EPA/625/R-96/010a
Compendium of Methods
for the Determination of
Inorganic Compounds
in Ambient Air
Compendium Method IO-3.5
DETERMINATION OF METALS
IN AMBIENT PARTICULATE
MATTER USING
INDUCTIVELY COUPLED PLASMA/
MASS SPECTROMETRY (ICP/MS)
Center for Environmental Research Information
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
June 1999
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Method 10-3.5
Acknowledgments
This Method is a part of Compendium of Methods for the Determination of Inorganic Compounds in
Ambient Air (EPA/625/R-96/010a), which was prepared under Contract No. 68-C3-0315, WA No. 2-10,
by Midwest Research Institute (MRI), as a subcontractor to Eastern Research Group, Inc. (ERG), and
under the sponsorship of the U.S. Environmental Protection Agency (EPA). Justice A. Manning, John
O'Burckle, Scott Hedges, Center for Environmental Research Information (CERI), and Frank F.
McElroy, National Exposure Research Laboratory (NERL), all in the EPA Office of Research and
Development, were responsible for overseeing the preparation of this method. Other support was
provided by the following members of the Compendia Workgroup:
• James L. Cheney, U.S. Army Corps of Engineers, Omaha, NE
• Michael F. Davis, U.S. EPA, Region 7, KC, KS
• Joseph B. Elkins Jr., U.S. EPA, OAQPS, RTF, NC
• Robert G. Lewis, U.S. EPA, NERL, RTF, NC
• Justice A. Manning, U.S. EPA, ORD, Cincinnati, OH
• William A. McClenny, U.S. EPA, NERL, RTF, NC
• Frank F. McElroy, U.S. EPA, NERL, RTF, NC
• William T. "Jerry" Winberry, Jr., EnviroTech Solutions, Gary, NC
This Method is the result of the efforts of many individuals. Gratitude goes to each person involved in
the preparation and review of this methodology.
Author (s)
• William T. "Jerry" Winberry, Jr., EnviroTech Solutions, Gary, NC
Peer Reviewers
• Doug Duckworth, Lockheed-Martin Energy Research, Oak Ride, TN
• David Brant, West Virginia University, Morgantown, WV
• Jiansheng Wang, Midwest Research Institute, Kansas City, MO
• Lauren Drees, U.S. EPA, NRMRL, Cincinnati, OH
DISCLAIMER
This Compendium has been subjected to the Agency's peer and administrative review, and it has
been approved for publication as an EPA document. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
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Method IO-3.5
Determination of Metals in Ambient Particulate Matter Using
Inductively Coupled Plasma/Mass Spectrometry (ICP/MS)
TABLE OF CONTENTS
1. Scope 3.5-1
2. Applicable Documents 3.5-2
2.1 ASTM Standards 3.5-2
2.2 Other Documents 3.5-2
3. Summary of Method 3.5-2
4. Definitions 3.5-3
5. Interferences 3.5-4
5.1 Isobaric Elemental Interferences 3.5-4
5.2 Abundance Sensitivity 3.5-4
5.3 Isobaric Polyatomic Ion Interferences 3.5-5
5.4 Physical Interferences 3.5-5
5.5 Memory Interferences 3.5-5
6. Safety 3.5-6
7. Apparatus and Equipment 3.5-6
7.1 Inductively Coupled Plasma/Mass Spectrometer (ICP/MS) 3.5-6
7.2 Labware 3.5-7
7.3 Sample Processing Equipment 3.5-7
8. Reagents and Consumable Materials 3.5-8
8.1 Reagents 3.5-8
8.2 Water 3.5-8
8.3 Standard Stock Solutions 3.5-8
8.4 Multi-Element Stock Standard Solutions 3.5-10
8.5 Internal Standards Stock Solution, 1 mL = 100 ,ug 3.5-11
8.6 Blanks 3.5-11
8.7 Tuning Solution 3.5-12
8.8 Quality Control Sample (QCS) 3.5-12
8.9 Laboratory Fortified Blank (LFB) 3.5-12
9. Sample Receipt in the Laboratory 3.5-12
10. Calibration and Standardization 3.5-12
10.1 Calibration 3.5-12
10.2 Internal Standardization 3.5-13
10.3 Instrument Performance 3.5-13
11. Quality Control (QC) 3.5-14
11.1 Laboratory 3.5-14
11.2 Initial Demonstration of Performance 3.5-14
11.3 General Quality Control 3.5-15
11.4 Assessing Analyte Recovery - Laboratory Fortified Sample Matrix 3.5-16
11.5 Internal Standards Responses 3.5-16
12. Procedure 3.5-17
13. Calculations 3.5-18
14. Precision and Accuracy 3.5-19
15. References 3.5-19
in
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Chapter IO-3
Chemical Species Analysis
of Filter-Collected SPM
Method IO-3.5
DETERMINATION OF METALS IN AMBIENT PARTICULATE MATTER USING
INDUCTIVELY COUPLED PLASMA/MASS SPECTROMETRY
1. Scope
1.1 Suspended particulate matter (SPM) in air generally is a complex multi-phase system of all airborne solid
and low vapor pressure liquified particles having aerodynamic particles sizes from below 0.01-100 pm and
larger. Historically, SPM measurement has concentrated on total suspended particulates (TSP), with no
preference to size selection.
1.2 On July 1, 1987, the U. S. Environmental Protection Agency (EPA) promulgated a new size-specific air
quality standard for ambient particulate matter. This new primary standard applies only to particles with
aerodynamic diameters < 10 ,um (PM10) and replaces the original standard for TSP. To measure
concentrations of these particles, the EPA also promulgated a new federal reference method (FRM). This
method is based on the separation and removal of non-PM10 particles from an air sample, followed by
filtration and gravimetric analysis of PM10 mass on the filter substrate.
1.3 The new primary standard (adopted to protect human health) limits PM10 concentrations to 150 p.g/std
m3, averaged over a 24-h period. These smaller particles are able to reach the lower regions of the human
respiratory tract and, therefore, are responsible for most of the adverse health effects associated with
suspended particulate pollution. The secondary standard, used to assess the impact of pollution on public
welfare, has also been established at 150 p.g/std. m3.
1.4 Ambient air SPM measurements are used (among other purposes) to determine whether defined
geographical areas are in attainment or non-attainment with the national ambient air quality standards
(NAAQS) for PM10. These measurements are obtained by the states in their state local air monitoring station
(SLAMS) networks as required under 40 CFR Part 58. Further, Appendix C of Part 58 requires that the
ambient air monitoring methods used in these EPA-required SLAMS networks must be methods that have
been designated by EPA as either reference or equivalent methods.
1.5 The procedure for analyzing the elemental metal components in ambient air particulate matter collected
on high volume filter material is described in this method. The high volume filter material may be associated
with either the TSP or PM10 sampler, as delineated in Inorganic Compendium Method 10-2.1.
1.6 Filters are numbered, pre-weighted, field deployed and sampled, returned to the laboratory, extracted
using microwave or hot acid, then analyzed by inductively coupled plasma/mass spectrometry (ICP/MS).
The extraction procedure is accomplished by following Inorganic Compendium Method 10-3.1. Those metals
and their associated method detection limit (MDL) applicable to this technology are listed in Table 1.
1.7 This 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. A minimum of 6-months' experience with
commercial instrumentation is required.
June 1999 Compendium of Methods for Inorganic Air Pollutants Page 3.5-1
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Method IO-3.5 Chapter IO-3
ICP/MS Methodology Chemical Analysis
2. Applicable Documents
2.1 ASTM Standards
• D1356 Definition of Terms Related to Atmospheric Sampling and Analysis.
• D1357 Planning the Sampling of the Ambient Atmosphere.
• D4096 Application of the High Volume Sample Method for Collection and Mass Determination of
Airborne Particle Matter.
2.2 Other Documents
• U. S. Environmental Protection Agency, Quality Assurance Handbook for Air Pollution Measurement
Systems, Volume I: A Field Guide for Environmental Quality Assurance, EPA-600/R-94-038a.
• U. S. Environmental Protection Agency, Quality Assurance Handbook for Air Pollution Measurement
Systems, Volume II: Ambient Air Specific Methods (Interim Edition), EPA-600/R-94/038b.
• Reference Method for the Determination of Particulate Matter in the Atmosphere, Code of Federal
Regulations. 40 CFR 50, Appendix].
• Reference Method for the Determination of Suspended Particulates in the Atmosphere (High Volume
Method), Code of Federal Regulations. 40 CFR 50, Appendix B.
• Reference Method for the Determination of Lead in Suspended Particulate Matter Collected from
Ambient Air, Federal Register 43 (194): 46258-46261.
• U. S. EPA Project Summary Document (1).
• U. S. EPA Laboratory Standard Operating Procedures (2).
