EP A/625/R-96/01 Oa
Compendium of Methods
for the Determination of
Inorganic Compounds
in Ambient Air
Compendium Method 10-3.2
DETERMINATION OF METALS
IN AMBIENT PARTICULATE MATTER
USING ATOMIC ABSORPTION (AA)
SPECTROSCOPY
Center for Environmental Research Information
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
June 1999
-------
Method 10-3.2
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 0. 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, RTP, NC
• Robert G. Lewis, U.S. EPA, NERL, RTP, NC
• Justice A. Manning, U.S. EPA, ORD, Cincinnati, OH
• William A. McClenny, U.S. EPA, NERL, RTP, NC
• Frank F. McElroy, U.S. EPA, NERL, RTP, NC
• William T. "Jerry" Winberry, Jr., EnviroTech Solutions, Cary, 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, Cary, NC
Peer Reviewers
• David Brant, National Research Center for Coal and Energy, Morgantown, WV
• John Glass, SC Department of Health and Environmental Control, Columbia, SC
• Jim Cheney, U.S. Army Corps of Engineers, Omaha, NE
• Eric Prestbo, Frontier GeoScience, Seattle, WA
• Anne M. Falke, Frontier GeoScience, Seattle WA
• Gary Wester, Midwest Research Institute, Kansas City, MO
• Margaret Zimmerman, Texas Natural Resource Conservation Commission, Austin, TX
• Doug Duckworth, Lockheed-Martin Energy Research, Oak Ridge, TN
• 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.
ii
-------
Method 10-3.2
Determination of Metals in Ambient
Particulate Matter Using Atomic Absorption (AA) Spectroscopy
TABLE OF CONTENTS
Page
1. Scope 3.2-1
2. Applicable Documents 3.2-2
2.1 ASTM Standards 3.2-2
2.2 Other Documents 3.2-2
3. Summary of Method 3.2-2
3.1 Collection of Sample 3.2-2
3.2 Sample Extraction 3.2-2
3.3 Sample Analysis 3.2-3
4. Significance 3.2-3
5. Definitions 3.2-3
6. Interferences 3.2-4
7. Apparatus 3.2-5
7.1 Glassware 3.2-5
7.2 Analysis Equipment 3.2-5
8. Reagents 3.2-6
8.1 Nitric Acid (HN03) Concentrated 3.2-6
8.2 Hydrochloric Acid (HC1) Concentrated 3.2-6
8.3 Water 3.2-6
8.4 Standard stock solutions (1,000 ,ug/mL) 3.2-6
8.5 Working Standards 3.2-7
8.6 Ionization and Chemical Interference Suppressants 3.2-8
9. Determination of Background Concentration of Metals in Filters 3.2-8
10. Analysis 3.2-8
10.1 Receiving of Sample From Extraction Laboratory 3.2-8
10.2 Flame Procedure 3.2-9
10.3 Furnace Procedure 3.2-10
10.4 Method of Standard Additions 3.2-10
10.5 Background Correction Methods 3.2-11
11. Spectrometer Calibration Curve 3.2-12
12. Calculations 3.2-13
12.1 Sample Air Volume 3.2-13
12.2 Metal Concentration 3.2-13
13. Maintenance 3.2-14
13.1 Scheduled Maintenance 3.2-14
13.2 Light Source 3.2-15
13.3 No Absorbance Response 3.2-15
13.4 Readout Noisy, Flame On 3.2-15
13.5 Poor Sensitivity 3.2-15
14. Quality Assurance (QA) and Performance Criteria 3.2-15
14.1 QA Program 3.2-15
14.2 Performance Criteria 3.2-18
15. Method Safety 3.2-18
16. References 3.2-19
iii
-------
iv
-------
Chapter IO-3
CHEMICAL SPECIES ANALYSIS
OF FILTER COLLECTED SPM
Method 10-3.2
DETERMINATION OF METALS IN AMBIENT PARTICULATE MATTER
USING ATOMIC ABSORPTION (AA) SPECTROSCOPY
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 liquid particles having aerodynamic particle sizes from below 0.01-100 fim and larger.
Historically, SPM measurement has concentrated on total suspended particulates (TSP), with no preference to
size selection.
1.2 Research on the health effects of TSP in ambient air has focused increasingly on particles that can be
inhaled into the respiratory system, i.e., particles of aerodynamic diameter less than 10 (im. Researchers
generally recognize that these particles may cause significant, adverse health effects. Recent studies involving
particle transport and transformation strongly suggest that atmospheric particles commonly occur in two distinct
modes: the fine (<2.5 (im) mode and the coarse (2.5 to 10.0 |im) mode. The fine or accumulation mode (also
termed the respirable particulate matter) is attributed to growth of particles from the gas phase and subsequent
agglomeration, while the coarse mode is made of mechanically abraded or ground particles. Because of their
initially gaseous origin, particle sizes in this range include inorganic ions such as sulfate, nitrate, ammonia,
combustion-form carbon, organic aerosols, metals, and other combustion products. Coarse particles, on the
other hand, are produced mainly by mechanical forces such as crushing and abrasion. Coarse particles of soil
or dust result primarily from entrainment by the motion of air or from other mechanical action within their area.
Since the size of these particles is normally >2.5 |im. their retention time in the air parcel is shorter than the fine
particle fraction.
1.3 Several methods are available for measuring SPM in ambient air. The most commonly used device is the
high volume sampler, which consists essentially of a blower and a filter, and which is usually operated in a
standard shelter to collect a 24-h sample. The sample is weighed to determine concentration and is usually
analyzed chemically. The high volume is considered a reliable instrument for measuring the weight of TSP in
ambient air.
1.4 The procedures for determining toxic metals in particulate matter in ambient air is described in this method.
The method is based on active sampling with a high-volume sampler. Analysis is done by atomic absorption
(AA) spectrometry. This method describes both flame atomic absorption (FAA) spectroscopy and graphite
furnace atomic absorption (GFAA) spectroscopy. Of the two methods, the detection limit for GFAA is about
two orders of magnitude better than FAA.
1.5 The trace metal to be detected is dissociated from its chemical bonds by flame or in a furnace and is put
into an unexcited or "ground" state. The metal is then capable of absorbing radiation at discrete lines of narrow
bandwidth. A hollow cathode or electrode less discharge lamp for the determined metal provides a source of
the characteristic radiation energy for that particular metal. The absorption of this characteristic energy by the
atoms of interest in the flame or furnace is measured and is related to the concentration of the metal in the
aspirated sample.
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-1
-------
Method 10-3.2
AA Methodology
Chapter 10-3
Chemical Analysis
1.6 The sensitivity, detection limit, and optimum working range for each metal detected by this methodology
are given in Table 1.
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.
• D4185-83 Standard Test Methods for Metals in Workplace Atmosphere by Atomic Absorption
Spectrophotometry.
2.2 Other Documents
• Federal Regulations (1,2).
• Laboratory and Ambient Air Documents (3-14).
3. Summary of Method
3.1 Collection of Sample
3.1.1 Particulate matter from ambient air may be collected on glass fiber filters using a high-volume sampler.
The high-volume sampler must be capable of sampling at an average flow rate of 1.70 mVmin (60 ft3/min).
