905R78105
5602
Reference Method for the
Determination of Lead
in Suspended Particulate
Matter Collected
from Ambient Air
and
Proposed Equivalency
Regulations
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
September 1978
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August 1978
REFERENCE METHOD FOR THE DETERMINATION OF LEAD IN
SUSPENDED PARTICIPATE MATTFR COLLECTED FROM AMBIENT AIR
1. Principle and Applicability
1.1 Ambient air suspended particulate matter is collected on a
glass-fiber filter for 24-hours using a high volume air sampler.
1.2 Lead in the particulate matter is solubilized by extraction with
nitric acid (HNOO, facilitated by heat or by a mixture of HNO-, and hydrochloric
O O
acid (HC1) facilitated by ultrasonication.
1.3 The lead content of the sample is analyzed by atomic absorption
spectrometry using an air-acetylene flame, the 283.3 or 217.0 nm lead absorption
line, and the optimum instrumental conditions recommended by the manufacturer.
1.4 The ultrasonication extraction with HN03/HC1 will extract metals
other than lead from ambient particulate matter.
2. Range, Sensitivity and Lower Detectable Limit
The values given below are typical of the methods capabilities. Absolute
values will vary for individual situations depending on the type of instrument
used, the lead line, and operating conditions.
2.1 Range. The typical range of the method is 0.07 to 7.5 ug Pb/m
assuming an upper linear range of analysis of 15 ug/ml and an air volume of
2400 m3.
2.2 Sensitivity. Typical sensitivities for a 1* change in absorption
(0.0044 absorbance units) are 0.2 and 0.5 ug Pb/ml for the 217.0 and 283.3 nm
lines, respectively.
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2.3 Lower Detectable Limit (LDL). A typical LDL is 0.07 yg Pb/m3.
The above value was calculated by doubling the between-laboratory standard
deviation obtained for the lowest measurable lead concentration in a colla-
borative test of the method. An air volume of 2400 m was assumed.
3. Interferences
Two types of interferences are possible: chemical, and light scattering.
3.1 Chemical. Reports on the absence '>2>3»4>5 Of chemical inter-
ferences far outweigh those reporting their presence, therefore, no correction
for chemical interferences is given here. If the analyst suspects that the
sample matrix is causing a chemical interference, the interference can be
verified and corrected for by carrying out the analysis with and without the
method of standard additions.
3.2 Light Scattering. Non-atomic absorption or light scattering,
produced by high concentrations of dissolved solids in the sample, can produce
2
a significant interference, especially at low lead concentrations. The inter-
ference is greater at the 217.0 nm line than at the 283.3 nm line. No inter-
ference was observed using the 283.3 nm line with a similar method.
Light scattering interferences can, however, be corrected for
instrumentally. Since the dissolved solids can vary depending on the origin
of the sample, the correction may be necessary, especially when using the
217.0 nm line. Dual beam instruments with a continuum source give the most
accurate correction. A less accurate correction can be obtained by using a
non-absorbing lead line that is near the lead analytical line. Information
on use of these correction techniques can be obtained from instrument manu-
facturers' manuals.
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If instrumental correction is not feasible, the interference can
be eliminated by use of the ammonium pyrrolfdinecarbodithioate-methylisobutyl
Q
ketone, chelation-solvent extraction technique of sample preparation.
4. Precision and Bias
4.1 The high-volume sampling procedure used to collect ambient air particulate
matter has a between-laboratory relative standard deviation of 3.7% over the range
3 9
80 to 125 yg/m . The combined extraction - analysis procedure has an average with-
in-laboratory relative standard deviation of 5 to 6% over the range 1.5 to 15 ug
Pb/ml, and an average between laboratory relative standard deviation of 7 to 9% over
the same range. These values include use of either extraction procedure.
4.2 Single laboratory experiments and collaborative testing indicate that
there is no significant difference in lead recovery between the hot and ultrasonic
15
extraction procedures.
5. Apparatus
5.1 Sampling.
5.1.1 High-volume sampler. Use and calibrate the sampler as described
in reference 10.
5.2 Analysis.
5.2.1 Atomic Absorption Spectrophotometer. Equipped with lead hollow
cathode or electrodeless discharge lamp.
5.2.1.1 Acetylene. The grade recommended by the instrument manufacturer
should be used. Change cylinder when pressure drops below 50-100 psig.
5.2.1.2 Air. Filtered to remove particulate, oil and water.
5.2.2 Glassware. Class A borosilicate glassware should be used through-
out the analysis.
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5.2.2.1 Beakers. 30 and 150 ml. graduated, Pyrex.
5.2.2.2 Volumetric flasks. 100-ml.
5.2.2.3 Pipettes. To deliver 50, 30, 15, 8, 4, 2, 1 ml.
5.2.2.4 Cleaning. All glassware should be scrupulously cleaned. The
following procedure is suggested. Wash with laboratory detergent, rinse, soak
for 4 hours in 20% (w/w) HNO-,, rinse 3 times with distilled-deionized water,
and dry in a dust free manner.
5.2.3 Hot plate.
5.2.4 Ultrasonication water bath, unheated. Commercially available
laboratory ultrasonic cleaning baths of 450 watts or higher "cleaning power", i.e.,
actual ultrasonic power output to the bath have been found satisfactory.
5.2.5 Template. To aid in sectioning the glass-fiber filter. See
Figure 1 for dimensions.