• Scientific Publications of Ambient Air Studies (3-14).
3. Summary of Method
3.1 The method describes the multi-element determination of trace elements by ICP/MS. Sample material
in solution is introduced by pneumatic nebulization into a radiofrequency plasma where energy transfer
processes cause desolvation, atomization, and ionization.
3.2 The ions are extracted from the plasma through a differentially pumped vacuum interface and separated
on the basis of their mass-to-charge ratio by a quadrupole mass spectrometer having a minimum resolution
capability of 1 amu peak width at 5% peak height.
3.3 The ions transmitted through the quadruple are registered by a continuous dynode electron multiplier or
Faraday detector and the ion information processed by a data handling system.
3.4 Interferences relating to the technique (see Section 5) must be recognized and corrected for. Such
corrections must include compensation for isobaric elemental interferences and interferences from polyatomic
ions derived from the plasma gas, air, reagents, or sample matrix. Instrumental drift as well as suppressions
or enhancements of instrument response caused by the sample matrix must be corrected for by internal
standardization.
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Chapter IO-3 Method IO-3.5
Chemical Analysis ICP/MS Methodology
4. Definitions
[Note: Definitions used in this document are consistent with ASTM methods. All pertinent abbreviations and
symbols are defined within this document at point of use.]
4.1 Instrument Detection Limit (IDL). The concentration equivalent of the analyte signal, which is equal
to three times the standard deviation of the blank signal at the selected analytical mass(es).
4.2 Method Detection Limit (MDL). The minimum concentration of an analyte that can be identified,
measured and reported with 99% confidence that the analyte concentration is greater than zero. MDLs are
intended as a guide to instrumental limits typical of a system optimized for multi-element determinations and
employing commercial instrumentation and pneumatic nebulization sample introduction. However, actual
MDLs and linear working ranges will be dependent on the sample matrix, instrumentation and selected
operating conditions.
4.3 Linear Dynamic Range (LDR). The concentration range over which the analytical working curve
remains linear.
4.4 Laboratory Reagent Blank (LRB) (Preparation Blank). An aliquot of reagent water that is treated
exactly as a sample including exposure to all labware, equipment, solvents, reagents, and internal standards
that are used with other samples. The LRB is used to determine if method analytes or other interferences are
present in the laboratory environment, the reagents or apparatus.
4.5 Calibration Blank. A volume of ASTM Type I water acidified with the same acid matrix as is present
in the calibration standards.
4.6 Internal Standard. Pure analyte(s) added to a solution in known amount(s) and used to measure the
relative responses of other method analytes that are components of the same solution. The internal standard
must be an analyte that is not a sample component.
4.7 Stock Standards Solutions. A concentrated solution containing one or more analytes prepared in the
laboratory using assayed reference compounds or purchased from a reputable commercial source.
4.8 Calibration Standard (CAL). A solution prepared from the stock standard solution(s) which is used
to calibrate the instrument response with respect to analyte concentration.
4.9 Tuning Solution. A solution used to determine acceptable instrument performance prior to calibration
and sample analyses.
4.10 Quality Control Sample (QCS). A solution containing known concentrations of method analytes
which is used to fortify an aliquot of LRB matrix. The QCS is obtained from a source external to the
laboratory and is used to check laboratory performance.
June 1999 Compendium of Methods for Inorganic Air Pollutants Page 3.5-3
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Method IO-3.5 Chapter IO-3
ICP/MS Methodology Chemical Analysis
4.11 Nebulizer. A device creating a fine spray of sample solution to be carried into the plasma for
measurement. Its performance is critical for good analysis.
4.12 Mass Spectrometer (MS). For a quadrupole mass spectrometer, an analytical system which consist
of parallel set of four rod electrodes mounted in a square configuration. By coupling composite pairs of rods
together and applying radio frequency (RF) and direct current (DC) potentials between the pairs of rods, ions
(generated from the ion source of reaction of chemical compound with a high intense beam of electrons)
moving through the field, based upon their trajectories, can be separated according to their atomic mass units
(amu) and subsequently detected by an electron multiplier detector.
4.13 MS-SCAN. The MS is programmed to SCAN all ions repeatedly over a specified mass range.
4.14 MS-SIM. The MS is programmed to scan a selected number of ions repeatedly [i.e., selected ion
monitoring (SIM) mode].
5. Interferences
[Note: Several interference sources may cause inaccuracies in the determination of trace elements by
ICP/MS.]
5.1 Isobaric Elemental Interferences
Isobaric elemental interferences are caused by isotopes of different elements that form single- or double-
charged ions of the same nominal mass-to-charge ratio and cannot be resolved by mass spectrometer in use.
All elements determined by this method have, at a minimum, one isotope free of isobaric elemental
interference. Of the analytical isotopes recommended for use with this method, only molybdenum-98
(ruthenium) and selenium-82 (krypton) have isobaric elemental interferences. If alternative analytical
isotopes having higher natural abundance are selected to achieve greater sensitivity, an isobaric interference
may occur. All data obtained under such conditions must be corrected by measuring the signal from another
isotope of the interfering element and subtracting the appropriate signal ratio from the isotope of interest.
A record of this correction process should be included with the report of the data. These corrections will
only be as accurate as the accuracy of the isotope ratio used in the elemental equation for data calculations.
Relevant isotope ratios and instrument bias factors should be established prior to the application of any
corrections.
5.2 Abundance Sensitivity
Abundance sensitivity is a property defining the degree to which the wings of a mass peak contribute to
adjacent masses. The abundance sensitivity is affected by ion energy and quadruple operating pressure.
Wing overlap interferences may result when a small ion peak is being measured adjacent to a large one. The
potential for these interferences should be recognized and the spectrometer resolution adjusted to minimize
them.
Page 3.5-4 Compendium of Methods for Inorganic Air Pollutants June 1999
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Chapter IO-3 Method IO-3.5
Chemical Analysis ICP/MS Methodology
5.3 Isobaric Polyatomic Ion Interferences
Isobaric polyatomic ion interferences are caused by ions consisting of more than one atom that have the same
nominal mass-to-charge ratio as the isotope of interest and that cannot be resolved by the mass spectrometer
in use. These ions are commonly formed in the plasma or interface system from support gases or sample
components. Most of the common interferences have been identified and are listed in Table 2, together with
the method elements affected. Such interferences must be recognized, and when they cannot be avoided by
the selection of alternative analytical isotopes, appropriate corrections must be made to the data. Equations
for the correction of data should be established at the time of the analytical run sequence as the polyatomic
ion interferences will be highly dependent on the sample matrix and chosen instrument conditions.
5.4 Physical Interferences
Physical interferences are associated with the physical processes that govern the transport of sample into the
plasma, sample conversion processes in the plasma, and the transmission of ions through the plasma-mass
spectrometer interface. These interferences may result in differences between instrument responses for the
sample and the calibration standards. Physical interferences may occur in the transfer of solution to the
nebulizer (e.g., viscosity effects), at the point of aerosol formation and transport to the plasma (e.g., surface
tension), or during excitation and ionization processes within the plasma itself. High levels of dissolved
solids in the sample may contribute deposits of material on the extraction and/or skimmer cones reducing the
effective diameter of the orifices and therefore ion transmission. Internal standardization may be effectively
used to compensate for many physical interference effects. Internal standards ideally should have similar
analytical behavior to the elements being determined.
5.5 Memory Interferences
Memory interferences result when isotopes of elements in a previous sample contribute to the signals
measured in a new sample. Memory effects can result from sample deposition on the sampler and skimmer
cones and from the buildup of sample material in the plasma torch and spray chamber. The site where these
effects occur is dependent on the element and can be minimized by flushing the system with a rinse blank
between samples (see Section 8.6.3). The possibility of memory interferences should be recognized within
an analytical run and suitable rinse times should be used to reduce them. The rinse times necessary for a
particular element should be estimated prior to analysis. This estimate may be calculated by aspirating a
standard containing elements corresponding to 10 times the upper end of the linear range for a normal sample
analysis period, followed by analysis of the rinse blank at designated intervals. The length of time required
to reduce analyte signals to within a factor of 10 of the method detection limit, should be noted. Memory
interferences may also be assessed within an analytical run by using a minimum of three replicate integrations
for data acquisition. If the integrated signal values drop consecutively, the analyst should be alerted to the
possibility of a memory effect and should examine the analyte concentration in the previous sample to identify
if this was high. If a memory interference is suspected, the sample should be reanalyzed after a long rinse
period.
