ASTM D7439-21

Standard Test Method for Determination of Elements in Airborne Particulate Matter by Inductively Coupled Plasma–Mass Spectrometry

SIGNIFICANCE AND USE
5.1 The health of workers in many industries is at risk through exposure by inhalation to toxic metals and metalloids. Industrial hygienists and other public health professionals need to determine the effectiveness of measures taken to control workplace exposure. This is generally achieved by making workplace air measurements. This test method has been developed to make available a standard methodology for valid exposure measurements for a wide range of metals and metalloids that are used in industry. It will be of benefit to agencies concerned with health and safety at work; analytical laboratories; industrial hygienists and other public health professionals; industrial users of metals and metalloids and their workers; and other groups.  
5.2 This test method specifies a generic method for determination of the concentration of metals and metalloids in workplace air samples using ICP-MS. For many metals and metalloids, analysis by ICP-MS may be advantageous, when compared to methods such as ICP atomic emission spectrometry, due to its sensitivity and the presence of fewer spectral interferences.  
5.3 The analysis results can be used for the assessment of workplace exposures to metals and metalloids in workplace air.
SCOPE
1.1 This test method specifies a procedure for sample preparation and analysis of airborne particulate matter for the content of metals and metalloids in workplace air samples using inductively coupled plasma–mass spectrometry (ICP-MS). This test method can be used for other air samples provided the user ensures the validity of the test method (by ensuring that appropriate data quality objectives can be achieved).  
1.2 This test method assumes that samples will have been collected in accordance with Test Method D7035 with consideration of guidance regarding wall deposits provided in Guide D8358.  
1.3 This test method should be used by analysts experienced in the use of ICP-MS, the interpretation of spectral and matrix interferences and procedures for their correction.  
1.4 This test method specifies a number of alternative methods for preparing test solutions from samples of airborne particulate matter. One of the specified sample preparation methods is applicable to the measurement of soluble metal or metalloid compounds. Other specified methods are applicable to the measurement of total metals and metalloids.  
1.5 It is the user's responsibility to ensure the validity of this test method for samples collected from untested matrices.  
1.6 Table 1 provides a non-exclusive list of metals and metalloids for which one or more of the sample dissolution methods specified in this document is applicable.  
1.7 This test method is not applicable to compounds of metals and metalloids that are present in the gaseous or vapor state.  
1.8 Table 3 provides examples of instrumental detection limits (IDL) that can be achieved with this test method. Table 5 provides examples of method detection limits (MDL) that can be achieved.  
1.9 No detailed operating instructions are provided because of differences among various makes and models of suitable ICP-MS instruments. Instead, the analyst shall follow the instructions provided by the manufacturer of the particular instrument. This test method does not address comparative accuracy of different devices or the precision between instruments of the same make and model.  
1.10 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.11 This test method contains notes that are explanatory and are not part of the mandatory requirements of the method.  
1.12 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.13 Th...

General Information

• Status: Published
• Publication Date: 31-Aug-2021
• ICS: 13.040.30 - Workplace atmospheres
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.04 - Workplace Air Quality

Relations

• Refers: ASTM E438-92(2024) - Standard Specification for Glasses in Laboratory Apparatus
• Effective Date: 01-Feb-2024
• Refers: ASTM E3193-23 - Standard Test Method for Measurement of Lead (Pb) by Flame Atomic Absorption Spectrophotometry (FAAS)
• Effective Date: 01-Nov-2023
• Refers: ASTM D7440-23 - Standard Practice for Characterizing Uncertainty in Air Quality Measurements
• Effective Date: 01-Sep-2023
• Refers: ASTM D4185-23 - Standard Test Method for Measurement of Metals in Workplace Atmospheres by Flame Atomic Absorption Spectrophotometry
• Effective Date: 01-Sep-2023
• Refers: ASTM D1356-20a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Sep-2020
• Refers: ASTM D1356-20 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Mar-2020
• Refers: ASTM E3203-19 - Standard Test Method for Determination of Lead in Dried Paint, Soil, and Wipe Samples by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES)
• Effective Date: 01-Apr-2019
• Refers: ASTM E3193-19 - Standard Test Method for Measurement of Lead (Pb) in Dust by Wipe, Paint, and Soil by Flame Atomic Absorption Spectrophotometry (FAAS)
• Effective Date: 01-Jan-2019
• Refers: ASTM D4840-99(2018)e1 - Standard Guide for Sample Chain-of-Custody Procedures
• Effective Date: 15-Aug-2018
• Refers: ASTM E438-92(2018) - Standard Specification for Glasses in Laboratory Apparatus
• Effective Date: 01-Jan-2018
• Refers: ASTM E288-10(2017) - Standard Specification for Laboratory Glass Volumetric Flasks
• Effective Date: 01-Nov-2017
• Refers: ASTM D5011-17 - Standard Practices for Calibration of Ozone Monitors Using Transfer Standards
• Effective Date: 01-Oct-2017
• Refers: ASTM D4185-17 - Standard Test Method for Measurement of Metals in Workplace Atmospheres by Flame Atomic Absorption Spectrophotometry
• Effective Date: 01-Mar-2017
• Refers: ASTM E882-10(2016) - Standard Guide for Accountability and Quality Control in the Chemical Analysis Laboratory
• Effective Date: 01-Dec-2016
• Refers: ASTM E882-10(2016)e1 - Standard Guide for Accountability and Quality Control in the Chemical Analysis Laboratory
• Effective Date: 01-Dec-2016

Overview

ASTM D7439-21: Standard Test Method for Determination of Elements in Airborne Particulate Matter by Inductively Coupled Plasma–Mass Spectrometry (ICP-MS) establishes a comprehensive procedure for the accurate measurement of metals and metalloids in airborne particulate matter, specifically in workplace environments. Developed by ASTM, this method is vital for assessing occupational exposure to toxic elements, directly supporting industrial hygiene initiatives and worker safety programs. Using ICP-MS provides enhanced sensitivity and reduces spectral interferences compared to other analytical techniques.

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Key Topics

Scope and Intent

• Specifies procedures for sample preparation and analysis of airborne particulate matter for metal and metalloid content.
• Applicable primarily to workplace air samples, but can be adapted for other types of air samples with proper validation.
• Assumes air particulate sampling is performed according to ASTM D7035 and that potential wall deposits are considered as per ASTM D8358.

Elements Covered

• The method applies to a broad range of metals and metalloids, including but not limited to: aluminum, arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, tin, zinc, and uranium.

Sample Handling and Preparation

• Outlines multiple sample dissolution techniques suitable for different analytical needs, including soluble and total metals/metalloids.
• Emphasizes the importance of using clean, contamination-free equipment and high-purity reagents to ensure reliability.

Analyst Qualifications

• Analysis must be carried out by professionals experienced in ICP-MS operation and the interpretation/correction of spectral and matrix interferences.

Detection Limits

• Includes reference tables for instrumental and method detection limits achievable through the standardized process.

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Applications

Workplace Exposure Assessment

• Crucial for industrial hygienists, safety officers, and regulatory agencies to monitor and control worker exposure to hazardous metals and metalloids.
• Supports the effectiveness review of engineering controls and protective measures in diverse industries such as manufacturing, mining, and metallurgy.

Compliance and Reporting

• Assists organizations in meeting occupational exposure limits (OELs), regulatory requirements, and industry best practices for air quality.
• Results can be used for compliance documentation, hazard communication, and risk assessment.

Laboratory Analysis

• Provides analytical laboratories with a validated, internationally recognized protocol, increasing confidence in results and facilitating comparison across studies.

Process Control

• Industrial employers benefit from routine air monitoring, identifying process leaks, fugitive emissions, or breakdowns in containment safeguards.

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Related Standards

For improved implementation and to ensure comprehensive occupational and environmental monitoring, the following ASTM and international standards are relevant:

• ASTM D7035: Determination of Metals and Metalloids in Airborne Particulate Matter by ICP Atomic Emission Spectrometry (ICP-AES)
• ASTM D4185: Measurement of Metals in Workplace Atmospheres by Flame Atomic Absorption Spectrophotometry
• ASTM D7440: Practice for Characterizing Uncertainty in Air Quality Measurements
• ASTM D8358: Guide for Assessment and Inclusion of Wall Deposits in Airborne Particulate Matter Sampling
• ISO 15202 Series: Workplace air - Determination of metals and metalloids in airborne particulate matter by ICP techniques
• ISO 17294: Application of ICP-MS for Water Quality

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Practical Value

Implementing ASTM D7439-21 enables organizations and laboratories to protect employee health, ensure regulatory compliance, and maintain robust quality assurance programs. ICP-MS technology, coupled with standardized sample collection and preparation, empowers professionals to obtain accurate, actionable data on hazardous workplace airborne pollutants. This method is essential for modern occupational health and industrial hygiene programs, promoting safer work environments through precise airborne particulate monitoring.

