[Federal Register Volume 78, Number 24 (Tuesday, February 5, 2013)]
[Proposed Rules]
[Pages 8066-8076]
From the Federal Register Online via the Government Publishing 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: [email protected]
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:
[email protected].
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
[[Page 8070]]
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