5.2.6 Pizza cutter. Thin wheel. Thickness <1 mm.
5.2.7 Watch glass.
5.2.8 Polyethylene bottles. For storage of samples. Linear polyethylene
gives better storage stability than other polyethylenes and is preferred.
5.2.9 Parafilm "M".* American Can Company, Marathon Products, Nennah,
Wisconsin, or equivalent.
6. Reagents
6.1 Sampling
6.1.1 Glass fiber filters. The specifications given below are intended
to aid the user in obtaining high quality filters with reproducible properties.
These specifications have been met by EPA contractors.
*Mention of commercial products does not imply endorsement by the U.S. Environmental
Protection Agency.
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6.1.1.1 Lead content. The absolute lead content of filters is not critical,
but low values are, of course, desirable. EPA typically obtains filters with a
lead content of <75 ^/filter.
It is important that the variation in lead content from filter to
filter, within a given batch, be small.
6.1.1.2 • Testing.
6.1.1.2.1 For 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 one 3/4" x 8" strip from each filter any-
where in the filter. Analyze all strips, separately, according to the directions
in Sections 7 and 8.
6.1.1.2.2 Calculate the total lead in each filter as
c ~ DK/mi v 100 nil v 12 strips
Fb= yg Pb/ml x ^^^p- x fH
where :
F,= Amount of lead per 72 square inches of filter, yg.
6.1.1.2.3 Calculate the mean, F, , 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 analysts opinion, subtraction of F. , (Section 10.3)
3
may result in a significant error in the yg Pb/m , the batch should be rejected.
6.1.1.2.4 For acceptable batches, use the value of F, to correct all lead
analyses (Section 10.3) of particulate matter collected using that batch of filters.
If the analyses are below the LDL (Section 2.3) no correction is necessary.
6.2 Analysis
6.2.1 Concentrated (15.6 M_) HN03< ACS reagent grade HN03 and commer-
cially available redistilled HN03 has been found to have sufficiently low lead con-
centrations.
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6.2.2 Concentrated (11.7 M) HC1. ACS reagent grade.
6.2.3 Distilled-deionized water. (D.I. water).
6.2.4 3 M HN03> This solution is used in the hot extraction procedure.
To prepare, add 192 ml of concentrated HNCL to D.I. water in a 1 i volumetric
flask. Shake well, cool, and dilute to volume with D.I. water. CAUTION: Nitric
Acid Fumes Are Toxic. Prepare in a well ventilated fume hood.
6.2.5 0.45 M_ HNCL. This solution is used as the matrix for calibration
standards when using the hot extraction procedure. To prepare, add 29 ml of con-
centrated HNCL to D.I, water in a 1 £ volumetric flask. Shake well, cool, and
dilute to volume with D.I. water.
6.2.6 2.6 M HN03 + 0 to 0.9 M HC1. This solution is used in the ultra-
sonic extraction procedure. The concentration of HC1 can be varied from 0 to
0.9 M. Directions are given for preparation of a 2.6 M HNCL + 0.9 M^ HC1 solution.
Place 167 ml of concentrated HN03 into a H volumetric flask and add 77 ml of
concentrated HC1. Stir 4 to 6 hours, dilute to nearly 1 i with D.I. water, cool
to room temperature, and dilute to U.
6.2.7 0.40 M HN03 + X M HC1. This solution is used as the matrix
for calibration standards when using the ultrasonic extraction procedure. To
prepare, add 26 ml of concentrated HN03, plus the ml of HC1 required, to a U
volumetric flask. Dilute to nearly U with D.I. water, cool to room temperature,
and dilute to U. The amount of HC1 required can be determined from the follow-
ing equation:
= J2 ml x °-15 x
0.9 M
where:
y = ml of concentrated HC1 required
x = molarity of HC1 in 6.2.6
0.15 = dilution factor in 7.2.2
6.2.8 Lead Nitrate, Pb(N03)2- ACS reagent grade, purity 99.0%. Heat
for 4-hours at 120°C and cool in a desiccator.
6
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6.3 Calibration Standards
6.3.1 Master standard, 1000 ug Pb/ml in HN03- Dissolve 1.598 g of
Pb(N03)2 in 0.45 M_ HN03 contained in a 1 i volumetric flask and dilute to volume
with 0.45 M_ HN03.
6.3.2 Master Standard, 1000 yg Pb/ml in HN03/HC1. Prepare as in
6.3.1 except use the HNCL/HC1 solution in 6.2.7.
Store standards in a polyethylene bottle. Commercially avail-
able certified lead standard solutions may also be used.
7. Procedure
7.1 Sampling. Collect samples for 24-hours using the procedure
described in reference 10 with glass-fiber filters meeting the specifications in
6.1.1. Transport collected samples to the laboratory taking care to minimize
contamination and loss of sample.
7.2 Sample Preparation.
7.2.1 Hot Extraction Procedure
7.2.1.1 Cut a 3/4" x 8" strip from the exposed filter using a template
and a pizza cutter as described in Figures 1 and 2. Other cutting procedures may
be used.
Lead in ambient particulate matter collected on glass fiber
filters has been shown to be uniformly distributed across the filter ' '
12
suggesting that the position of the strip is unimportant. However, another study
has shown that when sampling near a road-way lead is not uniformly distributed aero:
the filter. The nonuniformity has been attributed to large variations in particle
size. Therefore, when sampling near a road-way, additional strips at different
positions within the filter should be analyzed.