June 1999 Compendium of Methods for Inorganic Air Pollutants Page 3.5-5
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Method IO-3.5 Chapter IO-3
ICP/MS Methodology Chemical Analysis
6. Safety
Page 3.5-6 Compendium of Methods for Inorganic Air Pollutants June 1999
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Chapter IO-3 Method IO-3.5
Chemical Analysis ICP/MS Methodology
6.1 The toxicity or carcinogenicity of reagents used in this method have not been fully established. Each
chemical should be regarded as a potential health hazard, and exposure to these compounds should be as low
as reasonably achievable. Each laboratory is responsible for maintaining a current awareness file of OSHA
regulations regarding the safe handling of the chemicals specified in this method. A reference file of material
data handling sheets should also be available to all personnel involved in the chemical analyses.
6.2 Analytical plasma sources emit radiofrequency radiation in addition to intense UV radiation. Suitable
precautions should be taken to protect personnel from such hazards.
7. Apparatus and Equipment
7.1 Inductively Coupled Plasma/Mass Spectrometer (ICP/MS)
7.1.1 ICP/MS Instrument. Capable of scanning the mass 5-250 amu with a minimum resolution
capability of 1 amu peak width at 5% peak height. Instrument may be fitted with a conventional or extended
dynamic range detection system.
7.1.2 Argon Gas Supply (high-purity grade, 99.99%). Best source.
7.1.3 A Variable-Speed Peristaltic Pump. Required for solution delivery to the nebulizer.
7.1.4 A Mass-Flow Controller. One mass flow controller is required on the nebulizer gas supply. A
water-cooled spray chamber may reduce some types of interferences (e.g., from polyatomic oxide species).
7.1.5 Operating Conditions. Because of the diversity of instrument hardware, no detailed instrument
operating conditions are provided. The analyst is advised to follow the recommended operating conditions
provided by the manufacturer. The analyst must verify that the instrument configuration and operating
conditions satisfy the analytical requirements and maintain quality control data verifying instrument
performance and analytical results. Instrument operating conditions used to generate precision and recovery
data for this method (Section 14) are included in Table 3.
7.1.6 Electron Multiplier Detector. If an electron multiplier detector is being used, precautions should
be taken, where necessary, to prevent exposure to high ion flux. Otherwise, changes in instrument response
or damage to the multiplier may result. Samples having high concentrations of elements beyond the linear
range of the instrument and with isotopes falling within scanning windows should be diluted prior to analysis.
7.2 Labware
To determine trace level elements, contamination and loss are of prime consideration. Potential
contamination sources include improperly cleaned laboratory apparatus and general contamination within the
laboratory environment from dust, etc. A clean laboratory work area designated for trace element sample
handling must be used. Sample containers can introduce positive and negative errors in the determination
of trace elements by (1) contributing contaminants through surface desorption or leaching and (2) depleting
element concentrations through adsorption processes. All reusable labware (glass, quartz, polyethylene,
Teflon®, etc.), including the sample container, should be cleaned prior to use. Labware may be soaked
overnight and thoroughly washed with laboratory-grade detergent and water, rinsed with water, and soaked
for 4 h in a mixture of dilute nitric and hydrochloric acid (1 + 2 + 9). It should then be rinsed with ASTM
type I water and oven-dried.
[Note: Do not use chromic acid to clean glassware.]
June 1999 Compendium of Methods for Inorganic Air Pollutants Page 3.5-7
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Method IO-3.5 Chapter IO-3
ICP/MS Methodology Chemical Analysis
7.2.1 Glassware. Volumetric flasks, graduated cylinders, funnels and centrifuge tubes.
7.2.2 Assorted Calibrated Pipettes. Dust sources.
7.2.3 Conical Phillips Beakers, 350-mL with 50-mm Watch Glasses. Griffin beakers, 350-mL with
75-mm watch glasses.
7.2.4 Storage Bottles. Narrow mouth bottles, Teflon® FEP (fluorinated ethylene propylene) with Tefzel
ETFE (ethylene tetrafluorethylene) screw closure, 125-mL and 250-mL capacities.
7.3 Sample Processing Equipment
7.3.1 Air Displacement Pipetter. Digital pipet system capable of delivering volumes from 10 to
2,500 p.L with an assortment of high quality disposable pipet tips.
7.3.2 Balance. Analytical, capable of accurately weighing to 0.1 mg.
7.3.3 Hot Plate. (Corning PC100 or equivalent).
7.3.4 Centrifuge. Steel cabinet with guard bowl, electric timer and brake.
7.3.5 DryingOven. Gravity convection oven with thermostatic control capable of maintaining 105°C ±
5°C.
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Chapter IO-3 Method IO-3.5
Chemical Analysis ICP/MS Methodology
8. Reagents and Consumable Materials
8.1 Reagents
[Note: Owing to the high sensitivity of ICP/MS, high-purity reagents should be used whenever possible. All
acids used for this method must be of ultra high-purity grade. Suitable acids are available from a number
of manufacturers or may be prepared by sub-boiling distillation. Nitric acid is preferred for ICP/MS to
minimize polyatomic ion interferences. Several polyatomic ion interferences result when hydrochloric acid
is used (see Table 2). However, hydrochloric acid is required to maintain stability in solutions containing
antimony and silver. When hydrochloric acid is used, corrections for the chloride polyatomic ion
interferences must be applied to all data. As discussed in Method 10-3.1, a mixture of 3% HNO 3 / 8% HC1
is the best extraction matrix for total extraction of metals from quartz filters.]
8.1.1 Nitric Acid, Concentrated (sp.gr. 1.41). Best source.
8.1.2 Nitric Acid (1+1). Add 500 mL cone, nitric acid to 400 mL of ASTM type I water and dilute to
1 L.
8.1.3 Nitric Acid (1+9). Add 100 mL cone, nitric acid to 400 mL of ASTM type I water and dilute to
1 L.
8.1.4 Hydrochloric Acid, Concentrated (sp.gr. 1.19). Best source.
8.1.5 Hydrochloric Acid (1+1). Add 500 mL cone, hydrochloric acid to 400 mL of ASTM type I water
and dilute to 1 L.
8.1.6 Hydrochloric Acid (1+4). Add 200 mL cone, hydrochloric acid to 400 mL of ASTM type I water
and dilute to 1 L.
8.1.7 Ammonium Hydroxide, Concentrated (sp.gr. 0.902). Best source.
8.1.8 Tartaric Acid (CASRN 87-69-4). Best source.
8.2 Water
For all sample preparation and dilutions, ASTM type I water (ASTM Dl 193) is required. Suitable water may
be prepared by passing distilled water through a mixed bed of anion and cation exchange resins.
8.3 Standard Stock Solutions
Standard stock solutions may be purchased from a reputable commercial source or prepared from ultra
high-purity grade chemicals or metals (99.99 - 99.999% pure). All salts should be dried for 1 h at 105°C,
unless otherwise specified. Stock solutions should be stored in Teflon® bottles. Use the following procedures
for preparing standard stock solutions:
Caution: Many metal salts are extremely toxic if inhaled or swallowed. Wash hands thoroughly after
handling.
[Note: Some metals, particularly those that form surface oxides, require cleaning prior to being weighed,
which requires pickling the surface of the metal in acid. An amount in excess of the desired weight should
be pickled repeatedly, rinsed with water, dried, and weighed until the desired weight is achieved.]
June 1999 Compendium of Methods for Inorganic Air Pollutants Page 3.5-9
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Method IO-3.5 Chapter IO-3
ICP/MS Methodology Chemical Analysis
8.3.1 Aluminum Solution, Stock. 1 mL = 1,000 p.g Al: Pickle aluminum metal in warm (1 + 1) HC1
to an exact weight of 0.100 g. Dissolve in 10 mL cone. HC1 and 2 mL cone, nitric acid, heat to dissolve.
Continue heating until volume is reduced to 4 mL. Cool and add 4 mL ASTM type I water. Heat until the
volume is reduced to 2 mL. Cool and dilute to 100 mL with ASTM type I water.
8.3.2 Antimony Solution, Stock. 1 mL = 1,000 p.g Sb: Dissolve 0.100 g antimony powder in 2 mL
(1 + 1) nitric acid and 0.5 mL cone, hydrochloric acid, heat to dissolve. Cool and add 20 mL ASTM type I
water and 0.15 g tartaric acid. Warm the solution to dissolve the white precipitate. Cool and dilute to
100 mL with ASTM type I water.
8.3.3 Arsenic Solution, Stock. 1 mL = 1,000 p.g As: Dissolve 0.1320 g As203 in a mixture of 50 mL
ASTM type I water and 1 mL cone, ammonium hydroxide. Heat gently to dissolve. Cool and acidify the
solution with 2 mL cone, nitric acid. Dilute to 100 mL with ASTM type I water.
8.3.4 Barium Solution, Stock. 1 mL = 1,000 p.g Ba: Dissolve 0.1437 g BaC03 in a solution mixture
of 10 mL ASTM type I water and 2 mL cone, nitric acid. Heat and stir to dissolve and degassing. Dilute
to 100 mL with ASTM type I water.