Constant air flow is maintained by a mass flow controller over a 24-hr period.
3.1.2 Air is drawn into a covered housing and through a filter by means of a high-flow rate blower at a flow
rate [ 1.13 to 1.70 m3/min. (40 to 60 ft3/min)] that allows suspended particles having diameters < 100 |im (Stokes
equivalent diameter) to pass to the filter surface. Particles 100-0.1 |im diameter are ordinarily collected on glass
fiber filters. The mass concentration (|ig/m3) of suspended particulates in the ambient air is computed by
measuring the mass of collected particulates and the volume of air sampled. After the mass is measured, the
filter is ready for extraction to determine metal concentration.
3.2 Sample Extraction
3.2.1 Samples collected on glass fiber filters may be extracted by either hot acid procedure or by microwave
extraction (see Method IO-3.1).
3.2.2 The preferred method of extraction is by microwave extraction. In operation, a 1" x 8" strip is cut
from the 8" x 10" filter as described in the Federal Reference Method for Lead. The metals are extracted from
the filter strip by a hydrochloric/nitric acid solution using a laboratory microwave digestion system. After
cooling, the digestate is mixed and filtered with Acrodisc syringe filters to remove any insoluble material.
3.3 Sample Analysis
3.3.1 The trace element concentrations in each sample are determined by atomic absorption spectrometry.
This technique operates by measuring energy changes in the atomic state of the analyte. The sample is
vaporized and dissociates into its elements in the gaseous state. The element being measured is aspirated into
Page 3.2-2
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
Method 10-3.2
AA Methodology
a flame or injected into a graphite furnace and atomized. The atoms in the unionized or "ground" state absorb
energy, become excited, and advance to a higher energy level.
3.3.2 A light beam containing the corresponding wavelength of the energy required to raise the atoms of the
analyte from the ground state to the excited state is directed through the flame or furnace. This wavelength is
observed by a monochromator and a detector that measures the amount of light absorbed by the element, hence
the number of atoms in the ground state in the flame or furnace. A hollow cathode or electrode less discharge
lamp for the element being determined provides a source of that metal's particular absorption wavelength.
3.3.3 The data output from the spectrometer can be recorded on a strip chart recorder or processed by
computer. Determination of metal concentrations is performed from prepared calibration curves or read directly
from the instrument.
4. Significance
4.1 The area of toxic air pollutants has been the subject of interest and concern for many years. Exposure to
metal containing particulate can cause adverse health effects. For example, high levels of lead in the body can
cause motor nerve paralysis, anaemia, and, in children, inhibition of the nervous system's development. High
cadmium levels can cause cardiovascular problems and bone thinning. Effects of long-term exposure to
subacute levels of toxic metals in air pollution is, as yet, not well known.
4.2 Atomic absorption spectrophotometry is capable of quantitatively determining most metals at levels that
are required by federal, state, and local regulatory agencies. Sensitivity and detection limits may vary from
instrument to instrument.
5. 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.]
5.1 Analysis Spike Sample. An analytical sample taken through the analytical preparation method and then
spiked prior to analysis.
5.2 Analyte. The element or icon an analysis seeks to determine; the element of interest.
5.3 Analytical Preparation. An analytical sample taken through the analytical preparation method. Also
referred to as preparation or sample preparation.
5.4 Analytical Preparation Method. A method (digestion, dilution, extraction, fushion, etc.) used to dissolve
or otherwise release the analyte(s) of interest from its matrix and provide a final solution containing the analyte
which is suitable for instrumental or other analysis methods.
5.5 Analytical Sample. Any solution or media introduced into an instrument on which an analysis is
performed excluding instrument calibration, initial calibration verification, initial calibration blank, continuing
calibration verification and continuing calibration blank.
5.6 Calibration. The establishment of an analytical curve based on the absorbance, emission intensity, or
other measured characteristic of known standards.
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-3
-------
Method 10-3.2
AA Methodology
Chapter 10-3
Chemical Analysis
5.7 Calibration Standards. A series of known standard solutions used by the analyst for calibration of the
instrument (i.e., preparation of the analytical curve). The solutions are not subject to the preparation method
but contain the same matrix as the sample preparations to be analyzed.
5.8 Field Blank. Any sample submitted from the field identified as a blank.
5.9 Field Sample. A portion of material received to be analyzed that is contained in a single or multiple
containers and identified by a unique sample number.
5.10 Flame Atomic Absorption (FAA). Atomic absorption which utilizes flame for excitation.
5.11 Graphite Furnace Atomic Absorption (GFAA). Atomic absorption which utilizes a graphite cell for
excitation.
6. Interferences
6.1 In atomic absorption spectrometry, interferences, though less common than in other analytical methods,
can occur. In flame atomic absorption analysis of some elements, the type and temperature of the flame used
is critical; with improper conditions, chemical and ionization interferences can occur. In furnace atomic
absorption analysis, the advantages of enhanced sensitivity may be offset by the fact that interference is also
more of a problem. The categories of interference are discussed below.
6.1.1 Background or nonspecific absorption can occur from particles produced in the flame that can scatter
light and produce an apparent absorption signal. Light scattering may be encountered when solutions of high
salt content are being analyzed. They are most severe when measurements are made at shorter wavelengths
(for example, below about 250 nm). Background absorption may also occur as the result of the formation of
various molecular species that can absorb light. The background absorption can be accounted for by using
background correction techniques as discussed in Section 10.5.
6.1.2 Spectral interferences are interferences that result when an atom different from the one being
measured absorbs a portion of the radiation. Such interferences are extremely rare in AA. In some cases, multi-
element hollow cathode lamps may cause a spectral interference by having closely adjacent emission lines from
two different elements. In general, the use of multi-element hollow cathode lamps is discouraged.
6.1.3 Ionization interference occurs when easily ionized atoms are being measured. The degree to which
such atoms are ionized is dependent upon the atomic concentration and the presence of other easily ionized
atoms. This interference can be controlled by the addition of a high concentration of another easily ionized
element that will buffer the electron concentration in the flame. The addition of sodium or potassium to the
standards and samples is frequently used as an ionization suppressant.
6.1.4 Chemical interferences occur in AA when species present in the sample cause variations in the degree
to which atoms are formed in the flame, or when different valence states of a single element have different
absorption characteristics. Such interferences may be controlled by adjusting the sample matrix or by the
method of standard additions. For example, calcium phosphate does not dissociate completely in the flame.
Lanthanum may be added to bind the phosphate and allow the calcium to be ionized.
6.1.5 Physical interferences may result if the physical properties of the samples vary significantly. Changes
in viscosity and surface tension can affect the sample aspiration rate and, thus, cause erroneous results. Sample
dilution, the method of standard additions, or both, are used to correct such interferences. High concentrations
of silica in the sample can cause aspiration problems. If large amounts of silica are extracted from the samples,
they should be allowed to stand for several hours and centrifuged or filtered to remove the silica. The matrix
Page 3.2-4
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
AA Methodology
Method 10-3.2
components of the sample should match those of the standards. Any reagent added during extraction should
be added to the standards.