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: D7439 − 21
Standard Test Method for
Determination of Elements in Airborne Particulate Matter by
Inductively Coupled Plasma–Mass Spectrometry
This standard is issued under the fixed designation D7439; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.9 No detailed operating instructions are provided because
of differences among various makes and models of suitable
1.1 This test method specifies a procedure for sample
ICP-MS instruments. Instead, the analyst shall follow the
preparation and analysis of airborne particulate matter for the
instructions provided by the manufacturer of the particular
content of metals and metalloids in workplace air samples
instrument. This test method does not address comparative
using inductively coupled plasma–mass spectrometry (ICP-
accuracy of different devices or the precision between instru-
MS). This test method can be used for other air samples
ments of the same make and model.
provided the user ensures the validity of the test method (by
ensuring that appropriate data quality objectives can be 1.10 The values stated in SI units are to be regarded as
achieved). standard. No other units of measurement are included in this
standard.
1.2 This test method assumes that samples will have been
collected in accordance with Test Method D7035 with consid- 1.11 This test method contains notes that are explanatory
eration of guidance regarding wall deposits provided in Guide and are not part of the mandatory requirements of the method.
D8358.
1.12 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.3 Thistestmethodshouldbeusedbyanalystsexperienced
responsibility of the user of this standard to establish appro-
in the use of ICP-MS, the interpretation of spectral and matrix
priate safety, health, and environmental practices and deter-
interferences and procedures for their correction.
mine the applicability of regulatory limitations prior to use.
1.4 This test method specifies a number of alternative
1.13 This international standard was developed in accor-
methods for preparing test solutions from samples of airborne
dance with internationally recognized principles on standard-
particulate matter. One of the specified sample preparation
ization established in the Decision on Principles for the
methods is applicable to the measurement of soluble metal or
Development of International Standards, Guides and Recom-
metalloid compounds. Other specified methods are applicable
mendations issued by the World Trade Organization Technical
to the measurement of total metals and metalloids.
Barriers to Trade (TBT) Committee.
1.5 Itistheuser’sresponsibilitytoensurethevalidityofthis
test method for samples collected from untested matrices.
2. Referenced Documents
1.6 Table 1 provides a non-exclusive list of metals and
2.1 ASTM Standards:
metalloids for which one or more of the sample dissolution
D1193Specification for Reagent Water
methods specified in this document is applicable.
D1356Terminology Relating to Sampling and Analysis of
Atmospheres
1.7 This test method is not applicable to compounds of
D4185Test Method for Measurement of Metals in Work-
metals and metalloids that are present in the gaseous or vapor
placeAtmospheres by FlameAtomicAbsorption Spectro-
state.
photometry
1.8 Table 3 provides examples of instrumental detection
D4840Guide for Sample Chain-of-Custody Procedures
limits (IDL) that can be achieved with this test method. Table
D5011Practices for Calibration of Ozone Monitors Using
5 provides examples of method detection limits (MDL) that
Transfer Standards
can be achieved.
D6785TestMethodforDeterminationofLeadinWorkplace
This test method is under the jurisdiction of ASTM Committee D22 on Air
Quality and is the direct responsibility of Subcommittee D22.04 on WorkplaceAir
Quality. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2021. Published October 2021. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2008. Last previous edition approved in 2014 as D7439–14. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7439-21. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7439 − 21
TABLE 1 Applicable Metals and Metalloids
A A A
Element Symbol CASRN Element Symbol CASRN Element Symbol CASRN
Aluminum Al 7429-90-5 Antimony Sb 7440-36-0 Arsenic As 7440-38-2
Barium Ba 7440-39-3 Beryllium Be 7440-41-7 Bismuth Bi 7440-69-9
Boron B 7440-42-8 Cadmium Cd 7440-43-9 Calcium Ca 7440-70-2
Cesium Cs 7440-46-2 Chromium Cr 7440-47-3 Cobalt Co 7440-48-4
B
Copper Cu 7440-50-8 Gallium Ga 7440-55-3 Germanium Ge 7440-56-4
Hafnium Hf 7440-58-6 Indium In 7440-74-6 Iron Fe 7439-89-6
Lead Pb 7439-92-1 Lithium Li 7439-93-2 Magnesium Mg 7439-95-4
B
Manganese Mn 7439-96-5 Mercury Hg 7439-97-6 Molybdenum Mo 7439-98-7
B
Nickel Ni 7440-02-0 Niobium Nb 7440-03-1 Phosphorus P 7723-14-0
Platinum Pt 7440-06-4 Potassium K 7440-09-7 Rhodium Rh 7440-16-6
Selenium Se 7782-49-2 Silver Ag 7440-22-4 Sodium Na 7440-23-5
Tellurium Te 13494-80-9 Thallium Tl 7440-28-0 Tin Sn 7440-31-5
Tungsten W 7440-33-7 Uranium U 7440-61-1 Vanadium V 7440-62-2
Yttrium Y 7440-65-5 Zinc Zn 7440-66-6 Zirconium Zr 7440-67-7
A
CASRN = Chemical Abstracts Service Registry Number
B
For the elements in italics, there is insufficient information available on the effectiveness of the sample dissolution procedures in Annex A1 through Annex A5.
Air Using Flame or Graphite FurnaceAtomicAbsorption
2.2 ISO Standards:
Spectrometry
ISO 1042Laboratory glassware — One-mark volumetric
D7035Test Method for Determination of Metals and Met-
flasks
alloids in Airborne Particulate Matter by Inductively
ISO 3585Borosilicate glass 3.3 — Properties
Coupled Plasma Atomic Emission Spectrometry (ICP-
ISO 4225Air quality — General aspects — Vocabulary
AES)
ISO 8655Piston-operated volumetric apparatus (6 parts)
D7202Test Method for Determination of Beryllium in the
ISO 15202Workplace air — Determination of metals and
WorkplacebyExtractionandOpticalFluorescenceDetec-
metalloids in airborne particulate matter by inductively
tion
coupled plasma atomic emission spectrometry (3 parts)
D7440Practice for Characterizing Uncertainty in Air Qual-
ISO 17294Water quality — Application of inductively
ity Measurements
coupled plasma mass spectrometry (ICP-MS) (2 parts)
D8344Practice for Ammonium Bifluoride and Nitric Acid
ISO 18158Workplace air — Terminology
Digestion of Airborne Dust and Dust-Wipe Samples for
the Determination of Metals and Metalloids
3. Terminology
D8358GuideforAssessmentandInclusionofWallDeposits
3.1 Definitions—For definitions of other terms used in this
in the Analysis of Single-Stage Samplers for Airborne
test method, refer to Terminology D1356.
Particulate Matter
3.1.1 analytical recovery, n—ratio of the mass of analyte
E288Specification for Laboratory Glass Volumetric Flasks
measured to the known mass of analyte in the sample,
E438Specification for Glasses in Laboratory Apparatus
expressed as a percentage. D6785
E691Practice for Conducting an Interlaboratory Study to
3.1.2 batch, n—a group of field or quality control (QC)
Determine the Precision of a Test Method
samples that are collected or processed together at the same
E882Guide for Accountability and Quality Control in the
time using the same reagents and equipment. E3203
Chemical Analysis Laboratory
3.1.3 blank solution, n—solution prepared by taking a re-
E1154Specification for Piston or Plunger Operated Volu-
agent blank, laboratory blank or field blank through the same
metric Apparatus
procedure used for sample dissolution. ISO 15202
E1613Test Method for Determination of Lead by Induc-
3.1.3.1 Discussion—A blank solution may need to be sub-
tively Coupled Plasma Atomic Emission Spectrometry
jected to further operations, such as addition of an internal
(ICP-AES), Flame Atomic Absorption Spectrometry
standard, if the sample solutions are subjected to such opera-
(FAAS), or Graphite Furnace Atomic Absorption Spec-
tions in order to produce test solutions that are ready for
trometry (GFAAS) Techniques (Withdrawn 2021)
analysis.
E3193Test Method for Measurement of Lead (Pb) in Dust
by Wipe, Paint, and Soil by Flame Atomic Absorption
3.1.4 calibrationblanksolution,n—calibrationsolutionpre-
Spectrophotometry (FAAS) pared without the addition of any stock standard solution or
E3203Test Method for Determination of Lead in Dried working standard solution. ISO 15202
Paint, Soil, and Wipe Samples by Inductively Coupled 3.1.4.1 Discussion—The concentration of the analyte(s) of
Plasma-Optical Emission Spectroscopy (ICP-OES) interest in the calibration blank solution is taken to be zero.
3 4
The last approved version of this historical standard is referenced on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
www.astm.org. 4th Floor, New York, NY 10036, http://www.ansi.org.
D7439 − 21
3.1.5 calibration curve, n—a plot of instrument response 3.1.14 inductively coupled plasma (ICP) torch, n—a device
versus concentration of standards (1). used to support and introduce sample into an ICP discharge.
ISO 15202
3.1.6 calibration solution, n—solution prepared by dilution
of the stock standard solution(s) or working standard 3.1.15 initial calibration blank (ICB), n—a standard con-
solution(s), containing the analyte(s) of interest at a concen- taining no analyte that is used for the initial calibration and
tration(s) suitable for use in calibration of the analytical zeroing of the instrument response. E1613/E3193
instrument. ISO 15202 3.1.15.1 Discussion—The ICB must be matrix matched to
3.1.6.1 Discussion—The technique of matrix matching is the acid content of sample extracts and digestates. The ICB
normally used when preparing calibration solutions. must be measured during and after calibration. The measured
concentration of the ICB should not exceed 10% of the
3.1.7 chemical agent, n—any chemical element or
applicable occupational exposure limit or minimum level of
compound, on its own or admixed as it occurs in the natural
concern.
state or as produced, used or released including release as
waste, by any work activity, whether or not produced inten- 3.1.16 initial calibration verification (ICV), n—a solution
tionally and whether or not placed on the market. ISO 4225 (or set of solutions) of known analyte concentration used to
verify calibration standard levels. E1613/E3193
3.1.8 collision cell, n—chamberintheionpathbetweenm/z
3.1.16.1 Discussion—The concentration of analyte is to be
separation elements, or between ion source acceleration region
near the mid-range of the calibration curve. It is made from a
and the first analyzer, in tandem mass spectrometry in space
stock solution having a different manufacturer or manufacturer
configurations (2).
lot identification than the calibration standards. E1613/E3193
3.1.9 collision reaction cell, n—collisioncellforremovalof
3.1.16.2 Discussion—The ICV must be matrix matched to
interfering ions by ion/neutral reactions in ICP-MS (2).