8.3.5 Beryllium Solution, Stock. 1 mL = 1,000 \ig Be: Dissolve 1.965 gBeS04-4H20 (DO NOT DRY)
in 50 mL ASTM Type I water. Add 1 mL cone, nitric acid. Dilute to 100 mL with ASTM type I water.
8.3.6 Bismuth Solution, Stock. 1 mL = 1,000 p.g Bi: Dissolve 0.1115 g Bi203 in 5 mL cone, nitric
acid. Heat to dissolve. Cool and dilute to 100 mL with ASTM type I water.
8.3.7 Cadmium Solution, Stock. 1 mL = 1,000 p.g Cd: Pickle cadmium metal in (1 + 9) nitric acid to
an exact weight of 0.100 g. Dissolve in 5 mL (1 + 1) nitric acid, heating to dissolve. Cool and dilute to 100
mL wit ASTM type I water.
8.3.8 Chromium Solution, Stock. 1 mL = 1,000 p.g Cr: Dissolve 0.1923 g Cr03 in a solution mixture
of 10 mL ASTM type I water and 1 mL cone, nitric acid. Dilute to 100 mL with ASTM type I water.
8.3.9 Cobalt Solution, Stock. 1 mL = 1,000 p.g Co: Pickle cobalt metal in (1 + 9) nitric acid to an
exact weight of 0.100 g. Dissolve in 5 mL (1 + 1) nitric acid, heating to dissolve. Cool and dilute to 100 mL
with ASTM type I water.
8.3.10 Copper Solution, Stock. 1 mL = 1,000 p.g Cu: Pickle copper metal in (1 + 9) nitric acid to an
exact weight of 0.100 g. Dissolve in 5 mL (1 + 1) nitric acid, heating to dissolve. Cool and dilute to 100 mL
with ASTM type I water.
8.3.11 Indium Solution, Stock. 1 mL = 1,000 p.g In: Pickle indium metal in (1 + 1) nitric acid to an
exact weight of 0.100 g. Dissolve in 10 mL (1 + 1) nitric acid, heating to dissolve. Cool and dilute to 100
mL with ASTM type I water.
8.3.12 Lead Solution, Stock. 1 mL = 1,000 pg Pb: Dissolve 0.1599 g PbN03 in 5 mL (1 +1) nitric
acid. Dilute to 100 mL with ASTM type I water.
8.3.13 Magnesium Solution, Stock. 1 mL = l,OOOp.gMg: dissolve 0.1658 gMgO in 10 mL (1 +1)
nitric acid, heating to dissolve. Cool and dilute to 100 mL with ASTM type I water.
8.3.14 Manganese Solution, Stock. 1 mL = 1,000 p.g Mn: Pickle manganese flake in (1 + 9) nitric acid
to an exact weight of 0.100 g. Dissolve in 5 mL (1 + 1) nitric acid, heating to effect solution. Cool and dilute
to 100 mL with ASTM type I water.
8.3.15 Molybdenum Solution, Stock. 1 mL = 100 p.g Mo: Dissolve 0.1500 g Mo03 in a solution
mixture of 10 mL ASTM type I water and 1 mL cone, ammonium hydroxide, heating to dissolve and 1 mL
cone, ammonium hydroxide, heating to effect solution. Cool and dilute to 100 mL with ASTM type I water.
8.3.16 Nickel Solution, Stock. 1 mL = 1,000 p.g Ni: Dissolve 0.100 g nickel powder in 5 mL cone.
nitric acid, heating to dissolve. Cool and dilute to 100 mL with ASTM type I water.
8.3.17 Scandium Solution, Stock. 1 mL = 1,000 p.g Sc: Dissolve 0.1534 g sc203 in 5 mL (1 + 1) nitric
acid, heating to dissolve. Cool and dilute to 100 mL ASTM type I water.
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Chapter IO-3 Method IO-3.5
Chemical Analysis ICP/MS Methodology
8.3.18 Selenium Solution, Stock. 1 mL = 1,000 p.g Se: Dissolve 0.1405 g Se02 in 20 mL ASTM type
I water. Dilute to 100 mL with ASTM type I water.
8.3.19 Silver Solution, Stock. 1 mL = 100 p.g Ag: Dissolve 0.100 g silver metal in 5 mL (1 + 1) nitric
acid, heating to dissolve. Cool and dilute to 100 mL with ASTM type I water. Store in dark container.
8.3.20 Terbium Solution, Stock. 1 mL = 1,000 p-gTb: Dissolve 0.1176 gTb407 in 5 mL cone, nitric
acid, heating to dissolve. Cool and dilute to 100 mL with ASTM type I water.
8.3.21 Thallium Solution, Stock. 1 mL = 1,000 p.gTl: Dissolve 0.1303 gT!N03 in a solution mixture
of 10 mL ASTM type I water and 1 mL cone, nitric acid. Dilute to 100 mL with ASTM type I water.
8.3.22 Thorium Solution, Stock. 1 mL = 1,000 \ig Th: Dissolve 0.2380 g Th(N03)4-4H20 (DO NOT
DRY) in 20 mL ASTM type I water. Dilute to 100 mL with ASTM type I water.
8.3.23 Uranium Solution, Stock. 1 mL = l.OOOpgU: Dissolve 0.2110 gU02(N03)2-6H20 (DO NOT
DRY) in 20 mL ASTM type I water and dilute to 100 mL with ASTM type I water.
8.3.24 Vanadium Solution, Stock. 1 mL = 1,000 p.g V: Pickle vanadium metal in (1 + 9) nitric acid
to an exact weight of 0.100 g. Dissolve in 5 mL (1 + 1) nitric acid, heating to dissolve. Cool and dilute to
100 mL with ASTM type I water.
8.3.25 Yttrium Solution, Stock. 1 mL = 1,000 p.g Y: Dissolve 0.1270 g Y203 in 5 mL (1 + 1) nitric
acid, heating to dissolve. Cool and dilute to 100 mL with ASTM type I water.
8.3.26 Zinc Solution, Stock. 1 mL = 1,000 p.g Zn: Pickle zinc metal in (1+9) nitric acid to an exact
weight of 0.100 g. Dissolve in 5 mL (1 +1) nitric acid, heating to effect solution. Cool and dilute to 100 mL
with ASTM type I water.
8.4 Multi-Element Stock Standard Solutions
Care must be taken in the preparation of multi-element stock standards so that the elements are compatible
and stable. Originating element stocks should be checked for impurities that might influence the accuracy
of the standard. Freshly prepared standards should be transferred to acid-cleaned, not previously used FEP
fluorocarbon bottles for storage and monitored periodically for stability. Suggested element combinations
are:
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Method IO-3.5
ICP/MS Methodology
Chapter IO-3
Chemical Analysis
Standard Solution A
Aluminum
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Manganese
Molybdenum
Nickel
Selenium
Thallium
Thorium
Uranium
Vanadium
Zinc
Standard Solution B
Barium
Silver
Multi-element stock standard solutions A and B (1 mL = 10 p.g) may be prepared by diluting 1 mL of each
single element stock in the combination list to 100 mL with ASTM type I water containing 1% (v/v) nitric
acid.
Fresh multi-element calibration standards should be prepared every 2 weeks, or as needed. Dilute each of
the stock multi-element standard solutions A and B to levels appropriate to the operating range of the
instrument using ASTM type I water containing 1% (v/v) nitric acid. The element concentrations in the
standards should be sufficiently high to produce good measurement precision and to accurately define the
slope of the response curve. Concentrations of 200 p.g/L are suggested. If the direct addition procedure and
internal standards (see Section 8.5) to the calibration standards are being used, store in Teflon® bottles.
Calibration standards should be verified initially using a quality control sample (see Section 8.8).
8.5 Internal Standards Stock Solution, 1 mL = 100 fig
Dilute 10 mL of scandium, yttrium, indium, terbium and bismuth stock standards (Section 8.3) to 100 mL
with ASTM type I water and store in Teflon® bottle. Use this solution concentrate to add to blanks,
calibration standards, and samples or dilute by an appropriate amount using 1% (v/v) nitric acid, if the
internal standards are being added by peristaltic pump.
8.6 Blanks
Three types of blanks are required for this method. A calibration blank establishes the analytical calibration
curve. The laboratory reagent blank assesses possible contamination from the sample preparation procedure
and spectral background. The rinse blank flushes the instrument between samples to reduce memory
interferences.
8.6.1 Calibration blank consists of 1% (v/v) nitric acid in ASTM type I water. If the direct addition
procedure is being used, add internal standards.
8.6.2 Laboratory reagent blank (LRB) must contain all the reagents in the same volumes as used in
processing the samples. The LRB must be carried through the entire sample digestion and preparation
scheme. If the direct addition procedure is being used, add internal standards to the solution after preparation
is complete.