6.2 Matching the matrix of the samples to the matrix of the standards minimizes interference. The method of
standard additions in Section 10.4 and the use of background correction techniques in Section 10.5 should
identify and correct for interference.
6.3 The known interferences and correction methods for each metal are indicated in Table 2.
7. Apparatus
7.1 Glassware
[Note: All glassware should be Class A borosilicate glass and should be cleaned with laboratory detergent,
rinsed, soaked for 4 hr in a 20% (w/w) HN03, and rinsed several times with distilled water.]
7.1.1 Beakers. Borosilicate glass, including 30 mL, 125 mL, 150 mL Phillips or Griffin.
7.1.2 Volumetric flasks. 10 mL, 100 mL, 1 L.
7.1.3 Pipettes. Volumetric, including 1, 2, 4, 8, 15, 30, 50 mL.
7.1.4 Additional glassware. As required depending on dilution required to obtain concentrations above
the detection limit, in the response range.
7.2 Analysis Equipment
7.2.1 Atomic Absorption Spectrometer. Equipped with air/acetylene and nitrous oxide/acetylene burner
heads or graphite furnace.
7.2.2 Hollow cathode or electrode less discharge lamp. For each element to be determined.
7.2.3 Acetylene gas and regulator. Cylinder of acetylene equipped with two gauge, two stage pressure
reducing regulator with hose connections.
7.2.4 Nitrous oxide gas and regulator. Cylinder of nitrous oxide equipped with 2 two gauge, two-stage
pressure reducing regulator with hose connections.
7.2.5 Heating tape and rheostat. May be required to heat second stage of nitrous oxide gas cylinder
regulator and hose to prevent freeze-up of line.
7.2.6 Air supply. Clean, dry compressed air with a two-stage regulator.
7.2.7 Parafilm M sealing film. A pliable, self-sealing, moisture-proof, thermoplastic sheet material,
substantially colorless is recommended for use in sealing the acidified sample beakers. Commercially available
Parafilm M satisfies this requirement.
8.1 Nitric Acid (HN03) Concentrated. ACS reagent grade HN03 and commercially available redistilled
HN03 which have sufficiently low metal concentrations.
8.2 Hydrochloric Acid (HC1) Concentrated. ACS reagent grade.
8. Reagents
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-5
-------
Method 10-3.2
AA Methodology
Chapter 10-3
Chemical Analysis
8.3 Water. ASTM Type I (ASTM D193) or equivalent. The same source or batch of distilled, deionized
water must be used for all purposes in the analysis.
8.4 Standard Stock Solutions (1,000 ^g/mL)
[Note: For each metal that is to be determined, standards of known quality and concentration must either
be made or acquired commercially. These solutions are stable for 1 yr when stored in polyethylene bottles,
except as noted. Instructions for laboratory preparation are described below.]
[Note: Nitric acid fumes are toxic. Prepare in a well-ventilated fume hood]
8.4.1 Stock Aluminum Solution. Dissolve 1.00 g of aluminum wire in a minimum volume of 1 + 1 HC1.
Dilute to volume in a 1-L flask with distilled water.
8.4.2 Stock Barium Solution. Dissolve 1.779 g of barium chloride (BaCl2 2H20) in water. Dilute to
volume in a 1-L flask with distilled water.
8.4.3 Stock Bismuth Solution. Dissolve 1.000 g of bismuth metal in a minimum volume of 6 N HN03.
Dilute to volume in a 1-L flask with 2% (v/v) HN03.
8.4.4 Stock Cadmium Solution. Dissolve 1.000 g of cadmium metal in a minimum volume of 6 N HC1.
Dilute to volume in a 1-L flask with 2% (v/v) HN03.
8.4.5 Stock Calcium Solution. To 2.497 g of primary standard calcium carbonate (CaC03), add 50 mL
of distilled water. Add drop wise a minimum volume of HC1 (approximately 10 mL) to dissolve the CaC03.
Dilute to volume in a 1-L flask with distilled water.
8.4.6 Stock Chromium Solution. Dissolve 3.735 g of potassium chromate (K2Cr04) in distilled water.
Dilute to volume in a 1-L flask with distilled water.
8.4.7 Stock Cobalt Solution. Dissolve 1.000 g of cobalt metal in a minimum volume of HC1( 1+1). Dilute
to volume in a 1-L flask with 2% (v/v) HN03.
8.4.8 Stock Copper Solution. Dissolve 1.000 g of copper metal in a minimum volume of 6 N HN03.
Dilute to volume in a 1-L flask with 2% (v/v) HN03.
8.4.9 Stock Indium Solution. Dissolve 1.000 g of indium metal in a minimum volume of 1 + 1 HC1.
Addition of a few drops of HN03 and mild heating will aid in dissolving the metal. Dilute to volume in a 1-L
flask with 2% (v/v) HN03.
8.4.10 Stock Iron Solution. Dissolve 1.000 g of iron wire in 50 mL of 6 N HN03. Dilute to volume in
a 1-L flask with 2% (v/v) HN03.
8.4.11 Stock Lead Solution. Dissolve 1.598 g of lead nitrate [Pb(N03)2)]in 2% (v/v) HN03. Dilute to
volume in a 1-L flask with 2% (v/v) HN03.
8.4.12 Stock Lithium Solution. Dissolve 5.324 g of lithium carbonate (L2C03) in a minimum volume of
6 N HC1. Dilute to volume in a 1-L flask with distilled water.
8.4.13 Stock Magnesium Solution. Dissolve 1.000 g of magnesium ribbon in a minimum volume of 6
N HC1. Dilute to volume in a 1-L flask with 2% (v/v) HN03.
8.4.14 Stock Manganese Solution. Dissolve 1.000 g of manganese metal in a minimum volume of 6 N
HN03. Dilute to volume in a 1-L flask with 2% (v/v) HN03.
8.4.15 Stock Nickel Solution. Dissolve 1.000 g of nickel metal in a minimum volume of 6 N HN03.
Dilute to volume in a 1-L flask with 2% (v/v) HN03.
8.4.16 Stock Potassium Solution. Dissolve 1.907 g of potassium chloride (KC1) in distilled water. Dilute
to volume in a 1-L flask with distilled water.
8.4.17 Stock Rubidium Solution. Dissolve 1.415 g of rubidium chloride (RbCl) in distilled water. Dilute
to volume in a 1-L flask with distilled water.
Page 3.2-6
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
Method 10-3.2
AA Methodology
8.4.18 Stock Silver Solution. Dissolve 1.575 g of silver nitrate (AgN03) in 100 mL of distilled water.
Dilute to volume in a 1-L volumetric flask with 2% (v/v) HN03. The silver nitrate solution will deteriorate in
light and must be stored in an amber bottle away from direct light. New stock silver solution shall be prepared
every few months.
8.4.19 Stock Sodium Solution. Dissolve 2.542 g of sodium chloride (NaCl) in distilled water. Dilute to
volume in a 1-L flask with distilled water.
8.4.20 Stock Strontium Solution. Dissolve 2.415 g of strontium nitrate (Sr(N03)2) in distilled water.
Dilute to volume in a 1-L flask with distilled water.
8.4.21 Stock Thallium Solution. Dissolve 1.303 g of thallium nitrate (T1N03) in a 10% (v/v) HN03.
Dilute to volume in a 1-L flask with 2% (v/v) HN03.
