[Federal Register Volume 89, Number 42 (Friday, March 1, 2024)]
[Proposed Rules]
[Pages 15101-15115]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-04359]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 63
[EPA-HQ-OAR-2022-0491; FRL-9992-01-OAR]
RIN 2060-AV81
EPA Method 320--Measurement of Vapor Phase Organic and Inorganic
Emissions by Extractive Fourier Transform Infrared (FTIR) Spectroscopy
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: This action proposes editorial and technical revisions to the
Environmental Protection Agency's (EPA's) Method 320 (Measurement of
Vapor Phase Organic and Inorganic Emissions by Extractive Fourier
Transform Infrared (FTIR) Spectroscopy). The proposed revisions include
updating the validation and quality assurance (QA) spiking procedures
of the method to provide a more performance-based approach with
specified acceptance criteria. The proposed revisions will provide
flexibility to the stack testing community while ensuring consistent
implementation and quality of the measurement results across emissions
sources and facilities.
DATES: Comments. Comments must be received on or before April 30, 2024.
Public Hearing. The EPA will hold a virtual public hearing on March
29, 2024 if a request for a virtual public hearing is received on or
before March 8, 2024. Refer to the SUPPLEMENTARY INFORMATION section
for additional information on the virtual public hearing.
ADDRESSES: You may submit comments, identified by Docket ID No. EPA-HQ-
OAR-2022-0491, by any of the following methods:
Federal eRulemaking Portal: https://www.regulations.gov/
(our preferred method). Follow the online instructions for submitting
comments.
Email: [email protected]. Include Docket ID No. EPA-
HQ-OAR-2022-0491 in the subject line of the message.
Fax: (202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-
2022-0491.
Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Docket ID No. EPA-HQ-OAR-2022-0491, Mail Code 28221T, 1200
Pennsylvania Avenue NW, Washington, DC 20460.
Hand/Courier Delivery: EPA Docket Center, WJC West
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004.
The Docket Center's hours of operation are 8:30 a.m.--4:30 p.m.,
Monday--Friday (except Federal Holidays).
Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to https://www.regulations.gov/, including any personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the ``Public Participation''
heading of the SUPPLEMENTARY INFORMATION section of this document.
FOR FURTHER INFORMATION CONTACT: Dr. David Nash, Office of Air Quality
Planning and Standards, Air Quality Assessment Division (E143-02),
Environmental Protection Agency, Research Triangle Park, NC 27711;
telephone number: (919) 541-9425; fax number: (919) 541-0516; email
address: [email protected].
SUPPLEMENTARY INFORMATION:
Preamble acronyms and abbreviations. Throughout this document, the
use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We
use multiple acronyms and terms in this preamble. While this list may
not be exhaustive, to ease the reading of this preamble and for
reference purposes, the EPA defines the following terms and acronyms
here:
ASTM American Society for Testing and Materials
CAA Clean Air Act
CBI Confidential Business Information
CFR Code of Federal Regulations
CTS calibration transfer standard
EPA Environmental Protection Agency
FTIR Fourier Transform Infrared
FTP File Transfer Protocol
IR infrared
NAICS North American Industry Classification System
NESHAP National Emissions Standards for Hazardous Air Pollutants
NIST National Institute of Standards and Technology
NSPS New Source Performance Standards
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards OMB Office of
Management and Budget
PRA Paperwork Reduction Act
PTFE polytetrafluoroethane
QA quality assurance
RFA Regulatory Flexibility Act
SF6 sulfur hexafluoride
TTN Technology Transfer Network
UMRA Unfunded Mandates Reform Act
VCS Voluntary Consensus Standard
WJC William Jefferson Clinton
[micro]m micron
Organization of this document. The information in this preamble is
organized as follows:
I. General Information
A. Does this action apply to me?
B. Where can I get a copy of this document and other related
information?
II. Public Participation
A. Written Comments
B. Participation in Virtual Public Hearing
III. Background
IV. Summary of Proposed Revisions to Method 320
A. Section 1.0 (Introduction)
B. Section 2.0 (Summary of Method)
C. Section 3.0 (Definitions)
D. Section 4.0 (Interferences)
[[Page 15102]]
E. Section 5.0 (Safety)
F. Section 6.0 (Equipment and Supplies)
G. Section 7.0 (Reagents and Standards)
H. Section 8.0 (Sampling and Analysis Procedure)
I. Section 9.0 (Quality Control)
J. Section 10.0 (Calibration and Standardization)
K. Section 11.0 (Data Analysis and Calculations)
L. Section 12.0 (Method Performance Data Analysis and
Calculations)
M. Section 13.0 (Method Validation Procedure)
N. Section 14.0 (Pollution Prevention)
O. Section 15.0 (Waste Management)
P. Section 16.0 (References)
Q. New Section 17.0 (Tables, Diagrams, Flowcharts, and
Validation Data)
R. Addendum To Test Method 320
IV. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 14094: Modernizing Regulatory Review
B. Paperwork Reduction Act (PRA)
C. Regulatory Flexibility Act (RFA)
D. Unfunded Mandates Reform Act (UMRA)
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 Risks and Safety Risks
H. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act (NTTAA)
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations and Executive Order 14096: Revitalizing Our Nation's
Commitment to Environmental Justice for All
I. General Information
A. Does this action apply to me?
The proposed amendments to Method 320 apply to industries that are
subject to certain provisions of 40 CFR parts 60 and 63. The source
categories and entities potentially affected are listed in table 1 of
this preamble. This table is not intended to be exhaustive, but rather
provides a guide for readers regarding entities likely to be regulated
by this action. This table lists the types of entities that EPA is now
aware could potentially be affected by this action. Other types of
entities not listed in the table could also be regulated.
Table 1--Potentially Affected Source Categories
------------------------------------------------------------------------
Examples of regulated
Category NAICS \a\ entities
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Industry...................... 321211........... Plywood and Composite
Wood Products.
324110........... Petroleum Refineries.
325211........... Polyvinyl Chloride
and Copolymers
Production.
327410........... Lime Manufacturing
Plants.
333242........... Semiconductor
Manufacturing.
562211........... Hazardous Waste
Combustors.
327993........... Mineral Wool
Production.
322120........... Kraft Pulp and Paper
Mills.
2211, 48621, Stationary
92811, 211111, Reciprocating
211112, and Internal Combustion
622110. Engines.
------------------------------------------------------------------------
\a\ North American Industry Classification System (2022).
If you have any questions regarding the applicability of the
proposed changes to Method 320, contact the person listed in the
preceding FOR FURTHER INFORMATION CONTACT section.
B. Where can I get a copy of this document and other related
information?
The docket number for this action is Docket ID No. EPA-HQ-OAR-2022-
0491. In addition to being available in the docket, an electronic copy
of the proposed method revisions is available on the Technology
Transfer Network (TTN) website at https://www3.epa.gov/ttn/emc/methods/. The TTN provides information and technology exchange in
various areas of air pollution control.
II. Public Participation
A. Written Comments
Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2022-
0491, at https://www.regulations.gov (our preferred method), or the
other methods identified in the ADDRESSES section. Once submitted,
comments cannot be edited or removed from the docket. The EPA may
publish any comment received to its public docket. Do not submit to
EPA's docket at https://www.regulations.gov any information you
consider to be Confidential Business Information (CBI), Proprietary
Business Information (PBI), or other information whose disclosure is
restricted by statute. Multimedia submissions (audio, video, etc.) must
be accompanied by a written comment. The written comment is considered
the official comment and should include discussion of all points you
wish to make. The EPA will generally not consider comments or comment
contents located outside of the primary submission (i.e., on the web,
cloud, or other file sharing system). Please visit https://www.epa.gov/dockets/commenting-epa-dockets for additional submission methods; the
full EPA public comment policy; information about CBI, PBI, or
multimedia submissions; and general guidance on making effective
comments.
B. Participation in Virtual Public Hearing
If a request for a virtual public hearing is received on or before
March 8, 2024 the EPA will hold a virtual public hearing on March 29,
2024. To request a virtual public hearing or to register to speak at
the virtual hearing, please contact Mr. David Nash at (919) 541-9425 or
[email protected]. The last day to pre-register to speak at the hearing
will be March 22, 2024. On March 26, 2024, the EPA will post a general
agenda for the hearing that will list pre-registered speakers in
approximate order at: https://www3.epa.gov/ttn/emc/methods.
The EPA encourages commenters to provide the EPA with a copy of
their oral testimony electronically by emailing it to Mr. David Nash at
[email protected]. The EPA also recommends submitting the text of your
oral comments as written comments to the rulemaking docket.
The EPA may ask clarifying questions during the oral presentations
but will not respond to the presentations at that time. Written
statements and supporting information submitted during the comment
period will be considered with the same weight as oral comments and
supporting information presented at the public hearing.
Please note that any updates made to any aspect of the hearing are
posted online at https://www3.epa.gov/ttn/
[[Page 15103]]
emc/methods. The EPA does not intend to publish a document in the
Federal Register announcing updates.
III. Background
Method 320 describes the procedures for the measurement of vapor
phase organic and inorganic emissions by Fourier Transform Infrared
(FTIR) spectroscopy. The EPA promulgated Method 320 along with the
National Emissions Standards for Hazardous Air Pollutants (NESHAP) for
Portland Cement Manufacturing Industry (40 CFR part 63, subpart LLL) on
June 14, 1999 (64 FR 31898) under section 112 of the Clean Air Act
(CAA) as amended. Since promulgation, the EPA has incorporated the use
of Method 320 for demonstrating compliance with emissions standards
into numerous NESHAP and New Source Performance Standards (NSPS).
