Method for the Determination of Lead in Total Suspended Particulate Matter, 40000-40011 [2013-15880]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 78, Number 128 (Wednesday, July 3, 2013)]
[Rules and Regulations]
[Pages 40000-40011]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-15880]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 50

[EPA-HQ-OAR-2012-0210; FRL-9822-1]
RIN 2060-AP89


Method for the Determination of Lead in Total Suspended 
Particulate Matter

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The EPA is establishing a new Federal Reference Method (FRM) 
for measuring Lead (Pb) in total suspended particulate matter (TSP) 
collected from ambient air. This method is intended for use by 
analytical laboratories performing the analysis of Pb in TSP to support 
data collection for the Pb National Ambient Air Quality Standard 
(NAAQS). The existing FRM for Pb is designated as a new Federal 
Equivalent Method (FEM), and the currently designated FEMs are 
retained. This action avoids any disruption to existing Pb monitoring 
networks and data collection and does not affect the FRM

[[Page 40001]]

for TSP sample collection (High-Volume Method).

DATES: This final rule is effective on August 2, 2013.

ADDRESSES: The EPA has established a docket for this action under 
Docket No. EPA-HQ-OAR-2012-0210. All documents in the docket are listed 
on the www.regulations.gov Web site. Although listed in the index, some 
information is not publicly available, e.g., Confidential Business 
Information (CBI) or other information whose disclosure is restricted 
by statute. Certain other material, such as copyrighted material, is 
not placed on the Internet and will be publicly available only in hard 
copy form. Publicly available docket materials are available either 
electronically at www.regulations.gov or in hard copy at the Air 
Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Avenue NW., 
Washington, DC. The Air Docket and the Public Reading Room are open 
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal 
holidays. The telephone number for the Public Reading Room is (202) 
566-1744, and the telephone number for the Air Docket is (202) 566-
1742. For additional information about EPA's public docket visit the 
EPA Docket Center homepage at: https://www.epa.gov/epahome/dockets.htm.

FOR FURTHER INFORMATION CONTACT: Ms. Joann Rice, Office of Air Quality 
Planning and Standards, Air Quality Assessment Division, Ambient Air 
Monitoring Group (C304-06), U.S. Environmental Protection Agency, 
Research Triangle Park, North Carolina 27711; telephone number: (919) 
541-3372; fax number: (919) 541-1903; email address: 
rice.joann@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Background
    A. Purpose of the New Reference Method
    B. Rationale for Selection of the New Reference Method
    C. Comments on the Proposed Rule
    D. Conclusions
II. Summary of Method
III. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    K. Congressional Review Act

I. Background

A. Purpose of the New Reference Method

    On November 12, 2008, the EPA substantially strengthened the NAAQS 
for Pb (73 FR 66964). The EPA revised the level of the primary (health-
based) standard from 1.5 micrograms per cubic meter ([mu]g/m\3\) of Pb 
to 0.15 [mu]g/m\3\ of Pb measured in TSP and revised the secondary 
(welfare-based) standard to be identical in all respects to the primary 
standard. The current Pb in TSP FRM is based on Flame Atomic Absorption 
Spectroscopy (FAAS) as specified in 40 CFR part 50, Appendix G. The FRM 
in Appendix G was originally promulgated in 1978 when FAAS was widely 
used and considered the best available method to support Pb NAAQS data 
collection at a level of 1.5 [mu]g/m\3\. A new Pb in TSP FRM is needed 
to: (1) Take advantage of improved extraction methods that are now 
available with improved precision, sample throughput, and extraction 
efficiency; (2) address advances in measurement technology that have 
occurred since promulgation of the original FRM; and (3) address the 
improved measurement sensitivity (detection limits) needed in response 
to the tightened Pb NAAQS.
    The reference method for Pb in TSP includes two parts: the analysis 
method for Pb in TSP as specified in 40 CFR 50, Appendix G, and the 
reference method for high-volume sampling of TSP as specified in 40 CFR 
50, Appendix B. The new FRM is for the analysis of Pb in TSP based on 
Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The FRM serves 
as the definitive method for routinely analyzing Pb for comparison to 
the NAAQS and also serves as the standard of comparison for determining 
equivalence of candidate FEMs. This method replaces the existing method 
in 40 CFR 50, Appendix G. The FRM that was promulgated in 1978 as 
Appendix G becomes an approved FEM and the currently designated FEMs 
are retained. The EPA believes this is appropriate because the new FRM 
is based on two methods that were tested and approved as FEMs (EQL-
0510-191 and EQL-0710-192) to ensure comparability with the FAAS 
method. This approach permits continued use of the legacy FRM (as an 
FEM) and the existing FEMs. This avoids any disruption to state and 
local air monitoring agencies using these methods for Pb monitoring. 
The reference method for high volume sampling of TSP will continue to 
be performed in accordance with the FRM described in Appendix B, and, 
therefore, is not included as part of this FRM.
    With the tightened NAAQS in 2008 and the need for increased 
measurement sensitivity, an improved measurement technology has become 
available to meet the needs of the current NAAQS. The FAAS method is 
less frequently used in the Pb ambient monitoring network (about 10 
percent of the sites reported Pb in TSP data to the EPA's Air Quality 
System in 2012 using the FAAS method) and ICP-based methods have 
increased in popularity. Recently, the FAAS method has mainly been used 
as the reference method for testing and designation of candidate FEMs 
for Pb in accordance with 40 CFR 53.33. With the lowered Pb 
concentration testing range in Part 53 and new requirement for a Method 
Detection Limit (MDL) of 0.0075 [mu]g/m\3\ (described below), the FAAS 
method sensitivity and availability of laboratories with FAAS 
capability have created some challenges for comparability testing of 
new FEMs.
    In 2008, the EPA also revised the performance-based requirements 
for Pb FEMs in Part 53. The performance requirements were revised to be 
consistent with the revised Pb NAAQS level. Specifically, the Pb 
concentration range at which the FEM comparability testing is conducted 
was lowered to a range of 0.045 to 0.375 [mu]g/m\3\ and the requirement 
for a minimum method detection limit was established at 0.0075 [mu]g/
m\3\. The detection limit of the new FRM is more than adequate to meet 
the reduced testing range and detection limit requirements. The FRM's 
average detection limit for Pb-spiked filters is estimated at 0.00009 
[mu]g/m\3\, which is well below the requirement of 0.0075 [mu]g/m\3\.

B. Rationale for Selection of the New Reference Method

    The FRM is based on two recently approved FEMs for extracting Pb 
from glass fiber filters for subsequent analysis by ICP-MS: (1) Method 
EQL-0510-191 which uses a heated (80  5[deg]C) ultrasonic 
water bath with 1.03M nitric (HNO3)/2.23M hydrochloric (HCl) 
acids, and (2) Method EQL-0710-192 which uses a heated (95  
5[deg]C) graphite block (hot block) with 3.5 percent volume/

[[Page 40002]]