8.4.22 Stock Vanadium Solution. Dissolve 1.000 g of vanadium metal in a minimum volume of 6 N
HN03. Dilute to volume in a 1-L flask with 2% (v/v) HN03.
8.4.23 Stock Zinc Solution. Dissolve 1.000 g of zinc metal in a minimum volume of 6 N HN03. Dilute
to volume in a 1-L flask with 2% (v/v) HN03.
8.5 Working Standards
8.5.1 Working Standards. Working standards are prepared by appropriate single or multiple dilutions of
the standard solutions listed in Section 8.4. Mixed standards should be prepared with any chemical
incompatibilities in mind. For those metals in Table 2 that indicate chemical or ionization interferences, the final
dilution shall contain 2% (v/v) of the 50-mg/mL cesium and lanthanum solutions.
8.5.2 Match Matrices. The acid concentration of the working standards should be matrix-matched to that
of the final sample extract. The final sample extract acid concentration is 3% HN03/8% HC1. When using
those atomic absorption spectrometers equipped with concentration read-out, follow the manufacturer's
suggestions as to the spacing of the standard concentrations over the range of interest.
8.6 Ionization and Chemical Interference Suppressants
8.6.1 Cesium Solution (50 mg/mL). Dissolve 73.40 g of cesium nitrate (CsN03) in distilled water. When
stored in a polyethylene bottle, this solution is stable for at least 1 yr.
8.6.2 Lanthanum Solution (50 mg/mL). Dissolve 156.32 g of lanthanum nitrate (La(N03)3,6H20) in a
2% (v/v) HN03. Dilute to volume in a 1-L flask with 2% (v/v) HN03. When stored in a polyethylene bottle,
this solution is stable for at least 1 yr.
9. Determination of Background Concentration of Metals in Filters
9.1 Use glass fiber filters to collect particulate matter with the high volume sampler. High quality filters with
reproducible properties must be used in sampling for metals in ambient air. Analyze 5% of the total number
of filters for the presence of specific metals, prior to sample collection, to verify reproducibility and low
background metal concentrations.
9.2 Cut one 1" x 8" strip from each filter. Extract and analyze all strips separately, according to the directions
given as delineated in Inorganic Compendium Method IO-3.1.
9.3 Calculate the total metal in each filter as:
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-7
-------
Method 10-3.2
Chapter 10-3
Chemical Analysis
AA Methodology
Fb = |ig metal/mL x (20 mL/strip) x (9)
where:
Fb = Amount of metal per 72 square inches of filter, |ig.
|ig metal/mL = metal concentration determined from Section 11.2.
20 mL/strip = total sample volume from extraction procedure.
9 = 464.52 cm2/51.61 cm2.
9.4 Calculate the mean, Fm, of the values and the relative standard deviation (standard deviation/mean x 100).
If the relative standard deviation is high enough so that, in the analyst's opinion, subtraction of Fm may result
in a significant error in the |ig metal/m3, the batch should be rejected.
9.5 For acceptable metal/batches, use the value of Fm to correct all metal/analyses of particulate matter
collected using that batch of filters. If the analyses are below the method detection limit (MDL) from Table 1,
no correction is necessary.
10. Analysis
10.1 Receiving of Sample From Extraction Laboratory
10.1.1 The sample should be received by the atomic absorption spectroscopist in a centrifuge tube from the
extraction procedure outlined in Method IO-3.1.
[Note: The entire extract volume offilter digestate was not received from extraction laboratory. The total
volume should have been 20 mL ± 0.5 mL, but only 10 mL may have been sent for analysis.]
10.1.2 The solution may be analyzed directly for any elements of very low concentration in the sample.
Aliquots of this solution may be then diluted to an appropriate volume for the other elements of interest present
at higher concentrations.
10.1.3 Filter blanks must be subject to the entire extraction and analytical procedure and processed as
described.
10.1.4 Some relatively rare chemical forms of some of the elements listed in Table 2 may not be dissolved
by the procedures stated in this method. If such chemical forms are suspected, results of their procedure should
be compared to results of a non-destructive technique, which does not require sample dissolution, such as X-ray
fluorescence.
10.1.5 Because of the differences between makes and models of atomic absorption spectrometers,
formulating detailed instructions applicable to every instrument is difficult. Consequently, the user should follow
manufacturer's operating instructions.
10.2 Flame Procedure
10.2.1 Set the atomic absorption spectrometer for the standard conditions as follows: choose the correct
hollow cathode lamp or electrode less discharge lamp, install, and align in the instrument; position the
monochromator at the value recommended by the manufacturer; select the proper monochromator slit width;
set the light source current according to the manufacturer's recommendation; light the flame and regulate the
flow of fuel and oxidant; adjust the burner for maximum absorption and stability; and balance the meter.
Page 3.2-8
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
Method 10-3.2
AA Methodology
10.2.2 If using a chart recorder, set the chart speed at 8-15 cm/min and turn on the power, servo, and chart
drive switches. Adjust the chart pen to the 5% division line. Also adjust instrument span using highest
calibration standard. While aspirating the standard sample, span instrument to desired response.
10.2.3 Run a series of standards of the metal of interest and construct a calibration curve as in Section 11.3.
Set the curve corrector of a direct reading instrument to read the proper concentration.
10.2.4 To evaluate the contribution to the absorbance from the filters and reagents used, blank samples
must be analyzed. Usually blanks will be provided with each set of samples (see Section 9.2). Subject the
blank to the entire analysis procedure. The absorbance obtained from the aspiration of the blank solution is
subtracted from the sample absorbance.
10.2.5 The sample can be analyzed from the centrifuge tube or an appropriate amount of sample decanted
into a sample analysis tube. At least the minimum sample volume required by the instrument should be available
for each aspiration.
10.2.6 Aspirate samples, standards, and blank into the flame and record the absorbance. Aspirate distilled
water after each sample or standard. If using a recorder, wait for response to stabilize before recording
absorbance.
10.2.7 To the extent possible, all determinations should be based on replicate analyses.
10.2.8 Determine the average absorbance value for each known concentration and correct all absorbance
values by subtracting the blank absorbance value. Determine the metal concentration in/ug metal/mL from the
calibration curve as presented in Section 11.3 or by direct reading from the instrument.
10.2.8.1 Dilute samples that exceed the calibration range by taking an aliquot of the sample and diluting
the sample to a known volume with a solution of the same acid concentration and ionization and chemical
suppressants as the calibration standards and reanalyzed.
10.2.8.2 Check for drift of the zero point resulting from possible nebulizer clogging, especially when
dealing with samples of low absorbance.
10.2.8.3 Aspirate a mid-range standard with sufficient frequency (once every 10 samples, after every
5 full MSAs or every 2 hr) to verify the continuing accuracy of the calibration curve.
10.3 Furnace Procedure
10.3.1 In graphite furnace atomic absorption, only a few microliters of the sample are placed in the furnace.
Within seconds or fractions of a second, the sample is atomized. Graphite furnace analysis is more sensitive
for trace element determination than the flame detection limit because it requires a smaller sample volume. As
a general rule, samples that can be analyzed by flame or furnace may be more conveniently run with flame since
flame atomic absorption is faster, simpler, and has fewer interference problems.