Over the 24-year period since promulgation, the use of FTIR
spectroscopy has evolved as testing contractors, analytical
laboratories, the EPA, and State entities have developed new standard
operating procedures and methods to reflect improvements in sampling
and analytical techniques. In 2017, the EPA held a series of informal
discussions with stakeholders in the measurement community to identify
technical issues related to measuring emissions using FTIR spectroscopy
and potential revisions to Method 320. The stakeholders consisted of a
cross-section of interested parties including representatives from
State regulatory entities, various EPA offices, analytical
laboratories, emission testing firms, analytical standards vendors,
instrument vendors, and others with experience in FTIR spectroscopy and
Method 320. The docket for this action contains summaries of the
stakeholder discussions.
IV. Summary of Proposed Revisions to Method 320
In this action, the EPA proposes technical revisions that update
the validation and quality assurance (QA) spiking procedures of Method
320 to provide a more performance-based approach. The proposed
revisions would more closely align Method 320 with the EPA's approach
to emissions measurement, which emphasizes specifying performance-based
criteria in test methods. Instead of specifying exactly how stack
testers should use or perform a particular method procedure, the method
defines the criteria that must be met for a specific method element,
which provides stack testers with flexibility while maintaining the
quality and reliability of the measurement results. The EPA is also
proposing technical revisions and editorial changes to clarify and
update the requirements and procedures specified in Method 320,
including removing the batch sampling procedures.
A. Section 1.0 (Introduction)
In this action, the EPA proposes to revise the name of section 1.0
from ``Introduction'' to ``Scope and Application,'' to update the
introductory paragraph to remove references to the FTIR Protocol, and
to remove the note regarding use of sample conditioning systems. The
EPA also proposes to renumber and update sections 1.1.1 (Analytes) and
1.1.2 (Applicability) to sections 1.1 and 1.2, respectively, and to
replace the existing sections 1.2 (Method Range and Sensitivity), 1.3
(Sensitivity), and 1.4 (Data Quality) with a revised section 1.3 (Data
Quality Objectives).
B. Section 2.0 (Summary of Method)
In this action, the EPA proposes to update section 2.0 by revising
sections 2.1 (Principle) and 2.2 (untitled) and removing sections 2.3
(Reference Spectra Availability) and 2.4 (Operator Requirements). In
section 2.1, the EPA proposes to remove the title and consolidate
sections 2.1.1 through 2.1.5 and the introductory paragraph to section
2.2 (Sampling and Analysis) into a single paragraph. In section 2.2,
the EPA also proposes to remove the discussion of Beer's Law in section
2.2.1 and to update the references to method evaluation and validation
and pre-test procedures.
C. Section 3.0 (Definitions)
In this action, the EPA proposes to remove the following
definitions for technical terms that are not needed in the proposed
Method 320 and for terms commonly used in the emissions measurement
community for which a definition is unnecessary:
Batch Sampling.
Concentration.
Continuous Sampling.
Emissions Test.
Gas Cell.
Independent Sample.
Interferant.
Measurement.
One Hundred Percent Line.
Quantitation Limit.
Reference Calibration Transfer Standard (CTS).
Root Mean Square Difference.
Sample Analysis.
Sampling Resolution.
Sampling System.
Screening.
Sensitivity.
Standard Spectrum.
Surrogate.
Test CTS.
Truncation.
Zero Filling.
Validation.
Validation Run.
The EPA also proposes revisions to five definitions currently used
in Method 320. Table 2 of this preamble presents the proposed revisions
for each definition.
Table 2--Proposed Revisions to Existing Definitions
------------------------------------------------------------------------
Term Revision Proposed definition
------------------------------------------------------------------------
Analyte..................... Clarify that Method Analyte means a
320 can measure compound that the
more than one method is intended
analyte per test. to measure. This
method is a multi-
component method;
therefore, several
analytes may be
targeted for a
given test.
Background Deviation........ Move the performance Background deviation
criteria from the means a deviation
definition to from 100%
revised section transmittance in
13.2 (Background any region of the
Deviation). 100% line.
CTS [Calibration Transfer Update the Calibration transfer
Standard] Standard. definition to standard (CTS)
remove the means a certified
redundant gas calibration
``standard'' in the standard used to
term and to specify verify instrument
the acceptable CTS stability. For the
gases. purposes of this
method, the CTS
must be ethylene,
methane, or carbon
dioxide. Other
compounds may be
used only with the
Administrator's
approval.
[[Page 15104]]
Reference Spectrum.......... Change the term to Reference spectra
plural (i.e., means a spectra of
``Reference a pure sample gas
Spectra''), clarify obtained at a known
the definition, and concentration under
remove the controlled
reference to the conditions of
FTIR Protocol. pressure,
temperature, and
pathlength.
Run......................... Replace Run means a series
``measurements'' of samples taken
with ``samples'' successively from
and remove the the stack or duct.
minimum requirement A test normally
specifications. consists of a
specific number of
runs.
------------------------------------------------------------------------
The EPA also proposes to add definitions for the key technical
terms shown in table 3 of this preamble to improve the clarity of the
principles and procedures used in Method 320.
Table 3--Proposed New Definitions
------------------------------------------------------------------------
Term Proposed definition
------------------------------------------------------------------------
Absorbance................... The negative logarithm of transmission
represented by the relationship A = -
log(I/I0), where I is the transmitted
intensity of light, and I0 is the
incident intensity of light upon a
molecule.
Absorptivity................. The amount of infrared radiation absorbed
by each molecule.
Analyte Spiking.............. The process of quantitatively adding
calibration standards to source
effluent. Analyte spiking is used to
evaluate the ability of the sample
transport and FTIR measurement systems
to quantify the target analyte(s).
Analytical Algorithm......... The method used to quantify the
concentration of both target analyte(s)
and additional compounds in a sample
matrix that may introduce analytical
interferences in each FTIR spectrum.
Analytical Interference...... A spectral feature that complicates, and
may even prevent, the analysis of an
analyte. Analytical interferences can be
background or spectral interferences.
Background interferences result from a
change in light throughput relative to
the single beam background. This can be
due to factors such as deposits on
reflective surfaces and windows,
temperature changes, a change in
detector sensitivity, a change in
infrared source output, or instrument
electronics failure. Spectral
interferences arise due to the presence
of interfering compounds that have
overlapping absorption features with the
analytes of interest.
Apodization.................. A mathematical transformation that is
used to adjust the instrument line shape
for measured peaks. There are various
types of apodization functions; the most
common are boxcar, triangular, Happ-
Genzel, and Beer-Norton functions.
Background Spectrum.......... A spectrum taken in the absence of
absorbing species or sample gas matrix,
typically conducted using nitrogen or
zero air.
Bandwidth.................... The width of a spectral feature. This
width is commonly listed as the full
width at half the maximum of the
spectral feature.
Beam Splitter................ A device located in the interferometer
that divides the incoming infrared
radiation into two separate beams that
travel two separate paths before
recombination.
Classical Least Squares...... A method of analyzing multicomponent
spectra by scaling reference absorbance
spectra to unknown measured spectra.
Double Beam Spectrum......... A transmission or absorbance spectrum
derived by dividing the sample single
beam spectrum by the background
spectrum.
Fourier Transform............ A mathematical transform that allows the
conversion of the detector response as a
function of time to intensity as a
function of frequency.
Fundamental CTS.............. An NIST-traceable CTS reference spectrum
with known temperature and pressure that
has been obtained using an absorption
cell with an accurately known optical
pathlength.
Interferogram................ A pattern that contains the effects of
the wave interference that are produced
from an interferometer.
Interferometer............... A device used to produce interference
spectra, by dividing a beam of radiant
energy into two or more paths. One path
strikes a fixed mirror and the second
path strikes a moving mirror generating
an optical path difference that varies
over time between them. The recombined
beams produce constructive and
destructive interference as a function
of changing pathlength. The Michelson
interferometer, used in FTIR
instruments, performs this function.
Partial Least Squares........ A method for analyzing multicomponent
spectra by combining features from
principal component and multiple
regression analysis. It has been found
to be most useful when predicting a set
of dependent variables from a large set
of independent variables.
Resolution................... The minimum separation that two spectral
features must have to distinguish one
feature from the another.
Retardation.................. The optical path difference between two
beams in an interferometer.
Single Beam Spectrum......... The Fourier transformed interferogram
representing detector response versus
wavenumber.
Test......................... The series of runs required by the
applicable regulation.
Tracer Gas................... A stable, non-reactive species that is
easily transportable and can be blended
in a gas cylinder with a target analyte
to confirm the dilution ratio of a
dynamic spike.
Transmittance................ The amount of infrared radiation that is
not absorbed by the sample. Percent
transmittance is represented by the
following equation: %T = (I/I0) x 100.
------------------------------------------------------------------------
D. Section 4.0 (Interferences)
In section 4.0 (Interferences), the EPA proposes to consolidate
sections 4.1 (Analytical Interferences) and 4.2 (Sampling System
Interferences) into revised section 4.0 and to incorporate the
discussion of background and spectral interferences in sections 4.1.1
and 4.1.2, respectively, into the
[[Page 15105]]
definition of ``Analytical Interference.'' The EPA also proposes to
remove sections 4.1.1, 4.1.2, and 4.2.