7.2.1.2 Fold the strip in half twice and place in a 150-ml beaker. Add
15 ml of 3 M_ HN03 to cover the sample. The acid should completely cover the sample
Cover the beaker with a watch glass.
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7.2.1.3 Place beaker on the hot-plate, contained in a fume hood, and boil
gently for 30 min. Do not let the sample evaporate to dryness. CAUTION: Nitric
Acid Fumes Are Toxic.
7.2.1.4 Remove beaker from hot plate and cool to near room temperature.
7.2.1.5 Quantitatively transfer the sample as follows:
7.2.1.5.1 Rinse watch glass and sides of beaker with D.I. water.
7.2.1.5.2 Decant extract and rinsings into a 100-ml volumetric flask.
7.2.1.5.3 Add D.I. water to 40 ml mark on beaker, cover with watch glass,
and set aside for a minimum of 30 minutes. This is a critical step and cannot
be omitted since it allows the HNQ- trapped in the filter to diffuse into the
rinse water.
7.2.1.5.4 Decant the water from the filter into the volumetric flask.
7.2.1.5.5 Rinse filter and beaker twice with D.I. water and add rinsings
to volumetric flask until total volume is 80 to 85 ml.
7.2.1.5.6 Stopper flask and shake vigorously. Set aside for approximately
5 minutes or until foam has dissipated.
7.2.1.5.7 Bring solution to volume with D.I. water. Mix thoroughly.
7.2.1.5.8 Allow solution to settle for one hour before proceeding with
analysis.
7.2.1.5.9 If sample is to be stored for subsequent analysis, transfer to
a linear polyethylene bottle.
7.2.2 Ultrasonic Extraction Procedure
7.2.2.1 Cut a 3/4" x 8" strip from the exposed filter as described in
Section 7.2.1.1.
7.2.2.2 Fold the strip in half twice and place in a 30 ml beaker. Add
15 ml of the HNCL/HC1 solution in 6.2.6. The acid should completely cover the
sample. Cover the beaker with Parafilm.
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The Parafilm should be placed over the beaker such that none of
the Parafilm is in contact with water in the ultrasonic bath. Otherwise, rinsing
of the Parafilm (Section 7.2.2.4.1) may contaminate the sample.
7.2.2.3 Place the beaker in the ultrasonication bath and operate for
30 minutes.
7.2.2.4 Quantitatively transfer the sample as follows:
7.2.2.4.1 Rinse Parafilm and sides of beaker with D.I. water.
7.2.2.4.2 Decant extract and rinsings into a 100 ml volumetric flask.
7.2.2.4.3 Add 20 ml D.I. water to cover the filter strip, cover with para-
film, and set aside for a minimum of 30 minutes. This is a critical step and
cannot be omitted. The sample is then processed as in Sections 7.2.1.5.4 through
7.2.1.5.9. NOTE: Samples prepared by the hot extraction procedure are now in
0.45 M HN03. Samples prepared by the ultrasonication procedure are in 0.40 M^ HNO-, +
X MHC1.
8. Analysis
8.1 Set the wavelength of the monochromator at 283.3 or 217.0 nm.
Set or align other instrumental operating conditions as recommended by the manu-
facturer.
8.2 The sample can be analyzed directly from the volumetric flask, or
an appropriate amount of sample decanted into a sample analysis tube. In either
case, care should be taken not to disturb the settled solids.
8.3 Aspirate samples, calibration standards and blanks (Section 9.2)
into the flame and record the equilibrium absorbance.
8.4 Determine the lead concentration in ug Pb/ml, from the calibration
curve, Section 9.3.
8.5 Samples that exceed the linear calibration range should be diluted
with acid of the same concentration as the calibration standards and reanalyzed.
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9. Calibration
9.1 Working Standard, 20 ug Pb/ml. Prepared by diluting 2.0 ml
of the master standard (6.3.1 if the hot acid extraction was used or 6.3.2 if
the ultrasonic extraction procedure was used) to 100 ml with acid of the same
concentration as used in preparing the master standard.
9.2 Calibration standards. Prepare daily by diluting the working
standard, with the same acid matrix, as indicated below. Other lead concen-
trations may be used.
Volume of 20 ug/ml Final Concentration
Working Standard, _m]_ Volume, ml ^ ...pb/m_l__.
0 100 0.0
1.0 200 0.1
2.0 200 0.2
2.0 100 0.4
4.0 100 0.8
8.0 100 1.6
15.0 100 3.0
30.0 100 6.0
50.0 100 10.0
100 100 20.0
9.3 Preparation of calibration curve. Since the working range of
analysis will vary depending on which lead line is used and the type of instrument,
no one set of instructions for preparation of a calibration curve can be given.
Select standards (plus the reagent blank), in the same acid concentration as the
samples, to cover the linear absorption range indicated by the instrument manu-
facturer. Measure the absorbance of the blank and standards as in Section 8.0.
Repeat until good agreement is obtained between replicates. Plot absorbance
10
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(y-axis) versus concentration in yg Pb/ml (x-axis). Draw (or compute) a straight
line through the linear portion of the curve. Do not force the calibration curve
through zero. Other calibration procedures may be used.
To determine stability of the calibration curve, remeasure - alternately -
one of the following calibration standards for every 10th sample analyzed: con-
centration £ 1 jag Pb/ml; concentration £ 10 ug Pb/ml. If either standard deviates
by more than 5% from the value predicted by the calibration curve, recalibrate
and repeat the previous 10 analyses.