10.3.2 When some samples are atomized, they may absorb or scatter light causing sample absorbance to
be greater than it should be, necessitating background correction. If some sample remains unburned, memory
effects can occur. Blank burns should be run, and the graphite furnace should be cleaned by running at full
power at intervals during determination series.
10.3.3 Inject a measured |iL aliquot of sample into the furnace and atomize. If the concentration found is
greater than the highest standard, the sample should be diluted in the same acid matrix and reanalyzed. Multiple
injections can improve accuracy and help detect furnace pipetting errors.
10.3.4 Run a mid level check standard and a blank standard after every 10 sample injections, after 5 full
MSAs, or at 2-hr intervals. Standards are run in part to monitor the life and performance of the graphite tube.
Lack of reproducibility or significant change in the signal for the standard indicates that the tube should be
replaced. Tube life depends on sample matrix and atomization temperature. A conservative estimate of tube
life is about 50 firings. A pyrolytic coating will extend that estimated life by a factor of three.
10.3.5 To determine the metal concentration by direct aspiration and furnace, read the metal value in jj.g/L
from the calibration curve or directly from the read-out of the instrument.
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-9
-------
Method 10-3.2
AA Methodology
Chapter 10-3
Chemical Analysis
10.3.6 If sample dilution was required, calculate the final concentration using the following formula:
|ig/L metal in sample = A x (C + B) / C
where:
A = |ig/L of metal in diluted aliquot from calibration curve.
B = Acid blank matrix used for dilution, mL.
C = Sample aliquot, mL.
10.4 Method of Standard Additions
10.4.1 If chemical interferences are suspected, the method of standard additions may be used to evaluate
them; and if deemed desirable, the method may be used to make an accurate determination of metal
concentration in the presence of an interference.
10.4.2 Take three identical portions from a sample. Dilute the first portion to a known volume with the
solvent used in the standard solutions. Add known but different amounts of the metal of interest to the second
and third portions. The additions and dilutions should be kept as small as possible by using micro liter pipets.
10.4.3 Aspirate each portion and measure the absorbance. Plot the absorbance values (Y-axis) against metal
concentration (X-axis). Consider the first portion concentration to be 0 and that of the others as the known
amount added to each. Draw the curve through these points; it should be a straight line. The metal
concentration in the unknown is measured as the distance from the origin along the X-axis in the negative
direction using the same concentration scale factor.
10.4.4 Compare the values obtained for the same samples by direct comparison to the calibration curve.
If the values are the same, no chemical interferences are present, and subsequent analyses can be made by
direct comparison to the standard working curve.
10.4.5 If the slope of the spiked sample curve is not parallel to the original calibration curve, an interference
may be present. Standard additions may allow metal concentration to be determined in the presence of
interference by using the standard addition curve as the calibration. This method can give incorrect values if
the interferant does not associate with the additions to the same extent as in the original analyte.
10.5 Background Correction Methods
10.5.1 Spurious absorption, absorption not due to the atoms of the metal being determined, can be caused
by the presence of small particles in the resonance beam, the presence of radicals or molecular species resulting
from components of the prepared sample, or from combustion reactions of the flame itself. The effects of
background absorption and scatter are an increase in the absorption signal and in the noise component of the
signal. The final results may be considerably higher than the true value and a loss of sensitivity because of the
increased noise. Various correction systems exist as indicated in the following sections.
10.5.2 The deuterium arc automatic correction system operates by rapidly alternating light from a deuterium
arc and the hollow cathode tube through the sample. The light from the arc is essentially unabsorbed by the
element, but absorbed by the background. The difference is the element's actual absorbance. Most deuterium
arc systems correct up to 0.5 absorbance (about 70% absorption) at wavelengths as high as that of copper
(324.7 nm). Improved optical designs can extend this performance.
10.5.3 The Zeeman effect automatic correction system operates by placing the light source or atomizer
between the poles of a strong magnet, thus splitting the spectral line emitted or absorbed by the atoms of interest
into a central • component having the original wavelength and two sideband • components, which are shifted
in wavelength. The components are polarized in different planes relative to the magnetic field. Various magnet
Page 3.2-10
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
AA Methodology
Method 10-3.2
and polarizer configurations are employed in various instrument designs, all ultimately allowing subtraction of
the • signal from the • signal to produce background correction. The Zeeman system, though expensive,
overcomes some weaknesses inherent in the deuterium arc system.
10.5.4 The Smith-Hieftje automatic correction system operates on the principle of self-reversal: when
excessive current is passed through a hollow cathode lamp, the emission line is broadened and absorbance from
the analyte is reduced. Correction is accomplished by comparing low current absorption where the sample and
the background absorb light to a brief pulse of much higher current causing self-reversal and greatly reducing
the sample's absorption, while background absorption remains proportional. The background correction is
determined by the difference between the two signals. The Smith-Hieftje system also overcomes some
weaknesses inherent in the deuterium arc system and is comparable to the Zeeman system.
10.5.5 For atomic absorption spectrometers without automatic background correction devices, background
correction can be accomplished by using a deuterium continuum lamp.
10.5.5.1 Measure the absorbance of a sample and a suitable standard in the usual manner.
10.5.5.2 Remove the hollow cathode lamp and replace with the continuum lamp; without changing the
flame conditions or any other parameters, adjust the output of the amplifier to read 0 absorbance.
10.5.5.3 Measure the absorbance of the same sample and standard and subtract the continuum lamp
values from the hollow cathode lamp values to get an absorbance value free of background absorbance
interference.
11. Spectrometer Calibration Curve
[Note: Calibration is one of the most important factors in maintaining good quality data. Equipment must
be calibrated regularly, when first purchased, after maintenance, and whenever audit checks indicate greater
than acceptable deviation.]
11.1 The analytical application of atomic absorption, like other analytical methods, has a lower detection limit,
which is specific for each individual instrument. Therefore, calibration curves must be constructed using not
only standard solutions, but also standard conditions for each individual instrument. The standard conditions
include instrumental parameters, burner gas flames, and aspiration rates. In routine sample analysis, several
standards must be run with each set of samples so that the operating parameters are exactly the same for sample
and standard. Standard procedures for analysis are supplied with most commercially available atomic absorption
instruments. Standard curves must be constructed for each element, and standards must be analyzed each time
a set of samples are run. The standard curves should list all parameters of the instrument, as well as sample
preparation methods.
11.2 Prepare standard solutions from the solutions listed in Sections 8.4 and 8.5 to bracket the estimated
concentration of the metal in the samples. Select at least three standards (plus the reagent blank) to cover the
linear range indicated by the instrument manufacturer's instructions. Aspirate the standards into the flame (or
inject the standards into the furnace as appropriate) and record the absorbance. Repeat until good agreement
is obtained between replicates. Prepare a calibration graph by plotting absorbance (y-axis) versus the metal
concentration in |ig metal/mL (x-axis). Calculate the best fit straight line for the data points by the method of
least squares (see Section 11.3), and draw it in. Use the best fit line or its equation to obtain the metal
concentration in the samples to be analyzed.