E. Section 5.0 (Safety)
In this action, the EPA proposes updates to the language of section
5.0, including a recommendation to provide safety data sheets for gas
standards to all personnel using the method.
F. Section 6.0 (Equipment and Supplies)
In this action, the EPA proposes to organize the equipment list in
section 6.0 into analytical instrumentation and sampling system
components. The EPA also proposes to remove the descriptions of the
following equipment, which are not needed to perform revised Method
320:
Calibration/Analyte Spike Assembly.
Mass Flow Meter.
Rotameter.
FTIR Cell Pump.
In this action, the EPA proposes to revise the current descriptions
for the equipment components shown in table 4 of this preamble.
Table 4--Proposed Revisions to Existing Definitions
------------------------------------------------------------------------
Equipment Revision Proposed description
------------------------------------------------------------------------
FTIR Analytical System...... Change ``FTIR An instrument that
Analytical System'' collects and
to ``FTIR digitizes the
Spectrometer,'' spectral
clarify the interference
description, and pattern from an
remove the interferometer and
requirement that mathematically
the system include transforms this
a personal computer signal into
and processing infrared frequency
software. spectra.
Gas Regulators.............. Clarify the A regulator used to
description and add introduce
recommendations individual gas or
regarding materials gas mixtures from
of construction. cylinders.
Regulator should be
constructed of the
appropriate
materials that
minimize analyte
adsorption and
reactivity.
Gas Sample Manifold......... Change ``Gas Sample A manifold capable
Manifold'' to ``Gas of delivering
Distribution nitrogen or
Manifold'' and calibration gases
clarify the through the
description to sampling system or
include directly to the
requirements for FTIR. The
accurately diluting calibration gas
calibration gas, manifold must
monitoring provide accurate
calibration gas dilution of the
pressure, and calibration gas as
precisely necessary, monitor
introducing analyte calibration gas
spikes. pressure, and
introduce analyte
spikes into the
sample stream
(prior to the
particulate filter)
at a precise and
known flowrate.
Particulate Filters......... Clarify the A glass wool plug
description and (optional) inserted
remove the example at the probe tip
cited. (for large
particulate
removal) and a
filter (required)
connected at the
outlet of the
heated probe and
rated for 99%
removal efficiency
of 1 micron ([mu]m)
aerodynamic
particulate.
Polytetrafluoroethane Tubing Incorporate the Polytetrafluoroethan
description into a e (PTFE), 316-
single description stainless steel, or
for ``Tubing''. other inert
material, of
suitable length and
diameter used to
connect cylinder
regulators to the
gas manifold.
Sampling Line/Heating System Change ``Sampling Heated to prevent
Line/Heating sample
System'' to condensation, and
``Sample Line'' and made of stainless
clarify that the steel, PTFE, or
construction other material that
material should minimizes
minimize adsorption adsorption of
of analytes and the analytes. Line
length of line length should be
needed. the minimum
necessary to reach
sampling locations.
Sample Pump................. Update the minimum A leak-free pump
flow rate with bypass valve,
requirements, capable of
clarify the options producing a sample
for pump placement, flow rate equal to
remove the 5 cell volumes per
requirement to sample cycle. The
record the gas cell pump may be
sample pressure for positioned upstream
pumps located or downstream of
downstream of the the FTIR cell. If
FTIR system, and the pump is
remove the example positioned upstream
cited. of the distribution
manifold and FTIR
system, use a
heated head pump
that is constructed
from materials non-
reactive with the
analytes of
interest.
Sample Conditioning......... Clarify the role of An optional part of
the optional sample the sampling system
conditioning in the used to dilute or
sampling system. remove particulate
matter, water
vapor, or other
interfering species
depending upon the
source matrix
composition.
Sampling Probe.............. Clarify the Glass, stainless
description and steel, PTFE, or
remove the example other appropriate
for high- material to
temperature stack transport analytes
samples and the to the IR gas cell.
recommendation to The sampling probe
use a dilution must be capable of
probe for high- sustained heating
moisture sources. to prevent water
condensation and
adsorption of
analytes.
Stainless Steel Tubing...... Incorporate the PTFE, 316-stainless
description into a steel, or other
single description inert material, of
for ``Tubing''. suitable length and
diameter used to
connect cylinder
regulators to the
gas manifold.
------------------------------------------------------------------------
The EPA also proposes to add descriptions for the equipment
components shown in table 5 of this preamble.
[[Page 15106]]
Table 5--Proposed New Equipment Descriptions
------------------------------------------------------------------------
Term Proposed description
------------------------------------------------------------------------
Computer/Data Acquisition A computer with compatible FTIR software
System. for control of the FTIR system,
acquisition of infrared (IR) data, and
analysis of resulting spectra. This
system must have enough data storage
space to archive all necessary infrared
and meta data (see section 11.6 of this
method).
Gas Absorption Cell.......... The container through which the infrared
beam interacts with the sample gas. The
gas absorption cell must have the
ability to monitor the pressure and
temperature of the sample gas.
Sampling System.............. The sampling system consists of the
components listed in sections 6.2.1
through 6.2.9 of this method, validated
as detailed in section 9.4.
------------------------------------------------------------------------
G. Section 7.0 (Reagents and Standards)
In this action, the EPA proposes to rename current section 7.1 from
``Analyte(s) and Tracer Gas'' to ``Analyte(s) and Tracer Standard
Gases'' and to require the use of EPA protocol gases (with expanded
uncertainty <=2%) be used for criteria pollutants. The EPA proposes to
specify that other pollutants (non-criteria) be dual certified and that
target analytes be within 25% of the emission source level or
applicable compliance limit. The EPA also proposes to remove the
suggestion regarding the use of sulfur hexafluoride (SF6)
tracer gas. The EPA is specifically soliciting comment on the approach
of using expanded uncertainty for criteria pollutants as well as not
being prescriptive on the tracer that is used.
In section 7.2 (Calibration Transfer Standard(s)), the EPA proposes
to remove the requirements to select CTS according to section 4.5 of
the FTIR Protocol and to obtain a NIST-traceable standard. The EPA also
proposes to clarify that the CTS must be vendor-certified to 2percent of the cylinder tag value and specifying the list of CTS
standard gases that may be used. The EPA is soliciting comments
regarding CTS gases and providing standardization there to ensure
coverage over a wide wavelength range by using one of the listed gases.
The EPA also proposes to change the name of section 7.3 from
``Reference Spectra'' to ``Chemical Standards,'' and to replace the
reference to EPA reference spectra and procedures in the FTIR Protocol
for preparing reference spectra with requirements to use NIST-certified
or NIST-traceable, vendor-certified chemical standards that meet an
accuracy specification of 5 percent for preparing reference
spectra.
H. Section 8.0 (Sampling and Analysis Procedure)
In this action, the EPA proposes to change the name of section 8.0
from ``Sampling and Analysis Procedure'' to ``Sample Collection,
Preservation, Storage, and Transport,'' to clarify the purpose of the
section in the introductory paragraph, and to remove the list of
testing requirements. The EPA proposes to remove the recommendation to
obtain an initial spectrum for determining a suitable operational path
length and the reference to Figure 1 (sampling train).
In section 8.1 (currently Pretest Preparations and Evaluations),
the EPA proposes to rename the section to ``Pretest Preparations'' and
to remove reference to section 4 of the FTIR Protocol for determining
the optimum sampling system configuration. In section 8.2 (Leak-Check),
the EPA proposes to remove the hyphen from the section title, add a
statement for the user to follow the leak check procedures in the
proposed revised section 11.1 (Leak Check), and remove sections 8.2.1
(Sampling System) and 8.2.2 (Analytical System Leak Check).
In section 8.3 (Detector Linearity), the EPA proposes to replace
the text with a statement for the user to follow the detector linearity
verification procedures in proposed revised section 11.2 (Detector
Linearity). The EPA proposes to remove sections 8.3.1 and 8.3.2, which
provide the options to verify detector linearity by varying the power
incident on the detector by modifying the aperture setting or by using
neutral density filters to attenuate the infrared beam in current,
respectively. The EPA also proposed to incorporate section 8.3.3 into
the proposed revised section 11.2.
For section 8.4 (Data Storage Requirements), the EPA proposes to
replace the data storage requirements with a statement for the user to
follow the data storage requirements in new proposed section 11.8
(Digital Data Storage). The EPA also proposes to remove the requirement
to prepare a backup copy of the field test spectra and the requirement
to record sample conditions, instrument settings, and test records.
In section 8.5 (Background Spectra), the EPA proposes to remove the
requirement to evacuate the gas cell and fill the cell with dry
nitrogen to ambient pressure. The EPA also proposes to remove the
requirement to create a backup copy of the background interferogram and
processed single-beam spectrum and remove sections 8.5.1 (Interference
Spectra) and 8.5.2 for collection of water vapor spectra.
For section 8.6 (Pre-Test Calibrations), the EPA proposes to revise
the requirements for the CTS in section 8.6.1 (Calibration Transfer
Standard) and to replace the QA spike requirements in section 8.6.2 (QA
Spike) with a statement for the user to follow the QA spike
requirements in new proposed section 11.4 (QA Spike).
The EPA proposes to revise section 8.7 (Sampling) by replacing the
introductory paragraph with a statement for the user to follow the
sampling procedures specified in new proposed section 11.5
(Stratification Check). The EPA also proposes to incorporate the
requirements for the signal transmittance from section 8.9 (Sampling QA
and Reporting) into the introductory paragraph and to remove sections
8.7.1 (Batch Sampling) and 8.7.2 (Continuous Sampling).