10. Calculation.
10.1 Measured air volume. Calculate the measured air volume as
Qi + Qf
V = ••-•• I . ' x T
vm 2 x '
where:
V = Air volume sampled (uncorrected), m
Q.J = Initial air flow rate, m /min.
3
Q.p = Final air flow rate, m /min.
T = Sampling Time, min.
The flow rates Q- and Q* should be corrected to the temperature and pressure
conditions existing at the time of orifice calibration as directed in addendum B
of reference 10, before calculation of V .
10.2 Air volume at STP. The measured air volume is corrected to reference
conditions of 760 mm Hg and 25°C as follows. The units are standard cubic meters,
sm .
11
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V' = Measured \clurpe f>orr 10 1
1(1
?9 - Atmospheric pressure at time of orifice
calibration, mm Hg
P., = 760 ran Hg
^2 ~ Atmospheric temperature at time of orifice
calibration, °K
TI = 298°K
10.3 Lead Concentration. Calculate lead concentration in the air sample.
(yg Pb/ml x 100 ml/strip x 12 strips/filter) - F,
C =
VSTP
rfhere :
C - Concentration, yg Pb/sm
yg Pb/ml = Lead concentration determined from Section 8
100 ml/strip = Total sample volume
T> c+..ine /«!*•<». Useable filter area. 7" x 9" _
u strips/ niter - Exposed area of one str1pj 3/4- j-j*
F, = Lead concentration of blank filter, ug, from Section
6.1.1.2.3
= Air volume from 10. 2
II. Quality Control
3/4" x 8" glass fiber filter strips containing 80 to 2000 ^g Pb/strlp
!as lead salts) and blank strips with zero Pb content should be used to
12
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determine if the method - as being used - has any bias. Quality control charts
should be established to monitor differences between measured and true values.
The frequency of such checks will depend on the local quality control program.
To minimize the possibility of generating unreliable data, the user should
follow practices established for assuring the quality of air pollution data,
and take part in EPA's semi-annual audit program for lead analyses.
12. Trouble Shooting
1. During extraction of lead by the hot extraction procedure, it is
important to keep the sample covered so that corrosion products - formed on
fume hood surfaces which may contain lead - are not deposited in the extract.
2. The sample acid concentration should minimize corrosion of the
nebulizer. However, different nebulizers may require lower acid concentrations.
Lower concentrations can be used provided samples and standards have the same
acid concentration.
3. Ashing of particulate samples has been found, by EPA and contractor
laboratories, to be unnecessary in lead analyses by Atomic Absorption. Therefore,
this step was omitted from the method.
4. Filtration of extracted samples, to remove particulate matter, was
specifically excluded from sample preparation, because some analysts have observed
losses of lead due to filtration.
5. If suspended solids should clog the neublizer during analysis of samples,
centrifuge the sample to remove the solids.
13. References
1. Scott, D. R. et al. Atomic Absorption and Optical Emission Analysis
of NASN Atmospheric Particulate Samples for Lead. Envir. Sci. and
13
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Tech., TO., 877-880 (1976).
2. Skogerboe, R. K. et al. Monitoring for Lead in the Environment.
pp. 57-66, Department of Chemistry, Colorado State University,
Fort Collins, Colorado 80523. Submitted to National Science
Foundation for publication, 1976.
3. Zdrojewski, A. et al. The Accurate Measurement of Lead in Airborne
Particulates. Inter. J. Environ. Anal. Chem., 2_, 63-77 (1972).
4. Slavin, W. Atomic Absorption Spectroscopy. Published by Inter-
. science Company, New York, NY (1968).
5. Kirkbright, G. F., and Sargent, M. Atomic Absorption and Fluorescence
Spectroscopy. Published by Academic Press, New York, N.Y. 1974.
6. Burnham, C. D. et al. Determination of Lead in Airborne Particulates
in Chicago and Cook County, Illinois by Atomic Absorption Spectroscopy.
Envir. Sci. and Tech., .3, 472-475 (1969).
7. Proposed Recommended Practices for Atomic Absorption Spectrometry.
ASTM Book of Standards, Part 30, pp. 1596-1608 (July 1973).
8. Koirttyohann, S. R., and Wen, J. W. Critical Study of the APCD-MIBK
Extraction System for Atomic Absorption. Anal. Chem., 45, 1986-1989
(1973).
9. Collaborative Study of Reference Method for the Determination of
Suspended Particulates in the Atmosphere (High Volume Method).
Obtainable from National Technical Information Service, Department
of Commerce, Port Royal Road, Springfield, Virginia 22151, as
PB-205-891.
10. 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).
14
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11. Dubois, L., et al. The Metal Content of Urban Air. JAPCA, ]6_,
77-78 (1966).
12. EPA Report No. 600/4-77-034, June 1977. Los Angeles Catalyst Study
Symposium. Page 223.
13. Quality Assurance Handbook for Air Pollution Measurement Systems.
Volume 1 - Principles. EPA-600/9-76-005, March 1976.
14. Thompson, R. J. et al. Analysis of Selected Elements in Atmospheric
Particulate Matter by Atomic Absorption. Atomic Absorption News-
letter, £, No. 3, May-June 1970.
15. To be published. EPA, QAB, EMSL, RTP, N.C. 27711
16. Hirschler, D. A. et al. Particulate Lead Compounds in Automobile
Exhaust Gas. Industrial and Engineering Chemistry, 49, 1131-1142
(1957).
17. Quality Assurance Handbook for Air Pollution Measurement Systems.
Volume II - Ambient Air Specific Methods. EPA-600/4-77-027a, May 1977.