11.3 Calculate the calibration line by the least squares regression procedure as follows:
y = mx + c
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-11
-------
Method 10-3.2
Chapter 10-3
Chemical Analysis
AA Methodology
where:
m = nf*
n[* xy) • x(« y)] / [n(« x2) - (• x)2].
c = y - mx.
n = number of points used to fit the curve,
y = arithmetic mean of the y-coordinates for n points,
x = arithmetic mean of the x-coordinates for n points.
• xy = the sum of the products of the x-coordinate times the y-coordinate for the n points.
• x = the sum of the x-coordinates of n points.
• y = the sum of the y-coordinates of n points.
• x2 = the sum of the squares of the x-coordinates of n points.
(• x)2 = the square of the sum of the x-coordinates of n points.
12. Calculations
12.1 Sample Air Volume
At standard temperature and pressure (stp) [25 °C and 760 mm Hg] for sample air volume rotameter, use the
following equation:
where:
Vstd = air volume sampled, m3.
Qj = initial air flow rate, m3/min at stp.
Qf = final air flow rate, m3/min at stp.
t = sampling period (elapsed time), min.
For samplers equipped with flow recorders:
Q = average sampling rate, m3/min at stp.
12.2 Metal Concentration
12.2.1 Estimation of Metal of Interest Concentration of the Blank Filter. For testing large batches of
filters (>500 filters), select at random 20 to 30 filters from a given batch. For small batches (<500 filters) a
lesser number of filters may be taken. Cut a 2.5 x 20.3 cm (1" x 8") strip from each filter. Analyze all strips
separately.
Vstd=[(QI + Qf)/2]t
V = (Q) (t)
where:
Page 3.2-12
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
Method 10-3.2
AA Methodology
12.2.2 Calculate total metal of interest in each filter as:
Fbl = (|ig metal/mL) x (final extraction volume [i.e., 20 mL]/strip) x (9)
where:
Fbl = amount of metal per 465 square cm (72 square in.) of blank filter, |ig.
|ig metal/mL = metal concentration determined from Section 11.2.
final extract volume (mL)/strip = total sample extraction volume from extraction procedure (i.e., 20 mL).
9 = 464.52 cm2/51.61 cm2.
12.2.3 Calculate the mean, Fm, and the relative standard deviation (100 x standard deviation/mean).
Fm = • Fbl / n
where:
Fm = average amount of metal per 72 in.2 of filter, |ig
Fbl = amount of metal per 72 in.2 for each filter, |ig
n = number of blank filters analyzed.
12.2.4 The standard deviation (SD) of the analyses for the blank filters is given by equation
SD = [• (Fbl-Fm)2/n-lf
The relative standard deviation (RSD) is given by the following equation:
RSD = (100) (SD) / Fm
If the relative standard deviation is high enough so that in the analyst's opinion subtraction of Fm the mean may
result in a significant error in the |ig metal/m3, the batch should be rejected. For acceptable batches, use the
value of Fm to correct all analyses (see Section 12.2.3) collected using that batch of filters. If Fm is below the
lower detectable limit (LDL), no correction is necessary.
12.2.5 Calculation of Metal of Interest Concentration of the Exposed Filter. Metal concentration in
the air sample can be calculated from data tabulated on data record form as follows:
C = [(jag metal/mL x (final extraction volume [i.e., 20 mL]/strip)(9) - Fm]/ Vstd
where:
C = concentration, |ig metal/std. m3.
|ig metal/mL = metal concentration determined from Section 10.
final extract volume (mL)/strip = total sample extraction volume from extraction procedure (i.e., 20 mL),
g = [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, ,«g.
Vstd = air volume pulled through filter, std. m3.
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-13
-------
Method 10-3.2
AA Methodology
Chapter 10-3
Chemical Analysis
13. Maintenance
13.1 Scheduled Maintenance
13.1.1 Scheduled maintenance of the sampling equipment and the atomic absorption spectrophotometer will
reduce downtime and remedial maintenance. The major maintenance checks are summarized in Table 3.
Record all maintenance activities in a maintenance log book. Normally, two to three remedial maintenance
activities are required per year.
13.1.2 Major maintenance and calibration should be done by service engineers or qualified operators. The
following general maintenance procedures should be carried out only after consulting the manufacturer's manual.
13.2 Light Source
13.2.1 When problems are suspected with a light source, check the hollow cathode lamp or electrode less
discharge lamp mounting bracket and lamp connection. Make sure the instrument is plugged in, turned on, and
warmed up. If line voltages are low, operate the power supply from a variance that is set to give maximum
voltage. Lamp current meter fluctuation can be reduced by using a constant voltage sine wave transformer.
13.2.2 As the lamp is used, a loss of the element from the hollow cathode source occurs. Some lamps will
evolve hydrogen, which will contaminate the element's spectrum and reduce sensitivity and calibration linearity.
Hydrogen contamination may be reversed by running the lamp with reversed polarity at a few mill amperes for
several minutes.
13.3 No Absorbance Response
Make sure that the lamp is lighted, properly aligned, and that the wavelength, slit, and range controls are
properly adjusted. If the meter cannot be zeroed, adjust the level of the burner head to avoid intercepting the
light beam and clean the lamp and window, or meter cover windows, with a diluted solution of a mild detergent;
rinse several times with distilled water. Dirty windows or lenses are a major problem when operating the
instrument below 2300 A0 (230 nm).
13.4 Readout Noisy, Flame On
Check the lamp current setting, fuel, and oxidizer flow rates; the leviner to make sure it is draining properly; the
nebulizer for corrosion around the tip; the adjustment of the nebulizer capillary; the burner head (it may need
cleaning with razor blade); the acetylene cylinder pressure; the air pressure; and the air line filter.
13.5 Poor Sensitivity (Within 50% of That Suggested in the Analytical Method Book)
Check the sensitivity obtainable for several other elements to ascertain that the low sensitivity is not due to the
lamp used. Check the slit width, wavelength, range setting, burner alignment, adjustment of the nebulizer
capillary, and fuel/oxidant flow rate ratio to ascertain that it is optimized for the element to be analyzed. Make
sure that the lamp current is not above the recommended value. Check the lamp alignment and the
Page 3.2-14
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
Method 10-3.2
AA Methodology
concentration of the standard solution used. All other maintenance problems, such as cleaning of mirrors or
gratings, should be discussed with the manufacturer or service representative.
14. Quality Assurance (QA) and Performance Criteria
14.1 QA Program
14.1.1 To achieve quality data, two essential considerations are necessary: the measurement process must
be in a state of statistical control at the time of the measurement and the systematic errors, when combined with
the random variation (errors of measurement), must result in an acceptable level of uncertainty. To produce
good quality data, perform quality control checks and independent audits of the measurement process,
document these data, and use materials, instruments, and measurement procedures that can be traced to an
appropriate standard of reference. Repeat measurements of standard reference samples (primary, secondary,
and/or working standards) aid in establishing a condition of process control. The working calibration standards
should be traceable to standards of higher accuracy.
Several other procedures are usually necessary to ensure that the instrument is providing good quality data.