8.6.3 Rinse blank consists of 2% (v/v) nitric acid in ASTM type I water.
8.7 Tuning Solution
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Chapter IO-3 Method IO-3.5
Chemical Analysis ICP/MS Methodology
This solution is used for instrument tuning and mass calibration prior to analysis. The solution is prepared
by mixing beryllium, magnesium, cobalt, indium and lead stock solutions (see Section 8.3) in 1% (v/v) nitric
acid to produce a concentration of 100 p.g/L of each element. Internal standards are not added to this
solution.
8.8 Quality Control Sample (QCS)
The QCS should be obtained from a source outside the laboratory. Dilute an appropriate aliquot of analytes
(concentrations not to exceed 1,000 p-g/L) in 1% (v/v) nitric acid. If the direct addition procedure is being
used, add internal standards after dilution, mix, and store in a Teflon® bottle.
8.9 Laboratory Fortified Blank (LFB)
To an aliquot of LFB, add aliquots from multi-element stock standards A and B (see Section 8.4) to produce
the LFB with a final concentration of 100 p.g/L for each analyte. The LFB must be carried through the entire
sample digestion and preparation scheme. If the direct addition procedure is being used, add internal
standards to this solution after preparation.
9. Sample Receipt in the Laboratory
9.1 The sample should be received from the extraction laboratory as documented in Inorganic Compendium
Method 10-3.1.
9.2 No additional preservation is needed at this time. Sample is ready for ICP/MS analysis. However, the
samples contain hydrochloric acid, and the calibration standards do not. Correction for interferences for
chloride must be made (see Section 13.4).
10. Calibration and Standardization
10.1 Calibration
[Note: Demonstration and documentation of acceptable initial calibration is required before samples are
analyzed and periodically throughout sample analysis as dictated by results of continuing calibration checks.
After initial calibration is successful, a calibration check is required at the beginning and end of each period
during which analyses are performed and at requisite intervals.]
10.1.1 Allow a period of not less than 30 min for instrument warm up. During this process, conduct
mass calibration and resolution checks using the tuning solution. Resolution at low mass is indicated by
magnesium isotopes 24, 25, and 26. Resolution at high mass is indicated by lead isotopes 206, 207, and 208.
For good performance, adjust spectrometer resolution to produce a peak width of approximately 0.75 amu
at 5% peak height. Adjust mass calibration if it has shifted by more than 0.1 amu from unit mass.
10.1.2 Instrument stability must be demonstrated by running the tuning solution (see Section 8.7) a
minimum of five times with resulting relative standard deviations of absolute signals for all analytes of less
than 5%.
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10.1.3 Prior to initial calibration, set up proper instrument software routines for quantitative analysis.
The instrument must be calibrated for the analytes to be determined using the calibration blank (see
Section 8.6.1) and calibration standards A and B (see Section 8.4) prepared at one or more concentration
levels. A minimum of three replicate integrations are required for data acquisition. Use the average of the
integrations for instrument calibration and data reporting.
10.1.4 The rinse blank should be used to flush the system between solution changes for blanks,
standards, and samples. Allow sufficient rinse time to remove traces of the previous sample or a minimum
of 1 min. Solutions should be aspirated for 30 s prior to the acquisition of data to establish equilibrium.
10.2 Internal Standardization
10.2.1 Internal standardization must be used in all analyses to correct for instrument drift and physical
interferences. A list of acceptable internal standards is provided in Table 4.
10.2.2 For full mass range scans, a minimum of three internal standards must be used. Procedures
described in this method for general application detail five internal standards: scandium, yttrium, indium,
terbium, and bismuth. These standards were used to generate the precision and recovery data attached to this
method. Internal standards must be present in all samples, standards, and blanks at identical levels.
10.2.3 This may be achieved by directly adding an aliquot of the internal standards to the CAL standard,
blank, or sample solution or alternatively by mixing with the solution prior to nebulization using a second
channel of the peristaltic pump and a mixing coil. The concentration of the internal standard should be
sufficiently high to obtain a precise measurement of the isotope used for data correction and to minimize the
possibility of correction errors if the internal standard is naturally present in the sample.
10.2.4 A concentration of 200 p.g/L of each internal standard is recommended. Internal standards should
be added to blanks, samples, and standards in a like manner so that dilution effects from the addition may be
disregarded.
10.3 Instrument Performance
[Note: Check the performance of the instrument and verify the calibration using data gathered from analyses
of calibration blanks, calibration standards and the QCS.]
10.3.1 After establishing calibration, it must be initially verified for all analytes by analyzing the QCS
(see Section 8.8). If measurements exceed ± 10% of the established QCS value, terminate the analysis,
identify and correct the problem, recalibrate the instrument, and reverify the calibration reverified before
continuing analyses.
10.3.2 To verify that the instrument is properly calibrated on a continuing basis, run the calibration blank
and calibration standards as surrogate samples after every 10 analyses. The results of the analyses of the
standards will indicate whether the calibration remains valid. If the indicated concentration of any analyte
deviates from the true concentration by more than 10%, reanalyze the standard. If the analyte is again
outside the 10% limit, the instrument must be recalibrated and the previous ten samples reanalyzed. The
instrument responses from the calibration check may be used for recalibration purposes. If the sample matrix
is responsible for the calibration drift, the previous 10 samples should be reanalyzed in groups of five
between calibration checks to prevent a similar drift situation from occurring.
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Chemical Analysis ICP/MS Methodology
11. Quality Control (QC)
11.1 Laboratory
Each laboratory using this method is required to operate a formal QC program. The minimum requirements
of this program are an initial demonstration of laboratory capability and the analysis of laboratory reagent
blanks, fortified blanks, and samples as a continuing check on performance. The laboratory is required to
maintain performance records that define the quality of the data thus generated.
11.2 Initial Demonstration of Performance
11.2.1 The initial demonstration of performance is used to characterize instrument performance (method
detection limits and linear calibration ranges) for analyses conducted by this method.
11.2.2 Method detection limits (MDL) should be established for all analytes, using reagent water (blank)
fortified at a concentration of two to five times the estimated detection limit. To determine MDL values, take
seven replicate aliquots of the fortified reagent water and process through the entire analytical method.
Perform all calculations defined in the method and report the concentration values in the appropriate units.
Calculate the MDL as follows:
MDL = (t) x (S)
where:
t = Student's t value for a 99% confidence level and a standard deviation estimate with n-1 degrees
of freedom [t = 3.14 for seven replicates].
S = standard deviation of the replicate analyses.
MDLs should be determined every 6 months or whenever a significant change in background or instrument
response is expected (e.g., detector change).
11.2.3 Linear calibration ranges are primarily detector limited. The upper limit of the linear calibration
range should be established for each analyte by determining the signal responses from a minimum of three
different concentration standards, one of which is close to the upper limit of the linear range. Avoid damage
to the detector during this process. The linear calibration range, which may be used for the analysis of
samples, should be judged by the analyst from the resulting data. Linear calibration ranges should be
determined every 6 months or whenever a significant change in instrument response is expected
(e.g., detector change).
11.3 General Quality Control
[Note: The required general quality control requirements for ICP analysis are discussed below and
summarized in Table 8.]
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11.3.1 Initial Calibration. At least two calibration standards and a calibration blank are analyzed at the
beginning of an analysis run. The standards used to calibration are diluted from certified stock standards and
are used within the expiration dates. The calibration standards and blanks are prepared in the same matrix as
the samples.
11.3.2 Initial Calibration Verification (ICV). The QCS is analyzed immediately following initial
calibration to verify the initial calibration. The QCS is prepared at the midpoints of the calibration curves. It
is prepared from certified stocks having a different manufacturer than the calibration standards. The measured
concentration should be within 90% to 110% of the actual concentration.
11.3.3 Initial Calibration Blank (ICB). The ICB is analyzed immediately following ICV and prior to
the high standard verification. The acceptance criteria for the ICB is the same as for continuing calibration
blank (CCB) verification.
11.3.4 High Standard Verification (HSV). Immediately after the analysis of the ICB, and prior to the
analysis of samples, the HSVs are reanalyzed. The measured concentration should be within 95% to 105% of
actual concentration.
11.3.5 Interference Check Standards (ICS). The ICSs are analyzed at the beginning and end of the
run and for every 8 hours of continuous operation. The results for the analytes should be within 80% and 120%
of the actual concentration. Samples containing levels of interferences above the levels in the ICS should be
considered for dilution.
11.3.6 Continuing Calibration Verification (CCV). CCV standards are prepared from the calibration
standard stocks at the midpoint of the calibration curve. The CCV standards are analyzed at the beginning of
the run prior to samples, after every 10 samples, and at the end of the run prior to the last continuing calibration
blank (CCB) analysis. The measured concentration should be within 90% and 110% of the actual
concentration.