For section 8.8 (Sampling QA and Reporting), the EPA proposes to
rename the section ``Post-Run CTS'' and add a requirement to record a
post-run CTS. The EPA proposes to incorporate the requirement that
sample integration times be sufficient to achieve the required signal-
to-noise ratio from section 8.8.1 into a proposed revised section
9.1.1.1. The EPA also proposes to remove sections 8.8.1, 8.8.2, 8.8.3,
and 8.8.4 and instead specify the requirements to assign unique file
names, store two copies of interferograms and spectra, and prepare
sample spectrum documentation, respectively.
For section 8.9 (Signal Transmittance), the EPA proposes to
incorporate the requirements for the signal transmittance from section
8.9 into revised section 8.7, and to replace the text in section 8.9
with a proposed requirement to perform post-run QA according to
proposed revised section 9.1.2 (Post-Run QA).
In section 8.10 (Post-Test QA), the EPA proposes to move the post-
test CTS requirements to new proposed section 11.6 (Post-Test CTS). The
EPA also
[[Page 15107]]
proposes to move section 8.11 (Post-Test QA) to proposed revised
section 9.1.2 (Post-Run QA).
I. Section 9.0 (Quality Control)
In this action, the EPA proposes to rename section 9.0 to ``Quality
Assurance and Quality Control'' and to remove the introductory
sentence. The EPA proposes to replace section 9.1 (Spike Materials),
which specifies the accuracy requirements for spike materials, with
revised section 9.1 (Quality Assurance) and to add requirements for
performing pre-test QA. The EPA proposes to move the existing section
8.11 to the proposed revised section 9.1.2 and to remove the reference
to the FTIR Protocol.
For section 9.2 (Spiking Procedure), the EPA proposes to replace
the spiking procedures with a proposed revised section 9.2 (Quality
Control) stating that analyte spike procedure in new proposed section
9.3 (Spike Procedure) and the validation procedure in new proposed
section 9.4 (Method Validation Procedure) evaluate the sampling system
performance and quantify sampling system effects on the measured
concentrations. The EPA also proposes to clarify that the method is
self-validating, provided that the results meet the performance
requirement of the QA spike in new proposed section 11.4, and to remove
the requirement that the results from a previous method validation
support the use of this method in the application.
J. Section 10.0 (Calibration and Standardization)
In this action, the EPA proposes updates to section 10.0 by
replacing section 10.1 (Signal-to-Noise Ratio) with a revised section
10.1 (Analytes) that specifies the procedures for calibrating and
standardizing analytes, replacing section 10.2 (Absorbance Path Length)
with a revised section 10.2 (Interferents), and replacing section 10.3
(Instrument Resolution) with revised section 10.3 (CTS Absorption
Bands). The EPA proposes to replace section 10.4 (Apodization Function)
with a revised section 10.4 (Reference Spectra), which would provide
users with procedures for collecting reference spectra, and to replace
section 10.5 (FTIR Cell Volume) with a revised section 10.5 (Absorption
Cell Path Length Determination), which would specify the revised
procedures for determining the absorption cell path length. The EPA
also proposes to add new section 10.6 (Instrument Resolution) to revise
procedures for determining instrument resolution.
K. Section 11.0 (Data Analysis and Calculations)
In this action, the EPA proposes to change the title of current
section 11.0 to ``Method Procedures.'' The EPA proposes to replace
section 11.1 (Spectral De-Resolution) with a revised section 11.1 that
would provide two options to verify that there are no significant
vacuum-side leaks (i.e., the low-flow test and the vacuum-decay test)
and to replace section 11.2 (Data Analysis) with a revised section 11.2
that would incorporate the requirements in the current introductory
paragraph for section 8.3 and requirements in section 8.3.3. The EPA
also proposes to add several new sections as summarized in table 6 of
this preamble. The EPA requests comment on these leak check approaches.
Table 6--Proposed Additions to Section 11
------------------------------------------------------------------------
Section Description
------------------------------------------------------------------------
11.3 (Gas Cell Pathlength)... Requires verification of the gas cell
pathlength according to the procedures
in revised section 10.6.4.
11.4 (QA Spike).............. Clarifies that the QA spike procedure
assumes that the method has been
validated for each of the target analyte
at the source, rather than for only some
of the target analytes as specified in
current section 8.6.2 and presents the
revised QA spike procedures for use of a
certified standard or use of a non-
certified standard.
11.5 (Sampling).............. Specifies the revised sampling
procedures, including performing a
stratification check.
11.6 (Post-Test CTS)......... Requires comparison of the pre- and post-
test CTS spectra.
11.7 (Record and Report)..... Specifies the revised recording and
reporting requirements.
11.8 (Digital Data Storage).. Incorporates the requirements from
section 8.4.
------------------------------------------------------------------------
L. Section 12.0 (Method Performance Data Analysis and Calculations)
For section 12.0, the EPA proposes to rename the section ``Data
Analysis and Calculations'' and to replace section 12.1 (Spectral
Quality) with a revised section 12.1 that specifies the required
capabilities of the concentration algorithm. The EPA also proposes to
remove section 12.2 (Sampling QA/QC).
M. Section 13.0 (Method Validation Procedure)
In this action, the EPA proposes to rename current section 13.0
from ``Method Validation Procedure'' to ``Method Performance'' and to
remove the introductory paragraph. The EPA also proposes to replace
section 13.1 with a revised section 13.1 (Detection Level), which would
include the proposed requirement that the detection level must be
within 20 percent of the applicable compliance limit, and to replace
section 13.2 (Batch Sampling) with a revised section 13.2 (Background
Deviation), which would incorporate the performance criteria in the
current definition of ``Background Deviation.''
N. Section 14.0 (Pollution Prevention)
In section 14.0, the EPA proposes to remove the sentence describing
the mass of HAP that may be emitted by the extracted sample gas for a
typical 3-hour validation run.
O. Section 15.0 (Waste Management)
The EPA is not proposing any changes to section 15.0 in this
action.
P. Section 16.0 (References)
In section 16.0, the EPA proposes to remove references 1, 2, 4, and
5 through 7, and to add the reference citation and link for the FTIR
Protocol (the current addendum to Method 320).
Q. Section 17.0 (Tables, Diagrams, Flowcharts, and Validation Data)
In this action, the EPA proposes to add new section 17.0, to update
Figure 1 (Extractive FTIR Sampling System), and to remove Table 1
(Example Presentation of Sampling Documentation) and Figure 2
(Fractional Reproducibility).
R. Addendum to Test Method 320
In this action, the EPA proposes to remove the addendum and
associated appendices from Method 320. The proposed revised section
16.0 will include a reference citation and link for the FTIR Protocol.
IV. Statutory and Executive Order Reviews
Additional information about these statutes and Executive orders
can be found at https://www2.epa.gov/laws-regulations/laws-and-executive-orders.
[[Page 15108]]
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 14094: Modernizing Regulatory Review
This action is not a significant regulatory action as defined in
Executive Order 12866, as amended by Executive Order 14094, and was
therefore not subject to a requirement for Executive Order 12866
review.
B. Paperwork Reduction Act (PRA)
This action does not impose an information collection burden under
the PRA. The revisions being proposed in this action to Method 320 do
not add information collection requirements but make corrections,
clarifications, and updates to existing testing methodology.
C. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
proposed action will not impose any requirements on small entities. The
proposed revisions to Method 320 do not impose any requirements on
regulated entities. Rather, the proposed changes improve the quality of
the results when required by other rules to use Method 320. Revisions
proposed for Method 320 allow contemporary advances in analysis
techniques to be used.
D. Unfunded Mandates Reform Act (UMRA)
This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. This action imposes no enforceable duty on any
State, local or Tribal governments or the private sector.
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.
F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This action does not have Tribal implications as specified in
Executive Order 13175. The revisions being proposed in this action make
corrections, clarifications, and updates to existing testing
methodology. Thus, Executive Order 13175 does not apply to this action.
G. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the EPA has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive order.
Therefore, this action is not subject to Executive Order 13045
because it does not concern an environmental health risk or safety
risk. Since this action does not concern human health, EPA's Policy on
Children's Health also does not apply.
H. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution or Use
This action is not subject to Executive Order 13211 because it is
not a significant regulatory action under Executive Order 12866.
I. National Technology Transfer and Advancement Act (NTTAA)
This action involves technical standards. While the EPA identified
ASTM D6348 as being potentially applicable, the Agency does not propose
to use it. Currently, ASTM International (formerly the American Society
for Testing and Materials) is revising ASTM D6348 (Standard Test Method
for Determination of Gaseous Compounds by Extractive Direct Interface
FTIR Spectroscopy), which specifies sampling and analytical procedures
that are similar to EPA Method 320. Because the revised ASTM D6348 may
be an equivalent method, the EPA will reconsider it when the revised
ASTM D6348 becomes available.
J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations and
Executive Order 14096: Revitalizing Our Nation's Commitment to
Environmental Justice for All
The EPA believes that this type of action does not concern human
health or environmental conditions and, therefore, cannot be evaluated
with respect to potentially disproportionate and adverse effects on
communities with environmental justice concerns. This action would
correct, update, and clarify Method 320 to improve the quality of the
results when used.
List of Subjects in 40 CFR Part 63
Environmental protection, Air pollution control, Hazardous air
pollutants, Method 320, FTIR, Test methods.