theacidcontentofsampleextractsordigestates.TheICVmust
3.1.10 continuing calibration blank (CCB), n—a solution
bemeasuredaftercalibrationandbeforemeasuringanysample
containing no analyte added, that is used to verify blank
digestates or extracts. The measured value is to fall within
response and freedom from carryover. E1613/E3203
610% of the known value.
3.1.10.1 Discussion—The CCB must be analyzed after the
3.1.17 injectortube,n—theinnermosttubeofaninductively
CCV (see 3.1.11). The measured concentration of the CCB
coupled plasma torch, usually made of quartz or ceramic
should not exceed 10% of the applicable occupational expo-
materials, through which the sample aerosol is introduced to
sure limit or minimum level of concern.
the plasma. ISO 15202
3.1.11 continuing calibration verification (CCV), n—a solu-
3.1.18 inner (nebulizer) argon flow, n—the flow of argon
tion (or set of solutions) of known analyte concentration used
gasthatisdirectedthroughthenebulizerandcarriesthesample
to verify freedom from excessive instrumental drift.
aerosol through the injector and into the plasma; typically 0.5
E1613/E3203
L/min – 2 L/min. ISO 15202
3.1.11.1 Discussion—TheconcentrationoftheCCVistobe
3.1.19 instrumental detection limit (IDL), n—the lowest
near the mid-range of a linear calibration curve.
concentration at which the instrumentation can distinguish
3.1.11.2 Discussion—The CCV must be matrix matched to
analyte content from the background generated by a minimal
the acid content present in sample digestates or extracts. The
matrix. E1613/E3203
CCV must be analyzed before and after all samples and at a
3.1.19.1 Discussion—The IDL can be determined from
frequency of not less than every ten samples. The measured
blank,acidified,deionized,orultrapurewaterasthematrixand
value is to fall within 610% of the known value.
fromthesamecalculationmethodsusedtodetermineamethod
3.1.12 field blank, n—sampling media (for example, an air
detection limit (see 3.1.28).
filter) that is taken through the same handling procedure as a
3.1.20 instrumental QC standards, n—these provide infor-
sample, except that no sample is collected (that is, no air is
mation on measurement performance during the instrumental
purposely drawn through the sampler), and is then returned to
analysis portion of the overall analyte measurement process.
the laboratory for analysis. D7035
E1613/E3193
3.1.12.1 Discussion—Analysisresultsfromfieldblankspro-
3.1.20.1 Discussion—These standards include CCBs,
vide information on the analyte background level in the
CCVs, ICBs, and ICVs.
sampling media, combined with the potential contamination
experienced by samples collected within the batch resulting
3.1.21 intermediate (auxiliary) argon flow, n—the flow of
from handling.
argongasthatiscontainedbetweentheintermediateandcenter
(injector) tubes of an inductively coupled plasma torch; typi-
3.1.13 inductively coupled plasma (ICP), n—a high-
cally 0.1 L/min – 2 L/min. ISO 15202
temperature discharge generated by a flowing conductive gas,
normallyargon,throughamagneticfieldinducedbyaloadcoil
3.1.22 internalstandard,n—non-analyteelement,presentin
that surrounds the tubes carrying the gas. ISO 15202
all solutions analyzed, the signal from which is used to correct
for matrix interferences or improve analytical precision.
ISO 15202
3.1.22.1 Discussion—The internal standard is added in
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard. knownandconstantamount(s)toallanalyzedsolutions.Thisis
D7439 − 21
used to correct for instrument drift and some matrix effects by 3.1.34 primary standard, n—anacceptablereferencesample
measuring the relative instrument response of the internal or device used for establishing measurement of a physical
standard(s) to the other analytes that are components of the quantity, directly defined and established by some authority,
same solution. The element(s) selected for use as an internal against which all secondary standards are compared. adapted
standard must be initially absent from the sample solution. from D5011
3.1.35 reagent blank, n—all reagents used in sample
3.1.23 laboratory blank, n—unused sample media (for
preparation, in the same quantities used to prepare blank and
example, an air filter), taken from the same batch used for
sample solutions. ISO 18158
sampling, that does not leave the laboratory. ISO 15202
3.1.35.1 Discussion—The reagent blank is used to assess
3.1.24 linear dynamic range, n—therangeofconcentrations
contamination from the laboratory environment and to charac-
over which the calibration curve for an analyte is linear. It
terize background from the reagents used in sample
extends from the detection limit to the onset of calibration
preparation. ISO 18158
curvature. ISO 15202
3.1.36 sample dissolution, n—the process of obtaining a
3.1.25 load coil, n—a length of metal tubing (typically
solution containing the analyte(s) of interest from a sample.
copper) which is wound around the end of an inductively
This may or may not involve complete dissolution of the
coupled plasma torch and connected to the radio frequency
sample. D6785/ISO 15202
generator. ISO 15202
3.1.37 sample preparation, n—all operations carried out on
3.1.26 matrix interference, n—interferenceofanon-spectral
a sample, usually after transportation and storage, to prepare it
nature which is caused by the sample matrix. ISO 15202
for analysis, including transformation of the sample into a
3.1.27 matrix matching, n—a technique used to minimize
measurable state, where necessary. ISO 18158
the effect of the test solution matrix on the analytical results.
3.1.38 sample solution, n—solution prepared from a sample
ISO 15202
by the process of sample dissolution. ISO 15202
3.1.27.1 Discussion—Matrix matching involves preparing
3.1.39 secondary standard, n—an acceptable reference
calibration solutions in which the concentrations of acids and
sample or device used for establishing measurement of a
other major solvents and solutes are matched with those in the
physical quantity, used as a means of comparison, but checked
test solutions.
against a primary standard. adapted from D5011
3.1.28 method detection limit (MDL), n—the minimum
3.1.40 spectral interference, n—an isobaric interference
concentration of an analyte that can be reported with a 99%
caused by a species other than the analyte of interest.
confidence that the value is above zero. D1356
3.1.40.1 Discussion—Spectral interferences may involve an
3.1.28.1 Discussion—The MDL is also known as the limit
atomic, polyatomic, or doubly-charged ion species. An ex-
of detection (LOD) (3).
40 + 40 +
ampleofanatomicinterferenceis Ar on Ca .Anexample
40 16 + 56 +
3.1.29 method quantitation limit (MQL), n—the minimum
of a polyatomic interference is Ar O on Fe .An example
48 2+ 24 +
concentration of an analyte that can be measured with accept-
of a doubly-charged ion interference is Ti on Mg (4).
able precision. D7035
3.1.41 spiked reagent blank, n—a reagent blank aliquot that
3.1.29.1 Discussion—The MQL is also known as the limit
is spiked with a known amount of analyte.
of quantitation (3).
3.1.41.1 Discussion—Analysis results for spiked reagent
3.1.30 nebulizer, n—a device used to create an aerosol from
blanks are used to provide information on the precision and
a liquid. ISO 15202
bias of the overall analysis process.
3.1.31 occupational exposure limit value (OELV), n—limit 3.1.42 spiked media blank, n—a reagent blank aliquot that
of the time-weighted average of the concentration of a chemi-
includes the sampling media (that is, filter), but includes no
cal agent in the air within the breathing zone of a worker in
actual sample, that is spiked with a known amount of analyte.
relation to a specified reference period ISO 18158
3.1.43 spray chamber, n—a device placed between a nebu-
3.1.31.1 Discussion—The term “limit value” is often used
lizer and an inductively coupled plasma torch whose function
as a synonym for OELV, but the latter is preferred because
istoseparateoutaerosoldropletsinaccordancewiththeirsize,
thereismorethanonelimitvalue(forexample,biologicallimit
so that only very fine droplets pass into the plasma, and large
value and OELV).
droplets are drained or pumped to waste. ISO 15202
3.1.31.2 Discussion—An example of an OELV would be a
3.1.44 stock standard solution, n—solution used for prepa-
PermissibleExposureLimit(PEL)suchasthoseestablishedby
rationofworkingstandardsolutionsorcalibrationsolutions,or
the U.S. Occupational Safety and Health Administration.
both, containing the analyte(s) of interest at a certified concen-
3.1.32 outer (plasma) argon flow, n—the flow of argon gas
tration(s) traceable to primary standards (National Institute of
thatiscontainedbetweentheouterandintermediatetubesofan Standards and Technology or international measurement
inductively coupled plasma torch; typically 7 L/min – 15
standards). ISO 15202
L/min. ISO 15202
3.1.45 test solution, n—blank solution or sample solution
3.1.33 pneumatic nebulizer, n—a nebulizer that uses high- thathasbeensubjectedtoalloperationsrequiredtobringitinto
speed gas flows to create an aerosol from a liquid. ISO 15202 a state in which it is ready for analysis. ISO 15202
D7439 − 21
graphite furnace atomic absorption spectrometry, electroanalysis, and so
3.1.45.1 Discussion—“Ready for analysis” includes any
forth).
requireddilution(s)oradditionofaninternalstandard,orboth.
Whenblanksolutionsandsamplesolutionsarenotsubjectedto
5. Significance and Use
anyfurtheroperationsbeforeanalysis,theythenareinfacttest
5.1 The health of workers in many industries is at risk
solutions.
through exposure by inhalation to toxic metals and metalloids.
3.1.46 transport interference, n—non-spectral interference
Industrialhygienistsandotherpublichealthprofessionalsneed
caused by a difference in viscosity, surface tension, or density
to determine the effectiveness of measures taken to control
between the calibration and test solutions (for example, due to
workplace exposure. This is generally achieved by making
differences in dissolved solids content, type and concentration
workplace air measurements. This test method has been
of acid, and so forth). ISO 15202
developed to make available a standard methodology for valid
3.1.47 tune, n—analyze a solution containing a range of
exposure measurements for a wide range of metals and
isotopic masses to establish ICP-MS mass-scale accuracy,
metalloids that are used in industry. It will be of benefit to
massresolution,signalintensity,andprecisionpriortocalibra-
agencies concerned with health and safety at work; analytical
tion (1).
laboratories; industrial hygienists and other public health
professionals; industrial users of metals and metalloids and
3.1.48 ultrasonic nebulizer, n—a nebulizer in which the
their workers; and other groups.
aerosol is created by flowing a liquid across a surface that is
oscillating at an ultrasonic frequency. ISO 15202