Following the initial instrument calibration with a calibration blank and at least three calibration (standard
reference) samples, a calibration verification sample is prepared at the midpoint of the calibration curve from
certified stock solutions. The use of additional calibration standards and blanks during the sample analyses were
discussed in Section 11. In addition to the standard and blank samples, laboratory control spike samples, matrix
spike samples, and duplicate spike samples are prepared and analyzed with most sample batches. A summary
of the quality control procedures for FAA and GFAA is provided in Table 4. Depending upon the specific
requirements of the client, some of these procedures may be deleted, or additional procedures may be initiated
to comply with specific analysis requirements.
14.1.2 The user should develop, implement, and maintain a quality assurance program to ensure that the
sampling system is operating properly and collecting accurate data. Established calibration, operation, and
maintenance procedures should be conducted on a regularly scheduled basis and should be part of the quality
assurance program. The manufacturer's instruction manual should be followed and included in the QA program.
Additional QA measures (e.g., troubleshooting) as well as further guidance in maintaining the sampling system
are provided by the manufacturer.
14.1.2.1 Consult the latest copy of the Quality Assurance Handbook for Air Pollution Measurement
Systems to determine the level of acceptance of zero and span errors.
14.1.2.2 For detailed guidance in setting up a quality assurance program, refer to the EPA Quality
Assurance Handbook and the Code of Federal Regulations.
14.1.3 Sampling Quality Assurance
14.1.3.1 Select a site with the highest expected geometric mean concentrations.
14.1.3.2 Locate two high-volume samplers within 4 m of each other, but at least 2 m apart, to
preclude air flow interference.
14.1.3.3 Identify one of the two samplers at the time of installation as the sampler for normal routine
monitoring; identify the other as the duplicate sampler.
14.1.3.4 Be sure that the calibration, sampling, and analysis are the same for the collocated sampler
as for all other samplers in the network.
14.1.3.5 Operate the collocated sampler whenever the routine sampler is operated.
14.1.3.6 Use the differences in the concentrations (ug metal/std. m3) between the routine and
duplicate samplers to calculate precision.
14.1.4 Analysis Quality Assurance
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-15
-------
Method 10-3.2
AA Methodology
Chapter 10-3
Chemical Analysis
14.1.4.1 Perform a linearity test on the atomic absorption spectrometer employing a series of
standard metal solutions. This procedure should be done at regular intervals and when the analyst suspects
erroneous readings. Refer to Table 3 and manufacturer's instructions for details on instrument performance
checkout.
14.1.4.2 Obtain Standard Reference Materials (SRM) from National Institute of Standards
Technology (NIST) and EPA reference standards. Analyze these standards at regular intervals along with
samples and record accuracy.
Page 3.2-16
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
Method 10-3.2
AA Methodology
14.1.5 Standard Operating Procedures (SOPs)
14.1.5.1 SOPs should be generated by the users to describe and document the following activities in
their laboratory:
• assembly, calibration, leak check, and operation of the specific sampling system and equipment
used;
• preparation, storage, shipment, and handling of the sampler system;
• purchase, certification, and transport of standard reference materials; and
• all aspects of data recording and processing, including lists of computer hardware and software
used.
14.1.5.2 Provide specific instructions in the SOPs that are available and understood by the personnel
conducting the monitoring work.
14.2 Performance Criteria
The sensitivity, detection limit, and optimum working range for each metal are given in Table 1. The values
for the sensitivity and detection limits are instrument-dependent and may vary from instrument to
instrument.
14.2.1 The sensitivity is defined as that concentration of a given element that will absorb 1% of the
incident radiation (0.0044 absorbance units) when aspirated into the flame. The atomic absorption
sensitivity for an element can be calculated using the absorbance of a know concentration and solving the
equation below.
cone of std / measured abs = sensitivity / 0.0044
therefore:
sensitivity = (cone of std x 0.0044) / measured abs
14.2.2 The detection limit is defined as that concentration of a given element that produces a
signal-to-noise ratio of 2, which is the lowest limit of concentration that can be distinguished from zero.
[Note: The blank signal is defined as that signal that results from all added reagents and a clean filter that
has been extracted exactly as the samples.]
14.2.3 The working range for an analytical precision better than 3% is generally defined as those sample
concentrations that will absorb 10%-70% of the incident radiation (0.05-0.52 absorbance units.)
15. Method Safety
15.1 This procedure may involve hazardous materials, operations, and equipment. This method does not
purport to address all of the safety problems associated with its use. The user must establish appropriate safety
and health practices and determine the applicability of regulatory limitations prior to the implementation of this
procedure. This requirement should be part of the user's SOP manual.
15.2 Hazards to personnel exist in the operation of the atomic absorption spectrometer. Atomic absorption
units are potentially dangerous when using a nitrous oxide/acetylene flame. Do not operate these unit until the
manufacturer's instruction manual has been read and completely understood. Follow all safety instructions in
the manual and the safety requirements pertaining to the handling, storage, and use of compressed gases.
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-17
-------
Method 10-3.2
Chapter 10-3
Chemical Analysis
AA Methodology
15.3 Hazards to personnel exist in all operations in which hot, concentrated mineral acids are used. The
appropriate laboratory procedures for working with reagents of this nature should be observed.
15.4 Many of the metals that can be determined by atomic absorption are health hazards (for example,
cadmium, arsenic, beryllium, mercury) and must be handled in a manner consistent with the danger they
present.
15.5 The instrument exhaust gases contain the combustion products of the flame as well as metal vapor from
the sample. Both the combustion products and the metal vapor are definite personnel hazards. The instrument
combustion gases should be mechanically exhausted from the laboratory.
16. References
1. Code of Federal Regulations, Vol. 40, Part 58, Appendix A, B.
2. "Reference Method for Lead," Code of Federal Regulations, Vol.43(194), Appendix G, October 5, 1978.
3. Methods of Air Sampling and Analysis, Second Edition, Ed. M. Katz, APHA Intersociety Committee,
4. Technical Assistance Document for Sampling and Analysis of Toxic Organic Compounds in Ambient
Air, EPA-600/4-83-027, U. S. Environmental Protection Agency, Research Triangle Park, NC, 1983.
5. Harper, S., et al., "Simplex Optimization of Multielement Ultrasonic Extraction of Atmospheric
Particulates," Analytical Chemistry, Vol.55(9), August 1983.
6. Kahn, H.L., et al., "Background Correction in AAS," American Laboratory, November 1982.
7. Quality Assurance Handbookfor Air Pollution Measurement Systems, Volume II - Ambient Air Specific
Methods (Interim Edition), EPA 600/R-94/038b.
8. Air Pollution, W. Strauss and S. J. Main Waring, Edward Arnold (Publishers) LTD, London, England,
9. Slavin W., Atomic Absorption Spectroscopy, Interscience Publishers, New York, NY, 1968.
10. Ramirez Munoz, J., Atomic Absorption Spectroscopy, Elsevier Publishing Company, New York, NY,
11. Smith, G. F., Wet Chemical Oxidation of Organic Compositions, G. Frederick Smith Chemical Company,
Columbus, OH, 1965.
12. "Some Fundamentals of Analytical Chemistry," ASTMSpecial Technical Publication 564, Philadelphia,
PA, 1973.