11.3.7 Continuing Calibration Blanks (CCBs). The CCBs are analyzed following each CCV. The
results of the CCBs are evaluated as follows:
The CCBs are compared to the method detection limits.
The absolute value of the instrument response must be less than the method detection limits.
If not, then sample results for analyses < 5 times the amount of the blank must be flagged or analysis
must be repeated.
11.3.8 Method Blank (MB). A MB sample is prepared and analyzed with each sample batch. This
analysis is used to determine if concentrations reflect background levels from sample digestion. If the
instrument measured response is greater than the method detection limits, then the sample results for the
affected analyte(s) must be flagged. Samples may be considered candidates for redigestion and reanalysis
for that analyte.
11.3.9 Laboratory Control Spike (LCS). An LCS is the same as a laboratory fortified blank. An LCS
is prepared and analyzed with each sample batch (or 1 per 20 samples). The results for the analytes should be
within 80% to 120% of actual concentration. If the results are not within this criterion, then the results must
be qualified.
11.3.10 Matrix Spike (MS). A MS sample is prepared and analyzed with each sample batch (or 1 per
20 samples). These samples are used to provide information about the effect of the sample matrix on the
digestion and measurement methodology. The spike is added before the digestion, (i.e., prior to the addition
of other reagents). The percent recovery for the analyte as part of the MS should be between 75% and 125%
for all analytes.
11.3.11 Duplicate and/or Spike Duplicate. Duplicate samples and/or matrix spike duplicates are
prepared and analyzed with each sample batch. These samples are used to estimate method precision,
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Chapter IO-3 Method IO-3.5
Chemical Analysis ICP/MS Methodology
expressed as relative percent difference (RPD). The RPD between the duplicate and/or matrix spike duplicate
final concentrations should be <20%.
11.3.12 Serial Dilution. The ICP serial dilution analysis must be performed on one sample per batch.
After a fivefold serial dilution, the analyte concentration must be within 90% and 110% of the undiluted sample
results.
11.3.13 Sample Dilution. Dilute and reanalyze samples that are more concentrated than the linear
calibration limit.
11.4 Assessing Analyte Recovery - Laboratory Fortified Sample Matrix
11.4.1 The laboratory must add a known amount of analyte to a minimum of 5% of the routine samples
or one sample per sample set, whichever is greater.
11.4.2 Calculate the percent recovery for each analyte, corrected for background concentrations
measured in the unfortified sample and compare these values to the control limits established in
Section 11.3.3 for the analyses of LFBs. Recovery calculations are not required if the concentration of the
analyte added is less than 10% of the sample background concentration. Percent recovery may be calculated
in units appropriate to the matrix using the following equation:
R = (Cs-C)/sxlOO
where:
R = percent recovery, %.
Cs = fortified sample concentration, ng/L.
C = sample background concentration, ng/L.
s = concentration equivalent of fortifier added to sample, ng/L.
11.4.3 If recovery of any analyte falls outside the designated range and laboratory performance for that
analyte is shown to be in control (see Section 11.3), the recovery problem encountered with the fortified
sample is judged to be matrix-related, not system-related. The analyte in the unfortified sample must be
labeled "suspect/matrix" to inform the user that the results are suspect due to matrix effects.
11.5 Internal Standards Responses
The analyst is expected to monitor the responses from the internal standards throughout the sample set being
analyzed. Ratios of the internal standards responses against each other should also be monitored routinely.
This information may be used to detect potential problems caused by mass dependent drift, errors incurred
in adding the internal standards, or increases in the concentrations of individual internal standards caused by
background contributions from the sample. The absolute response of any one internal standard should not
deviate more than 60-125% of the original response in the calibration blank. If deviations greater than this
are observed, use the following test procedure:
11.5.1 Flush the instrument with the rinse blank and monitor the responses in the calibration blank. If
the responses of the internal standards are now within the limit, take a fresh aliquot of the sample, dilute by
a further factor of two, add the internal standards and reanalyze.
11.5.2 If the test is not satisfied or if it is a blank or calibration standard that is out of limits, terminate
the analysis and determine the cause of the drift. Possible causes may be a partially blocked sampling cone
or a change in the tuning condition of the instrument.
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12. Procedure
12.1 Samples should be received from the extraction laboratory in a 10-mL centrifuge tube. The samples
contain a mixture of nitric and hydrochloric acids. This is not the most appropriate solution for ICP/MS
determination. Therefore, corrections described in Section 13.4 must be applied.
12.2 For every new or unusual matrix, a semi-quantitative analysis should be carried out to screen for high
element concentrations. Information gained from this procedure may be used to prevent potential damage
to the detector during sample analysis and to identify elements that may be higher than the linear range.
Matrix screening may be carried out by using intelligent software, if available, or by diluting the sample by
a factor of 500 and analyzing in a semi-quantitative mode. The sample should also be screened for
background levels of all elements chosen for use as internal standards to prevent bias.
12.3 Initiate instrument operating configuration. Tune and calibrate the instrument for the analytes of
interest (see Section 10).
12.4 Establish instrument software run procedures for quantitative analysis. For all sample analyses, a
minimum of three replicate integrations are required for data acquisition. Discard any integrations
considered to be statistical outliers and use the average of the integrations for data reporting.
12.5 Monitor all masses that might affect data quality during the analytical run. At a minimum, those masses
prescribed in Table 5 must be monitored in the same scan as is used for the collection of the data. This
information should be used to correct the data for identified interferences.
12.6 Use the rinse blank to flush the system between samples. Allow sufficient time to remove traces of the
previous sample or a minimum of 1 min. Aspirate the samples for 30 s prior to the collection of data.
12.7 Samples having concentrations higher than the established linear dynamic range should be diluted into
range and reanalyzed. First, analyze the sample for trace elements, protecting the detector from the high
concentration elements, if necessary, by selecting appropriate scanning windows. Then dilute the sample to
determine the remaining elements. Alternatively, the dynamic range may be adjusted by selecting an
alternative isotope of lower natural abundance, provided quality control data for that isotope have been
established. Do not adjust the dynamic range by altering instrument conditions to an uncharacterized state.
13. Calculations
13.1 Elemental equations recommended for sample data calculations are listed in Table 6. Sample data
should be reported in units of ng/m3.
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Chapter IO-3 Method IO-3.5
Chemical Analysis ICP/MS Methodology
13.1.1 Calculate the air volume sampled, corrected to EPA-reference conditions:
Vstd = Vs (3SL)&
1 m *std
where:
Vstd = volume of ambient air sampled at EPA-reference conditions, m3
Vs = volume of ambient air pulled through the sampler, m3.
Tstd = absolute EPA-reference temperature, 298°K.
Tm = average ambient temperature, °K.
Pbar = barometric pressure during sampling measurement condition, mm Hg.
Pstd = EPA-reference barometric pressure, 760 mm Hg.
13.1.2 Metal concentration in the air sample can then be calculated as follows:
C = [(p.g metal/mL) x (Digestion volume (i.e., 20 mL) mL/strip)(9) - FJ/Vstd
where:
C = concentration, p.g metal/m3.
p.g metal/mL = metal concentration determined from Section 12.
final extract volume (mL)/strip = total sample extraction volume from extraction procedure
(i.e., 20 mL).
Useable filter area, [20 cm x 23 cm (8" x 9")]
Exposed area of one strip, [2.5 cm x 20 cm (1" x 8")].
Fm = average concentration of blank filters, p.g.
Vstd = standard air volume pulled through filter, std. m3 (25°C and 760 mm Hg).
Do not report element concentrations below the determined MDL.
13.2 For data values less than 10, use two significant figures to report element concentrations. For data
values greater than or equal to 10, three significant figures.
13.3 Reported values should be calibration blank subtracted (see Inorganic Compendium Method 10-
3.1).
13.4 Correct data values for instrument drift or sample matrix induced interferences by applying internal
standardization. Corrections for characterized spectral interferences should be applied to the data.
Chloride interference corrections should be made on all samples, because of the addition of hydrochloric
acid during filter extraction, as the chloride ion is a common constituent of environmental samples.
13.5 If an element has more than 1 monitored isotope, examine the concentration calculated for each
isotope, or the isotope ratios, to detect a possible spectral interference. Consider both primary and
secondary isotopes when evaluating the element concentration. In some cases, secondary isotopes may be
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less sensitive or more prone to interferences that the primary recommended isotopes; therefore,
differences between the results do not necessarily indicate a problem with data calculated for the primary
isotopes.
13.6 The QC data obtained during the analyses provide an indication of the quality of the sample data and
should be provided with the sample results.
14. Precision and Accuracy
14.1 Instrument operating conditions for single laboratory testing of the method are summarized in
Table 3.