5.2 This test method specifies a generic method for deter-
mination of the concentration of metals and metalloids in
3.1.49 working standard solution, n—solution, prepared by
workplace air samples using ICP-MS. For many metals and
dilution of the stock standard solution(s), that contains the
metalloids, analysis by ICP-MS may be advantageous, when
analyte(s) of interest at a concentration(s) better suited for
compared to methods such as ICP atomic emission
preparationofcalibrationsolutionsthantheconcentration(s)of
spectrometry, due to its sensitivity and the presence of fewer
the analyte(s) in the stock standard solution(s). ISO 15202
spectral interferences.
3.1.50 workplace, n—designated area or areas in which the
5.3 The analysis results can be used for the assessment of
work activities are carried out. ISO 18158
workplaceexposurestometalsandmetalloidsinworkplaceair.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 collision/reaction system, n—any system (for
6. Apparatus
example,acollisioncelloracollisionreactioncell)thatisused
6.1 Apparatus for Sample Preparation and Analysis—
for charge exchange neutralization of interfering ions in
Details regarding laboratory apparatus required for individual
ICP-MS.
sample dissolution methods are given in Annex A1 through
3.2.1.1 Discussion—Collision/reaction systems utilize one
AnnexA5.Ordinarylaboratoryapparatusarenotlisted,butare
or more techniques to reduce or eliminate spectral interfer-
assumed to be present.
ences. These may include (but are not necessarily limited to)
6.1.1 Disposable Gloves, impermeable and powder-free, to
oscillating radio frequency, ion-neutral reactions, and kinetic
avoidthepossibilityofcontaminationandtoprotectthemfrom
energy discrimination. References (5) and (6) provide addi-
contact with toxic and corrosive substances. PVC gloves are
tional information.
suitable.
6.1.2 Glassware, beakers and volumetric flasks complying
4. Summary of Test Method
with the requirements of Specification E288 or ISO 1042,
made of borosilicate glass and complying with the require-
4.1 A known volume of air is drawn through appropriate
ments of Specification E438 or ISO 3585. Glassware shall be
sampling media to collect airborne particulates suspected to
cleanedbeforeusebysoakinginnitricacidforatleast24hours
contain metals or metalloids, or both, in accordance with Test
and then rinsing thoroughly with water. Alternatively, before
MethodD7035,takingintoaccountadditionalinformationand
use, glassware shall be cleaned with a suitable laboratory
methodologies in Guide D8358.
detergent using a laboratory washing machine.
4.2 In general, particulate metals and metalloids (and their
6.1.3 Flat-tipped Forceps, polytetrafluoroethylene (PTFE)-
compounds) that are commonly of interest in samples of
tipped, for unloading filters from samplers or from filter
workplace air are converted to water- or acid-soluble ions in
transport cassettes.
sample solutions by one of the sample dissolution methods
6.1.4 Piston-operated Volumetric Pipettors and Dispensers,
specified.
complying with the requirements of Specification E1154 or
4.3 Test solutions, prepared from the sample solutions after
ISO 8655, for pipetting and dispensing of leach solutions,
sample dissolution, are analyzed using inductively coupled acids, and so forth.
plasma – mass spectrometry (ICP-MS) to determine the
6.1.5 Polyethylene Bottles, low density, with leak-proof
concentration of target elements in the sampled air. screw cap.
NOTE 1—The sample dissolution procedures described in this standard
6.1.6 Inductively Coupled Plasma–Mass Spectrometer,
may be suitable for preparation of samples for subsequent analysis by
computer-controlled, equipped with an auto-sampler.
other methods besides ICP-MS (for example: inductively coupled plas-
ma–emission spectrometry as described in Test Method D7035, flame NOTE 2—An auto-sampler having a flowing rinse is strongly recom-
atomic absorption spectrophotometry as described in Practice D4185, mended.
D7439 − 21
NOTE 8—Analytes that are grouped together in working standard
7. Reagents
solutions should be chosen carefully to ensure chemical compatibility and
7.1 Reagents for Sample Preparation and Analysis—Details
to avoid spectral interferences. Also, the type and volume of each acid
regarding reagents that are required for individual sample
added should be selected carefully to ensure the stability of elements of
interest.
dissolutionmethodsaregiveninAnnexA1throughAnnexA5.
During sample preparation and analysis, use only reagents of
7.1.8.2 Storeworkingstandardsolutionsinsuitablecontain-
spectroscopic grade or greater purity. The concentration of
ers for a maximum period of one month.
metals and metalloids of interest shall be less than 0.1 µg/L.
NOTE 9—Containers such as bottles made of perfluoroalkoxy (PFA)
The use of ultrapure acids is recommended.
polymer, polytetrafluoroethylene (PTFE), or low-density polyethylene are
normally suitable.
NOTE 3—Reagents of higher purity are needed in order to obtain
adequatedetectionlimitsforsomemetalsandmetalloids(forexample,for
7.1.8.3 From the working standard solutions, prepare a set
beryllium measurements, a Be concentration of less than 0.01 µg/L is
of calibration solutions by serial dilutions, covering the range
recommended).
of concentrations for each of the metals and metalloids of
7.1.1 Water, complying with the requirements for ASTM
interest.Itisrecommendedthataminimumofthreecalibration
Type I water (see Specification D1193).
solutions be prepared. Also prepare a calibration blank solu-
7.1.2 Nitric Acid (HNO ), concentrated, ρ ~1.42 g/mL
3 tion. During preparation of calibration solutions, add reagents
(~70% m⁄m).
(for example, acids), as required, to matrix-match the calibra-
7.1.3 Laboratory Detergent, suitable for cleaning of labora-
tion solutions with the test solutions. Calibration solutions
tory ware. The use of detergents containing phosphorus or
should be prepared fresh daily.
other potential analytes should be avoided.
NOTE 10—The shelf life of calibration solutions may be extended if
7.1.4 PerchloricAcid (HClO ),concentrated,ρ~1.67g/mL,
they are demonstrated, by comparison with calibration verification
~70% (m⁄m).
solutions, to be acceptable.
7.1.5 HydrochloricAcid (HCl),concentrated,ρ~1.18g/mL,
NOTE 11—The type(s) and volume(s) of reagents required to matrix
~36% (m/m). match the calibration and test solutions will depend on the sample
dissolution method used.
NOTE4—UseofHClistypicallynotrecommendedinICP-MSsystems
7.1.9 Internal Standard Stock Solutions:
that do not include a collision/reaction system, or when such a system is
not used. 7.1.9.1 Select elements to be used as internal standards.
Table 2 provides a list of elements frequently used. For full
7.1.6 Sulfuric Acid (H SO ), concentrated, ρ ~1.84 g/mL,
2 4
mass range scans use a minimum of three internal standards
~98% (m/m).
with the use of five suggested. Internal standards in low,
NOTE 5—Use of H SO is typically not recommended in ICP-MS
2 4
middle, and high mass ranges are recommended.
systems that do not include a collision/reaction system, or when such a
system is not used. NOTE12—Internalstandardsarerecommendedinallanalysestocorrect
for instrument drift and physical interferences. Internal standards should
7.1.7 Stock Standard Solutions:
be added to blanks, samples and standards in a like manner. Internal
7.1.7.1 Forstockstandardsolutions,usecommercialsingle-
standards are typically selected to match the mass range of the analytes of
element or multi-element standard solutions with certified
interest; however, for analytes with high ionization potential (such as
arsenic and selenium), consideration should be given to matching ioniza-
concentrations traceable to primary standards (National Insti-
tion potential.
tuteofStandardsandTechnologyorinternationalmeasurement
NOTE 13—Internal standards may be added to each test solution during
standards). Observe the manufacturer’s expiration date or
the sample preparation process or, alternatively, by use of an on-line
recommended shelf life.
internal standard addition system.
NOTE 6—Commercially available stock standard solutions for metals 7.1.9.2 Usestockstandardsolutionstopreparetestsolutions
and metalloids have nominal concentrations of 10 to 10000 mg/L for
that contain the internal standard elements. Observe the manu-
singleelementstandards,and10to1000mg/Lformultielementstandards.
facturer’s expiration date or recommended shelf life.
7.1.7.2 Alternatively, prepare stock standard solutions from
7.1.10 Argon, high purity grade (99.99% or better).
high-purity metals and metalloids or their salts. The procedure
used to prepare the solutions shall be fit for purpose, and the
TABLE 2 Internal Standards and Limitations of Use
calibration of any apparatus used shall be traceable to primary
Internal
Mass Possible Limitation
standards. The maximum recommended shelf life is one year
Standard
from date of initial preparation.
Lithium 6 May be present in samples
A
Scandium 45 Polyatomic ion interference; may be present in samples
7.1.7.3 Storestockstandardsolutionsinsuitablecontainers,
A
Yttrium 89 May be present in samples
such as low-density polyethylene bottles.
Rhodium 103 .
A
7.1.8 Working Standard Solutions and Calibration Solu-
Indium 115 Isobaric interference by Sn
A
Terbium 159 .
tions:
Holmium 165 .
7.1.8.1 From the stock standard solutions, prepare working
Lutetium 175 .
standardsolutionsbyserialdilutions;theseshallincludeallthe Platinum 195 {
A
Bismuth 209 May be present in samples
metals and metalloids of interest at suitable concentration.
A
Internal standards recommended for use with this test method. It is also
NOTE 7—Suitable concentrations will typically fall between 1 µg/Land
necessary when analyzing a new sample matrix that a scan for the presence of
100 µg/L; however, newer ICP-MS systems can detect some metals and
internal standards be performed.
metalloids reliably at levels below 1 µg/L.
D7439 − 21
8. Hazards 10.1.2 Alternatively, if it is known that no insoluble com-
poundsofthemetals,ormetalloids,orboth,ofinterestareused
8.1 Concentrated NitricAcidiscorrosiveandoxidizing,and
in the workplace, and that none are produced in the processes
nitric acid vapor is an irritant.Avoid exposure by contact with
carried out, prepare test solutions for ICP-MS analysis using
the skin or eyes, or by inhalation of fumes. Use suitable
one of the sample dissolution methods for total metals and
personal protective equipment (including impermeable gloves,
metalloids and their compounds, as prescribed in Annex A2
safety goggles, laboratory coat, and so forth) when working
(hot plate digestion), AnnexA3 (microwave digestion), Annex
withconcentratednitricacid,andcarryoutopen-vesselsample
A4 (hot block digestion), and Annex A5 (microwave diges-
dissolution with nitric acid in a fume hood.
tion).
8.2 Concentrated Perchloric Acid is corrosive and