volume (v/v) HNO3. In selecting this methodology, the EPA's 
primary considerations were: methods that have already been tested and 
approved against the FAAS method; use of equipment that is commonly 
used; a method that is practical (use of a single vessel for the entire 
extraction process and storage); and a method with improved sensitivity 
and throughput to increase efficiency and cost effectiveness over the 
legacy FRM. ICP-MS was chosen as the analytical technique because it 
has improved sensitivity, selectivity, linear range, and is more 
readily available than FAAS in laboratories today.
    The FRM uses methods from two existing FEMs that have been proven 
comparable to FAAS and, therefore, retains consistency with the legacy 
FRM (Rice, 2013). The FRM is only intended for the analysis of Pb in 
TSP and allows for the use of glass fiber, quartz, or 
polytetrafluoroethylene (PTFE) filters. HNO3 alone is 
sufficient for the extraction of Pb; however, the ultrasonic extraction 
method includes HCl to allow monitoring agencies some flexibility for 
future needs that may include the extraction of other metals. HCl is 
needed to aid the extraction of other metals that are not easily 
brought into solution with HNO3 alone. The FRM was evaluated 
for the extraction of Pb only. If the FRM is used for metals other than 
Pb, the user must evaluate the FRM's applicability before use. The hot 
block extraction method uses only HNO3 and must also be 
evaluated by the user before use to extract metals other than Pb.
    The approach and key specifications of the method were submitted 
for peer review to the Clean Air Scientific Advisory Committee (CASAC) 
Ambient Air Monitoring and Methods Subcommittee. Public meetings were 
held to discuss the method and related monitoring issues on September 
15, 2010. Comments on the method and approach were provided in writing 
in a letter dated November 30, 2010 (EPA-CASAC-11-002),\1\ forwarded by 
CASAC to the Administrator.
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    \1\ CASAC's final report on the Approach for the Development of 
a New Federal Reference Method (FRM) for Lead in Total Suspended 
Particulates (Pb-TSP) can be found at: https://yosemite.epa.gov/sab/
sabproduct.nsf/DA39026E54BAF46E8525781D00606633/$File/EPA-CASAC-11-
002-unsigned.pdf.
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    The CASAC was supportive of the ICP-MS analytical method and found 
the approach to be appropriate with superior sensitivity and 
specificity for Pb. The CASAC recommended a strategy, using a 
performance-based FRM, to provide flexibility for use of non-FRM or FEM 
measurement methods and recommended that a third extraction method 
(microwave) be added to the FRM for its greater sample throughput and 
potential for reduced sample-to-sample variability. The CASAC viewed 
the comprehensiveness of the FRM test plan to be appropriate, and 
recommended that the EPA consider separating the extraction methods 
from the analytical methods so that any of the FRM extraction methods 
can be used with any of the FRM analytical measurement methods.
    The federal reference and equivalence testing method for Pb in 40 
CFR 53.33 serves as the performance-based method approach for the FEM 
approval process. Candidate methods are tested using the performance 
specifications of part 40 CFR part 53 for acceptance and approval as 
equivalent methods. Users also have the flexibility to test and submit 
additional extraction and analysis methods for review and approval as 
equivalent methods. The EPA believes that microwave extraction is a 
viable option and is already available as an approved FEM.\2\ The 
ultrasonic and hot block approaches are sufficient for the extraction 
of Pb and provide high sample throughput, low consumable costs, and 
lower equipment costs while minimizing the risk of cross contamination 
and sample loss. In addition, the EPA believes that the existing FEMs 
\3\ currently provide a wide variety of extraction and analytical 
methods and the EPA strongly encourages monitoring agencies to consider 
adopting one of the already approved FEMs in lieu of submitting new FEM 
applications. The FRM has two extraction methods (heated ultrasonic and 
hot block) and one analytical method (ICP-MS). The FRM allows for the 
use of either of the two extraction methods specified with the ICP-MS 
analytical method. The method also allows for the use of glass fiber, 
PTFE, or quartz filter media for the collection of Pb in TSP.
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    \2\ FEM EQL-0400-0140 (65 FR 26603, May 8, 2000).
    \3\ The list of current FEMs is located at: https://epa.gov/ttn/amtic/files/ambient/criteria/reference-equivalent-methods-list.pdf.
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C. Comments on the Proposed Rule

    On February 5, 2013, the EPA proposed a new FRM for determination 
of Pb in TSP (78 FR 8066) and solicited comment on the proposed method. 
The EPA received one public comment by the close of the public comment 
period on March 7, 2013. The commenter questioned the meaning of the 
MDLs estimated from the analysis of blanks. The commenter recommended 
that an MDL estimated from blanks include the mean of the blanks and be 
consistent with the Report of the Federal Advisory Committee on 
Detection and Quantitation (FACDQ) Approaches and Uses in Clean Water 
Act Programs (FACDQ, 2007). The Federal Advisory Committee recommended 
that EPA adopt a new procedure for estimated method sensitivity and 
replace 40 CFR 136, Appendix B (Definition and Procedure for the 
Determination of the Method Detection Limit) with the new procedure. 
The FACDQ procedure described an approach for calculating MDLs and 
quantitation limits. The EPA conducted a pilot study to assess whether 
the procedure recommended by the FACDQ could generate reliable 
estimates of the lowest concentration at which measurement quality 
objectives could be achieved (U.S. EPA, 2011). Based on the pilot study 
results, the EPA concluded that none of the procedures tested 
consistently generated accurate estimates of the lowest concentration 
at which the study measurement quality objectives were achieved. The 
EPA believes that more development and testing of the FACDQ procedure 
are warranted.\4\ Accordingly, based on the currently available 
information, the EPA believes that the procedures identified in 40 CFR 
135, Appendix B are a more appropriate basis for estimating MDLs for 
the FRM.
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    \4\ Refer to: https://water.epa.gov/scitech/methods/cwa/det/index.cfm for EPA's Procedures for Detection and Quantitation.
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    The EPA provided estimates in the proposed rule for MDLs based on 
reagent/filter blanks and reagent/filter blanks spiked with a Pb 
solution. The EPA estimated MDLs based on 40 CFR 136, Appendix B which 
recommends that MDLs be determined using a concentration value that is 
between 1 and 5 times the estimated MDL. However, 40 CFR 136, Appendix 
B does not specify the use of reagent/filter blanks for estimating the 
detection limit. The estimate of MDLs based on reagent/filter blanks is 
not consistent with 40 CFR 136, Appendix B; therefore, the MDL 
estimates from reagent/filter blanks have been removed. The remaining 
MDL estimates in Tables 1, 3, and 5 were determined using reagent/
filter blanks that were spiked with Pb at three times the estimated 
detection limit of 0.001 [mu]g/mL. The MDLs were estimated to 
demonstrate method performance that is more than adequate to meet the 
MDL requirements of 0.0075 [mu]g/m\3\ for Pb in TSP. It is recommended 
that laboratories performing this method initially estimate MDLs in 
accordance with 40 CFR Part 136, Appendix B and

[[Page 40003]]

confirm the MDLs annually. In addition, the EPA recommends that 
laboratories consider performing the optional iterative procedure in 
Part 136, Appendix B to verify the reasonableness of the initially 
estimated MDL and subsequent MDL determinations.

D. Conclusions

    After consideration of the public comment on the estimate of MDL 
from reagent/filter blanks, the EPA has concluded that the rule should 
be consistent with the provisions of 40 CFR Part 136, Appendix B. 
Accordingly, any language referring to the estimate of MDLs using 
reagent/filter blanks and the MDLs estimated from reagent/filter blanks 
in Tables 1, 3, and 5 have been removed. The MDLs estimated from the 
Pb-spiked reagent/filter blanks remain and demonstrate that the method 
has more than adequate sensitivity to support the Pb-TSP MDL 
requirement of 0.0075 [mu]g/m\3\. No other comments were received nor 
revisions made to the proposed rule. The rule is otherwise finalized as 
proposed.

II. Summary of Method

    The FRM uses the ambient air sample collection procedures of the 
high-volume TSP method (40 CFR Part 50, Appendix B) and the analytical 
procedure for the measurement of Pb based on ICP-MS. Two extraction 
methods are used: One using heated ultrasonic and one using hot block 
digestion. The extraction methods and ICP-MS analysis method have been 
tested and found acceptable for extraction of Pb from glass fiber, 
PTFE, or quartz filter media. This method also met the precision and 
bias goals for Pb in TSP (Rice 2013). This method replaces the previous 
FRM specified in 40 CFR Part 50, Appendix G. Although the previous FRM 
in Appendix G is adequate, this method offers advantages over the 
previous FRM by providing improved sensitivity or detection limits, 
precision, sample throughput, and extraction efficiency.

III. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is not a ``significant regulatory action'' under the 
terms of Executive Order 12866 (58 FR 51735, October 4, 1993) and is, 
therefore, not subject to review under Executive Orders 12866 and 13563 
(76 FR 3821, January 21, 2011).

B. Paperwork Reduction Act

    This action does not impose an information collection burden under 
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. 
Burden is defined at 5 CFR 1320.3(b). This rule is to promulgate a new 
FRM for Pb in TSP, and to designate the existing FRM as an FEM, and 
does not add any information collection requirements beyond those 
imposed by the existing Pb monitoring requirements.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency 
to prepare a regulatory flexibility analysis of any rule subject to 
notice and comment rulemaking requirements under the Administrative 
Procedure Act or any other statute unless the agency certifies that the 
rule will not have a significant economic impact on a substantial 
number of small entities. Small entities include small businesses, 
small organizations, and small governmental jurisdictions.
    For purposes of assessing the impacts of this rule on small 
entities, small entity is defined as (1) a small business as defined by 
the Small Business Administration's (SBA) regulations at 13 CFR 
121.201; (2) a small governmental jurisdiction that is a government of 
a city, county, town, school district or special district with a 
population of less than 50,000; and (3) a small organization that is 
any not-for-profit enterprise which is independently owned and operated 
and is not dominant in its field.
    After considering the economic impacts of this rule on small 
entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities. This rule 
will not impose any additional monitoring requirements beyond those 
specified in the current regulations, nor will it require any changes 
in approved monitoring methods. As such, it will not impose any 
requirements on small entities.