14.2 Data obtained from single laboratory testing of the method for three solid samples consisting of
SRM 1645 River Sediment, EPA Hazardous Soil, and EPA Electroplating Sludge are summarized in
Table 7. For each method element, the sample background concentration, mean percent recovery,
standard deviation of the percent recovery, and relative percent difference between the duplicate fortified
samples were determined. Data for matrices other than air are presented because only very limited data
on air samples was available when this method was written.
14.3 Activities required to be performed using ICP/MS to validate method precision and accuracy are
summarized in Table 8.
15. References
1. "Standard Operating Procedures for the ICP-DES Determination of Trace Elements in Suspended
Particulate Matter Collected on Glass-Fiber Filters," EMSL/RTP-SOP-EMO-002, Revision, October,
1983.
2. "Reference Method for the Determination of Suspended Particulates in the Atmosphere (High Volume
Method)," Code of Federal Regulations, Title 40, Part 50, Appendix B, pp. 12-16 (July 1, 1975).
3. "Reference Method for the Determination of Lead in Suspended Particulate Matter Collected from
Ambient Air.," Federal Register 43 (194): 46262-3, 1978.
4. Rhodes, R.C., 1981, "Special Extractability Study of Whatman and Schleicher and Schuell Hi-Vol
Filters," Memo to file, August 5, 1981, Quality Assurance Division, Environmental Monitoring
Systems Laboratory, U. S. Environmental Protection Agency, Research Triangle Park NC.
5. Ward, A. F., The Jarrell-Ash Plasma Newsletter, Volumes I, II, and III.
6. Nygard, D., and Sot, J., "Determination Near the Detection Limit: A Comparison of Sequential and
Simultaneous Plasma Emission Spectrometers," Spectroscopy, Vol. 3(4).
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Chapter IO-3 Method IO-3.5
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7. "Simplex Optimization of Multielement Ultrasonic Extraction of Atmospheric Particulates," Harper,
et. al., Analytical Chemistry, Vol 55(9), August 1983.
8. A. L. Gray and A. R. Date, Analyst, Vol 108:1033.
9. R. S. Houk et al., Anal. Chem., Vol 52:2283.
10. R. S. Houk, Anal. Chem. Vol. 58(97A).
11. J. J. Thompson and R. S. Houk, Appl. Spec., Vol. 41:801, 1987.
12. "OSHA Safety and Health Standards, General Industry," (29 CFR 1910), Occupational Safety and
Health Administration, OSHA 2206, revised January 1976.
13. "Proposed OSHA Safety and Health Standards, Laboratories," Federal Register, July 24, 1986.
14. Code of Federal Regulations 40, Ch. 1, Pt. 136 Appendix B.
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Chapter IO-3
Chemical Analysis
TABLE 1. ESTIMATED METHOD DETECTION3 LIMITS
Element
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Manganese
Molybdenum
Nickel
Selenium
Silver
Thallium
Thorium
Uranium
Vanadium
Zinc
Recommended analytical
mass
27
121
75
137
9
111
52
59
63
206,207,208
55
98
60
82
107
205
232
238
51
66
Estimated Method Detection Limits (MDLs)b
UR/L
0.05
0.08
0.9
0.5
0.1
0.1
0.07
0.03
0.03
0.08
0.1
0.1
0.2
5
0.05
0.09
0.03
0.02
0.02
0.2
ng/m3
0.01
0.01
0.30
0.10
0.02
0.02
0.01
0.01
0.01
0.01
0.02
0.02
0.02
1.10
0.01
0.01
0.01
0.01
0.01
0.04
"Instrument detection limits (3a) estimated from seven replicate integrations of the blank (1% v/v nitric acid) following
calibration of the instrument with three replicate integrations of a multi-element standard.
bBased upon sampling rate of 1.13 mVmin for 24-h for a total sample volume of 1,627.2 in3, factor of 9 for partial filter analysis;
digestion of 0.040 L/filter.
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Method IO-3.5
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TABLE 2. COMMON POLYATOMIC ION INTERFERENCES IN ICP-MS
BACKGROUND MOLECULAR IONS
Molecular Ion
NH+
OH+
OH2+
C2+
CN+
co+
N2+
N2H+
N0 +
NOH+
02+
OH+
36ArH+
38ArH+
4oArH+
C02+
C02H+
ArC+, ArO +
ArN+
ArNH +
ArO +
ArOH +
40Ar36Ar +
A ^"3" A -p +
JT\.L JT\.L
4°Ar2
Mass
15
17
18
24
26
28
28
29
30
31
32
33
37
39
41
44
45
52
54
55
56
57
76
78
80
Element Interference1
Sc
Cr
Cr
Mn
Se
Se
Se
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.5-23
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Method IO-3.5
ICP/MS Methodology
Chapter IO-3
Chemical Analysis
TABLE 2. (continued)
MATRIX MOLECULAR IONS
CHLORIDE
Polyatomic Ion
35C10+
35C10H+
37C10+
37C10H+
Ar35Cl+
Ar37Cl+
SULFATE
Polyatomic Ion
32SO +
32SOH+
34SO +
34SOH+
S02, S2+
Ar32S+
Ar^S*
PHOSPHATE
Polyatomic Ion
PO +
POH +
P02+
ArP2
GROUP I, II METALS
Polyatomic Ion
ArNa+
ArK+
ArCa +
MATRIX OXIDES2
Polyatomic Ion
TiO
ZrO
MoO
Mass
51
52
53
54
75
77
Mass
48
49
50
51
64
72
74
Mass
47
48
63
71
Mass
63
79
80
Masses
62-66
106-112
108-116
Element Interference
V
Cr
Cr
Cr
As
Se
Element Interference
T,
T.
V, Cr
V
Zn
Element Interference
Cu
Element Interference
Cu
Element Interference
Ni, Cu, Zn
Ag, Cd
Cd
'Method elements or internal standards affected by the polyatomic ions.
20xide interferences will normally be very small and will only impact the method elements when present at relatively high
concentrations. Some examples of matrix oxides are listed of which the analyst should be aware. It is recommended that
Ti and Zr isotopes are monitored in solid waste samples, which are likely to contain high levels of these elements. Mo is
monitored as a method analyte.
Page 3.5-24
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter IO-3
Chemical Analysis
Method IO-3.5
ICP/MS Methodology
TABLE 3. EXAMPLE INSTRUMENT OPERATING CONDITIONS
Instrument
Plasma forward power
Coolant flow rate
Auxiliary flow rate
Nebulizer flow rate
Solution uptake rate
Spray chamber temperature
Data Acquisition
Detector mode
Replicate integrations
Mass range
Dwell time
Number of MCA channels
Number of scan sweeps
Total acquisition time
VG PlasmaQuad Type I
1.35kW
13.5 L/min
0.6 L/min
0.78 L/min
0.6 mL/min
15°C
Pulse counting
3
8 - 240 amu
320 p.s
2048
85
3 min per sample
TABLE 4. INTERNAL STANDARDS AND LIMITATIONS OF USE
Internal Standard
Lithium
Scandium
Yttrium
Rhodium
Indium
Terbium
Holmium
Lutetium
Bismuth
Mass
6
45
89
103
115
159
165
175
209
Possible Limitation
a
polyatomic ion interference
a,b
isobaric interference by Sn
a
"May be present in environmental samples.
bln some instruments yttrium may form measurable amounts of YO + (105 amu) and YOH + (106 amu). If this is the case, care
should be taken in the use of the cadmium elemental correction equation.
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.5-25
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Method IO-3.5
ICP/MS Methodology
Chapter IO-3
Chemical Analysis
TABLE 5. RECOMMENDED ANALYTICAL ISOTOPES
AND ADDITIONAL MASSES WHICH
MUST BE MONITORED
Isotope
27
121,123
75
135,137
9
106,108,111,114
52,53
59
63,65
206,207,208
55
95,97,98
60,62
77,82
107,109
203,205
232
238
51
66,67,68
83
99
105
118
Element of Interest
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Manganese
Molybdenum
Nickel
Selenium
silver
Thallium
Thorium
Uranium
Vanadium
Zinc
Krypton
Ruthenium
Palladium
Tin
NOTE: Isotopes recommended for analytical determination are underlined.