15
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ENVIRONMENTAL PROTECTION AGENCY
[40 CFR Parts 51 and 53]
AMBIENT AIR MONITORING REFERENCE AND
EQUIVALENT METHODS FOR LEAD
Notice of Proposed Rulemaking
AGENCY: Environmental Protection Agency (EPA)
ACTION: Proposed rulemaking
SUMMARY: On December 14, 1977, new national primary and secon-
dary ambient air quality standards for lead were proposed (42FR
63076). Atmospheric lead is proposed to be measured as elemental
lead, either by the proposed reference method or "by an equiva-
lent method." The amendments proposed below would provide the
necessary and appropriate changes in the existing equivalent
method regulations (primarily contained in 40 CFR Part 53) to
allow the designation of equivalent methods for measuring atmos-
pheric lead concentrations.
DATES: Comments relative to these proposed regulations must be
received by [45 days after publication in the Federal Register].
ADDRESS: Send comments to: Mr. Larry 0. Purdue
Department E (MD-76)
Environmental Monitoring and Support
Laboratory
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U.S. Environmental Protection
Agency
Research Triangle Park, N.C. 27711
FOR FURTHER INFORMATION CONTACT: Mr. Larry Purdue, Telephone
919/541-3076 (FTS 629-3076).
INCIDENTAL INFORMATION: The proposed reference method for mea-
suring atmospheric lead, as well as much associated information,
was published in the December 14, 1977 issue of the Federal
Register (Volume 42), starting on page 63076.
SUPPLEMENTARY INFORMATION:
Background
When the first National Ambient Air Quality Standards were
promulgated in 1971 (36 FR 8186, April 30, 1971), EPA established
the concept that measurements of ambient air pollutants used to
determine compliance with the standards must be made with either
a specified "reference method" or with an alternate method which
could be shown to be "equivalent" to the reference method. The
air quality standards are now contained in Part 50 of Title 40 of
the Code of Federal Regulations (40 CFR Part 50). Appendixes to
Part 50 specify either a prescribed reference method, or a measure-
ment principle and calibration procedure applicable to reference
methods, for each pollutant for which a standard has been promulgated.
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On February 18, 1975, EPA promulgated regulations to estab-
lish definitive requirements and procedures by which methods for
measuring specified air pollutants may be designated "reference
J methods" or "equivalent methods" (40 FR 7044, February 18, 1975).
~'f
H These regulations are contained in 40 CFR Part 53. Originally
these "equivalency" regulations were applicable only to methods
for measuring SO^, CO, and photochemical oxidants (O.J, but were
subsequently amended to cover methods for N02 as well (41 FR
52692, December 1, 1976).
On December 14, 1977, EPA proposed amendments to 40 CFR Part
50 to establish new National Primary and Secondary Ambient Air
Quality Standards for lead. Also proposed was a new appendix to
Part 50 specifying a reference method for measuring atmospheric
lead. The method proposed measures the lead content of suspended
particulate matter collected on glass fiber filters using high
volume samples. The lead is extracted from the particulate
matter and measured by atomic absorption spectroscopy. The
procedure proposed is necessarily very restrictive and specific
in order to maintain the high level of accuracy and reproduci-
bility and the low level of variability requisit for a reference
method. However, other procedures are available for measuring
lead which are likely to be as good as the reference method and
may be advantageous to particular users. For example, using the
same sampling procedure as the reference method (high volume
sampler), several alternate analytical principles (flameless
atomic absorption, optical emission spectrometry, and anodic
stripping voltametry) are known to be suitable for lead analysis.
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If these alternate procedures can be designated as "equivalent"
methods, then users would have much more flexibility in selecting
a method for lead measurements which fits their own circumstances
of available equipment, personnel, and expertise.
Also, EPA sees no reason why lead-measurements must be
restricted to a particular sampling technique, such as the high
volume sampler. For example, low volume particulate samples can
be analyzed for lead by X-ray fluorescence. Other non-high
volume techniques may also be available or under development. By
allowing for the possibility of qualifying such alternate methods
as equivalent methods, EPA hopes to permit and encourage contin-
ued advancement in the technology of measuring atmospheric lead.
For the reasons given above, EPA believes it 1s advantageous
to propose appropriate amendments to 40 CFR Part 53 to extend the
equivalent method regulations to cover methods for measuring lead
in the atmosphere. Since most, if not all, candidate equivalent
methods for lead are likely to be manual methods, EPA expects
relatively little initial incentive for commercial organizations
to apply for equivalent method determinations. Consequently,
most equivalent method applications for lead methods will have to
be originated by EPA under section 53.7 "Testing of methods at
the Initiative of the Administrator." Specifically, EPA intends
to pursue designation of some of the methods noted earlier, which
are already in use among some monitoring agencies. These would
include methods which use the same sampling procedure as the
reference method, but use alternate analytical principles such as
flameless atomic absorption, optical emission spectrometry, and
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anodic stripping voltametry. Direct analysis of high volume
filters by X-ray fluorescence is also a likely candidate method
for early designation by EPA.
General Approach
As suggested above, any method which purports to measure
atmospheric lead could be considered as a candidate equivalent
method, regardless of the sampling procedure or analytical tech-
nique used. To be designated as an equivalent method, the candi-
date method must demonstrate a "consistent relationship" to the
reference method. This is done by taking simultaneous measure-
ments with both methods in accordance with the procedures and
requirements to be specified in 40 CFR Part 53. In addition, the
candidate method must also demonstrate adequate precision among
repeated analyses of the same sample.