Michael S. Regan,
Administrator.
For the reasons stated in the preamble, the Environmental
Protection Agency proposes to amend title 40, chapter I of the Code of
Federal Regulations as follows:
PART 63--NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS
FOR SOURCE CATEGORIES
0
1. The authority citation for part 63 continues to read as follows:
Authority: 42 U.S.C. 7401 et seq.
0
2. Appendix A to part 63 is amended by revising Test Method 320 to read
as follows:
Appendix A to Part 63--Test Methods
* * * * *
Test Method 320--Measurement of Vapor Phase Organic and Inorganic
Emissions by Extractive Fourier Transform Infrared (FTIR) Spectroscopy
1.0 Scope and Application
This method describes the extractive sampling and quantitative
analysis of gaseous compounds in stationary source effluent using
Fourier transform infrared (FTIR) spectrometry. Analysis procedures,
quality control, and quality assurance requirements are included to
assure that you, the tester, collect data of known and acceptable
quality for each testing program.
1.1 Analytes. This method is designed to measure individual gas
phase hazardous air pollutants (HAPs) for which reference spectra
have been developed. Other gas phase compounds can also be measured
with this method so long as reference spectra obtained according to
section 10.5 of this method are used. Candidate gaseous compounds
must have infrared features (i.e., a non-zero dipole moment) to be
detected using this method.
1.2 Applicability. This method applies to the analysis of vapor
phase compounds that absorb energy in the mid-infrared spectral
region, from about 400 to 4000 cm-1 (25 to 2.5 [mu]m).
The method is used to determine compound-specific concentrations in
a multi-component gas sample extracted from a stack or ducted
source.
1.3 Data Quality Objectives (DQOs). Method 320 contains
performance-based DQOs to provide data of known quality. With this
method, you must evaluate the accuracy and precision of data in each
gas matrix and at actual emissions concentrations that are
encountered during its application. Data quality requirements
include appropriate field evaluation procedures.
2.0 Summary of Method
2.1 A sample is extracted from the source at a constant rate.
Samples are conditioned, if necessary, and transported via heated
lines composed of inert material (to prevent
[[Page 15109]]
condensation of the measured compounds) from the source to a heated
cell in the FTIR, wherein data are generated by directing an
infrared beam through the sample to a detector. Most molecules
absorb infrared radiation, and the absorbance occurs in a
characteristic and reproducible pattern. FTIR data are transformed
into a frequency-based spectra and curve fitting calculations (e.g.,
classical least squares, partial least squares) are used to
determine compound quantities and minimize residuals. Target
compound concentrations are determined using their unique infrared
absorption features and reference calibration spectra. This method
may be used simultaneously for multiple gaseous components.
2.2 Measurement evaluation and validation for a source gas
matrix are described in section 9.2 of this method. Pre-test
preparation and procedures are described in section 8.1 of this
method. These procedures are designed to verify that an appropriate
sampling system has been chosen and performs in a manner that
provides results of known and acceptable quality is also discussed.
Dynamic spiking is used to confirm target compound transport
accuracy in potentially complex matrices.
3.0 Definitions
3.1 Absorbance means the negative logarithm of transmission
represented by the relationship A = -log(I/I0), where I
is the transmitted intensity of light, and I0 is the
incident intensity of light upon a molecule.
3.2 Absorptivity means the amount of infrared radiation absorbed
by each molecule.
3.3 Analyte means a compound that the method is intended to
measure. This method is a multi-component method; therefore, several
analytes may be targeted for a given test.
3.4 Analyte spiking means the process of quantitatively adding
calibration standards to source effluent. Analyte spiking is used to
evaluate the ability of the sample transport and FTIR measurement
systems to quantify the target analyte(s).
3.5 Analytical algorithm means the method used to quantify the
concentration of both target analyte(s) and additional compounds in
a sample matrix that may introduce analytical interferences in each
FTIR spectrum.
3.6 Analytical interference means a spectral feature that
complicates, and may even prevent, the analysis of an analyte.
Analytical interferences can be background or spectral
interferences. Background interferences result from a change in
light throughput relative to the single beam background. This can be
due to factors such as deposits on reflective surfaces and windows,
temperature changes, a change in detector sensitivity, a change in
infrared source output, or instrument electronics failure. Spectral
interferences arise due to the presence of interfering compounds
that have overlapping absorption features with the analytes of
interest.
3.7 Apodization means a mathematical transformation used to
adjust the instrument line shape for measured peaks. There are
various types of apodization functions; the most common are boxcar,
triangular, Happ-Genzel, and Beer-Norton functions.
3.8 Background deviation means a deviation from 100%
transmittance in any region of the 100% line.
3.9 Background spectrum means a spectrum taken in the absence of
absorbing species or sample gas matrix, typically conducted using
nitrogen or zero air.
3.10 Bandwidth means the width of a spectral feature. This width
is commonly listed as the full width at half the maximum of the
spectral feature.
3.11 Beam splitter means a device located in the interferometer
that divides the incoming infrared radiation into two separate beams
that travel two separate paths before recombination.
3.12 Calibration transfer standard (CTS) means a certified gas
calibration standard used to verify instrument stability. For the
purposes of this method, the CTS must be ethylene, methane, or
carbon dioxide. Other compounds may be used only with administrator
approval.
3.13 Classical least squares (CLS) means a method of analyzing
multicomponent spectra by scaling reference absorbance spectra to
unknown measured spectra.
3.14 Double beam spectrum means a transmission or absorbance
spectrum derived by dividing the sample single beam spectrum by the
background spectrum.
Note: The term ``double-beam'' is used elsewhere to denote a
spectrum in which the sample and background interferograms are
collected simultaneously along physically distinct absorption paths.
In this method, the term denotes a spectrum in which the sample and
background interferograms are collected at different times along the
same absorption path.
3.15 Fourier transform means a mathematical transform that
allows the conversion of the detector response as a function of time
to intensity as a function of frequency.
3.16 Fundamental CTS means an NIST-traceable CTS reference
spectrum with known temperature and pressure, that has been obtained
using an absorption cell with an accurately known optical
pathlength.
3.17 Interferogram means a pattern that contains the effects of
the wave interference that are produced from an interferometer.
3.18 Interferometer means a device used to produce interference
spectra, by dividing a beam of radiant energy into two or more
paths. One path strikes a fixed mirror, and the second path strikes
a moving mirror generating an optical path difference that varies
over time between them. The recombined beams produce constructive
and destructive interference as a function of changing pathlength.
The Michelson interferometer, used in FTIR instruments, performs
this function.
3.19 Partial least squares means a method for analyzing
multicomponent spectra by combining features from principal
component and multiple regression analysis. It has been found to be
most useful when predicting a set of dependent variables from a
large set of independent variables.
3.20 Reference spectra means a spectra of a pure sample gas
obtained at a known concentration under controlled conditions of
pressure, temperature, and pathlength.
3.21 Resolution means the minimum separation that two spectral
features must have to distinguish one feature from the another.
3.22 Retardation means the optical path difference between two
beams in an interferometer.
3.23 Run means a series of samples taken successively from the
stack or duct. A test normally consists of a specific number of
runs.
3.24 Single beam spectrum means the Fourier transformed
interferogram representing detector response versus wavenumber.
3.25 Test means the series of runs required by the applicable
regulation.
3.26 Tracer gas means a stable, non-reactive species that is
easily transportable and can be blended in a gas cylinder with a
target analyte to confirm the dilution ratio of a dynamic spike.
3.27 Transmittance means the amount of infrared radiation that
is not absorbed by the sample. Percent transmittance is represented
by the following equation: %T = (I/I0) x 100.
4.0 Interferences
Interferences to precise, accurate measurement using FTIR
include both analytical interferences defined in section 3.6 of this
method, and sampling system interferences. Sampling system
interferences are conditions that prevent analytes from reaching the
instrument due to factors such as sample line temperature, sample
line materials, condensation, and sample transport time.
5.0 Safety
This method does not address all potential safety risks
associated with its use. The hazards of performing this method are
those associated with any stack sampling method. Anyone performing
this method must follow safety and health practices consistent with
stationary source sampling, including applicable legal and site-
specific safety requirements. Many HAPs measured by this method are
suspected toxic or hazardous and may present serious health risks.
Exposure to these compounds from stack gas or from spiking standards
should be avoided. Ensure safety data sheets (SDS) for gas standards
are available to all personnel using this method. When using analyte
standards, ensure that gases are properly vented and that the gas
handling system is leak free.
6.0 Equipment and Supplies
The equipment and supplies described in this section are based
on the schematic of the example sampling system shown in Figure 1.
6.1 Analytical Instrumentation.
6.1.1 Fourier Transform Infrared (FTIR) Spectrometer. An
instrument that collects and digitizes the spectral interference
pattern from an interferometer and mathematically transforms this
signal into infrared frequency spectra.
6.1.2 Computer/Data Acquisition System. A computer with
compatible FTIR software for control of the FTIR system, acquisition
of infrared (IR) data, and analysis of resulting spectra. This
system must have enough data
[[Page 15110]]
storage space to archive all necessary infrared and meta data (see
section 11.6 of this method).
6.1.3 Gas Absorption Cell. The container through which the
infrared beam interacts with the sample gas. The gas absorption cell
must have the ability to monitor the pressure and temperature of the
sample gas.
6.2 Sampling System. The sampling system consists of the
components listed in sections 6.2.1 through 6.2.9 of this method and
validated as detailed in section 9.4.