D. Unfunded Mandates Reform Act

    This action contains no federal mandates under the provisions of 
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), 2 U.S.C. 
1531-1538 for state, local, or tribal governments or the private 
sector. This action imposes no enforceable duty on any state, local or 
tribal governments or the private sector. Therefore, this action is not 
subject to the requirements of sections 202 or 205 of the UMRA. This 
action is also not subject to the requirements of section 203 of UMRA 
because it contains no regulatory requirements that might significantly 
or uniquely affect small governments. This action establishes a new FRM 
for state and local air monitoring agencies to use as one of the 
approved methods for measurement of Pb in TSP and to designate the 
existing FRM as an FEM. It does not create any additional monitoring 
requirements or require changes in approved monitoring methods.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government, as 
specified in Executive Order 13132. This action establishes a new FRM 
for state and local air monitoring agencies to use as one of the 
approved methods for measurement of Pb in TSP and designates the 
existing FRM as an FEM. This action does not create any new monitoring 
requirements or require any changes in approved monitoring methods. 
Thus, Executive Order 13132 does not apply to this action.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    This action does not have tribal implications, as specified in 
Executive Order 13175 (65 FR 67249, November 9, 2000). This rule 
imposes no requirements on tribal governments. This action establishes 
a new FRM for state and local air monitoring agencies to use as one of 
the approved methods for measurement of Pb in TSP and designates the 
existing FRM as an FEM. This action does not create any new monitoring 
requirements, nor require any changes in approved monitoring methods. 
Thus, Executive Order 13175 does not apply to this action.

G. Executive Order 13045: Protection of Children From Environmental 
Health and Safety Risks

    The EPA interprets EO 13045 (62 F.R. 19885, April 23, 1997) as 
applying only to those regulatory actions that concern health or safety 
risks, such that the analysis required under section 5-501 of the EO 
has the potential to influence the regulation. This action is not 
subject to EO 13045 because it does not establish an environmental 
standard intended to mitigate health or safety risks.

[[Page 40004]]

H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    This action is not subject to Executive Order 13211 (66 FR 28355 
(May 22, 2001)), because it is not a significant regulatory action 
under Executive Order 12866.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (``NTTAA''), Public Law 104-113 (15 U.S.C. 272 note), 
directs the EPA to use voluntary consensus standards in its regulatory 
activities unless to do so would be inconsistent with applicable law or 
otherwise impractical. Voluntary consensus standards are technical 
standards (e.g., materials specifications, test methods, sampling 
procedures, and business practices) that are developed or adopted by 
voluntary consensus standards bodies. NTTAA directs the EPA to provide 
Congress, through OMB, explanations when the agency decides not to use 
available and applicable voluntary consensus standards.
    This rule involves environmental monitoring and measurement 
consistent with the agency's Performance Based Measurement System 
(PBMS). The PBMS approach is intended to be more flexible and cost-
effective for the regulated community; it is also intended to encourage 
innovation in analytical technology and improved data quality. 
Specifically, this rule establishes a new FRM for Pb in TSP 
measurements. The EPA used voluntary consensus standards in the 
preparation of this FRM. The FRM is the benchmark against which all 
ambient monitoring methods are compared. The FRM is not a voluntary 
consensus standard.
    The FEM equivalency criteria contained in 40 CFR part 53 constitute 
performance criteria. Therefore, the EPA is not precluding the use of 
any method, whether it constitutes a voluntary consensus standard or 
not, as long as it meets the specified performance criteria in 40 CFR 
part 53 and is approved by the EPA pursuant to those regulations.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    Executive Order (EO) 12898 (59 FR 7629 (Feb. 16, 1994)) establishes 
federal executive policy on environmental justice. Its main provision 
directs federal agencies, to the greatest extent practicable and 
permitted by law, to make environmental justice part of their mission 
by identifying and addressing, as appropriate, disproportionately high 
and adverse human health or environmental effects of their programs, 
policies, and activities on minority populations and low-income 
populations in the United States.
    The EPA has determined that this rule will not have 
disproportionately high and adverse human health or environmental 
effects on minority or low-income populations because it does not 
affect the level of protection provided to human health or the 
environment. This action establishes a new FRM for state and local air 
monitoring agencies to use as one of the approved methods for 
measurement of Pb in TSP and designates the existing FRM as an FEM.

K. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. The EPA will submit a report containing this rule and 
other required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
804(2). This rule will be effective August 2, 2013.

List of Subjects in 40 CFR Part 50

    Environmental protection, Air pollution control, and Lead.

    Dated: June 26, 2013.
Bob Perciasepe,
Acting Administrator.

    For reasons stated in the preamble, title 40, chapter I of the Code 
of Federal Regulations sets forth the following.

PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY 
STANDARDS

0
1. The authority citation for part 50 continues to read as follows:

    Authority: 42 U.S.C. 7401, et seq.


0
2. Appendix G to part 50 is revised to read as follows:

Appendix G to Part 50--Reference Method for the Determination of Lead 
in Total Suspended Particulate Matter

1.0 Scope and Applicability

    Based on review of the air quality criteria and national ambient 
air quality standard (NAAQS) for lead (Pb) completed in 2008, the 
EPA made revisions to the primary and secondary NAAQS for Pb to 
protect public health and welfare. The EPA revised the level from 
1.5 [mu]g/m\3\ to 0.15 [mu]g/m\3\ while retaining the current 
indicator of Pb in total suspended particulate matter (Pb-TSP).
    Pb-TSP is collected for 24 hours on a TSP filter as described in 
Appendix B of part 50, the Reference Method for the Determination of 
Suspended Particulate Matter in the Atmosphere (High-Volume Method). 
This method is for the analysis of Pb from TSP filters by 
Inductively Coupled Plasma Mass Spectrometry (ICP-MS) using a heated 
ultrasonic bath with nitric acid (HNO3) and hydrochloric 
acid (HCl) or a heated block (hot block) digester with 
HNO3 for filter extraction.
    This method is based on the EPA's Office of Solid Waste (SW-846) 
Method 6020A--Inductively Coupled Plasma Mass Spectrometry (U.S. 
EPA, 2007). Wording in certain sections of this method is 
paraphrased or taken directly from Method 6020A.
    1.1 ICP-MS is applicable for the sub-[micro]g/mL (ppb) 
determination of Pb in a wide variety of matrices. Results reported 
for monitoring or compliance purposes are calculated in [mu]g/m\3\ 
at local conditions (LC). This procedure describes a method for the 
acid extraction of Pb in particulate matter collected on glass 
fiber, quartz, or PTFE filters and measurement of the extracted Pb 
using ICP-MS.
    1.2 Due to variations in the isotopic abundance of Pb, the value 
for total Pb must be based on the sum of the signal intensities for 
isotopic masses, 206, 207, and 208. Most instrument software 
packages are able to sum the primary isotope signal intensities 
automatically.
    1.3 ICP-MS requires the use of an internal standard. \115\In 
(Indium), \165\Ho (Holmium), and \209\Bi (Bismuth) are recommended 
internal standards for the determination of Pb.
    1.4 Use of this method is restricted to use by, or under 
supervision of, properly trained and experienced laboratory 
personnel. Requirements include training and experience in inorganic 
sample preparation, including acid extraction, and also knowledge in 
the recognition and in the correction of spectral, chemical and 
physical interference in ICP-MS.

2.0 Summary of Method

    2.1 This method describes the acid extraction of Pb in 
particulate matter collected on glass fiber, quartz, or PTFE ambient 
air filters with subsequent measurement of Pb by ICP-MS. Estimates 
of the Method Detection Limit (MDL) or sensitivity of the method are 
provided in Tables 1, 3 and 5 and determined using Pb-spiked filters 
or filter strips analyzed in accordance with the guidance provided 
in 40

[[Page 40005]]

CFR 136, Appendix B--Determination and procedures for the 
Determination of the Method Detection Limit--Revision 1.1. The 
analytical range of the method is 0.00024 [micro]g/m\3\ to 0.60 
[micro]g/m\3\, and based on the low and high calibration curve 
standards and a nominal filter sample volume of 2000 m\3\.
    2.2 This method includes two extraction methods. In the first 
method, a solution of HNO3 and HCl is added to the 
filters or filter strips in plastic digestion tubes and the tubes 
are placed in a heated ultrasonic bath for one hour to facilitate 
the extraction of Pb. Following ultrasonication, the samples are 
brought to a final volume of 40 mL (50 mL for PTFE filters), vortex 
mixed or shaken vigorously, and centrifuged prior to aliquots being 
taken for ICP-MS analysis. In the second method, a solution of 
dilute HNO3 is added to the filter strips in plastic 
digestion tubes and the tubes placed into the hot block digester. 
The filter strip is completely covered by the solution. The tubes 
are covered with polypropylene watch glasses and refluxed. After 
reflux, the samples are diluted to a final volume of 50 mL with 
reagent water and mixed before analysis.
    2.3 Calibration standards and check standards are prepared to 
matrix match the acid composition of the samples. ICP-MS analysis is 
then performed. With this method, the samples are first aspirated 
and the aerosol thus created is transported by a flow of argon gas 
into the plasma torch. The ions produced (e.g., Pb\+1\) in the 
plasma are extracted via a differentially-pumped vacuum interface 
and are separated on the basis of their mass-to-charge ratio. The 
ions are quantified by a channel electron multiplier or a Faraday 
detector and the signal collected is processed by the instrument's 
software. Interferences must be assessed and corrected for, if 
present.

