
[Federal Register Volume 78, Number 24 (Tuesday, February 5, 2013)]
[Proposed Rules]
[Pages 8066-8076]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-02382]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 50

[EPA-HQ-OAR-2012-0210; FRL-9775-6]
RIN 2060-AP89


Method for the Determination of Lead in Total Suspended 
Particulate Matter

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: Data used for comparison with the lead (Pb) national ambient 
air quality standards (NAAQS), must be collected using either a Federal 
Reference Method (FRM) or a Federal Equivalent Method (FEM) as defined 
in the Code of Federal Regulations (CFR). The EPA is proposing to 
establish a new FRM for measuring Pb in total suspended particulate 
matter (TSP) collected from ambient air. The proposed method is 
intended for use by analytical laboratories performing the analysis of 
Pb in TSP to support data collection for the Pb NAAQS. The EPA is also 
proposing to make the existing FRM for Pb a new FEM, and retain 
currently designated FEMs. This proposed action avoids any disruption 
to existing Pb monitoring networks and data collection and would also 
not affect the FRM for TSP sample collection (High-Volume Method).

DATES: Comments must be received on or before March 7, 2013

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2012-0210 by one of the following methods:
     www.regulations.gov: Follow the on-line instructions for 
submitting comments.
     Email: a-and-r-docket@epamail.epa.gov
     Fax: (202) 566-9744
     Mail: Federal Reference Method for Lead in Total Suspended 
Particulate Matter, U.S. Environmental Protection Agency, EPA Docket 
Center (EPA/DC), Air and Radiation Docket and Information Center, MC 
2822T, 1200 Pennsylvania Ave. NW., Washington, DC 20460.
     Hand Delivery: EPA Docket Center, Room 3334 in the EPA 
West Building, located at 1301 Constitution Ave. NW., Washington, DC 
20460. The Docket is open to the public on all federal government work 
days from 8:30a.m. to 4:30p.m. Such deliveries are only accepted during 
the Docket's normal hours of operation, and special arrangements should 
be made for deliveries of boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2012-0210. The EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI or otherwise protected through www.regulations.gov 
or email. The www.regulations.gov Web site is an ``anonymous access'' 
system, which means the EPA will not know your identity or contact 
information unless you provide it in the body of your comment. If you 
send an email comment directly to the EPA without going through 
www.regulations.gov, your email address will be automatically captured 
and included as part of the comment that is placed in the public docket 
and made available on the

[[Page 8067]]

Internet. If you submit an electronic comment, the EPA recommends that 
you include your name and other contact information in the body of your 
comment and with any disk or CD-ROM you submit. If the EPA cannot read 
your comment due to technical difficulties and cannot contact you for 
clarification, the EPA may not be able to consider your comment. 
Electronic files should avoid the use of special characters, any form 
of encryption, and be free of any defects or viruses. For additional 
information about the EPA's public docket, visit the EPA Docket Center 
homepage at http://www.epa.gov/epahome/dockets.htm. All documents in 
the docket are listed in the http://www.regulations.gov index. Although 
listed in the index, some information is not publicly available, e.g., 
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 
Docket Facility 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 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
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

I. Background

A. Purpose of the New Reference Method

    On November 12, 2008, the EPA substantially strengthened the 
National Ambient Air Quality Standard for Lead (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 Appendix G and the reference 
method for high-volume sampling of TSP as specified in 40 CFR 50, 
Appendix B. The proposed FRM will become a replacement for the 
analytical method in Appendix G. The EPA is proposing a new FRM for the 
analysis of Pb in TSP based on Inductively Coupled Plasma Mass 
Spectrometry (ICP-MS). The FRM would serve as the definitive method for 
routinely analyzing Pb for comparison to the NAAQS and also serve as 
the standard of comparison for determining equivalence of candidate 
FEMs. The method is proposed as a new Appendix G to 40 CFR part 50. The 
FRM that was promulgated in 1978 as Appendix G would become an approved 
FEM and the currently designated FEMs would be 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 existing FRM. The proposed 
approach permits continued use of the old 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 proposed FRM.
    With the much tightened NAAQS in 2008 and the need for increased 
measurement sensitivity, an improved measurement technology has become 
available to better meet the needs of the current NAAQS. The FAAS FRM 
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 FRM) and ICP-based methods have increased in 
popularity. The FAAS method is mainly 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 
[micro]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 proposed FRM is more than adequate to 
meet the reduced testing range and detection limit requirements. The 
proposed 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 proposed 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]

