an estimate of the overall uncertainty of the result and express that uncertainty as an expanded uncertainty, U = ku ,
c
where u is a combined uncertainty expressed at the level of one standard deviation (1s) and k is an expansion factor typically
c
chosen as k = 2. It is expected that the laboratory will include all significant sources of uncertainty in their estimate of the combined
uncertainty. Express the value of U with two significant digits. Then, expr
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