Since the proposed reference method provides 24-hour inte-
grated measurements, candidate methods would have to be compared
on that basis. Shorter-term integrated methods or even automated
methods could be considered as candidate methods. But only 24-
hour averages could be compared to the reference method. There-
fore, any subsequent designation of such a method as an equivalent
method would apply only to 24-hour averages.
Amendments to 40 CFR Part 51
-£! Paragraph (a) of section 51.17a provides general requirements
.' -"3,
I
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for air quality monitoring methods used by States in their Imple-
mentation Plan monitoring networks. Subparagraph (1) requires use
of reference or equivalent methods for SCL, CO, 03 and NO-,
and would be amended to also include lead. Subparagraph (3)
provides certain "grandfather" periods "for use of existing methods
for S02, CO, 0- and N02> It would be amended by adding a similar
"grandfather" provision allowing existing methods for lead to be
used until February 18, 1980--the same expiration date as that for
existing methods for S02, CO, and 03.
Amendments to Part 53
Subpart C of Part 53 contains the test procedures prescribed
for determining a consistent relationship between the reference
method and a candidate equivalent method. Since these test pro-
cedures were originally designed for gaseous pollutants, several
significant changes and additions are required to adapt the proce-
dures for lead.
Determination of Consistent Relationship
Section 53.30, paragraph (a) pertaining to the determination
of a consistent relationship would be changed to indicate that the
specifications for lead appear 1n a separate table (table C-3)
than the specifications for S02, CO, 03 and NOo-
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Test Site
Section 53.30, paragraph (b), pertaining to test sites would
be changed in several ways. First, the paragraph would be subdi-
vided to differentiate the various requirements applicable to (1)
all methods, (2) methods for gaseous pollutants, and (3) methods
for lead. Multiple test sites would be allowed for lead methods
in order to facilitate measurements in the required range, since
pollutant augmentation would not be feasible for particulate
methods. Also, a new provision would allow an applicant to request
approval of the test site or sites from EPA prior to conducting
the tests.
A final minor change proposed for paragraph (b) would delete
the stipulation that test sites be "...away from large bodies of
water...". This change has nothing to do with lead, but is prompted
by general confusion among applicants as to its specific meaning.
Since the requirement is not essential, the current revision of
the paragraph provides a good opportunity to eliminate both the
stipulation and the confusion.
Other General Provisions
Paragraphs (c), (d), and (e) of section 53.30 would also be
revised and reorganized to reflect the differences in requirements
for methods for gaseous pollutants and for lead particulates.
Revised paragraph (c) specifies the general requirement for simul-
taneous measurements at the test site 1n each of the required
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concentration ranges indicated by Tables C-l or C-3. Paragraph
(d) would be revised and subdivided to clarify the different
requirements for sample collection. Subparagraph (1) indicates
the general requirement for homogenous samples. Subparagraph (2)
specifies the use of a common distribution manifold and allows
artificial pollutant augmentation for gaseous pollutants. Sub-
paragraph (3) specifies the relative location requirements for
lead samplers. And paragraph (4) would specifically allow the use
of a common sample when the candidate method uses a sampling
procedure identical to that of the reference method. Finally, the
present paragraph (d) on "Submission of Test Data..." would be
changed to paragraph (e).
Test Conditions
In section 53.31 on "Test Conditions," paragraphs (a), (c),
and (d) would be revised slightly to clarify certain differences
between gaseous and parti oilate methods, and to clarify the re-
quirements pertaining to calibration and range.
Test Procedures
Because the test procedures being proposed for lead differ
considerably from those for gaseous pollutants, existing section
53.32 would be retitled "Test procedures for gaseous pollutants"
and a new section 53.33, "Test procedures for lead," would be
added. The proposed new section 53.33 is similar in form to
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section 53.32, but the specific requirements for lead methods
differ in several ways from the requirements for gaseous pollutant
methods. First, a new Table C-3 summarizes the test specifications
pertinent to methods for lead. Only one concentration range is
specified, into which 5 or more of the'measurements must fall.
The difference specification for lead is specified as a per cent
of the reference method measurement, as opposed to the fixed,
absolute values specified for gaseous pollutant methods. An
accuracy specification for the reference method based on analysis
of audit samples supplied by EPA is specified. In addition, a
performance specification for analytical precision is also being
proposed to apply to lead methods.
Because most methods for lead provide a result only after
collected samples are analyzed in a laboratory, the test accep-
tance criteria are based on a single sampling plan rather than the
double sampling plan prescribed for gaseous pollutant methods.
Ten or more Csimultaneous) samples are collected and analyzed to
provide at least 5 samples which fall into the required range of
3
0.5 to 4.0 yg/m . Each sample is analyzed 3 times and the results
of all samples in the range are subjected to both the precision
test prescribed in paragraph (e) and the consistent relationship
test prescribed in paragraph (f). For the candidate method to
qualify for designation, no test failures would be permitted in
either test.
Public Participation
Interested persons are invited to comment on any aspect of
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these proposed amendments. Comments should be submitted in dup-
licate and must be received by [45 days after publication in the
Federal Register]. Address comments to:
Mr. Larry Purdue
Department E (MD-76)
Environmental Monitoring and Support Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Date Administrator
It is proposed to amend Chapter I, Title 40, Code of Federal
Regulations, as follows:
PART 51—REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL
OF IMPLEMENTATION PLANS
1. In section 51.17a, paragraph (a) is revised to read as follows:
§51.17a Air quality monitoring methods.