NOTE 14—The methods prescribed in AnnexA2 through AnnexA5 are
oxidizing, and its vapor is an irritant. Perchloric acid forms
not specific for soluble metal, or metalloid compounds, or both. However,
explosive compounds with organics and many metal salts.
in these circumstances, they may be used as an alternative to the method
Avoid exposure by contact with the skin or eyes, or by
described in Annex A1, if this is more convenient.
inhalation of fumes. Use suitable personal protective equip-
10.2 Total Metals and Metalloids and their Compounds:
ment (including impermeable gloves, safety goggles, labora-
10.2.1 If results are required for total metals, or metalloids,
tory coat, and so forth) when working with perchloric acid.
or both, and their compounds, select a suitable sample prepa-
Carry out sample dissolution with perchloric acid in a fume
ration method from those specified in Annex A2 (hot plate
hoodwithascrubberunitthatisspeciallydesignedforusewith
digestion), Annex A3 (microwave digestion), Annex A4 (hot
HClO . See Appendix X1 for further pertinent safety informa-
block digestion), and Annex A5 (microwave digestion). Prac-
tion.
tice D8344 may also be suitable. Take into consideration the
8.3 Concentrated Hydrofluoric Acidishighlycorrosive,and
applicability of each method for dissolution of target metals
is very toxic by inhalation or contact with the skin. Avoid
and metalloids of interest from materials that could be present
exposure by contact with the skin or eyes, or by inhalation of
in the test atmosphere (refer to the clause on the effectiveness
HF vapor. It is essential to use suitable personal protective
of the sample dissolution method in the Annex in which the
equipment, including impermeable gloves and eye protection)
method is specified), and the availability of the required
when working with HF. Use a fume hood when working with
laboratory apparatus.
concentrated HF and when carrying out open-vessel dissolu-
NOTE 15—In selection of a sample preparation method, consideration
tion with HF. See Appendix X1 for further pertinent safety
should be given to the metal or metalloid compounds that may be present
information.
inthetestatmosphere.Somecompounds,suchasrefractorymetaloxides,
8.4 Concentrated Hydrochloric Acid is corrosive, and HCl
mayrequireamorerobustsamplepreparationmethodthanisrequiredfor
other compounds, or for the metals or metalloids themselves.
vapor is an irritant.Avoid exposure by contact with the skin or
eyes, or by inhalation of the vapor. Use suitable personal
10.2.2 Use the selected sample dissolution method to pre-
protectiveequipment(suchasgloves,faceshield,andsoforth)
pare sample solutions, from which test solutions are prepared
when working with HCl. Handle open vessels containing
foranalysisoftotalmetalsandmetalloidsandtheircompounds
concentrated HCl in a fume hood. The vapor pressure of HCl
by ICP-MS.
ishigh,sobewareofpressurebuildupinstopperedflaskswhen
10.3 Deposits of Particles on Interior Sampler Surfaces—
preparing mixtures containing HCl.
Give consideration to metal and metalloid particles that may
8.5 Concentrated Sulfuric Acid is corrosive and causes
have deposited on interior sampler surfaces (for example, by
burns. Vapor produced when concentrated H SO is heated is
2 4
becoming dislodged from the filter during transportation), and
an irritant. Avoid exposure by contact with the skin or eyes.
determine whether the sample of interest should include such
Use suitable personal protective equipment (such as gloves,
particles. If the sample is determined to include such particles,
faceshield,andsoforth)whenworkingwithH SO .Carryout
2 4
determine a methodology for removing them from the interior
sample dissolution with H SO in a fume hood. Exercise
2 4
samplersurfacesandincludingthemintheanalysis.SeeGuide
cautionwhendilutingH SO withwater,asthisprocessisvery
2 4
D8358 for additional information and suggested methodolo-
exothermic. Do not add water to H SO , since it reacts
2 4
gies.
violently when mixed in this manner; rather, prepare H SO /
2 4
10.4 Mixed Exposures:
H O mixtures by adding H SO to water.
2 2 4
10.4.1 If analytical results are required for both soluble and
9. Sampling Procedure
insoluble metals, or metalloids, or both, and their compounds,
first use the sample preparation procedure specified in Annex
9.1 Samples to be prepared for analysis by this test method
A1 to prepare sample solutions, from which test solutions are
shall be collected in accordance with test method D7035.
prepared for determination of soluble metal and metalloid
10. Sample Preparation
compounds for subsequent analysis by ICP-MS.
10.1 Soluble Metals and Metalloids and their Compounds: 10.4.2 Select a suitable sample preparation method from
10.1.1 If results are required for soluble metal, or metalloid those specified in Annex A2 (hot plate digestion), Annex A3
compounds, or both, use the sample dissolution method speci- (microwave digestion), Annex A4 (hot block digestion), and
fied in AnnexA1 to prepare sample solutions, from which test Annex A5 (microwave digestion). Use this procedure to treat
solutions are prepared for analysis by ICP-MS. undissolved material left over after employing the preparation
D7439 − 21
air samples is applicable to a wide range of instruments. For example,
methodforsolublemetalsandmetalloidsandtheircompounds
ICP-MS systems may be equipped with a collision/reaction system, of
(Annex A1), and prepare sample solutions, from which test
which there are several types. Each of these different types of instruments
solutions are prepared for subsequent analysis by ICP-MS.
needs to be set up and operated in a different manner. There are some
principles that apply to the development of methods for all ICP-MS
10.5 Special Cases:
instruments,buttherearealsomanyparametersthatareonlyapplicableto
10.5.1 Effectiveness of Sample Dissolution Procedure—If
particular instruments.
there is any doubt about whether the selected sample prepara-
tion method will exhibit the required analytical recovery when 11.1.2 Quantitation Limit—For each metal and metalloid of
used for dissolution of the metals and metalloids of interest interest, determine a value for the lower limit of the analytical
from materials that could be present in the test atmosphere,
range that will be satisfactory for the intended measurement
determine its effectiveness for the particular application. task. For example, if the measurement task entails testing
10.5.1.1 Fortotalmetalsandmetalloids,analyticalrecovery
compliance with a limit value, use the following equation to
may be estimated by analyzing a performance evaluation calculate the least amount of metal or metalloid of interest that
material of known composition that is similar in nature to the
will need to be quantified when it is determined at the
materials being produced in the workplace. An example concentration of 0.1 × its limit value:
evaluation material would be a representative certified refer-
m 5 0.1 3LV 3q 3t
L v min
ence material (CRM).
where:
NOTE 16—It should be recognized that, for a bulk sample, certain
m = the required lower limit of the analytical range, in µg,
physical characteristics, such as particle size and agglomeration, could
L
haveasignificantinfluenceontheefficacyofitsdissolution.Also,smaller of the metal or metalloid;
quantities of material are often much more easily dissolved than greater
LV = the limit value, in mg/m , for the metal or metalloid;
quantities.
q = the design flow rate of the sampler to be used, in
v
10.5.1.2 For soluble metals and metalloids, analytical re- L/min (in accordance with Test Method D7035); and
t = the minimum sampling time that will be used, in min.
covery is best determined by analyzing spiked media blanks
min
(that is, filters spiked with solutions containing known masses
Then calculate the required quantitation limit, in mg/L, by
of the soluble compound(s) of interest).
dividing the lower limit of the analytical range, in µg, by the
10.5.1.3 Recovery should be at least 90% of the known
volume of the test solution, in mL.
value for all elements included in the spiked media blanks,
with a relative standard deviation of less than 5% (7).Ifthe NOTE 18—In some instances, it may not be possible to achieve a
quantitation limit that is 0.1 × the limit of interest. In those instances,
analytical recovery is outside the required range of acceptable
MDL data and other factors should be considered to achieve the lowest
values, investigate the use of an alternative sample dissolution
quantitation limit that meets specified method requirements.
method.
NOTE 19—For other measurement tasks it might be necessary to obtain
10.5.1.4 Donotuseacorrectionfactortocompensateforan
quantitative measurements below 0.1 times the limit value, in which case
apparently ineffective sample dissolution method, since this
an appropriate lower value for m would be used.
L
might equally lead to erroneous results.
11.1.3 Interferences—Give consideration to the significance
10.5.2 Treatment of Undissolved Material Following
of any known interferences in the context of the measurement
Sample Dissolution—If undissolved residue remains after car-
task (see Appendix X3 for information). For each potentially
ryingoutsampledissolutionusinghotplate,microwave,orhot
usefulmass-to-chargeratio,refertopublishedinformation,and
blocktechniques(AnnexA2,AnnexA3,AnnexA4,andAnnex
consider the relationship between the magnitude of interfer-
A5 respectively), further sample treatment may be required in
ences and the relative limit values of the elements to be
order to dissolve target analyte elements. This would normally
determined. If the sum of all potential interferences is greater
entail filtration to capture the undissolved material, with
than 0.1 × the limit value of the analyte, consider alternatives,
subsequentdigestionoftheresidueusinganalternativesample
suchasanalternativemass-to-chargeratiooruseofacollision/
preparation method.
reaction system (if available). See Appendix X3 for additional
information.
11. Analysis
11.1 Method Optimization:
NOTE 20—The use of interference correction equations for isobaric
11.1.1 General Guidance—Optimize the test method and overlaps is especially suitable when the source of the interference is
knownandconstant(forexample,acidmatchingwithknownquantitiesof
validate the performance of the method for analysis of test
HCl).
solutions,inaccordancewiththeperformancecriteriaprovided
NOTE 21—The use of a collision/reaction system may eliminate many
in this test method, or specified customer requirements, or
isobaric elemental or polyatomic interferences, and (if available) is
both, using sample solutions prepared as described in Section
typically preferable over use of alternative mass-to-charge ratios that may
9ofthistestmethod,whichissuitableforusewiththeavailable
not be as sensitive as the primary mass-to-charge ratio for the an
...