3.0 Definitions

Pb--Elemental or ionic lead
HNO3--Nitric acid
HCl--Hydrochloric acid
ICP-MS--Inductively Coupled Plasma Mass Spectrometer
MDL--Method detection limit
RSD--Relative standard deviation
RPD--Relative percent difference
CB--Calibration Blank
CAL--Calibration Standard
ICB--Initial calibration blank
CCB--Continuing calibration blank
ICV--Initial calibration verification
CCV--Continuing calibration verification
LLCV--Lower Level Calibration Verification, serves as the lower 
level ICV and lower level CCV
RB--Reagent blank
RBS--Reagent blank spike
MSDS--Material Safety Data Sheet
NIST--National Institute of Standards and Technology
D.I. water--Deionized water
SRM--NIST Standard Reference Material
CRM--Certified Reference Material
EPA--Environmental Protection Agency
v/v--Volume to volume ratio

4.0 Interferences

    4.1 Reagents, glassware, plasticware, and other sample 
processing hardware may yield artifacts and/or interferences to 
sample analysis. If reagent blanks, filter blanks, or quality 
control blanks yield results above the detection limit, the source 
of contamination must be identified. All containers and reagents 
used in the processing of the samples must be checked for 
contamination prior to sample extraction and analysis. Reagents 
shall be diluted to match the final concentration of the extracts 
and analyzed for Pb. Labware shall be rinsed with dilute acid 
solution and the solution analyzed. Once a reagent or labware 
article (such as extraction tubes) from a manufacturer has been 
successfully screened, additional screening is not required unless 
contamination is suspected.
    4.2 Isobaric elemental interferences in ICP-MS are caused by 
isotopes of different elements forming atomic ions with the same 
nominal mass-to-charge ratio (m/z) as the species of interest. There 
are no species found in ambient air that will result in isobaric 
interference with the three Pb isotopes (206, 207, and 208) being 
measured. Polyatomic interferences occur when two or more elements 
combine to form an ion with the same mass-to-charge ratio as the 
isotope being measured. Pb is not subject to interference from 
common polyatomic ions and no correction is required.
    4.3 The distribution of Pb isotopes is not constant. The 
analysis of total Pb should be based on the summation of signal 
intensities for the isotopic masses 206, 207, and 208. In most 
cases, the instrument software can perform the summation 
automatically.
    4.4 Physical interferences are associated with the sample 
nebulization and transport processes as well as with ion-
transmission efficiencies. Dissolved solids can deposit on the 
nebulizer tip of a pneumatic nebulizer and on the interface skimmers 
of the ICP-MS. Nebulization and transport processes can be affected 
if a matrix component causes a change in surface tension or 
viscosity. Changes in matrix composition can cause significant 
signal suppression or enhancement. These interferences are 
compensated for by use of internal standards. Sample dilution will 
reduce the effects of high levels of dissolved salts, but 
calibration standards must be prepared in the extraction medium and 
diluted accordingly.
    4.5 Memory interferences are related to sample transport and 
result when there is carryover from one sample to the next. Sample 
carryover can result from sample deposition on the sample and 
skimmer cones and from incomplete rinsing of the sample solution 
from the plasma torch and the spray chamber between samples. These 
memory effects are dependent upon both the analyte being measured 
and sample matrix and can be minimized through the use of suitable 
rinse times.

5.0 Health and Safety Cautions

    5.1 The toxicity or carcinogenicity of reagents used in this 
method has not been fully established. Each chemical should be 
regarded as a potential health hazard and exposure to these 
compounds should be as low as reasonably achievable. Each laboratory 
is responsible for maintaining a current file of OSHA regulations 
regarding the safe handling of the chemicals specified in this 
method. A reference file of material safety data sheets (MSDSs) 
should be available to all personnel involved in the chemical 
analysis. Specifically, concentrated HNO3 presents 
various hazards and is moderately toxic and extremely irritating to 
skin and mucus membranes. Use this reagent in a fume hood whenever 
possible and if eye or skin contact occurs, flush with large volumes 
of water. Always wear safety glasses or a shield for eye protection, 
protective clothing, and observe proper mixing when working with 
these reagents.
    5.2 Concentrated HNO3 and HCl are moderately toxic 
and extremely irritating to the skin. Use these reagents in a fume 
hood, and if eye and skin contact occurs, flush with large volumes 
of water. Always wear safety glasses or a shield for eye protection 
when working with these reagents. The component of this procedure 
requiring the greatest care is HNO3. HNO3 is a 
strong, corrosive, oxidizing agent that requires protection of the 
eyes, skin, and clothing. Items to be worn during use of this 
reagent include:
    1. Safety goggles (or safety glasses with side shields),
    2. Acid resistant rubber gloves, and
    3. A protective garment such as a laboratory apron. 
HNO3 spilled on clothing will destroy the fabric; contact 
with the skin underneath will result in a burn.
    It is also essential that an eye wash fountain or eye wash 
bottle be available during performance of this method. An eye wash 
bottle has a spout that covers the eye. If acid or any other 
corrosive gets into the eye, the water in this bottle is squirted 
onto the eye to wash out the harmful material. Eye washing should be 
performed with large amounts of water immediately after exposure. 
Medical help should be sought immediately after washing. If either 
acid, but especially HNO3, is spilled onto the skin, wash 
immediately with large amounts of water. Medical attention is not 
required unless the burn appears to be significant. Even after 
washing and drying, HNO3 may leave the skin slightly 
brown in color; this will heal and fade with time.
    5.3 Pb salts and Pb solutions are toxic. Great care must be 
taken to ensure that samples and standards are handled properly; 
wash hands thoroughly after handling.
    5.4 Care must be taken when using the ultrasonic bath and hot 
block digester as they are capable of causing mild burns. Users 
should refer to the safety guidance provided by the manufacturer of 
their specific equipment.
    5.5 Analytical plasma sources emit radio frequency radiation in 
addition to intense ultra violet (UV) radiation. Suitable 
precautions should be taken to protect personnel from such hazards. 
The inductively coupled plasma should only be viewed with proper eye 
protection from UV emissions.

6.0 Equipment

    6.1 Thermo Scientific X-Series ICP-MS or equivalent. The system 
must be capable of providing resolution better or equal to 1.0 
atomic mass unit (amu) at 10 percent peak height. The system must 
have a mass range from at least 7 to 240 amu that allows for the 
application of the internal standard technique. For the measurement 
of Pb, an

[[Page 40006]]

instrument with a collision or reaction cell is not required.

6.2 Ultrasonic Extraction Equipment

    6.2.1 Heated ultrasonic bath capable of maintaining a 
temperature of 80 [deg]C; VWR Model 750HT, 240W, or equivalent. 
Ultrasonic bath must meet the following performance criteria:
    1. Cut a strip of aluminum foil almost the width of the tank and 
double the depth.
    2. Turn the ultrasonic bath on and lower the foil into the bath 
vertically until almost touching the bottom of the tank and hold for 
10 seconds.
    3. Remove the foil from the tank and observe the distribution of 
perforations and small pin prick holes. The indentations should be 
fine and evenly distributed. The even distribution of indentations 
indicates the ultrasonic bath is acceptable for use.
    6.2.2 Laboratory centrifuge, Beckman GS-6, or equivalent.
    6.2.3 Vortex mixer, VWR Signature Digital Vortex Mixer, VWR 
Catalog No. 14005-824, or equivalent.
    6.3 Hot block extraction equipment
    6.3.1 Hot block digester, SCP Science DigiPrep Model MS, No. 
010-500-205 block digester capable of maintaining a temperature of 
95 [deg]C, or equivalent.
    6.4 Materials and Supplies
     Argon gas supply, 99.99 percent purity or better. 
National Welders Microbulk, or equivalent.
     Plastic digestion tubes with threaded caps for 
extraction and storage, SCP Science DigiTUBE[supreg] Item No. 010-
500-063, or equivalent.
     Disposable polypropylene ribbed watch glasses (for 
heated block extraction), SCP Science Item No. 010-500-081, or 
equivalent.
     Pipette, Rainin EDP2, 100 [mu]L,  1 percent 
accuracy, <=1 percent RSD (precision), with disposable tips, or 
equivalent.
     Pipette, Rainin EDP2, 1000 [mu]L,  1 
percent accuracy, <=1 percent RSD (precision), with disposable tips, 
or equivalent.
     Pipette, Rainin EDP2, 1-10 mL,  1 percent 
accuracy, <=1 percent RSD (precision), with disposable tips, or 
equivalent.
     Pipette, Thermo Lab Systems, 5 mL,  1 
percent accuracy, <=1 percent RSD (precision), with disposable tips, 
or equivalent.
     Plastic tweezer, VWR Catalog No. 89026-420, or 
equivalent.
     Laboratory marker.
     Ceramic knife, Kyocera LK-25, and non-metal ruler or 
other suitable cutting tools for making straight cuts for accurately 
measured strips.
     Blank labels or labeling tape, VWR Catalog No. 36425-
045, or equivalent.
     Graduated cylinder, 1 L, VWR 89000-260, or equivalent.
     Volumetric flask, Class A, 1 L, VWR Catalog No. 89025-
778, or equivalent.
     Millipore Element deionized water system, or 
equivalent, capable of generating water with a resistivity of >=17.9 
M[Omega]-cm).
     Disposable syringes, 10-mL, with 0.45 micron filters 
(must be Pb-free).
     Plastic or PTFE wash bottles.
     Glassware, Class A--volumetric flasks, pipettes, and 
graduated cylinders.
     Glass fiber, quartz, or PTFE filters from the same 
filter manufacturer and lot used for sample collection for use in 
the determination of the MDL and for laboratory blanks.