1977.
1984.
1968.
Page 3.2-18
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
Method 10-3.2
AA Methodology
13. Willard, H. H., and Rulf, C. L., "Decomposition and Dissolution of Samples: Inorganic," Treatise on
Analytical Chemistry, Part 1, Vol. 2, Eds. Kotthoff, I.M. and Elving, P.J, Interscience, New York, NY,
1961.
14. Laboratory Manual Physical/Chemical Methods, SW-846 Third Edition, U. S. Environmental Protection
Agency, Washington, DC, 1986.
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-19
-------
Method 10-3.2
AA Methodology
Chapter 10-3
Chemical Analysis
T3
I
s
O
J3
<1
O
03
cn
(U '—s
B#
id
^ a
1)
¦§
c
£3
to
c s
*
c
N
O £
O ^ u
^ 11
s 3 .s
jS *&
1 •§ i
§ 3 S
-2 « O
o c £-
JS s 3
Q.
0 « 5
h 2 m
t5 3 «s
« .. XI
» 5 a
1 1 c
I-1 3
o •tt *T3
25 § > *T3
s
VI
C
O W
'¦5 s-
c3 U
s-
"S is
1> —
o -»
e
-w O "C s—
-d s
S SI "«3
C/2 fli !>
fi S —
^ H ^
"s S
- Z
Page 3.2-20
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
Method 10-3.2
AA Methodology
TABLE 2. THE TYPE OF FLAME AND OPERATING CONDITIONS
FOR EACH ELEMENT AND IDENTIFICATION OF INTERFERENCES
Element
Type of Flame
Analytical
Wavelength nm
Interferences1"
Remedyb
Ag
Air-C2H2 (oxidizing)
328.1
I0r, W04"2, MnCV2
c
Ala
N20-C2H2 (reducing)
309.3
Ionization, S04"2,V
c,d,e
Ba
N20-C2H2 (reducing)
553.6
Ionization, large concentration Ca
d,f
Bi
Air-C2H2 (oxidizing)
223.1
None known
Ca
Air-C2H2 (reducing)
n2o-c2h2
422.7
Ionization and chemical
d,e
Cd
Air-C2H2 (oxidizing)
228.8
None known
Coa
Air-C2H2 (oxidizing)
240.7
None known
Cr1
Air-C2H2 (reducing)
357.9
Fe, Ni
c
Cu
Air-C2H2 (oxidizing)
324.8
None known
Fe
Air-C2H2 (oxidizing)
248.3
High Ni concentration, Si
c
In
Air-C2H2 (oxidizing)
303.9
Al, Mg, Cu, Zn
c
K
Air-C2H2 (oxidizing)
766.5
Ionization
d
Li
Air-C2H2 (oxidizing)
670.8
Ionization
d
Mg
Air-C2H2 (oxidizing)
N20-C2H2 (oxidizing)
285.2
Ionization and chemical
d,e
Mn
Air-C2H2 (oxidizing)
279.5
None known
Na
Air-C2H2 (oxidizing)
589.6
Ionization
e
Ni
Air-C2H2 (oxidizing)
232.0
None known
Pb
Air-C2H2 (oxidizing)
217.0
283.3
283.3
Ca, high concentration
so4-2
c
Rb
Air-C2H2 (oxidizing)
780.0
Ionization
d
Sr
Air-CoH, (oxidizing)
N20-C2H2 (oxidizing)
460.7
Ionization and chemical
d,e
T1
Air-C2H2 (oxidizing)
276.8
None known
Va
N20-C2H2 (oxidizing)
318.4
None known in N20-C2H2 flame
Zn
Air-C7H7 (oxidizing)
213.9
None known
aSome compounds of these elements will not be dissolved by the procedure described here. When determining these elements, one
should verify that the types of compounds suspected in the sample will dissolve using this procedure.
bHigh concentrations of silicon in the sample can cause an interference for many of the elements in this table and may cause
aspiration problems. No matter what elements are being measured, if large amounts of silica are extracted from the samples, the
samples should be allowed to stand for several hours and centrifuged or filtered to remove the silica.
'Samples are periodically analyzed by the method of additions to check for chemical interferences. If interferences are encountered,
determinations must be made by the standard additions method or, if the interferant is identified, it may be added to the standards,
ionization interferences are controlled by bringing all solutions to 1000 ppm cesium (samples and standards).
e1000-ppm solution of lanthanum as a releasing agent to all samples and standards.
In the presence of very large calcium concentrations (greater than 0.1%), molecular absorption from CaOH may be observed. This
interference may be overcome by using background corrections when analyzing for barium.
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-21
-------
Method 10-3.2
AA Methodology
Chapter 10-3
Chemical Analysis
O
O
^ OX) &
Page 3.2-22
Compendium of Methods for Inorganic Air Pollutants
June 1999
-------
Chapter 10-3
Chemical Analysis
Method 10-3.2
AA Methodology
TABLE 4. SUGGESTED QUALITY CONTROL PROCEDURES FOR BOTH FAA AND GFAA
« K
procedures1
Typical frequency
Acceptance
criteria
Aclion. ifoulside criteria
Initial
calibration
At the beginning of the analysis
Linear correlation
coefficient > 0.995
Terminate analysis and restart the
run with initial calibration
ICV
Immediately after initial calibration
90%-110% of the actual
concentration
Terminate analysis, recalibrate,
and restart the run
ICB
Immediately after the ICV
< method detection limits
Terminate analysis, recalibrate,
and restart the run
CCV
Analyzed before the first sample,
after every 10 samples or 5 full
MS As, and at the end of the run
80%-120% of the actual
concentration
Terminate analysis, recalibrate,
and reanalyze samples from last
acceptable CCV
CCB
Analyzed following each CCV
< method detection limits
Terminate analysis, recalibrate,
and reanalyze samples from last
acceptable CCB
Method blank
1 per 20 samples, a minimum of 1
per batch
< method detection limits
Redigest strips of the blank and all
associated samples.
LCS
1 per 20 samples, a minimum of 1
per batch
80%-120% recovery, with the
exception of Sb
Redigest strips of the LCS and all
associated samples.
SD or MSD
1 per 20 samples per matrix type
RPD s 20%
Report and qualify results in
analysis report
Matrix spike (MS)
1 per 20 sample per matrix type
Percent recovery of 75%-125%
Perform appropriate interference
tests
Serial dilution
1 per matrix type, if MS/MSD
criterion fails and if needed
^ 10% Difference
Analysis by method of standard
addition (MSA)
Post-digestion spike
1 per matrix type, if MS/MSD
criterion fails and if needed
%R = 85%-115%
Analysis by MSA recommended
Sample dilution
Dilute sample beneath the upper
calibration limit, minimizing the
dilution factor
As needed
Not applicable
'Legend of Abbreviations (alphabetical order):
CCB = Continuing Calibration Blank
CCV = Continuing Calibration Verification
ICB = Initial Calibration Blank
ICV = Initial Calibration Verification
LCS = Laboratory Control Spike
SD = Sample Duplicate
MSD = Matrix Spike Duplicate
June 1999
Compendium of Methods for Inorganic Air Pollutants
Page 3.2-23
------- |