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: D7439 − 14 D7439 − 21
Standard Test Method for
Determination of Elements in Airborne Particulate Matter by
Inductively Coupled Plasma–Mass Spectrometry
This standard is issued under the fixed designation D7439; 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 standard test method specifies a procedure for sample preparation and analysis of airborne particulate matter for the
content of metals and metalloids in workplace air samples using inductively coupled plasma–mass spectrometry (ICP-MS). This
test method can be used for other air samples provided the user ensures the validity of the test method (by ensuring that appropriate
data quality objectives can be achieved).
1.2 This standard test method assumes that samples will have been collected in accordance with Test Method D7035 with
consideration of guidance regarding wall deposits provided in Guide D8358.
1.3 This standard test method should be used by analysts experienced in the use of ICP-MS, the interpretation of spectral and
matrix interferences and procedures for their correction.
1.4 This standard test method specifies a number of alternative methods for preparing test solutions from samples of airborne
particulate matter. One of the specified sample preparation methods is applicable to the measurement of soluble metal or metalloid
compounds. Other specified methods are applicable to the measurement of total metals and metalloids.
1.5 It is the user’s responsibility to ensure the validity of the standardthis test method for filters of samples collected from untested
matrices.
1.6 Table 1 provides a non-exclusive list of metals and metalloids for which one or more of the sample dissolution methods
specified in this document is applicable.
1.7 This standard test method is not applicable to compounds of metals and metalloids that are present in the gaseous or vapor
state.
1.8 Table 3 provides examples of instrumental detection limits (IDL) that can be achieved with this test method. Table 5 provides
examples of method detection limits (MDL) that can be achieved.
1.9 No detailed operating instructions are provided because of differences among various makes and models of suitable ICP-MS
This test method is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Subcommittee D22.04 on Workplace Air Quality.
Current edition approved Jan. 15, 2014Sept. 1, 2021. Published May 2014October 2021. Originally approved in 2008. Last previous edition approved in 20082014 as
D7439 – 08.D7439 – 14. DOI: 10.1520/D7439-14.10.1520/D7439-21.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7439 − 21
TABLE 1 Applicable Metals and Metalloids
A A A
Element Symbol CASRN Element Symbol CASRN Element Symbol CASRN
Aluminum Al 7429-90-5 Antimony Sb 7440-36-0 Arsenic As 7440-38-2
Barium Ba 7440-39-3 Beryllium Be 7440-41-7 Bismuth Bi 7440-69-9
Boron B 7440-42-8 Cadmium Cd 7440-43-9 Calcium Ca 7440-70-2
Cesium Cs 7440-46-2 Chromium Cr 7440-47-3 Cobalt Co 7440-48-4
B
Copper Cu 7440-50-8 Gallium Ga 7440-55-3 Germanium Ge 7440-56-4
Hafnium Hf 7440-58-6 Indium In 7440-74-6 Iron Fe 7439-89-6
Lead Pb 7439-92-1 Lithium Li 7439-93-2 Magnesium Mg 7439-95-4
B
Manganese Mn 7439-96-5 Mercury Hg 7439-97-6 Molybdenum Mo 7439-98-7
B
Nickel Ni 7440-02-0 Niobium Nb 7440-03-1 Phosphorus P 7723-14-0
Platinum Pt 7440-06-4 Potassium K 7440-09-7 Rhodium Rh 7440-16-6
Selenium Se 7782-49-2 Silver Ag 7440-22-4 Sodium Na 7440-23-5
Tellurium Te 13494-80-9 Thallium Tl 7440-28-0 Tin Sn 7440-31-5
Tungsten W 7440-33-7 Uranium U 7440-61-1 Vanadium V 7440-62-2
Yttrium Y 7440-65-5 Zinc Zn 7440-66-6 Zirconium Zr 7440-67-7
A
CASRN = Chemical Abstracts Service Registry Number
B
For the elements in italics, there is insufficient information available on the effectiveness of the sample dissolution procedures in Annex A1 through Annex A4A5.
instruments. Instead, the analyst shall follow the instructions provided by the manufacturer of the particular instrument. This test
method does not address comparative accuracy of different devices or the precision between instruments of the same make and
model.
1.10 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.11 This standard test method contains notes that are explanatory and are not part of the mandatory requirements of the method.
1.12 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.13 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
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
D4185 Test Method for Measurement of Metals in Workplace Atmospheres by Flame Atomic Absorption Spectrophotometry
D4840 Guide for Sample Chain-of-Custody Procedures
D5011 Practices for Calibration of Ozone Monitors Using Transfer Standards
D6785 Test Method for Determination of Lead in Workplace Air Using Flame or Graphite Furnace Atomic Absorption
Spectrometry
D7035 Test Method for Determination of Metals and Metalloids in Airborne Particulate Matter by Inductively Coupled Plasma
Atomic Emission Spectrometry (ICP-AES)
D7202 Test Method for Determination of Beryllium in the Workplace by Extraction and Optical Fluorescence Detection
D7440 Practice for Characterizing Uncertainty in Air Quality Measurements
D8344 Practice for Ammonium Bifluoride and Nitric Acid Digestion of Airborne Dust and Dust-Wipe Samples for the
Determination of Metals and Metalloids
D8358 Guide for Assessment and Inclusion of Wall Deposits in the Analysis of Single-Stage Samplers for Airborne Particulate
Matter
E288 Specification for Laboratory Glass Volumetric Flasks
E438 Specification for Glasses in Laboratory Apparatus
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E882 Guide for Accountability and Quality Control in the Chemical Analysis Laboratory
E1154 Specification for Piston or Plunger Operated Volumetric Apparatus
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.
D7439 − 21
E1613 Test Method for Determination of Lead by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES),
Flame Atomic Absorption Spectrometry (FAAS), or Graphite Furnace Atomic Absorption Spectrometry (GFAAS) Techniques
(Withdrawn 2021)
E3193 Test Method for Measurement of Lead (Pb) in Dust by Wipe, Paint, and Soil by Flame Atomic Absorption
Spectrophotometry (FAAS)
E3203 Test Method for Determination of Lead in Dried Paint, Soil, and Wipe Samples by Inductively Coupled Plasma-Optical
Emission Spectroscopy (ICP-OES)
2.2 ISO and European Standards:
ISO 1042 Laboratory Glassware—One-Mark Volumetric Flasksglassware — One-mark volumetric flasks
ISO 3585 Borosilicate Glass 3.3—Propertiesglass 3.3 — Properties
ISO 4225 Air quality — General aspects — Vocabulary
ISO 8655 Piston-Operated Volumetric ApparatusPiston-operated volumetric apparatus (6 parts)
ISO 15202 Workplace Air—Determination of Metals and Metalloids in Airborne Particulate Matter by Inductively Coupled
Plasma Atomic Emission Spectrometryair — Determination of metals and metalloids in airborne particulate matter by
inductively coupled plasma atomic emission spectrometry (3 parts)
ISO 17294 Water Quality—Application of Inductively Coupled Plasma Mass Spectrometryquality — Application of inductively
coupled plasma mass spectrometry (ICP-MS) (2 parts)
EN 1540ISO 18158 Workplace Atmospheres—Terminologyair — Terminology
3. Terminology
3.1 Definitions—For definitions of other terms used in this standard test method, refer to Terminology D1356.
3.1 Definitions of Terms Specific to This Standard:—For definitions of other terms used in this test method, refer to Terminology
D1356.
3.1.1 analytical recovery—recovery, n—ratio of the mass of analyte measured to the known mass of analyte in the sample,
expressed as a percentage. D6785
3.1.2 batch—batch, n—a group of field or quality control (QC) samples that are collected or processed together at the same time
using the same reagents and equipment. E1613E3203
3.1.3 blank solution—solution, n—solution prepared by taking a reagent blank, laboratory blank or field blank through the same
procedure used for sample dissolution. ISO 15202
3.1.3.1 Discussion—
A blank solution may need to be subjected to further operations, such as addition of an internal standard, if the sample solutions
are subjected to such operations in order to produce test solutions that are ready for analysis.
3.1.4 calibration blank solution—solution, n—calibration solution prepared without the addition of any stock standard solution or
working standard solution. ISO 15202
3.1.4.1 Discussion—
The concentration of the analyte(s) of interest in the calibration blank solution is taken to be zero.
3.1.5 calibration curve—curve, n—a plot of instrument response versus concentration of standards (1).
3.1.6 calibration solution—solution, n—solution prepared by dilution of the stock standard solution(s) or working standard
solution(s), containing the analyte(s) of interest at a concentration(s) suitable for use in calibration of the analytical instrument.
ISO 15202
3.1.6.1 Discussion—
The technique of matrix matching is normally used when preparing calibration solutions.
3.1.7 chemical agent—agent, n—any chemical element or compound, on its own or admixed as it occurs in the natural state or
as produced, used or released including release as waste, by any work activity, whether or not produced intentionally and whether
or not placed on the market. EN 1540ISO 4225⁄ISO 15202
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.
The boldface numbers in parentheses refer to the list of references at the end of this standard.
D7439 − 21
3.1.8 collision/reaction system—collision cell, n—any system, such as a transmission collision cell, to which an oscillating radio
frequency potential is applied that is used for charge exchange neutralization of interfering ions in inductively coupled plasma mass
spectrometry chamber in the ion path between m/z separation elements, or between ion source acceleration region and the first
analyzer, in tandem mass spectrometry in space configurations (2).
3.2.8.1 Discussion—
Some collision systems also have one or more reaction modes that can further reduce selected interferences.
3.1.9 collision reaction cell, n—collision cell for removal of interfering ions by ion/neutral reactions in ICP-MS (2).
3.1.10 continuing calibration blank (CCB)—(CCB), n—a solution containing no analyte added, that is used to verify blank
response and freedom from carryover. E1613/E3203
3.1.10.1 Discussion—
The CCB must be analyzed after the CCV (see 3.2.103.1.11). The measured concentration of the CCB should not exceed 10 %
of the applicable occupational exposure limit or minimum level of concern.
3.1.11 continuing calibration verification (CCV)—(CCV), n—a solution (or set of solutions) of known analyte concentration used
to verify freedom from excessive instrumental drift; the concentration is to be near the mid-range of a linear calibration curve.drift.
E1613/E3203
3.1.11.1 Discussion—
The concentration of the CCV is to be near the mid-range of a linear calibration curve.
3.1.11.2 Discussion—
The CCV must be matrix matched to the acid content present in sample digestates or extracts. The CCV must be analyzed before
and after all samples and at a frequency of not less than every ten samples. The measured value is to fall within 610 % of the
known value.
3.1.12 field blank—blank, n—sampling media (for example, an air filter) that is taken through the same handling procedure as a
sample, except that no sample is collected (that is, no air is purposely drawn through the sampler), and is then returned to the
laboratory for analysis. ISO 15202/D7035
3.1.12.1 Discussion—
Analysis results from field blanks provide information on the analyte background level in the sampling media, combined with the
potential contamination experienced by samples collected within the batch resulting from handling.
3.1.13 inductively coupled plasma (ICP)—(ICP), n—a high-temperature discharge generated by a flowing conductive gas,
normally argon, through a magnetic field induced by a load coil that surrounds the tubes carrying the gas. ISO 15202
3.1.14 inductively coupled plasma (ICP) torch—torch, n—a device used to support and introduce sample into an ICP discharge.
ISO 15202
3.1.15 initial calibration blank (ICB)—(ICB), n—a standard containing no analyte that is used for the initial calibration.calibration
and zeroing of the instrument response. E1613/E3193
3.1.15.1 Discussion—
The ICB must be matrix matched to the acid content of sample extracts and digestates. The ICB must be measured during and after
calibration. The measured concentration of the ICB should not exceed 10 % of the applicable occupational exposure limit or
minimum level of concern.
3.1.16 initial calibration verification (ICV)—(ICV), n—a solution (or set of solutions) of known analyte concentration used to
verify calibration standard levels; the concentration of analyte is to be near the mid-range of the calibration curve that is made from
a stock solution having a different manufacturer or manufacturer lot identification than the calibration standards.levels.
E1613/E3193
3.1.16.1 Discussion—
The concentration of analyte is to be near the mid-range of the calibration curve. It is made from a stock solution having a different
manufacturer or manufacturer lot identification than the calibration standards. E1613/E3193
3.1.16.2 Discussion—
The ICV must be matrix matched to the acid content of sample extracts or digestates. The ICV must be measured after calibration
and before measuring any sample digestates or extracts. The measured value is to fall within 610 % of the known value.
D7439 − 21
3.1.17 injector tube—tube, n—the innermost tube of an inductively coupled plasma torch, usually made of quartz or ceramic
materials, through which the sample aerosol is introduced to the plasma. ISO 15202
3.1.18 inner (nebulizer) argon flow—flow, n—the flow of argon gas that is directed through the nebulizer and carries the sample
aerosol through the injector and into the plasma; typically 0.5 L/min – 2 L/min. ISO 15202
3.1.19 instrumental detection limit (IDL)—(IDL), n—the lowest concentration at which the instrumentation can distinguish analyte
content from the background generated by a minimal matrix. E1613/E3203