6.2.1 Sampling Probe. Glass, stainless steel,
polytetrafluoroethane (PTFE), or other appropriate material to
transport analytes to the IR gas cell. The sampling probe must be
capable of sustained heating to prevent water condensation and
adsorption of analytes.
Note: High stack sample temperatures may require special steel
or cooling of the probe. For very high moisture sources, it may be
desirable to use a dilution probe. Special materials or
configurations may be required for probes to traverse ducts or
stacks.
6.2.2 Particulate Filters. A glass wool plug (optional) inserted
at the probe tip (for large particulate removal) and a filter
(required) connected at the outlet of the heated probe and rated for
99% removal efficiency of 1 micron aerodynamic particulate.
6.2.3 Sampling Line. Heated to prevent sample condensation, and
made of stainless steel, PTFE, or other material that minimizes
adsorption of analytes. Line length should be the minimum necessary
to reach sampling locations.
6.2.4 Sample Pump. A leak-free pump with bypass valve, capable
of producing a sample flow rate equal to 5 cell volumes per sample
cycle. The pump may be positioned upstream or downstream of the FTIR
cell. If the pump is positioned upstream of the distribution
manifold and FTIR system, use a heated head pump that is constructed
from materials non-reactive with the analytes of interest.
6.2.5 Gas Distribution Manifold. A manifold capable of
delivering nitrogen or calibration gases through the sampling system
or directly to the FTIR. The calibration gas manifold must provide
accurate dilution of the calibration gas as necessary, monitor
calibration gas pressure, and introduce analyte spikes into the
sample stream (prior to the particulate filter) at a precise and
known flowrate.
6.2.6 Sample Conditioning. An optional part of the sampling
system used to dilute or remove particulate matter, water vapor, or
other interfering species depending upon the source matrix
composition.
6.2.7 Gas Regulator. A regulator used to introduce individual
gas or gas mixtures from cylinders. Regulator should be constructed
of the appropriate materials that minimize analyte adsorption and
reaction with the regulator.
6.2.8 Tubing. PTFE, 316-stainless steel, or other inert
material, of suitable length and diameter used to connect cylinder
regulators to the gas manifold.
7.0 Reagents and Standards
7.1 Analyte(s) and Tracer Standard Gases. Analyte(s) and tracer
gases must come from gas cylinder(s). Criteria pollutants must use
EPA Protocol gases, or equivalent (i.e., compressed gas standards
with an expanded uncertainty of <=2%). All other pollutants must use
``dual certified'' compressed gas standards (i.e., standards
certified by two independent techniques). Target analyte
concentrations should be within 25% of the emission
source levels or the applicable compliance limit unless otherwise
prescribed in the applicable standard. If practical, the analyte
standard cylinder shall also contain the tracer gas at a
concentration that gives a measurable absorbance at a dilution
factor of at least 10:1.
7.2 Calibration Transfer Standard (CTS). The CTS standard must
be NIST-traceable, per methods specified in the EPA Traceability
Protocol for Assay and Certification of Gaseous Calibration
Standards, to 2% of the cylinder tag value. The CTS
standard must be one of the following gases: ethylene, methane, or
carbon dioxide.
7.3 Chemical Standards. Chemical standards used to generate
reference spectra must be NIST certified via gravimetric
measurement, or NIST-traceable and vendor-certified accurate to
within 5%.
8.0 Sample Collection, Preservation, Storage, and Transport
8.1 Pretest Preparations. Determine the optimum sampling system
configuration for measuring the target analytes. Use available
information to make reasonable assumptions about moisture content
and other interferences.
8.1.1 Sampling System.
8.1.1.1 Based on the source gas characteristics (e.g.,
temperature, pressure profiles, moisture content, target and
interference physical characteristics, and particulate
concentration), select the equipment for extracting and transporting
gas samples.
8.1.1.2 Select the techniques and/or equipment for the
measurement of sample pressures and temperatures in the sample cell.
8.1.1.3 Heat sample transport lines to maintain sample
temperature at least 10 [deg]F (5 [deg]C) above the dew point for
all sample constituents. Sample transport lines and system
components must be heated sufficiently through their entire length
to transport target compounds to the IR sample cell.
8.1.2 Select Spectroscopic Setup. Select a spectroscopic
configuration for the application. Approximate the absorption
pathlength, sample pressure, absolute sample temperature, and signal
integration period necessary for the analysis. Specify the nominal
minimum instrumental linewidth (MIL) of the system.
8.1.3 Analytical Program.
8.1.3.1 Prepare an analysis algorithm for acquired spectra. Use
as input, reference spectra of all target analytes and expected
interferents. Include reference spectra of additional interferent
compounds in the program if their presence (even if transient) in
the samples is considered possible. The program output must be in
ppmv (or parts per billion by volume [ppbv]) and must correct for
differences between the reference pathlength (LR),
temperature (TR), and pressure (PR), and the
actual conditions used for collecting the sample spectra.
8.1.3.2 Choose a mathematical technique (e.g., classical least
squares, partial least squares, inverse least squares) for analyzing
spectral data by comparison with reference spectra.
8.1.3.3 Reference spectra incorporated in the program must
either bracket the observed sample matrix concentration or use a
direct injection to verify the calibration curve. Additionally, you
must use a sufficient number (>3) of reference spectra (or reference
spectra plus direct injection checks for low concentration regimes)
in the bracketed range to demonstrate linearity in that
concentration range. Alternatively, if the matrix concentration is
expected to be within three times the detection limit of this
method, you may use calculated reference spectra (i.e., HITRAN or
PNNL) at the lower end of the bracketing range.
8.1.3.4 Analysis regions selected for a target compound(s) must
have an absorbance value of less than 1. You must select specific
wavelengths in each region where the target analyte does not overlap
with an interfering compound and use the selected wavelengths
throughout the entire validation (section 9.4), QA spiking (section
11.4), and testing campaign.
8.2 Leak Check. To conduct the leak check, follow the procedures
specified in section 11.1.
8.3 Detector Linearity. To verify detector linearity, follow the
procedures specified in section 11.2.
8.4 Data Storage Requirements. For these requirements, follow
the procedures specified in section 11.8.
8.5 Background Spectrum. Flow dry nitrogen through the gas cell
and verify that no significant amounts of absorbing species are
present. Collect a background spectrum, using a signal averaging
period equal to or longer than that being used for averaging of
source sample spectra. Assign a unique file name to the background
spectrum.
8.6 Pre-Test Calibrations.
8.6.1 Calibration Transfer Standard. Flow the CTS gas through
the cell and verify that the measured concentration is stable to
within the uncertainty of the gas standard. Record the spectrum.
Additionally, measure the linewidth of appropriate CTS band(s) to
verify instrument resolution. Alternatively, compare CTS spectra to
a reference CTS spectrum, if available, measured at the nominal
resolution.
8.6.2 QA Spike. Conduct a QA spike per the instructions in
section 11.4 of this method.
8.7 Sampling. See section 11.5 of this method. While sampling,
monitor the signal transmittance. If the transmittance (relative to
background) changes by 5% or more in any analytical spectral region,
obtain a new background spectrum.
8.8 Post-Run CTS. After the sampling run, record another CTS
spectrum.
8.9 Perform post-run QA per section 9.1.2 of this method.
9.0 Quality Assurance and Quality Control
9.1 Quality Assurance (QA).
[[Page 15111]]
9.1.1 Pre-Test QA.
9.1.1.1 Prior to testing, verify that the sample integration
time is sufficient to achieve the required signal-to-noise ratio.
9.1.1.2 Assign a unique file name to each spectrum.
9.1.1.3 For reporting and recording requirements, see sections
11.6 and 11.7 of this method.
9.1.2 Post-Test QA.
9.1.2.1 Inspect the sample spectra immediately after the run to
verify the gas matrix composition was close to the expected matrix
composition.
9.1.2.2 Verify that the sampling and instrumental parameters
were appropriate for the actual stack conditions. For example, if
the moisture of the sampled gas was much higher than anticipated, a
shorter pathlength cell or more dilute sample may be needed.
9.1.2.3 Compare the pre- and post-test CTS spectra. The peak
absorbance in the pre- and post-test CTS must be 5% of
the mean value.
9.2 Quality Control (QC). The analyte spike procedure in section
9.3 of this method and the validation procedure in section 9.4 of
this method are used to evaluate the performance of the sampling
system and to quantify sampling system effects, if any, on the
measured concentrations. This method is self-validating provided
that the results meet the performance requirement of the QA spike in
section 11.4 of this method.
9.3 Spike Procedure. Spiking must be done per a standard
addition procedure consisting of measuring the source emissions
concentration (i.e., native source gas concentration), addition of
reference gas, and measurement of the resulting standard addition
(SA) elevated source gas concentration. Spiking must be done
dynamically accounting for the spike dilution of sample gas with the
addition of the reference gas.
9.3.1 Each dynamic spike (DS) or SA replicate consists of a
measurement of the source emissions concentration (native stack
concentration) with and without the addition of the species of
interest. With a single FTIR, you must alternate the measurement of
the native and SA-elevated source gas so that each measurement of
SA-elevated source gas is immediately preceded and followed by a
measurement of native stack gas. Introduce the SA gases in such a
manner that the entire sampling system is challenged. Alternatively,
you may use an independent FTIR and sampling system to measure the
native source concentration throughout each standard addition.