7.0 Reagents and Standards

    7.1 Reagent--or trace metals-grade chemicals must be used in all 
tests. Unless otherwise indicated, it is intended that all reagents 
conform to the specifications of the Committee on Analytical 
Reagents of the American Chemical Society, where such specifications 
are available.
    7.2 Concentrated nitric acid, 67-70 percent, SCP Science Catalog 
No. 250-037-177, or equivalent.
    7.3 Concentrated hydrochloric acid (for the ultrasonic 
extraction method), 33-36 percent, SCP Science Catalog No. 250-037-
175, or equivalent.
    7.4 Deionized water--All references to deionized water in the 
method refer to deionized water with a resistivity >=17.9 M[Omega]-
cm.
    7.5 Standard stock solutions may be commercially purchased for 
each element or as a multi-element mix. Internal standards may be 
purchased as a mixed multi-element solution. The manufacturer's 
expiration date and storage conditions must be adhered to.
    7.5.1 Lead standard, 1000 [mu]g/mL, NIST traceable, commercially 
available with certificate of analysis. High Purity Standards 
Catalog No. 100028-1, or equivalent.
    7.5.2 Indium (In) standard, 1000 [mu]g/mL, NIST traceable, 
commercially available with certificate of analysis. High Purity 
Standards Catalog No. 100024-1, or equivalent.
    7.5.3 Bismuth (Bi) standard, 1000 [mu]g/mL, NIST traceable, 
commercially available with certificate of analysis. High Purity 
Standards Catalog No. 100006-1, or equivalent.
    7.5.4 Holmium (Ho) standard, 1000 [mu]g/mL, NIST traceable, 
commercially available with certificate of analysis. High Purity 
Standards Catalog No. 100023-1, or equivalent.
    7.5.5 Second source lead standard, 1000 [mu]g/mL, NIST 
traceable, commercially available with certificate of analysis. Must 
be from a different vendor or lot than the standard described in 
7.5.1. Inorganic Ventures Catalog No. CGPB-1, or equivalent.
    7.5.6 Standard Reference Materials, NIST SRM 2583, 2586, 2587 or 
1648, or equivalent.\5\
---------------------------------------------------------------------------

    \5\ Certificates of Analysis for these SRMs can be found at: 
https://www.nist.gov/srm/index.cfm.
---------------------------------------------------------------------------

    Note: The In, Bi, and Ho internal standards may also be 
purchased as 10 [micro]g/mL standards. Calibration standards are 
prepared by diluting stock standards to the appropriate levels in 
the same acid concentrations as in the final sample volume. The 
typical range for calibration standards is 0.001 to 2.00 [micro]g/
mL. At a minimum, the curve must contain a blank and five Pb 
containing calibration standards. The calibration standards are 
stored at ambient laboratory temperature. Calibration standards must 
be prepared weekly and verified against a freshly prepared ICV using 
a NIST-traceable source different from the calibration standards.
    7.6 Internal standards may be added to the test solution or by 
on-line addition. The nominal concentration for an internal standard 
is 0.010 [micro]g/mL (10 ppb). Bismuth (Bi) or holmium (Ho) are the 
preferred internal standards for Pb, but indium (In) may be used in 
the event the sample contains Bi and high recoveries are observed.
    7.7 Three laboratory blank solutions are required for analysis: 
(1) The calibration blank is used in the construction of the 
calibration curve and as a periodic check of system cleanliness (ICB 
and CCB); (2) the reagent blank (RB) is carried through the 
extraction process to assess possible contamination; and (3) the 
rinse blank is run between samples to clean the sample introduction 
system. If RBs or laboratory blanks yield results above the 
detection limit, the source of contamination must be identified. 
Screening of labware and reagents is addressed in Section 4.1.
    7.7.1 The calibration blank is prepared in the same acid matrix 
as the calibration standards and samples and contains all internal 
standards used in the analysis.
    7.7.2 The RB contains all reagents used in the extraction and is 
carried through the extraction procedure at the same time as the 
samples.
    7.7.3 The rinse blank is a solution of 1 to 2 percent 
HNO3 (v/v) in reagent grade water. A sufficient volume 
should be prepared to flush the system between all standards and 
samples analyzed.
    7.7.4 The EPA currently provides glass fiber, quartz, and PTFE 
filters to air monitoring agencies as requested annually. As part of 
the procurement process, these filters are tested for acceptance by 
the EPA. The current acceptance criteria for glass fiber and quartz 
filters is 15 [micro]g per filter or 0.0075 [micro]g/m\3\ using a 
nominal sample volume of 2000 m\3\ and 4.8 ng/cm\2\ or 0.0024 
[micro]g/m\3\ for PTFE filters using a nominal sample volume of 24 
m\3\. Acceptance test results for filters obtained by the EPA are 
typically well below the criterion specified and also below the 
recently revised Pb method performance detection limit of 0.0075 
[micro]g/m\3\; therefore, blank subtraction should not be performed.
    7.7.5 If filters are not provided by the EPA for sample 
collection and analysis, filter lot blanks should be analyzed for Pb 
content. For large filter lots (>500 filters), randomly select 20 to 
30 filters from the lot and analyze the filter or filter strips for 
Pb. For smaller filter lots, a lesser number of filters can be 
analyzed. Glass, quartz and PTFE filters must not have levels of Pb 
above the criteria specified in section 7.7.4 and, therefore, blank 
correction should not be performed. If acceptance testing shows 
levels of Pb above the criteria in Section 7.7.4, corrective action 
must be taken to reduce the levels before proceeding.
    7.8 The Initial Calibration Verification (ICV), Lower Level 
Calibration Verification (LLCV), and Continuing Calibration 
Verification (CCV) solutions are prepared from a different Pb source 
than the calibration curve standards and at a concentration that is 
either at or below the midpoint on the calibration curve, but within 
the calibration range. Both are prepared in the same acid matrix as 
the calibration standards. Note that the same solution may be used 
for both the ICV and CCV. The ICV/

[[Page 40007]]

CCV and LLCV solutions must be prepared fresh daily.
    7.9 Tuning Solution. Prepare a tuning solution according to the 
instrument manufacturer's recommendations. This solution will be 
used to verify the mass calibration and resolution of the 
instrument.

8.0 Quality Control (QC)

    8.1 Standard QC practices shall be employed to assess the 
validity of the data generated, including: MDL, RB, duplicate 
samples, spiked samples, serial dilutions, ICV, CCV, LLCV, ICB, CCB, 
and SRMs/CRMs.
    8.2 MDLs must be calculated in accordance with 40 CFR part 136, 
Appendix B. RBs with low-level standard spikes are used to estimate 
the MDL. The low-level standard spike is added to at least 7 
individual filter strips and then carried through the entire 
extraction procedure. This will result in at least 7 individual 
samples to be used for the MDL. The recommended range for spiking 
the strips is 1 to 5 times the estimated MDL.
    8.3 For each batch of samples, one RB and one reagent blank 
spike (RBS) that is spiked at the same level as the sample spike 
(see Section 8.6) must be prepared and carried throughout the entire 
process. The results of the RB must be below 0.001 [micro]g/mL. The 
recovery for the RBS must be within  20 percent of the 
expected value. If the RB yields a result above 0.001 [micro]g/mL, 
the source of contamination must be identified and the extraction 
and analysis repeated. Reagents and labware must be suspected as 
sources of contamination. Screening of reagents and labware is 
addressed in Section 4.1.
    8.4 Any samples that exceed the highest calibration standard 
must be diluted and rerun so that the concentration falls within the 
curve. The minimum dilution will be 1 to 5 with matrix matched acid 
solution.
    8.5 The internal standard response must be monitored during the 
analysis. If the internal standard response falls below 70 percent 
or rises above 120 percent of expected due to possible matrix 
effects, the sample must be diluted and reanalyzed. The minimum 
dilution will be 1 to 5 with matrix matched acid solution. If the 
first dilution does not correct the problem, additional dilutions 
must be run until the internal standard falls within the specified 
range.
    8.6 For every batch of samples prepared, there must be one 
duplicate and one spike sample prepared. The spike added is to be at 
a level that falls within the calibration curve, normally the 
midpoint of the curve. The initial plus duplicate sample must yield 
a relative percent difference <= 20 percent. The spike must be 
within  20 percent of the expected value.
    8.7 For each batch of samples, one extract must be diluted five-
fold and analyzed. The corrected dilution result must be within 
10 percent of the undiluted result. The sample chosen 
for the serial dilution shall have a concentration at or above 10X 
the lowest standard in the curve to ensure the diluted value falls 
within the curve. If the serial dilution fails, chemical or physical 
interference should be suspected.
    8.8 ICB, ICV, LLCV, CCB and CCV samples are to be run as shown 
in the following table.