(a) General requirements. (1) Except as otherwise provided
in this paragraph (a), each method for measuring S02, CO, 0^, N02,
or lead used for purposes of §51.17(a) shall be a reference method
or equivalent method as defined in §53.1 of this chapter. ***
(2)
***
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(3) *** Any manual method for lead 1n use before [date
of promulgation of these amendments] may be used for purposes of
§51.17(a) until February 18, 1980.
PART 53—AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT
METHODS
2. In section 53.30, paragraphs (a), (b), (c), (d), and (e) are
revised to read as follows:
§53.30 General Provisions
(a) *** A consistent relationship is shown for S02, CO, 03
and N02 methods when the differences between (1) measurements made
by a candidate manual method or by a test analyzer representative
of a candidate automated method, and (2) measurements made simul-
taneously by a reference method are less than or equal to the
value specified in the last column of Table C-l. A consistent
relationship is shown for lead methods when the differences be-
tween (1) measurements made by a candidate method and (2) measure-
ments made simultaneously by the reference method are less than or
equal to the value specified in Table C-3.
(b) Selection of Test Sites. (1) All methods. Each test
site shall be in a predominantly urban area which can be shown to
have at least moderate concentrations of various pollutants. The
site shall be clearly identified and shall be justified as an
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appropriate test site with suitable supporting evidence such as
maps, population density data, vehicular traffic data, emission
inventories, pollutant measurements from previous years, concurrent
pollutant measurements and wind or weather data. If desired, a
request for approval of the test site or sites may be submitted
prior to conducting the tests. The Administrator may in his dis-
cretion select a different site (or sites) for any additional tests
he decides to conduct.
(2) Methods for gaseous pollutants. All test measure-
ments are to be made at the same test site. If necessary, the
concentration of pollutant in the sampled ambient air may be aug-
mented with artificially generated pollutant to facilitate measure-
ments in the specified ranges. (See paragraph (d) (2) of this
section.)
(3) Methods for lead. Test measurements may be made at
any number of test sites. Augmentation of pollutant concentrations
is not permitted, hence an appropriate test site or sites must be
selected to provide lead concentrations in the specified range.
Test sites for lead measurements must be between 5 and 100 meters
from the edge of a heavily-traveled roadway.
(c) Test Atmosphere. Ambient air sampled at an appropriate
test site shall be used for these tests. Simultaneous concentra-
tion measurements shall be made in each of the concentration
ranges specified in Table C-l or Table C-3.
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(d) Sample Collection. (1) All methods. All test concen-
tration measurements or samples shall be taken in such a way that
both the candidate method and the reference method receive air
samples that are homogenous or as nearly identical as practical.
(2) Methods for gaseous pollutants. Ambient air shall
be sampled from a common intake and distribution manifold designed
to deliver homogenous air samples to both methods. Precautions
shall be taken in the design and construction of this manifold to
minimize the removal of particulates and trace gases, and to
insure that identical samples reach the two methods. If necessary,
the concentration of pollutant in the sampled ambient air may be
augmented with artificially generated pollutant. However, at all
times the air sample measured by the candidate and reference
methods under test shall consist of not less than 80 percent
ambient air by volume. Schematic drawings, physical illustrations,
descriptions, and complete details of the manifold system and the
augmentation system (if used) shall be submitted.
(3) Methods for lead. The intake points of the candi-
date and reference samplers for lead shall be located between 3 and
5 meters apart, and between 1.5 and 5 meters above ground level.
(4) Methods employing a common sampling procedure.
Candidate methods which employ a sampler and sample collection
procedure which are identical to the sampler and sample collection
procedure specified in the reference method may be tested by ana-
lyzing common samples in accordance with the candidate and refer-
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ence analysis procedures. The common samples are to be collected
according to the sample collection procedure specified by the
reference method, and must be divided such that identical portions
are analyzed by the analysis procedures of the two methods.
(e) Submission of Test Data and Other Information. All
recorder charts, calibration data, records, test results, proce-
dural descriptions and details, and other documentation obtained
from (or pertinent to) these tests shall be identified, date,
signed by the analyst performing the test, and submitted.
3. In section 53.31, paragrphs (a), (c), and (d) are revised to
read as follows:
§53.31 Test Conditions.
(a) All Methods. All test measurements made or test samples
collected by means of a sample manifold as specified in §53.30 (d)
(2) shall be at a room temperature between 20° and 30°C, and at a
line voltage between 105 and 125 volts. All methods shall be
calibrated as specified in paragraph (c) of this section prior to
initiation of the tests.
(b) ***
(c) Calibration. The reference method shall be calibrated
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according to the appropriate appendix to Part 50 of this Chapter
(if it is a manual method) or according to the applicable operation
manual(s) (if it is an automated method). A candidate manual
method (or portion thereof) shall be calibrated if such calibration
is a part of the method. ***
(d) Range. (1) Except as provided in paragraph (d) (2) of
this section, each method shall be operated in the range specified
for the reference method in the appropriate appendix to Part 50
(for manual reference methods), or specified in Table B-l of this
part (for automated reference methods).
(2)
***
(e)
***
4. In section 53.32, the title of the section is revised to read
as follows:
§53.32 Test procedures for gaseous pollutants.
5. A new section is added to read as follows:
§53.33 Test procedure for lead methods.