9.3.1.1 Pre and post-test spiking must consist of at least 3
replicates. A replicate is defined as the following measurement
sequence: native gas concentration, SA-elevated gas concentration,
native gas concentration. In addition to the pre-test spike
instance, spiking must also be performed post-test.
9.3.1.2 It is recommended that spiking be performed after each
run to ensure continued compliance with the required spike recovery
criteria. If spiking is not performed after each run and the post-
test spike fails, all data for that test are invalid. However, if
spiking is performed after each run, data bracketed on each end by a
successful spike are valid test data.
9.3.2 Your spike gas flow rate must not contribute more than 10%
of the total volumetric flow rate through the FTIR.
9.3.3 Determine the response time (RT) of the system. First,
inject zero air into the system. For standard addition RT
determination, next measure the native stack concentration of the
species to be spiked. The concentration has stabilized when
variability appears constant for five minutes.
9.3.4 You must determine a dilution factor (DF) for each dynamic
spike. Determine the DF via a tracer, and use the following equation
for a source where the tracer is not native to the source emissions:
[GRAPHIC] [TIFF OMITTED] TP01MR24.037
Where:
Mspiked tracer = the measured diluted tracer gas
concentration in a spiked sample.
Ctracer spiked = the tracer gas concentration injected
with the spike gas.
Note: Use consistent concentration units for each variable in
Equation 1.
In instances where the tracer gas is native to the source
emissions, use the following equation:
[GRAPHIC] [TIFF OMITTED] TP01MR24.038
Where:
Mnative tracer = the measured tracer concentration
present in the native effluent gas.
Cnative tracer = the undiluted tracer gas concentration
in the cylinder.
Note: Use consistent concentration units for each variable in
Equation 2.
9.3.4.1 Standard Addition Response. The standard addition
response (SAR) represents the difference between the measured native
source concentration and the concentration measured upon
introduction of the standard addition (source + SA) via dynamic
spike. Calculate the SAR via the following equation:
[GRAPHIC] [TIFF OMITTED] TP01MR24.039
Where:
MCspiked = the measured reference analyte concentration.
MCnative = the measured concentration of the analyte in
the native effluent.
Note: Use consistent concentration units for each relevant
variable in Equation 3.
9.3.4.2 Effective Spike Addition. The effective spike addition
(ESA) is the expected increase in the measured concentration as a
result of injecting a spike. For the section 11.4 QA spike, the ESA
must be within 50% of the native stack concentration. Calculate the
ESA with the following equation, for use when using a certified
cylinder:
[GRAPHIC] [TIFF OMITTED] TP01MR24.040
Where:
Cspike = the certified reference analyte concentration.
When using a non-certified cylinder, replace the Cspike
term in Equation 4, with MCspiked.
Note: Use consistent concentration units for each relevant
variable in Equation 4.
9.3.4.3 Spike Recovery. The degree to which the SAR and the ESA
agree represents the spike recovery (SR), or the ability to measure
the spiked analyte on top of the amount of that analyte native to
the stack.
[[Page 15112]]
Spike recovery is calculated according to the following equation:
[GRAPHIC] [TIFF OMITTED] TP01MR24.041
9.3.4.4 Spiking Procedure for Highly Variable Sources. In some
instances, a source may be encountered that is too variable for the
procedures listed in sections 9.3 and 11.4 of this method. A highly
variable source, for which this procedure may be used is defined as
a source that varies randomly and by more than 25% from data point
to point, where two consecutive points are less than or equal to a
minute apart. For these types of sources, the approach outlined in
section 9.3.5.4.1 of this method may be used.
9.3.4.4.1 Dual FTIR and Extractive Systems Approach. This field
approach is performed using two independent FTIRs and sample
extraction systems that use tubing of the same length and diameter
and that pull the sample at approximately the same flow rate. One
FTIR characterizes the fluctuations of the target analyte(s) over
time and the second FTIR performs the spike recoveries. Note that
testers can use either a single probe attached to both systems or
separate probes for each system with the probe tips co-located
(within 6 inches) in the sample duct. In either case, it is
mandatory for the spike to occur prior to the PM filter. Perform the
spiking procedure as follows.
Note: This procedure assumes that the dilution factor is
calculated as stated in EPA Method 320 or ASTM D6348-12e from either
a spectroscopic tracer or metered flows.
9.3.4.4.1.1 After positioning the FTIR probes accordingly, begin
pulling sample gas into both FTIR sample analysis cells. Use the
same sampling period and the identical quantification method (i.e.,
same reference spectra for construction and the same regions for
quantification) for each FTIR.
a. Sample the source gas stream for approximately 15 minutes,
collecting at least 8 spectra on each FTIR.
b. Calculate the average concentration of the target analyte(s)
for each FTIR. If the average concentrations determined using the
two FTIRs are not within 10%, either the analysis routines were not
identical, the timing was not consistent, or the sample system or
FTIR cell in one of the FTIRs is reacting with the target
analyte(s). Note: If the average concentrations are not within 10%,
the spike recovery criterion will be more difficult to achieve.
9.3.4.4.1.2 If the average concentrations agree within 10%,
begin flow of the analyte spike into one of the FTIRs. At this
point, the spiked FTIR should have a consistent offset to the
unspiked FTIR. After this offset is consistent, collect a minimum of
8 data points.
9.3.4.4.1.3 Calculate the difference between the average
concentration of the spiked data and the average concentration of
the unspiked data (i.e., the average concentration of the spike)
using equation 6 of this method.
9.3.4.4.1.4 Calculate the recovery (equation 7) of the spike
using the predicted spiked concentration by the dilution factor (as
determined per the reference method used) and the resultant from
Step 3 (equation 6).
[GRAPHIC] [TIFF OMITTED] TP01MR24.042
Where:
SV = Concentration of target analyte spiked into the extracted gas
stream.
Si = Individual concentration results from the spiked FTIR.
n = Number of individual spiked concentration measurements
collected.
Up = Individual concentration results from the unspiked FTIR (native
gas concentration).
p = Number of individual, unspiked concentration measurements
collected.
Note: Use consistent concentration units for each relevant
variable in Equation 6.
[GRAPHIC] [TIFF OMITTED] TP01MR24.043
Where:
SV = Spiked concentration as calculated from Equation 6.
DF = Dilution Factor as determined from tracer in spike gas standard
or from flows.
Spike Cylinder Concentration = Concentration of target analyte(s)
from spike gas standard (e.g., determined from direct injection or
from certified cylinder tag value).
Note: Use consistent concentration units for each relevant
variable in Equation 7.
9.4 Method Validation Procedure.
This validation procedure, which is based on EPA Method 301 (40
CFR part 63, appendix A), must be used to validate this method for
the analytes in a gas matrix. Analytes that have not been validated
for a particular source type may not be measured using Method 320.
Validation at one source may also apply to another type of source,
if it can be shown that the exhaust gas characteristics are similar
at both sources.
9.4.1 Use section 5.3 of Method 301 (40 CFR part 63, appendix
A), the Analyte Spike procedure, with these modifications. The
statistical analysis of the results follows section 6.3 of EPA
Method 301. Section 3 of this method defines terms that are not
defined in Method 301.
9.4.2 The analyte spike is performed dynamically. This means the
spike flow is continuous and constant as spiked samples are
measured.
9.4.3 Introduce the spike gas at the back of the sample probe.
9.4.4 Spiked effluent is carried through all sampling components
downstream of the probe.
9.4.5 A single FTIR system (or more) may be used to collect and
analyze spectra (not quadruplicate integrated sampling trains).
9.4.6 All of the validation measurements are performed
sequentially in a single ``run'' (section 3.23 of this method).
9.4.7 The measurements analyzed statistically are each
independent (section 3.22 of this method).
9.4.8 A validation data set must consist of 12 or more spike
replicates.
10.0 Calibration and Standardization
10.1 Analytes. Select the required detection level
(DLi) and maximum permissible analytical uncertainty
(AUi) for each analyte (1 to i). The required DL must be
equal to or greater than the method DL determined via section 13.1
of this method. Estimate, if possible, the maximum expected
concentration for each analyte (CMAXi). The expected
measurement range is then bounded by DLi and
CMAXi for each analyte.
10.2 Interferents. List all potential interferents applicable to
your source matrix. Collect or obtain spectra of known and suspected
interferences that were acquired using the same optical system that
will be used in the field measurements. You may also use calculated
spectra from sources such as HITRAN as long as the spectral
resolution matches the resolution of source test sample spectra.
These interferents must be included in the analytical algorithm used
to fit FTIR spectra for quantitation.
[[Page 15113]]
10.3 CTS Absorption Bands. Absorption bands used for CTS
quantitation must be at least ten times the root mean square (RMS)
value of the noise equivalent absorbance (NEA) of a wavelength range
nearest to that absorption band. This value, NEARMS\CTS\
can be determined as follows:
10.3.1 Determine the absolute noise equivalent absorption (NEA)
for an analytical region by flowing nitrogen or zero air through the
gas sample cell. The NEA is the peak-to-peak noise in a spectrum
resulting from collection of two successive background spectra.
Therefore, collect two background spectra in succession while the
nitrogen or zero air is continuously flowing through the cell. Note
that the same averaging time must be used for NEA determination as
will be used for actual sample collection.
10.3.2 Calculate NEARMS\CTS\ per the following
equation:
[GRAPHIC] [TIFF OMITTED] TP01MR24.044
Where:
NCTS = the number of absorbance points in the analysis
region for the CTS.
NEAi\CTS\ = the individual absorbance values of the noise
spectrum in the analysis region, i.