3.1.19.1 Discussion—
The IDL can be determined from blank, acidified, deionized, or ultrapure water as the matrix and from the same calculation
methods used to determine a method detection limit (see 3.2.283.1.28).
3.1.20 instrumental QC standards—standards, n—these provide information on measurement performance during the instrumen-
tal analysis portion of the overall analyte measurement process. They include CCBs, CCVs, ICB, and ICVs. E1613/E3193
3.1.20.1 Discussion—
These standards include CCBs, CCVs, ICBs, and ICVs.
3.1.21 intermediate (auxiliary) argon flow—flow, n—the flow of argon gas that is contained between the intermediate and center
(injector) tubes of an inductively coupled plasma torch; typically 0.1 L/min – 2 L/min. ISO 15202
3.1.22 internal standard—standard, n—non-analyte element, present in all solutions analyzed, the signal from which is used to
correct for matrix interferences or improve analytical precision. ISO 15202
3.1.22.1 Discussion—
The internal standard is added in known and constant amount(s) to all analyzed solutions. This is used to correct for instrument
drift and some matrix effects by measuring the relative instrument response of the internal standard(s) to the other analytes that
are components of the same solution. The element(s) selected for use as an internal standard must be initially absent from the
sample solution.
3.1.23 laboratory blank—blank, n—unused sample media (for example, an air filter), taken from the same batch used for sampling,
that does not leave the laboratory. ISO 15202
3.2.23 limit value—reference figure for concentration of a chemical agent in air. ISO 15202
3.2.23.1 Discussion—
An example of a limit value would be a Permissible Exposure Limit (PEL) such as those established by the U.S. Occupational
Safety and Health Administration.
3.1.24 linear dynamic range—range, n—the range of concentrations over which the calibration curve for an analyte is linear. It
extends from the detection limit to the onset of calibration curvature. ISO 15202
3.1.25 load coil—coil, n—a length of metal tubing (typically copper) which is wound around the end of an inductively coupled
plasma torch and connected to the radio frequency generator. ISO 15202
3.1.26 matrix interference—interference, n—interference of a non-spectral nature which is caused by the sample matrix.
ISO 15202
3.1.27 matrix matching—matching, n—a technique used to minimize the effect of the test solution matrix on the analytical results.
ISO 15202
3.1.27.1 Discussion—
Matrix matching involves preparing calibration solutions in which the concentrations of acids and other major solvents and solutes
are matched with those in the test solutions.
3.1.28 method detection limit (MDL)—(MDL), n—the minimum concentration of an analyte that can be reported with a 99 %
confidence that the value is above zero. D1356
D7439 − 21
3.1.28.1 Discussion—
The MDL is also known as the limit of detection (LOD) (3).
3.1.29 method quantitation limit (MQL)—(MQL), n—the minimum concentration of an analyte that can be measured with
acceptable precision. D7035
3.1.29.1 Discussion—
The MQL is also known as the limit of quantitation (3).
3.1.30 nebulizer—nebulizer, n—a device used to create an aerosol from a liquid. ISO 15202
3.1.31 occupational exposure limit value (OELV), n—limit of the time-weighted average of the concentration of a chemical agent
in the air within the breathing zone of a worker in relation to a specified reference period ISO 18158
3.1.31.1 Discussion—
The term “limit value” is often used as a synonym for OELV, but the latter is preferred because there is more than one limit value
(for example, biological limit value and OELV).
3.1.31.2 Discussion—
An example of an OELV would be a Permissible Exposure Limit (PEL) such as those established by the U.S. Occupational Safety
and Health Administration.
3.1.32 outer (plasma) argon flow—flow, n—the flow of argon gas that is contained between the outer and intermediate tubes of
an inductively coupled plasma torch; typically 7 L/min – 15 L/min. ISO 15202
3.1.33 pneumatic nebulizer—nebulizer, n—a nebulizer that uses high-speed gas flows to create an aerosol from a liquid. ISO
3.1.34 primary standard—standard, n—an acceptable reference sample or device used for establishing measurement of a physical
quantity, directly defined and established by some authority, against which all secondary standards are compared. adapted from
D5011
3.1.35 reagent blank—blank, n—solution containing all reagents used in sample dissolution,preparation, in the same quantities
used for preparation of to prepare blank and sample solutions. ISO 15202ISO 18158
3.1.35.1 Discussion—
The reagent blank is used to assess contamination from the laboratory environment and to characterize spectral background from
the reagents used in sample preparation. ISO 18158
3.1.36 sample dissolution—dissolution, n—the process of obtaining a solution containing the analyte(s) of interest from a sample.
This may or may not involve complete dissolution of the sample. D6785/ISO 15202
3.1.37 sample preparation—preparation, n—all operations carried out on a sample sample, usually after transportation and
storage, to prepare it for analysis, including transformation of the sample into a measurable state, where necessary.
ISO 15202ISO 18158
3.1.38 sample solution—solution, n—solution prepared from a sample by the process of sample dissolution. ISO 15202
3.1.39 secondary standard—standard, n—an acceptable reference sample or device used for establishing measurement of a
physical quantity, used as a means of comparison, but checked against a primary standard. adapted from D5011
3.1.40 spectral interference—interference, n—an isobaric interference caused by a species other than the analyte of interest.
3.1.40.1 Discussion—
Spectral interferences may involve an atomic, polyatomic, or doubly-charged ion species. An example of an atomic interference
40 + 40 + 40 16 + 56 +
is Ar on Ca . An example of a polyatomic interference is Ar O on Fe . An example of a doubly-charged ion interference
48 2+ 24 +
is Ti on Mg (4).
3.1.41 spiked reagent blank—blank, n—a reagent blank aliquot that is spiked with a known amount of analyte.
D7439 − 21
3.1.41.1 Discussion—
Analysis results for spiked reagent blanks are used to provide information on the precision and bias of the overall analysis process.
3.1.42 spiked media blank—blank, n—a reagent blank aliquot that includes the sampling media (that is, filter), but includes no
actual sample, that is spiked with a known amount of analyte.
3.1.43 spray chamber—chamber, n—a device placed between a nebulizer and an inductively coupled plasma torch whose function
is to separate out aerosol droplets in accordance with their size, so that only very fine droplets pass into the plasma, and large
droplets are drained or pumped to waste. ISO 15202
3.1.44 stock standard solution—solution, n—solution used for preparation of working standard solutions and/oror calibration
solutions, or both, containing the analyte(s) of interest at a certified concentration(s) traceable to primary standards (National
Institute of Standards and Technology or international measurement standards). ISO 15202
3.1.45 test solution—solution, n—blank solution or sample solution that has been subjected to all operations required to bring it
into a state in which it is ready for analysis. ISO 15202
3.1.45.1 Discussion—
“Ready for analysis” includes any required dilution(s) and/oror addition of an internal standard. standard, or both. When blank
solutions and sample solutions are not subjected to any further operations before analysis, they then are in fact test solutions.
3.1.46 transport interference—interference, n—non-spectral interference caused by a difference in viscosity, surface tension, or
density between the calibration and test solutions (for example, due to differences in dissolved solids content, type and
concentration of acid, and so forth). ISO 15202
3.1.47 tune—tune, n—analyze a solution containing a range of isotopic masses to establish ICP-MS mass-scale accuracy, mass
resolution, signal intensity, and precision prior to calibration (1).
3.1.48 ultrasonic nebulizer—nebulizer, n—a nebulizer in which the aerosol is created by flowing a liquid across a surface that is
oscillating at an ultrasonic frequency. ISO 15202
3.1.49 working standard solution—solution, n—solution, prepared by dilution of the stock standard solution(s), that contains the
analyte(s) of interest at a concentration(s) better suited for preparation of calibration solutions than the concentration(s) of the
analyte(s) in the stock standard solution(s). ISO 15202
3.1.50 workplace—workplace, n—the defined designated area or areas in which the work activities are carried out. EN 1540 ISO
3.2 Definitions of Terms Specific to This Standard:
3.2.1 collision/reaction system, n—any system (for example, a collision cell or a collision reaction cell) that is used for charge
exchange neutralization of interfering ions in ICP-MS.
3.2.1.1 Discussion—
Collision/reaction systems utilize one or more techniques to reduce or eliminate spectral interferences. These may include (but are
not necessarily limited to) oscillating radio frequency, ion-neutral reactions, and kinetic energy discrimination. References (5) and
(6) provide additional information.
4. Summary of Test Method
4.1 A known volume of air is drawn through a filter appropriate sampling media to collect airborne particulates suspected to
contain metals or metalloids, or both, in accordance with Test Method D7035, taking into account additional information and
methodologies in Guide D8358.
4.2 A known volume of air is drawn through a filter to collect airborne particulates suspected to contain metals or metalloids, or
both, in accordance with Test Method D7035.
D7439 − 21
4.2 In general, particulate metals and metalloids (and their compounds) that are commonly of interest in samples of workplace
air are converted to water- or acid-soluble ions in sample solutions by one of the sample dissolution methods specified.
4.3 Test solutions, prepared from the sample solutions after sample dissolution, are analyzed using inductively coupled plasma –
mass spectrometry (ICP-MS) to determine the concentration of target elements in the sampled air.
NOTE 1—The sample dissolution procedures described in this standard may be suitable for preparation of samples for subsequent analysis by other
methods besides ICP-MS (for example: inductively coupled plasma–emission spectrometry as described in Test Method D7035, flame atomic absorption
spectrophotometry as described in Practice D4185, graphite furnace atomic absorption spectrometry, electroanalysis, and so forth).
5. Significance and Use
5.1 The health of workers in many industries is at risk through exposure by inhalation to toxic metals and metalloids. Industrial
hygienists and other public health professionals need to determine the effectiveness of measures taken to control workplace
exposure. This is generally achieved by making workplace air measurements. This test method has been developed to make
available a standard methodology for valid exposure measurements for a wide range of metals and metalloids that are used in
industry. It will be of benefit to agencies concerned with health and safety at work; analytical laboratories; industrial hygienists
and other public health professionals; industrial users of metals and metalloids and their workers; and other groups.
5.2 This standard test method specifies a generic method for determination of the concentration of metals and metalloids in
workplace air samples using ICP-MS. For many metals and metalloids, analysis by ICP-MS may be advantageous, when compared
to methods such as ICP atomic emission spectrometry, due to its sensitivity and the presence of fewer spectral interferences.
5.3 The analysis results can be used for the assessment of workplace exposures to metals and metalloids in workplace air.
6. Apparatus
6.1 Apparatus for Sample Preparation and Analysis—Details regarding laboratory apparatus required for individual sample
dissolution methods are given in Annex A1 through Annex A4A5. Ordinary laboratory apparatus are not listed, but are assumed
to be present.
6.1.1 Disposable Gloves, impermeable and powder-free, to avoid the possibility of contamination and to protect them from contact
with toxic and corrosive substances. PVC gloves are suitable.
6.1.2 Glassware, beakers and volumetric flasks complying with the requirements of Specification E288 or ISO 1042, made of
borosilicate glass and complying with the requirements of Specification E438 or ISO 3585. Glassware shall be cleaned before use
by soaking in nitric acid for at least 24 hours and then rinsing thoroughly with water. Alternatively, before use, glassware shall be
cleaned with a suitable laboratory detergent using a laboratory washing machine.
6.1.3 Flat-tipped Forceps, polytetrafluoroethylene (PTFE)-tipped, for unloading filters from samplers or from filter transport
cassettes.
6.1.4 Piston-operated Volumetric Pipettors and Dispensers, complying with the requirements of Specification E1154 or ISO 8655,
for pipetting and dispensing of leach solutions, acids, and so forth.
6.1.5 Polyethylene Bottles, low density, with leak-proof screw cap.
6.1.6 Inductively Coupled Plasma–Mass Spectrometer, computer-controlled, equipped with an auto-sampler.
NOTE 2—An auto-sampler having a flowing rinse is strongly recommended.
7. Reagents
7.1 Reagents for Sample Preparation and Analysis—Details regarding reagents that are required for individual sample dissolution
methods are given in Annex A1 through Annex A4A5. During sample preparation and analysis, use only reagents of analytical
grade. spectroscopic grade or greater purity. The concentration of metals and metalloids of interest shall be less than 0.1 μg/L. The
use of ultrapure acids is recommended.
D7439 − 21
NOTE 3—It will be necessary to use reagents Reagents of higher purity are needed in order to obtain adequate detection limits for some metals and
metalloids (for example, beryllium).for beryllium measurements, a Be concentration of less than 0.01 μg/L is recommended).