Page 3.5-26
Compendium of Methods for Inorganic Air Pollutants
June 1999
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Chapter IO-3
Chemical Analysis
Method IO-3.5
ICP/MS Methodology
TABLE 6. RECOMMENDED ELEMENTAL EQUATIONS FOR
DATA CALCULATIONS
Element
Element Equation
Note
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Bi
In
Sc
Tb
Y
(1.000)(27C)
(1.000)(121C)
(1.000)(75C)-(3.127)[(77C)-(0.815)(82C)]
(1.000)(137C)
(1.000)(9C)
(1.000)(111C)-(1.073)[(108C)-(0.712)(106C)]
(1.000)(52C)
(1.000)(59C)
(1.000)(63C)
(1.000) (206C) + (1.000) (207C) + (1.000) (208C)
(1.000)(55C)
(1.000)(98C)-(0.146)("C)
(1.000)(60C)
(1.000)(82C)
(1.000)(107C)
(1.000)(205C)
(1.000)(232C)
(1.000)(238C)
(1.000)(51C)-(3.127)[(53C)-(0.113)(52C)]
(1.000)(66C)
(1.000)(209C)
(1.000)(115C)-(0.016)(118C)
(1.000)(45C)
(1.000)(159C)
(1.000)(89C)
(1)
(2)
(3)
(4)
(5)
(7)
C - calibration blank subtracted counts at specified mass.
(1) - correction for chloride interference with adjustment for Se77. ArCl 75/77 ratio may be determined
from the reagent blank.
(2) - correction for MoO interference. An additional isobaric elemental correction should be made if
palladium is present.
(3) - in 0.4% v/v HC1, the background from C10H will normally be small. However, the contribution may
be estimated from the reagent blank.
(4) - allowance for isotopic variability of lead isotopes.
(5) - isobaric elemental correction for ruthenium.
(6) - some argon supplies contain krypton as an impurity. Selenium is corrected for Kr82 by background
subtraction.
(7) - correction for chloride interference with adjustment for Cr53 ratio may be determined from the reagent
blank.
(8) - isobaric elemental correction for tin.
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.5-27
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Method IO-3.5
ICP/MS Methodology
Chapter IO-3
Chemical Analysis
TABLE 7. PRECISION AND RECOVERY DATA
EPA HAZARDOUS SOIL #884
Element
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Sample
Concn.
(ug/L)
5170
5.4
8.8
113
0.6
1.8
83.5
7.1
115
152
370
4.8
19.2
<3.2
1.1
0.24
1.0
1.1
17.8
128
Low
Spike
(pg/L)
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
Average
Recovery
R (%)
*
69.8
104.7
54.9
100.1
97.3
86.7
98.8
86.3
85.0
*
95.4
101.7
79.5
96.1
94.3
69.8
100.1
109.2
87.0
S(R)
*
2.5
5.4
63.6
0.6
1.0
16.1
1.2
13.8
45.0
*
1.5
3.8
7.4
0.6
1.1
0.6
0.2
4.2
27.7
RPD
.
4.7
9.1
18.6
1.5
1.4
8.3
1.9
3.4
13.9
12.7
2.9
1.0
26.4
0.5
3.1
1.3
0.0
2.3
5.5
High
Spike
(pg/L)
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Average
Recovery
R (%)
*
70.4
102.2
91.0
102.9
101.7
105.5
102.9
102.5
151.7
85.2
95.2
102.3
100.7
94.8
97.9
76.0
102.9
106.7
113.4
S(R)
*
1.8
2.2
9.8
0.4
0.4
1.3
0.7
4.2
25.7
10.4
0.7
0.8
9.4
0.8
1.0
2.2
0.0
1.3
12.9
RPD
.
6.5
5.4
0.5
1.0
1.0
0.0
1.8
4.6
23.7
2.2
2.0
0.8
26.5
2.3
2.9
7.9
0.0
2.4
14.1
S(R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
* Spike concentration < 10% of sample background concentration.
Not determined.
+ Equivalent.
Page 3.5-28
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter IO-3
Chemical Analysis
Method IO-3.5
ICP/MS Methodology
TABLE 7. PRECISION AND RECOVERY DATA (continued)
NBS 1645 RIVER SEDIMENT
Element
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Sample
Concn.
(ug/L)
5060
21.8
67.2
54.4
0.59
8.3
29100
7.9
112
742
717
17.1
41.8
<3.2
1.8
1.2
0.90
0.79
21.8
1780
Low
Spike
(pg/L)
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
Average
Recovery
R (%)
*
73.9
104.3
105.6
88.8
92.9
*
97.6
121.0
*
*
89.8
103.7
108.3
94.8
91.2
91.3
95.6
91.8
*
S(R)
*
6.5
13.0
4.9
0.2
0.4
*
1.3
9.1
*
*
8.1
6.5
14.3
1.6
1.3
0.9
1.8
4.6
*
RPD
.
9.3
7.6
2.8
0.5
0.0
-
2.6
1.5
-
-
12.0
4.8
37.4
4.3
3.6
2.6
5.0
5.7
-
High
Spike
(pg/L)
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Average
Recovery
R (%)
*
81.2
107.3
98.6
87.9
95.7
*
103.1
105.2
-
-
98.4
102.2
93.9
96.2
94.4
92.3
98.5
100.7
*
S(R)
*
1.5
2.1
2.2
0.1
1.4
*
0.0
2.2
-
-
0.7
0.8
5.0
0.7
0.4
0.9
1.2
0.6
*
RPD
.
3.9
2.9
3.9
0.2
3.9
-
0.0
1.8
-
-
0.9
0.0
15.1
1.9
1.3
2.8
3.5
0.8
-
S(R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
* Spike concentration < 10% of sample background concentration.
Not determined.
+ Equivalent.
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.5-29
-------
Method IO-3.5
ICP/MS Methodology
Chapter IO-3
Chemical Analysis
TABLE 7. PRECISION AND RECOVERY DATA (continued)
EPA ELECTROPLATING SLUDGE #286
Element
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
Sample
Concn.
(ug/L)
5110
8.4
41.8
27.3
0.25
112
7980
4.1
740
1480
295
13.3
450
3.5
5.9
1.9
3.6
2.4
21.1
13300
Low
Spike
(pg/L)
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
Average
Recovery
R (%)
*
55.4
91.0
1.8
92.0
85.0
*
89.2
*
*
*
82.9
*
89.7
89.8
96.9
91.5
107.7
105.6
*
S(R)
*
1.5
2.3
7.1
0.9
5.2
*
1.8
*
*
*
1.2
*
3.7
2.1
0.9
1.3
2.0
1.8
*
RPD
.
4.1
1.7
8.3
2.7
1.6
-
4.6
6.0
-
-
1.3
6.8
4.2
4.6
2.4
3.2
4.6
2.1
-
High
Spike
(pg/L)
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Average
Recovery
R (%)
*
61.0
94.2
0
93.4
88.5
*
88.7
61.7
*
-
89.2
83.0
91.0
85.1
98.9
97.4
109.6
97.4
*
S(R)
*
0.2
0.8
1.5
0.3
0.8
*
1.5
20.4
*
-
0.4
10.0
6.0
0.4
0.9
0.7
0.7
1.1
*
RPD
.
0.9
1.5
10.0
0.9
0.5
-
4.6
5.4
-
-
1.0
4.5
18.0
1.1
2.4
2.0
1.8
2.5
-
S (R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
* Spike concentration < 10% of sample background concentration.
Not determined.
+ Equivalent.
Page 3.5-30
Compendium of Methods for Inorganic Air Pollutants
June 1999
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Chapter IO-3
Chemical Analysis
Method IO-3.5
ICP/MS Methodology
TABLE 8. EXAMPLE OF QUALITY CONTROL REQUIREMENTS FOR ICP/MS ANALYSIS
QC procedure
Initial calibration (1C)
Initial calibration verification
(ICV) using the QCS
Initial calibration blank (ICB)
High standard verification
(HSV)
Interference check standard
(ICS)
Continuing calibration
verification (CCV)
Continuing clarification blanks
(CCBs)
Reagent blank (RB) or Method
blank (MB)
Laboratory control spike (LCS)
or Laboratory fortified blanks
(LFB)
Duplicate and/or spike
duplicate
Matrix spike (MS)
Serial dilution
Sample dilution
Typical frequency
At the beginning of the analysis
Immediately after initial
calibration
Immediately after initial
calibration verification
Following the initial calibration
blank analysis
Following the high standard
verificatino, every 8 hours, and
at the end of a run
Analyzed before the first
sample, after every 10 samples,
and at the end of the run
Analyzed following each
continuing calibration
verification
1 per 40 samples, a minimum of
1 per batch
1 per 20 samples, a minimum of
1 per batch
1 per sample batch
1 per 20 samples per sample
batch
1 per sample batch
Dilute sample beneath the upper
calibration limit but no lower
than at least 5X the MDL
Criteria
None
90%- 110% of the actual
concentration
May be less than project
detection limits (MDLs)
95%- 105% of the actual
concentration
80%- 120% of the actual
concentration
90%- 110% of the actual
concentration
Must be less than project
detection limits (MDLs)
Must be less than project
detection limits (MDLs)
80%- 120% recovery, with the
exception of Ag and Sb
RPD ^20%
Percent recovery of 75%- 125%
90%- 1 10% of undiluted sample
As needed
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.5-31
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