------------------------------------------------------------------------
                                                        Performance
          Sample                  Frequency            specification
------------------------------------------------------------------------
ICB.......................  Prior to first sample  Less than 0.001 [mu]g/
                                                    mL.
ICV.......................  Prior to first sample  Within 90 to 110
                                                    percent of the
                                                    expected value.
LLCV......................  Daily, before first    10
                             sample and after       percent of the
                             last sample.           expected value.
CCB.......................  After every 10         Less than 0.001 [mu]g/
                             extracted samples.     mL.
CCV.......................  After every 10         Within 90-110 percent
                             extracted samples.     of the expected
                                                    value.
------------------------------------------------------------------------

    If any of these QC samples fails to meet specifications, the 
source of the unacceptable performance must be determined, the 
problem corrected, and any samples not bracketed by passing QC 
samples must be reanalyzed.
    8.9 For each batch of samples, one certified reference material 
(CRM) must be combined with a blank filter strip and carried through 
the entire extraction procedure. The result must be within 10 percent of the expected value.
    8.10 For each run, a LLCV must be analyzed. The LLCV must be 
prepared at a concentration not more than three times the lowest 
calibration standard and at a concentration not used in the 
calibration curve. The LLCV is used to assess performance at the low 
end of the curve. If the LLCV fails (10 percent of the 
expected value) the run must be terminated, the problem corrected, 
the instrument recalibrated, and the analysis repeated.
    8.11 Pipettes used for volumetric transfer must have the 
calibration checked at least once every 6 months and pass  1 percent accuracy and <= 1 percent RSD (precision) based on 
five replicate readings. The pipettes must be checked weekly for 
accuracy with a single replicate. Any pipette that does not meet 
 1 percent accuracy on the weekly check must be removed 
from service, repaired, and pass a full calibration check before 
use.
    8.12 Samples with physical deformities are not quantitatively 
analyzable. The analyst should visually check filters prior to 
proceeding with preparation for holes, tears, or non-uniform deposit 
which would prevent representative sampling. Document any 
deformities and qualify the data with flags appropriately. Care must 
be taken to protect filters from contamination. Filters must be kept 
covered prior to sample preparation.
    9.0 ICP MS Calibration
    Follow the instrument manufacturer's instructions for the 
routine maintenance, cleaning, and ignition procedures for the 
specific ICP-MS instrument being used.
    9.1 Ignite the plasma and wait for at least one half hour for 
the instrument to warm up before beginning any pre-analysis steps.
    9.2 For the Thermo X-Series with Xt cones, aspirate a 10 ng/mL 
tuning solution containing In, Bi, and Ce (Cerium). Monitor the 
intensities of In, Bi, Ce, and CeO (Cerium oxide) and adjust the 
instrument settings to achieve the highest In and Bi counts while 
minimizing the CeO/Ce oxide ratio. For other instruments, follow the 
manufacturer's recommended practice. Tune to meet the instrument 
manufacturer's specifications. After tuning, place the sample 
aspiration probe into a 2 percent HNO3 rinse solution for 
at least 5 minutes to flush the system.
    9.3 Aspirate a 5 ng/mL solution containing Co, In, and Bi to 
perform a daily instrument stability check. Run 10 replicates of the 
solution. The percent RSD for the replicates must be less than 3 
percent at all masses. If the percent RSD is greater than 3 percent, 
the sample introduction system, pump tubing, and tune should be 
examined, and the analysis repeated. Place the sample aspiration 
probe into a 2 percent HNO3 rinse solution for at least 5 
minutes to flush the system.
    9.4 Load the calibration standards in the autosampler and 
analyze using the same method parameters that will be used to 
analyze samples. The curve must include one blank and at least 5 Pb-
containing calibration standards. The correlation coefficient must 
be at least 0.998 for the curve to be accepted. The lowest standard 
must recover  15 percent of the expected value and the 
remaining standards must recover  10 percent of the 
expected value to be accepted.
    9.5 Immediately after the calibration curve is completed, 
analyze an ICV and an ICB. The ICV must be prepared from a different 
source of Pb than the calibration standards. The ICV must recover 
90-110 percent of the expected value for the run to continue. The 
ICB must be less than 0.001 [micro]g/mL. If either the ICV or the 
ICB fails, the run must be terminated, the problem identified and 
corrected, and the analysis re-started.
    9.6 A LLCV, CCV and a CCB must be run after the ICV and ICB. A 
CCV and CCB must be run at a frequency of not less than every 10 
extracted samples. A typical analytical run sequence would be: 
Calibration blank, Calibration standards, ICV, ICB, LLCV, CCV, CCB, 
Extracts 1-10, CCV, CCB, Extracts 11-20, CCV, CCB, Extracts 21-30, 
CCV, CCB, LLCV, CCV, CCB. Extracts are any field sample or QC 
samples that have been carried through the extraction process. The 
CCV solution is prepared from a different source than the 
calibration standards and may be the same as the ICV solution. The 
LLCV must be within  10 percent of expected value. The 
CCV value must be within  10 percent of expected for the 
run to continue. The CCB must be less than 0.001 [mu]g/mL. If either 
the CCV, LLCV, or CCB fails, the run must be terminated, the problem 
identified and

[[Page 40008]]

corrected, and the analysis re-started from the last passing CCV/
LLCV/CCB set.
    9.7 A LLCV, CCV, and CCB set must be run at the end of the 
analysis. The LLCV must be within  30 percent of 
expected value. If either the CCV, LLCV, or CCB fails, the run must 
be terminated, the problem identified and corrected, and the 
analysis re-started from the last passing CCV/LLCV/CCB set.