(a) Sample collection. Collect simultaneous 24-hour samples
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(filters) of lead at the test site or sites with both the reference
and candidate methods until at least 10 filter pairs have been
obtained. If the conditions of §53.30 (d)(4) apply, collect at
least 10 common samples (filters) in accordance with §53.30 (d)(4)
and divide each to form the filter pairs.
(b) Audit samples. Three audit samples must be obtained from
the Director, Environmental Monitoring and Support Laboratory,
Department E, United States Environmental Protection Agency, Research
Triangle Park, N.C. 27711. The audit samples are 3/4 x 8 inch
glass fiber strips containing known amounts of lead at the following
nominal levels: 100 yg/strip; 300 yg/strip; 750 yg/strip. The
true amount of lead in total yg/strip will be provided with each
audit sample.
(c) Filter Analysis . (1) For both the reference method and
the audit samples, analysis each filter extract 3 times in accord-
ance with the reference method analytical procedure. The analysis
of replicates should not be performed sequentially (i.e. any single
sample should not be analyzed 3 times in sequence). Calculate the
indicated lead concentrations for the reference method samples in
yg/m3 for each analysis of each filter. Calculate the indicated
total lead amount for the audit samples in yg/strip for each ana-
lysis of each strip. Label these test results as R-j^, R-|B, R-|C,
R2A, R2B, .... Q1A» Q]B» Qlc. » where R denotes results from
the reference method samples; Q denotes results from the Audit
samples; 1,2,3 indicates filter number and A,B,C indicates the
first, second and 3rd analysis of each filter, respectively.
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(2) For the candidate method samples, analyze each
sample filter or filter extract 3 times and calculate, in accord-
ance with the candidate method, the indicated lead concentration in
yg/m3 for each analysis of each filter. Label these test results
as C,,,, C,g, Cpp, ..., where C denotes'results from the candidate
method. (For candidate methods which provide a direct measurement
of lead concentrations without a seperable procedure, C,» = C,g =
C1C' C2A = C2B = C2C' etc>)
(d) For the reference method, calculate the average lead
concentration for each filter by averaging the concentrations
calculated from the 3 analyses:
RiA * RiB + RiC
R. = — ^ — , where i is the filter number.
1 Q V6 3
(e) Disregard all filter pairs for which the lead concentra-
tion as determined in the previous paragraph (d) by the average of
the 3 reference method determinations, falls outside the range of
0.5 to 4.0 yg/m3. All remaining filter pairs must be subjected to
both of the following tests for precision and consistent relation-
ship. At least 5 filter pairs must be within the 0.5 to 4.0 yg/m
range for the tests to be valid.
(f) Test for precision. (1) Calculate the precision (P) of
the analysis (in per cent) for each filter and for each method, as
the maximum minus the minimum divided by the average of the 3
concentration values, as follows:
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R. max - R. min C. max - C. min
PRi = RTI^e- * 100°^ °r pci = t. ave x 100%>
where i indicates the filter number.
(2) If any reference method precision value (Pn-)
exceeds 15 per cent, the precision of the reference method analy-
tical procedure is out of control. Corrective action must be
taken to determine the source(s) of imprecision and the reference
method determinations must be repeated according to paragraph (c)
of this section, or the entire test procedure (starting with para-
graph (a)) must be repeated.
(3) If any candidate method precision value (Pc^)
exceeds 15 per cent, the candidate method fails the precision test.
(4) The candidate method passes this test if all pre-
cision values (i.e. all PRl-'s and all PCl-'s) are less than 15 per
cent.
(g) Test for accuracy. 0) For the audit samples calculate
the average lead concentration for each strip by averaging the
concentrations calculated from the 3 analysis:
QiA + QiB + QiC
Qi ave = -^ - 3^ - lk.»
where i is audit sample number.
Calculate the percent difference (D ) between the indicated lead
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concentration for each audit sample and the true lead concentration
(T ) as follows:
Qi ave ' Tqi
°qi = T ' Xl°°
(2) If any difference value (D .) exceeds ±5 percent the
accuracy of the reference method analytical procedure is out of
control. Corrective action must be taken to determine the source
of the error(s) (e.g. calibration standard discrepancies, extrac-
tion problems, etc.) and the reference method and audit sample
determinations must be repeated according to paragraph (c) of this
section or the entire test procedure (starting with paragraph (a))
must be repeated.
(h) Test for consistent relationship. (1) For each filter
pair, calculate all 9 possible percent differences (D) between the
reference and candidate methods, using all 9 possible combinations
of the 3 determinations (A, B, and C) for each method, as:
C. . - R-.
D. = -^5 — x 100%, where i is the filter number, and n
in Rik
numbers from 1 to 9 for the 9 possible difference combinations for
the 3 determinations for each method (j = A, B, C, candidate; k = A,
B, C, reference).
(2) If none of the cent differences (D) exceeds ± 20
percent, the candidate method passes the test.
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(3) If one or more differences (D) exceeds ± 20 per
cent, the candidate method fails the test for consistent relation-
ship.
(i) The candidate method must pass both the precision test
and the consistent relationship test to qualify for designation as
an equivalent method.
TABLE C-3 TEST SPECIFICATIONS FOR LEAD METHODS.
Concentration range, yg/m3: 0.5 to 4.0
Minimum number of 24-hour measurements: 5
Maximum analytical precision, per cent: 15%
Maximum analytical accuracy, per cent: ± 5%
Maximum difference, per cent of reference method: ±20%
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