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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/volume (v/v) HNO3. In selecting the proposed 
methodology, the EPA's primary considerations were: methods that have 
already been tested and approved against the FAAS FRM (current Appendix 
G); 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 current FRM. ICP-MS was 
chosen as the analytical technique because it has much improved 
sensitivity, selectivity, linear range, and is much more readily 
available than FAAS in laboratories today.
    The proposed 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 proposed FRM is only intended for the 
analysis of Pb in TSP and allows for the use of glass fiber, quartz, or 
Teflon[supreg] 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 proposed FRM was evaluated for the 
extraction of Pb only. If the proposed FRM is used for metals other 
than Pb, the user must evaluate the FRM's applicability before use. The 
heated 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 proposed 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: http://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 proposed FRM extraction 
methods can be used with any of the proposed 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 proposed FRM has two extraction methods (heated 
ultrasonic and hot block) and one analytical method (ICP-MS). The 
proposed 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, Teflon[supreg], 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: http://epa.gov/ttn/amtic/files/ambient/criteria/reference-equivalent-methods-list.pdf
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II. Summary of Method

    The proposed 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 proposed: one using heated ultrasonic and one 
using heated block digestion. The proposed extraction methods and ICP-
MS analysis method have been tested and found acceptable for extraction 
of Pb from glass fiber, Teflon[supreg], or quartz filter media (Rice 
2013). The proposed method will replace the existing FRM specified in 
40 CFR part 50, Appendix G. Although the existing FRM in Appendix G is 
adequate, the proposed FRM offers advantages over the current 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). The proposed rule is for 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 proposed rule on 
small entities, small entity is defined as (1) a small

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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 proposed rule on 
small entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities. This 
proposed 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. The EPA continues to be interested 
in the potential impacts of the proposed rule on small entities and 
welcomes comments on issues related to such impacts.

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 proposes to establish 
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 proposes to establish 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. 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. In the 
spirit of Executive Order 13132, and consistent with the EPA policy to 
promote communications between the EPA and state and local governments, 
the EPA specifically solicits comment on this proposed rule from state 
and local officials.

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 proposed 
rule imposes no requirements on tribal governments. This action 
proposes to establish 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. 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. In the spirit of Executive order 13175, the EPA 
specifically solicits additional comment on this proposed action from 
tribal officials.

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.

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.
    The proposed 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 proposed rule would establish 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 
constitutes 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.
    The EPA welcomes comments on this aspect of the proposed rulemaking 
and, specifically, invites the public to identify potentially-
applicable voluntary consensus standards and to explain why such 
standards should be used in this regulation.

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 proposed rule will not have

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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 proposes to establish 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.

List of Subjects in 40 CFR Part 50

    Environmental protection, Air pollution control, and Lead.

    Dated: January 25, 2013.
Lisa P. Jackson,
Administrator.

    For reasons stated in the preamble, title 40, chapter I of the Code 
of Federal Regulations proposes to amend as set forth in 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 standards (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 determination of Pb from TSP filters by 
Inductively Coupled Plasma Mass Spectrometry (ICP-MS) using a heated 
ultrasonic bath with nitric and hydrochloric acid or a heated block 
(hot block) digester with nitric acid for filter extraction.
    This method is based on the EPA's Office of Solid Waste (SW-846) 
Method 6020A--Inductively Coupled Plasma Mass Spectrometry.\1\ 
Wording in certain sections of this method is paraphrased or taken 
directly from Method 6020A.
    1.1 ICP-MS is applicable for the sub-[mu]g/mL (ppb) 
determination of Pb in a wide variety of matrices. The method 
sensitivity is more than adequate for determining Pb at 
concentrations equal to, or less than, 5 percent of the level of the 
Pb NAAQS (0.15[mu]g/m\3\) for Pb-TSP. 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 Teflon[supreg] 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 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 
Teflon[supreg] 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 either blank filters or Pb-spiked filters or strips 
analyzed in accordance with the guidance provided in 40 CFR part 
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 [mu]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 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, 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 
heated 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

[[Page 8071]]

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 nitric acid 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 heated 
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 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 Heated block extraction equipment
    6.3.1 Heated 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 Teflon[supreg] wash bottles.
     Glassware, Class A--volumetric flasks, pipettes, and 
graduated cylinders.
     Glass fiber, quartz, or Teflon[supreg] 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

[[Page 8072]]

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\2\, 2586\3\, 
2587\4\ or 1648\5\, or equivalent.