10.0 Heated Ultrasonic Filter Strip Extraction

    All plasticware (e.g., Nalgene) and glassware used in the 
extraction procedures is soaked in 1 percent HNO3 (v/v) 
for at least 24 hours and rinsed with reagent water prior to use. 
All mechanical pipettes used must be calibrated to 1 
percent accuracy and <= 1 percent RSD at a minimum of once every 6 
months.
    10.1 Sample Preparation--Heated Ultrasonic Bath
    10.1.1 Extraction solution (1.03M HNO3 + 2.23M HCl). 
Prepare by adding 500 mL of deionized water to a 1000 mL flask, 
adding 64.4 mL of concentrated HNO3 and 182 mL of 
concentrated HCl, shaking to mix, allowing solution to cool, 
diluting to volume with reagent water, and inverting several times 
to mix. Extraction solution must be prepared at least weekly.
    10.1.2 Use a ceramic knife and non-metal ruler, or other cutting 
device that will not contaminate the filter with Pb. Cut a \3/4\ 
inch X 8 inch strip from the glass fiber or quartz filter by cutting 
a strip from the edge of the filter where it has been folded along 
the 10 inch side at least 1 inch from the right or left side to 
avoid the un-sampled area covered by the filter holder. The filters 
must be carefully handled to avoid dislodging deposits.
    10.1.3 Using plastic tweezers, roll the filter strip up in a 
coil and place the rolled strip in the bottom of a labeled 50 mL 
extraction tube. In a fume hood, add 15.00  0.15 mL of 
the extraction solution (see Section 10.1.1) using a calibrated 
mechanical pipette. Ensure that the extraction solution completely 
covers the filter strip.
    10.1.4 Loosely cap the 50 mL extraction tube and place it 
upright in a plastic rack. When all samples have been prepared, 
place the racks in an uncovered heated ultrasonic water bath that 
has been preheated to 80  5[deg]C and ensure that the 
water level in the ultrasonic is above the level of the extraction 
solution in the tubes but well below the level of the extraction 
tube caps to avoid contamination. Start the ultrasonic bath and 
allow the unit to run for 1 hour  5 minutes at 80  5[deg]C.
    10.1.5 Remove the rack(s) from the ultrasonic bath and allow the 
racks to cool.
    10.1.6 Add 25.00  0.25 mL of D.I. water with a 
calibrated mechanical pipette to bring the sample to a final volume 
of 40.0  0.4 mL. Tightly cap the tubes, and vortex mix 
or shake vigorously. Place the extraction tubes in an appropriate 
holder and centrifuge for 20 minutes at 2500 revolutions per minute 
(RPM).
    CAUTION--Make sure that the centrifuge holder has a flat bottom 
to support the flat bottomed extraction tubes.
    10.1.7 Pour an aliquot of the solution into an autosampler vial 
for ICP-MS analysis to avoid the potential for contamination. Do not 
pipette an aliquot of solution into the autosampler vial.
    10.1.8 Decant the extract to a clean tube, cap tightly, and 
store the sample extract at ambient laboratory temperature. Extracts 
may be stored for up to 6 months from the date of extraction.
    10.2 47 mm PTFE Filter Extraction--Heated Ultrasonic Bath
    10.2.1 Extraction solution (1.03M HNO3 + 2.23M HCl). 
Prepare by adding 500 mL of D.I. water to a 1000mL flask, adding 
64.4 mL of concentrated HNO3 and 182 mL of concentrated 
HCl, shaking to mix, allowing solution to cool, diluting to volume 
with reagent water, and inverting several times to mix. Extraction 
solution must be prepared at least weekly.
    10.2.2 Using plastic tweezers, bend the PTFE filter into a U-
shape and insert the filter into a labeled 50 mL extraction tube 
with the particle loaded side facing the center of the tube. Gently 
push the filter to the bottom of the extraction tube. In a fume 
hood, add 25.00  0.15 mL of the extraction solution (see 
Section 10.2.1) using a calibrated mechanical pipette. Ensure that 
the extraction solution completely covers the filter.
    10.2.3 Loosely cap the 50 mL extraction tube and place it 
upright in a plastic rack. When all samples have been prepared, 
place the racks in an uncovered heated ultrasonic water bath that 
has been preheated to 80  5[deg]C and ensure that the 
water level in the ultrasonic is above the level of the extraction 
solution in the tubes, but well below the level of the extraction 
tube caps to avoid contamination. Start the ultrasonic bath and 
allow the unit to run for 1 hour  5 minutes at 80  5[deg]C.
    10.2.4 Remove the rack(s) from the ultrasonic bath and allow the 
racks to cool.
    10.2.5 Add 25.00  0.25 mL of D.I. water with a 
calibrated mechanical pipette to bring the sample to a final volume 
of 50.0  0.4 mL. Tightly cap the tubes, and vortex mix 
or shake vigorously. Allow samples to stand for one hour to allow 
complete diffusion of the extracted Pb. The sample is now ready for 
analysis.
    Note: Although PTFE filters have only been extracted using the 
ultrasonic extraction procedure in the development of this FRM, PTFE 
filters are inert and have very low Pb content. No issues are 
expected with the extraction of PTFE filters using the heated block 
digestion method. However, prior to using PTFE filters in the heated 
block extraction method, extraction method performance test using 
CRMs must be done to confirm performance (see Section 8.9).

11.0 Hot Block Filter Strip Extraction

    All plasticware (e.g., Nalgene) and glassware used in the 
extraction procedures is soaked in 1 percent HNO3 for at 
least 24 hours and rinsed with reagent water prior to use. All 
mechanical pipettes used must be calibrated to 1 percent 
accuracy and <= 1 percent RSD at a minimum of once every 6 months.
    11.1 Sample Preparation--Hot Block Digestion
    11.1.1 Extraction solution (1:19, v/v HNO3). Prepare 
by adding 500 mL of D.I. water to a 1000 mL flask, adding 50 mL of 
concentrated HNO3, shaking to mix, allowing solution to 
cool, diluting to volume with reagent water, and inverting several 
times to mix. The extraction solution must be prepared at least 
weekly.
    11.1.2 Use a ceramic knife and non-metal ruler, or other cutting 
device that will not contaminate the filter with Pb. Cut a 1-inch X 
8-inch strip from the glass fiber or quartz filter. Cut a strip from 
the edge of the filter where it has been folded along the 10-inch 
side at least 1 inch from the right or left side to avoid the un-
sampled area covered by the filter holder. The filters must be 
carefully handled to avoid dislodging particle deposits.
    11.1.3 Using plastic tweezers, roll the filter strip up in a 
coil and place the rolled strip in the bottom of a labeled 50 mL 
extraction tube. In a fume hood, add 20.0  0.15 mL of 
the extraction solution (see Section 11.1.1) using a calibrated 
mechanical pipette. Ensure that the extraction solution completely 
covers the filter strip.
    11.1.4 Place the extraction tube in the heated block digester 
and cover with a disposable polyethylene ribbed watch glass. Heat at 
95  5[deg]C for 1 hour and ensure that the sample does 
not evaporate to dryness. For proper heating, adjust the temperature 
control of the hot block such that an uncovered vessel containing 50 
mL of water placed in the center of the hot block can be maintained 
at a temperature approximately, but no higher than 85[ordm]C. Once 
the vessel is covered with a ribbed watch glass, the temperature of 
the water will increase to approximately 95[deg]C.
    11.1.5 Remove the rack(s) from the heated block digester and 
allow the samples to cool.
    11.1.6 Bring the samples to a final volume of 50 mL with D.I. 
water. Tightly cap the tubes, and vortex mix or shake vigorously for 
at least 5 seconds. Set aside (with the filter strip in the tube) 
for at least 30 minutes to allow the HNO3 trapped in the 
filter to diffuse into the extraction solution.
    11.1.7 Shake thoroughly (with the filter strip in the digestion 
tube) and let settle for at least one hour. The sample is now ready 
for analysis.

12.0 Measurement Procedure

    12.1 Follow the instrument manufacturer's startup procedures for 
the ICP-MS.
    12.2 Set instrument parameters to the appropriate operating 
conditions as presented in the instrument manufacturer's operating 
manual and allow the instrument to warm up for at least 30 minutes.
    12.3 Calibrate the instrument per Section 9.0 of this method.
    12.4 Verify the instrument is suitable for analysis as defined 
in Sections 9.2 and 9.3.
    12.5 As directed in Section 8.0 of this method, analyze an ICV 
and ICB immediately after the calibration curve followed by a LLCV, 
then CCV and CCB. The acceptance requirements for these parameters 
are presented in Section 8.8.
    12.6 Analyze a CCV and a CCB after every 10 extracted samples.
    12.7 Analyze a LLCV, CCV and CCB at the end of the analysis.

[[Page 40009]]

    12.8 A typical sample run will include field samples, field 
sample duplicates, spiked field sample extracts, serially diluted 
samples, the set of QC samples listed in Section 8.8 above, and one 
or more CRMs or SRMs.
    12.9 Any samples that exceed the highest standard in the 
calibration curve must be diluted and reanalyzed so that the diluted 
concentration falls within the calibration curve.
    13.0 Results
    13.1 The filter results must be initially reported in [mu]g/mL 
as analyzed. Any additional dilutions must be accounted for. The 
internal standard recoveries must be included in the result 
calculation; this is done by the ICP-MS software for most 
commercially-available instruments. Final results should be reported 
in [mu]g Pb/m\3\ to three significant figures as follows:

C = (([mu]g Pb/mL * Vf * A)* D))/Vs

Where:
C = Concentration, [mu]g Pb/m\3\
[mu]g Pb/mL = Lead concentration in solution
Vf = Total extraction solution volume
A = Area correction; \3/4\'' x 8'' strip = 5.25 in\2\ analyzed, A = 
12.0 or 1'' x 8'' strip = 7 in\2\ analyzed, A = 9.0
D = dilution factor (if required)
Vs = Actual volume of air sampled

    The calculation assumes the use of a standard 8-inch x 10-inch 
TSP filter which has a sampled area of 9-inch x 7-inch (63.0 in\2\) 
due to the \1/2\-inch filter holder border around the outer edge. 
The \3/4\-inch x 8-inch strip has a sampled area of \3/4\-inch x 7-
inch (5.25 in\2\). The 1-inch x 8-inch strip has a sampled area of 
1-inch x 7-inch (7.0 in\2\). If filter lot blanks are provided for 
analysis, refer to Section 7.7.5 of this method for guidance on 
testing.