7.1.1 Water, complying with the requirements for ASTM Type I water (see Specification D1193).
7.1.2 Nitric Acid (HNO ), concentrated, ρ ~1.42 g/mL (~70 % m ⁄m).
7.1.3 Laboratory Detergent, suitable for cleaning of laboratory ware. The use of detergents containing phosphorus or other
potential analytes should be avoided.
7.1.4 Perchloric Acid (HClO ), concentrated, ρ ~1.67 g/mL, ~70 % (m ⁄m).
7.1.5 Hydrochloric Acid (HCl), concentrated, ρ ~1.18 g/mL, ~36 % (m/m).
NOTE 4—Use of HCl is typically not recommended in older ICP-MS systems that do not include a collision/reaction system, or when such a system is
not used.
7.1.6 Sulfuric Acid (H SO ), concentrated, ρ ~1.84 g/mL, ~98 % (m/m).
2 4
NOTE 5—Use of H SO is typically not recommended in older ICP-MS systems that do not include a collision/reaction system, or when such a system
2 4
is not used.
7.1.7 Stock Standard Solutions:
7.1.7.1 For stock standard solutions, use commercial single-element or multi-element standard solutions with certified
concentrations traceable to primary standards (National Institute of Standards and Technology or international measurement
standards). Observe the manufacturer’s expiration date or recommended shelf life.
NOTE 6—Commercially available stock standard solutions for metals and metalloids have nominal concentrations of 10010 to 10 000 mg/L for single
element standards, and 10 to 1000 mg/L for multielement standards.
7.1.7.2 Alternatively, prepare stock standard solutions from high-purity metals and metalloids or their salts. The procedure used
to prepare the solutions shall be fit for purpose, and the calibration of any apparatus used shall be traceable to primary standards.
The maximum recommended shelf life is one year from date of initial preparation.
7.1.7.3 Store stock standard solutions in suitable containers, such as low-density polyethylene bottles.
D7439 − 21
7.1.8 Working Standard Solutions and Calibration Solutions:
7.1.8.1 From the stock standard solutions, prepare working standard solutions by serial dilutions; these shall include all the metals
and metalloids of interest at suitable concentration (typically between 1 μg/L and 100 μg/L).concentration.
NOTE 7—Suitable concentrations will typically fall between 1 μg/L and 100 μg/L; however, newer ICP-MS systems can detect some metals and metalloids
reliably at levels below 1 μg/L.
NOTE 8—Analytes that are grouped together in working standard solutions should be chosen carefully to ensure chemical compatibility and to avoid
spectral interferences. Also, the type and volume of each acid added should be selected carefully to ensure the stability of elements of interest.
7.1.8.2 Store working standard solutions in suitable containers, such as low-density polyethylene bottles, containers for a
maximum period of one month.
NOTE 9—Containers such as bottles made of perfluoroalkoxy (PFA) polymer, polytetrafluoroethylene (PTFE), or low-density polyethylene are normally
suitable.
7.1.8.3 From the working standard solutions, prepare a set of calibration solutions by serial dilutions, covering the range of
concentrations for each of the metals and metalloids of interest. It is recommended that a minimum of three calibration solutions
be prepared. Also prepare a calibration blank solution. During preparation of calibration solutions, add reagents (for example,
acids), as required, to matrix-match the calibration solutions with the test solutions. Calibration solutions should be prepared fresh
daily.
NOTE 10—The shelf life of calibration solutions may be extended if they are demonstrated, by comparison with calibration verification solutions, to be
acceptable.
NOTE 11—The type(s) and volume(s) of reagents required to matrix match the calibration and test solutions will depend on the sample dissolution method
used.
7.1.9 Internal Standard Stock Solutions:
7.1.9.1 Select elements to be used as internal standards. Table 2 provides a list of elements frequently used. For full mass range
scans use a minimum of three internal standards with the use of five suggested. Internal standards in low, middle, and high mass
ranges are recommended.
NOTE 12—Internal standards are recommended in all analyses to correct for instrument drift and physical interferences. Internal standards should be added
to blanks, samples and standards in a like manner. Internal standards are typically selected to match the mass range of the analytes of interest; however,
for analytes with high ionization potential (such as arsenic and selenium), consideration should be given to matching ionization potential.
NOTE 13—Internal standards may be added to each test solution during the sample preparation process or, alternatively, by use of an on-line internal
standard addition system.
TABLE 2 Internal Standards and Limitations of Use
Internal
Mass Possible Limitation
Standard
Lithium 6 May be present in samples
A
Scandium 45 Polyatomic ion interference; may be present in samples
A
Yttrium 89 May be present in samples
Rhodium 103 .
A
Indium 115 Isobaric interference by Sn
A
Terbium 159 .
Holmium 165 .
Lutetium 175 .
Platinum 195 {
A
Bismuth 209 May be present in samples
A
Internal standards recommended for use with this standard test method. It is also
necessary when analyzing a new sample matrix that a scan for the presence of
internal standards be performed.
D7439 − 21
7.1.9.2 Use stock standard solutions to prepare test solutions that contain the internal standard elements. Observe the
manufacturer’s expiration date or recommended shelf life.
7.1.10 Argon, high purity grade (99.99 % or better).
8. Hazards
8.1 Concentrated Nitric Acid is corrosive and oxidizing, and nitric acid vapor is an irritant. Avoid exposure by contact with the
skin or eyes, or by inhalation of fumes. Use suitable personal protective equipment (including impermeable gloves, safety goggles,
laboratory coat, and so forth) when working with concentrated nitric acid, and carry out open-vessel sample dissolution with nitric
acid in a fume hood.
8.2 Concentrated Perchloric Acid is corrosive and oxidizing, and its vapor is an irritant. Perchloric acid forms explosive
compounds with organics and many metal salts. Avoid exposure by contact with the skin or eyes, or by inhalation of fumes. Use
suitable personal protective equipment (including impermeable gloves, safety goggles, laboratory coat, and so forth) when working
with perchloric acid. Carry out sample dissolution with perchloric acid in a fume hood with a scrubber unit that is specially
designed for use with HClO . See Appendix X1 for further pertinent safety information.
8.3 Concentrated Hydrofluoric Acid is highly corrosive, and is very toxic by inhalation or contact with the skin. Avoid exposure
by contact with the skin or eyes, or by inhalation of HF vapor. It is essential to use suitable personal protective equipment,
including impermeable gloves and eye protection) when working with HF. Use a fume hood when working with concentrated HF
and when carrying out open-vessel dissolution with HF. See Appendix X1 for further pertinent safety information.
8.4 Concentrated Hydrochloric Acid is corrosive, and HCl vapor is an irritant. Avoid exposure by contact with the skin or eyes,
or by inhalation of the vapor. Use suitable personal protective equipment (such as gloves, face shield, and so forth) when working
with HCl. Handle open vessels containing concentrated HCl in a fume hood. The vapor pressure of HCl is high, so beware of
pressure buildup in stoppered flasks when preparing mixtures containing HCl.
8.5 Concentrated Sulfuric Acid is corrosive and causes burns. Vapor produced when concentrated H SO is heated is an irritant.
2 4
Avoid exposure by contact with the skin or eyes. Use suitable personal protective equipment (such as gloves, face shield, and so
forth) when working with H SO . Carry out sample dissolution with H SO in a fume hood. Exercise caution when diluting H SO
2 4 2 4 2 4
with water, as this process is very exothermic. Do not add water to H SO , since it reacts violently when mixed in this manner;
2 4
rather, prepare H SO /H O mixtures by adding H SO to water.
2 4 2 2 4
9. Sampling Procedure
9.1 Samples to be prepared for analysis by this standard test method shall be collected in accordance with standard test method
D7035.
10. Sample Preparation
10.1 Soluble Metals and Metalloids and their Compounds:
10.1.1 If results are required for soluble metal, or metalloid compounds, or both, use the sample dissolution method specified in
Annex A1 to prepare sample solutions, from which test solutions are prepared for analysis by ICP-MS.
10.1.2 Alternatively, if it is known that no insoluble compounds of the metals, or metalloids, or both, of interest are used in the
workplace, and that none are produced in the processes carried out, prepare test solutions for ICP-MS analysis using one of the
sample dissolution methods for total metals and metalloids and their compounds, as prescribed in Annex A2 (hot plate digestion),
Annex A3 (microwave digestion), and Annex A4 (hot block digestion), and Annex A5 (microwave digestion).
NOTE 14—The methods prescribed in Annex A2 through Annex A4A5 are not specific for soluble metal, or metalloid compounds, or both. However, in
these circumstances, they may be used as an alternative to the method described in Annex A1, if this is more convenient.
10.2 Total Metals and Metalloids and their Compounds:
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10.2.1 If results are required for total metals, or metalloids, or both, and their compounds, select a suitable sample preparation
method from those specified in Annex A2 (hot plate digestion), Annex A3 (microwave digestion), and Annex A4 (hot block
digestion), and Annex A5 (microwave digestion). Practice D8344 may also be suitable. Take into consideration the applicability
of each method for dissolution of target metals and metalloids of interest from materials that could be present in the test atmosphere
(refer to the clause on the effectiveness of the sample dissolution method in the Annex in which the method is specified), and the
availability of the required laboratory apparatus.
NOTE 15—In selection of a sample preparation method, consideration should be given to the metal or metalloid compounds that may be present in the
test atmosphere. Some compounds, such as refractory metal oxides, may require a more robust sample preparation method than is required for other
compounds, or for the metals or metalloids themselves.
10.2.2 Use the selected sample dissolution method to prepare sample solutions, from which test solutions are prepared for analysis
of total metals and metalloids and their compounds by ICP-MS.
10.3 Deposits of Particles on Interior Sampler Surfaces—Give consideration to metal and metalloid particles that may have
deposited on interior sampler surfaces (for example, by becoming dislodged from the filter during transportation), and determine
whether the sample of interest should include such particles. If the sample is determined to include such particles, determine a
methodology for removing them from the interior sampler surfaces and including them in the analysis. (SeeAppendix X4
providesGuide D8358 for additional information and suggested methodologies).methodologies.
10.4 Mixed Exposures:
10.4.1 If analytical results are required for both soluble and insoluble metals, or metalloids, or both, and their compounds, first
use the sample preparation procedure specified in Annex A1 to prepare sample solutions, from which test solutions are prepared
for determination of soluble metal and metalloid compounds for subsequent analysis by ICP-MS.
10.4.2 Select a suitable sample preparation method from those specified in Annex A2 (hot plate digestion), Annex A3 (microwave
digestion), and Annex A4 (hot block digestion), and Annex A5 (microwave digestion). Use this procedure to treat undissolved
material left over after employing the preparation method for soluble metals and metalloids and their compounds (Annex A1), and
prepare sample solutions, from which test solutions are prepared for subsequent analysis by ICP-MS.
10.5 Special Cases:
10.5.1 Effectiveness of Sample Dissolution Procedure—If there is any doubt about whether the selected sample preparation method
will exhibit the required analytical recovery when used for dissolution of the metals and metalloids of interest from materials that
could be present in the test atmosphere, determine its effectiveness for the particular application.
10.5.1.1 For total metals and metalloids, analytical recovery may be estimated by analyzing a performance evaluation material of
known composition that is similar in nature to the materials being produced in the workplace. An example evaluation material
would be a representative certified reference material (CRM).
NOTE 16—It should be recognized that, for a bulk sample, certain physical characteristics, such as particle size and agglomeration, could have a significant
influence on the efficacy of its dissolution. Also, smaller quantities of material are often much more easily dissolved than greater quantities.
10.5.1.2 For soluble metals and metalloids, analytical recovery is best determined by analyzing spiked media blanks (that is, filters
spiked with solutions containing known masses of the soluble compound(s) of interest).
10.5.1.3 Recovery should be at least 90 % of the known value for all elements included in the spiked media blanks, with a relative
standard deviation of less than 5 % (57). If the analytical recovery is outside the required range of acceptable values, investigate
the use of an alternative sample dissolution method.
10.5.1.4 Do not use a correction factor to compensate for an apparently ineffective sample dissolution method, since this might
equally lead to erroneous results.
10.5.2 Treatment of Undissolved Material Following Sample Dissolution—If undissolved residue remains after carrying out
sample dissolution using hot plate, microwave, or hot block techniques (Annex A2, Annex A3, and Annex A4, and Annex A5
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