    Note: The In, Bi, and Ho internal standards may also be 
purchased as 10 [mu]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 [mu]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 bismuth 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 1-2 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 
Teflon[supreg] 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 Teflon[supreg] 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 done.
    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 Teflon[supreg] 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/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. Included are: 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 can be used to 
estimate the MDL. The low-level standard spike is added to at least 
seven 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 2-5 times the estimated MDL.
    8.3 For each batch of samples, one RB and one reagent blank 
spike (RBS) 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        Less than 0.001
                               sample.               [micro]g/mL.
ICV.........................  Prior to first        Within 90 to 110
                               sample.               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
                               extracted samples.    [micro]g/mL.
CCV.........................  After every 10        Within 90-110
                               extracted samples.    percent 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

[[Page 8073]]

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 [micro]g/mL. 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.
    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 six months from the date of extraction.
    10.2 47 mm Teflon[supreg] 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 Teflon[supreg] 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.

[[Page 8074]]

    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 Teflon[supreg] filters have only been extracted 
using the ultrasonic extraction procedure in the development of this 
FRM, Teflon[supreg] filters are inert and have very low Pb content. 
No issues are expected with the extraction of Teflon[supreg] filters 
using the heated block digestion method. However, prior to using 
Teflon[supreg] 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 Heated 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--Heated 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 one 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 
[deg]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 nitric acid 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.
    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 Ssection 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'' [deg] 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 determine MDL for 
this method. MDLs were determined in accordance with 40 CFR part 
136, Appendix B. MDLs were estimated for glass fiber, quartz, and 
Teflon[supreg] filters using seven reagent/filter blank solutions 
and seven reagent/filter blank solutions spiked with low level Pb at 
three times the estimated MDL. Tables 1, 3, and 5 shows the MDLs 
estimated using both the ultrasonic and heated block extraction 
methods for glass fiber and quartz filters and the ultrasonic method 
for Teflon[supreg] filters. The MDLs are well below the EPA 
requirement of 5 percent of the current Pb NAAQS or 0.0075 [mu]g/
m\3\.
    14.2 Extraction method recovery tests with glass fiber and 
quartz filter strips, and Teflon[supreg] 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 and Reagent/Glass
                              Fiber Filter Blanks Spiked With Low-Level Pb Solution
----------------------------------------------------------------------------------------------------------------
                                                                  Ultrasonic                   Hotblock
                                                         -------------------------------------------------------
                                                                          Pb-spiked                   Pb-spiked
                                                          Blank ([mu]g/    ([mu]g/    Blank ([mu]g/    ([mu]g/
                                                             m\3\)*        m\3\)*        m\3\)*        m\3\)*
----------------------------------------------------------------------------------------------------------------
n=1.....................................................     0.0000434     0.0000702      0.000362      0.000533
n=2.....................................................     0.0000420     0.0000715      0.000400      0.000482
n=3.....................................................     0.0000439     0.0000611      0.000386      0.000509
n=4.....................................................     0.0000407     0.0000587      0.000415      0.000427
n=5.....................................................     0.0000437     0.0000608      0.000414      0.000449
n=6.....................................................     0.0000437     0.0000607      0.000409      0.000539

[[Page 8075]]

 
n=7.....................................................     0.0000403     0.0000616      0.000361      0.000481
Average.................................................     0.0000425     0.0000635      0.000392      0.000489
Standard................................................     0.0000015     0.0000051      0.000023      0.000042
MDL**...................................................     0.0000047     0.0000161      0.000073      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 2709     NIST 2583     NIST 2582
                                                              plant         soil          dust          paint
----------------------------------------------------------------------------------------------------------------
Ultrasonic Bath.........................................     1004       minus>1       minus>8       minus>0
Block Digestion.........................................      927       minus>3       minus>4       minus>4
----------------------------------------------------------------------------------------------------------------