14.0 Method Performance

    Information in this section is an example of typical performance 
results achieved by this method. Actual performance must be 
demonstrated by each individual laboratory and instrument.
    14.1 Performance data have been collected to estimate MDLs for 
this method. MDLs were determined in accordance with 40 CFR 136, 
Appendix B. MDLs were estimated for glass fiber, quartz, and PTFE 
filters using seven reagent/filter blank solutions spiked with low 
level Pb at three times the estimated MDL of 0.001 [mu]g/mL. Tables 
1, 3, and 5 shows the MDLs estimated using both the ultrasonic and 
hot block extraction methods for glass fiber and quartz filters and 
the ultrasonic method for PTFE filters. The MDLs are well below the 
EPA requirement of five percent of the current Pb NAAQS or 0.0075 
[mu]g/m\3\. These MDLs are provided to demonstrate the adequacy of 
the method's performance for Pb in TSP. Each laboratory using this 
method should determine MDLs in their laboratory and verify them 
annually. It is recommended that laboratories also perform the 
optional iterative procedure in 40 CFR 136, Appendix B to verify the 
reasonableness of the estimated MDL and subsequent MDL 
determinations.
    14.2 Extraction method recovery tests with glass fiber and 
quartz filter strips, and PTFE filters spiked with NIST SRMs were 
performed using the ultrasonic/HNO3 and HCl filter 
extraction methods and measurement of the dissolved Pb with ICP-MS. 
Tables 2, 4, and 6 show recoveries obtained with these SRM. The 
recoveries for all SRMs were >=90 percent at the 95 percent 
confidence level.

Table 1--Method Detection Limits Determined by Analysis of Reagent/Glass
          Fiber Filter Blanks Spiked With Low-level Pb Solution
------------------------------------------------------------------------
                                                 Ultrasonic    Hotblock
                                                 extraction   extraction
                                                   method       method
                                               -------------------------
                                                [mu]g/m\3\*  [mu]g/m\3\*
------------------------------------------------------------------------
n = 1.........................................    0.0000702     0.000533
n = 2.........................................    0.0000715     0.000482
n = 3.........................................    0.0000611     0.000509
n = 4.........................................    0.0000587     0.000427
n = 5.........................................    0.0000608     0.000449
n = 6.........................................    0.0000607     0.000539
n = 7.........................................    0.0000616     0.000481
Average.......................................    0.0000635     0.000489
Standard Deviation............................    0.0000051     0.000042
MDL**.........................................    0.0000161     0.000131
------------------------------------------------------------------------
* Assumes 2000 m\3\ of air sampled.
** MDL is 3.143 times the standard deviation of the results for seven
  sample replicates analyzed.


                   Table 2--Recoveries of Lead From NIST SRMs Spiked Onto Glass Fiber Filters
----------------------------------------------------------------------------------------------------------------
                                                                    Recovery, ICP-MS, (percent)
                                                 ---------------------------------------------------------------
                Extraction method                    NIST 1547                                       NIST 2582
                                                       plant      NIST 2709 soil  NIST 2583 dust       paint
----------------------------------------------------------------------------------------------------------------
Ultrasonic Bath.................................      100  4        minus> 1        minus> 8        minus> 0
Block Digestion.................................       92  7        minus> 3        minus> 4        minus> 4
----------------------------------------------------------------------------------------------------------------


   Table 3--Method Detection Limits Determined by Analysis of Reagent/
         Quartz Filter Blanks Spiked With Low-level Pb Solution
------------------------------------------------------------------------
                                                 Ultrasonic    Hotblock
                                                 extraction   extraction
                                                   method       method
                                               -------------------------
                                                [mu]g/m\3\*  [mu]g/m\3\*
------------------------------------------------------------------------
n = 1.........................................     0.000533     0.000274
n = 2.........................................     0.000552     0.000271
n = 3.........................................     0.000534     0.000281
n = 4.........................................     0.000684     0.000269

[[Page 40010]]

 
n = 5.........................................     0.000532     0.000278
n = 6.........................................     0.000532     0.000272
n = 7.........................................     0.000552     0.000261
Average.......................................     0.000560     0.000272
Standard Deviation............................     0.000055     0.000007
MDL**.........................................     0.000174     0.000021
------------------------------------------------------------------------
* Assumes 2000 m\3\ of air sampled.
** MDL is 3.143 times the standard deviation of the results for seven
  sample replicates analyzed.


                   Table 4--Recoveries of Lead From NIST SRMs Spiked Onto Quartz Fiber Filters
----------------------------------------------------------------------------------------------------------------
                                                                    Recovery, ICP-MS, (percent)
                                                 ---------------------------------------------------------------
                Extraction method                    NIST 1547                                       NIST 2582
                                                       plant      NIST 2709 soil  NIST 2583 dust       paint
----------------------------------------------------------------------------------------------------------------
Ultrasonic Bath.................................      101  6        minus> 1        minus> 5        minus> 1
Block Digestion.................................      106  3        minus> 3        minus> 6        minus> 2
----------------------------------------------------------------------------------------------------------------


 Table 5--Method Detection Limits Determined by Analysis of Reagent/PTFE
             Filter Blanks Spiked With Low-Level Pb Solution
------------------------------------------------------------------------
                                                            Ultrasonic
                                                            extraction
                                                              method
                                                         ---------------
                                                            [mu]g/m\3\*
------------------------------------------------------------------------
n = 1...................................................        0.001775
n = 2...................................................        0.001812
n = 3...................................................        0.001773
n = 4...................................................        0.001792
n = 5...................................................        0.001712
n = 6...................................................        0.001767
n = 7...................................................        0.001778
Average.................................................        0.001773
Standard Deviation......................................        0.000031
MDL**...................................................        0.000097
------------------------------------------------------------------------
* Assumes 24 m\3\ of air sampled.
** MDL is 3.143 times the standard deviation of the results for seven
  sample replicates analyzed.


                       Table 6--Recoveries of Lead From NIST SRMs Spiked Onto PTFE Filters
----------------------------------------------------------------------------------------------------------------
                                                                    Recovery, ICP-MS, (percent)
                                                 ---------------------------------------------------------------
                Extraction method                    NIST 1547                                       NIST 2582
                                                       plant      NIST 2709 soil  NIST 2583 dust       paint
----------------------------------------------------------------------------------------------------------------
Ultrasonic Bath.................................      104  5        minus> 1       minus> 11        minus> 3
----------------------------------------------------------------------------------------------------------------

15.0 Pollution Prevention

    15.1 Pollution prevention encompasses any technique that reduces 
or eliminates the quantity and/or toxicity of waste at the point of 
generation. Numerous opportunities for pollution prevention exist in 
laboratory operations. Whenever feasible, laboratory personnel 
should use pollution prevention techniques to address their waste 
generation. The sources of pollution generated with this procedure 
are waste acid extracts and Pb-containing solutions.
    15.2 For information about pollution prevention that may be 
applicable to laboratories and research institutions, consult Less 
is Better: Laboratory Chemical Management for Waste Reduction, 
available from the American Chemical Society's Department of 
Government Relations and Science Policy, 1155 16th St. NW., 
Washington, DC 20036, www.acs.org.

16.0 Waste Management

    16.1 Laboratory waste management practices must be conducted 
consistent with all applicable rules and regulations. Laboratories 
are urged to protect air, water, and land by minimizing all releases 
from hood and bench operations, complying with the letter and spirit 
of any sewer and discharge permits and regulations, and by complying 
with all solid and hazardous waste regulation. For further 
information on waste management, consult The Waste Management Manual 
for Laboratory Personnel available from the American Chemical 
Society listed in Section 15.2 of this method.

[[Page 40011]]

    16.2 Waste HNO3, HCl, and solutions containing these 
reagents and/or Pb must be placed in labeled bottles and delivered 
to a commercial firm that specializes in removal of hazardous waste.

17.0 References

FACDQ (2007). Report of the Federal Advisory Committee on Detection 
and Quantitation Approaches and Uses in Clean Water Act Programs, 
submitted to the U.S. EPA December 2007. Available: https://water.epa.gov/scitech/methods/cwa/det/upload/final-report-200712.pdf.
Rice J (2013). Results from the Development of a New Federal 
Reference Method (FRM) for Lead in Total Suspended Particulate (TSP) 
Matter. Docket  EPA-HQ-OAR-2012-0210.
U.S. EPA (2007). Method 6020A--Inductively Coupled Plasma Mass 
Spectrometry. U.S. Environmental Protection Agency. Revision 1, 
February 2007. Available: https://www.epa.gov/osw/hazard/testmethods/sw846/pdfs/6020a.pdf.
U.S. EPA (2011). A Laboratory Study of Procedures Evaluated by the 
Federal Advisory Committee on Detection and Quantitation Approaches 
and Uses in Clean Water Act Programs. December 2011. Available: 
https://water.epa.gov/scitech/methods/cwa/det/upload/fac_report_2009.pdf.
[FR Doc. 2013-15880 Filed 7-2-13; 8:45 am]
BILLING CODE 6560-50-P