   Table 3--Method Detection Limits Determined by Analysis of Reagent/Quartz Filter Blanks and Reagent/Quartz
                                 Filter Blanks Spiked With Low-Level Pb Solution
----------------------------------------------------------------------------------------------------------------
                                                                  Ultrasonic                   Hotblock
                                                         -------------------------------------------------------
                                                                          Pb-spiked                   Pb-spiked
                                                          Blank ([mu]g/    ([mu]g/    Blank ([mu]g/    ([mu]g/
                                                             m\3\)*        m\3\)*        m\3\)*        m\3\)*
----------------------------------------------------------------------------------------------------------------
n=1.....................................................      0.000273      0.000533      0.000121      0.000274
n=2.....................................................      0.000270      0.000552      0.000112      0.000271
n=3.....................................................      0.000270      0.000534      0.000112      0.000281
n=4.....................................................      0.000279      0.000684      0.000111      0.000269
n=5.....................................................      0.000277      0.000532      0.000121      0.000278
n=6.....................................................      0.000282      0.000532      0.000117      0.000272
n=7.....................................................      0.000276      0.000552      0.000115      0.000261
Average.................................................      0.000275      0.000560      0.000116      0.000272
Standard................................................      0.000004      0.000055      0.000004      0.000007
MDL**...................................................      0.000014      0.000174      0.000013      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 2709     NIST 2583     NIST 2582
                                                              plant         soil          dust          paint
----------------------------------------------------------------------------------------------------------------
Ultrasonic Bath.........................................     1016       minus>1       minus>5       minus>1
Block Digestion.........................................     1063       minus>3       minus>6       minus>2
----------------------------------------------------------------------------------------------------------------


   Table 5--Method Detection Limits Determined by Analysis of Reagent/
 Teflon Filter Blanks and Reagent/Teflon Filter Blanks Spiked With Low-
                            Level Pb Solution
------------------------------------------------------------------------
                                                 Ultrasonic extraction
                                                        method
                                             ---------------------------
                                                              Pb-spiked
                                              Blank ([mu]g/    ([mu]g/
                                                 m\3\)*        m\3\)*
------------------------------------------------------------------------
n=1.........................................      0.000070      0.001775
n=2.........................................      0.000039      0.001812
n=3.........................................      0.000009      0.001773
n=4.........................................     -0.000012      0.001792
n=5.........................................      0.000062      0.001712
n=6.........................................     -0.000019      0.001767
n=7.........................................      0.000033      0.001778
Average.....................................      0.000026      0.001773
Standard Deviation..........................      0.000035      0.000031

[[Page 8076]]

 
MDL**.......................................      0.000109      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 Teflon Filters
----------------------------------------------------------------------------------------------------------------
                                                                    Recovery, ICP-MS, (percent)
                                                 ---------------------------------------------------------------
                Extraction method                    NIST 1547                                       NIST 2582
                                                       plant      NIST 2709 soil  NIST 2583 dust       paint
----------------------------------------------------------------------------------------------------------------
Ultrasonic Bath.................................      1045         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.
    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
    1. Method 6020A--Inductively Coupled Plasma Mass Spectrometry. 
U.S. Environmental Protection Agency. Revision 1, February 2007.
    2. NIST, Certificate of Analysis: Standard Reference Materials 
2583, Trace Elements in Indoor Dust, Nominal 90 mg/kg Lead, National 
Institute of Standards and Technology, Gaithersburg, MD, 1998.
    3. NIST, Certificate of Analysis: Standard Reference Materials 
2586, Trace Elements in Soil, Nominal 500 mg/Kg Lead, National 
Institute of Standards and Technology, Gaithersburg, MD, 2008.
    4. NIST, Certificate of Analysis: Standard Reference Materials 
2587, Trace Elements in Soil Containing Lead from Paint, Nominal 
3000 mg/Kg Lead, National Institute of Standards and Technology, 
Gaithersburg, MD, 2008.
    5. NIST, Certificate of Analysis: Standard Reference Materials 
1648, Urban Particulate Matter, 0.655  0.033% Lead, 
National Institute of Standards and Technology, Gaithersburg, MD, 
2008.
    6. Rice 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.

[FR Doc. 2013-02382 Filed 2-4-13; 8:45 am]
BILLING CODE 6560-50-P