10.4 Reference Spectra. Obtain reference spectra for each
analyte, interferant, surrogate, CTS, and tracer.
10.4.1 The tester must report traceability and other pertinent
information for each reference spectrum, for each compound,
including: temperature, pressure, concentration, cylinder source and
specifications, spectral regions of analysis used for quantitation
(with specific wavelength ranges used), and calibration fit
equations and correlations.
10.4.2 If commercially prepared, or other available reference
libraries are used to quantify data, the FTIR spectral resolution
and line position, cell pathlength, temperature and pressure, and
apodization function must be known and reported. Resolution, line
position, and apodization function used for collection of sample
spectra must be the same as those of the reference spectra used for
quantitation.
10.4.3 Reference spectra for each target compound must bracket
the concentration of that compound in the sample stream.
10.4.3.1 In the case where traceable reference spectra provided
by the FTIR manufacturer do not bracket the concentration of a
particular compound, two options are available. A direct injection
of the compound of interest (NIST traceable and certified to 5%) into the FTIR at a concentration lower than that found in
the sample stream and within three times the method detection level,
may be performed to demonstrate the appropriateness of the
calibration line at this level. To perform this check, while
directly injecting the compound of interest into the FTIR, wait for
the concentration of the compound to stabilize. Once stable, verify
that the concentration as determined via the calibration curve is
within 10% of the cylinder value or else do not proceed with
testing.
10.4.3.2 Alternatively, calculated spectra, such as those from
HITRAN or PNNL, may be used at the lower end of the bracketing
range, within three times the method detection level, as well.
10.4.4 Collecting Reference Spectra. In some cases, it may be
necessary for the tester to collect reference spectra prior to
testing. The procedure found in this section is to be used in such a
case.
10.4.4.1 Record a set of CTS spectra.
10.4.4.2 Collect a set of the reference spectra at two or more
concentrations in triplicate over the desired concentration range.
The top of the concentration range must be less than 10 times that
of the bottom of the range.
10.4.4.3 Collect a second set of CTS spectra. The maximum
accepted concentration for each compound shall be higher than the
maximum estimated concentration for both analytes and known
interferents in the effluent gas. For each analyte, the minimum
accepted concentration shall be no greater than ten times the
concentration-pathlength product of that analyte at its required
detection limit.
10.4.4.4 Permanently store the background and interferograms
digitally, and separately. Document details of the mathematical
process (i.e., apodization function) for generating the spectra from
these interferograms. Record sample pressure (Pr), sample
temperature (Tr), reference absorption pathlength
(Lr), and interferogram signal integration period
(tsr).
10.5 Absorption Cell Path Length Determination.
10.5.1 Flow the CTS through the FTIR cell. Once the absorbance
of two consecutive spectra differ by less than or equal to the
uncertainty of the cylinder standard, the CTS spectrum may be
recorded. Note that the CTS gas must be one of the following gases:
ethylene, methane, or carbon dioxide.
10.5.2 Record a set of the absorption spectra of the CTS, and
record the temperature, pressure, and concentration of the CTS.
10.5.3 Record the instrument manufacturer's nominal absorption
pathlength, nominal spectral resolution, and the CTS signal
integration period.
10.5.4 Calculate the reference cell absorption pathlength,
according to the following equation:
[GRAPHIC] [TIFF OMITTED] TP01MR24.045
Where:
Lr = reference cell absorption pathlength.
Lf = fundamental CTS absorption pathlength.
Tr = absolute temperature of reference CTS gas.
Tf = absolute temperature of fundamental CTS gas.
Pr = absolute pressure of reference CTS gas.
Pf = absolute pressure of fundamental CTS gas.
Cr = concentration of the reference CTS gas.
Cf = concentration of the fundamental CTS gas.
{Ar/Af{time} = ratio of the reference CTS
absorbance to the fundamental CTS absorbance, determined by
classical least squares, integrated absorbance area, spectral
subtraction, or peak absorbance techniques.
10.6 Instrument Resolution.
10.6.1 Flow ambient air through the gas cell.
10.6.2 Verify the instrument resolution using a water absorbance
peak near either 1,918 cm-1, 3,050 cm-1, or
3,920 cm-1.
10.6.3 The absorbance of the peak being used for the resolution
determination should be approximately 0.25 absorbance units. Mix
additional humified air or nitrogen with the ambient flow, to
achieve this absorbance.
10.6.4 Record an absorbance spectrum and measure the FWHH of the
chosen water peak. The measured FWHH of the water peak must be
within 5% of the nominal instrument resolution to proceed with
testing.
11.0 Method Procedures
11.1 Leak Check. Verify that there are no significant vacuum-
side leaks using one of the leak tests described in this section.
Perform the vacuum-side leak check after each installation at the
sampling or measurement location. Leak check must be performed prior
to the start of the field test, and after any relocation or
maintenance to the sample transport system. A leak may be detected
either by measuring a small amount of flow when there should be zero
flow, or by measuring the vacuum decay rate. To test for leaks using
loss of vacuum you must know the vacuum-side volume of your sampling
system to within 10% of its true volume.
[[Page 15114]]
11.1.1 Low-Flow Leak Test. Test a sampling system for leaks
using low-flow measurements as follows:
11.1.1.1 Seal the probe end of the system by capping or plugging
the end of the sample probe.
11.1.1.2 Start sampling pumps and operate them until the
pressure stabilizes.
11.1.1.3 Observe/measure the flow through the vacuum-side of the
sampling system. A flow of less than 0.5% of the system's normal in-
use flow rate is acceptable.
Note: For bypass systems, where the sample flow rate through the
vacuum side of the sample system is greater than the FTIR cell flow
rate, the higher flow rate (bypass plus analyzer/FTIR flow rate) is
used as the in-use flow rate when calculating acceptability of the
leak level.
11.1.2 Vacuum-Decay Leak Test. Perform a vacuum-decay leak test
as follows:
11.1.2.1 Seal the probe end of the system as close to the probe
opening as possible by capping or plugging the end of the sample
probe.
11.1.2.2 Operate all vacuum pumps. Draw a vacuum on the sampling
system and let the pressure on the system stabilize.
11.1.2.3 Turn off the sample pumps and seal the system under a
vacuum of 250 mmHg greater than the source static pressure. Record
the absolute pressure and the system absolute temperature every 30
seconds for 5 minutes. The leak rate must be equal to or less than
2.5 mmHg per minute.
11.2 Detector Linearity. Observe the single beam instrument
response in the frequency region below the detector cutoff (usually
<400 cm-1), where the detector response is known to be
zero. Verify that the detector response is ``flat'' and equal to
zero in this region, or at least 100 times less than the peak signal
in the entire spectrum. If the response is not linear, decrease the
aperture or attenuate the IR beam, and repeat the linearity check
until the detector response is linear.
11.3 Gas Cell Pathlength. Verify the gas cell pathlength of your
instrument by following the procedure found in section 10.6.4 of
this method.
11.4 QA Spike. This procedure assumes that the method has been
validated for each of the target analytes at the source. Choose one
of two options and perform the standard addition procedure listed in
ection 9.3 of this method.
Note: For unstable sources, QA spiking may be difficult. An
alternative procedure for such a source is described in section
9.3.5.4.
11.4.1 QA Spike Option 1. Use a certified standard (2% accuracy) for an analyte that has been validated at the
source. One may either spike each analyte of interest or choose an
appropriate surrogate. An appropriate surrogate must have a vapor
pressure that is less than or equal to the analyte of interest and
be less soluble in water. The wavelength at which the surrogate is
to be quantified must be reported and be within 100 wavenumbers of a
wavenumber that will be used to quantify the analyte of interest.
Additionally, the pKa of a surrogate must be within 20% of the pKa
of the analyte of interest. Surrogates are not allowed for the
following analytes: formaldehyde, HCl, HF, NH3, and vinyl
chloride. If the spike recovery, as calculated by Equation 5 of this
method, is within 70-130% then proceed with the testing.
11.4.2 QA Spike Option 2. Use a non-certified cylinder for an
analyte that has been validated at the source. As with Option 1, one
may either spike each analyte of interest or choose an appropriate
surrogate. If the spike recovery, as calculated by equation 5 of
this method, is within 90-110%, then proceed with the testing.
11.5 Sampling. Sampling must be done using a continuous flow of
source gas.
11.5.1 Stratification Check. A stratification check must be
performed, per the steps in this section, to justify sampling at a
single location during testing.
11.5.1.1 Use a probe of appropriate length to measure the
analyte of interest at each of 12 traverse points (MNi,
where i = 1 to 12) located according to section 11.3 of Method 1 in
appendix A-1 to 40 CFR part 60 for a circular stack or nine points
at the centroids of similarly shaped, equal area divisions of the
cross section of a rectangular stack.
11.5.1.2 Calculate the mean measured concentration for all
sampling points (MNavg).
11.5.1.3 Calculate the percent stratification (St) of
each traverse point using the following equation:
[GRAPHIC] [TIFF OMITTED] TP01MR24.046
11.5.1.4 The gas stream is considered to be unstratified and you
may perform testing at a single point that most closely matches the
mean if the concentration at each traverse point differs from the
mean concentration for all traverse points by no more than 5.0% of
the mean concentration.
11.5.1.5 If the criteria for single point sampling is not met,
but the concentration at each traverse point differs from the mean
concentration by no more than 10% of the mean, the gas stream is
considered minimally stratified, and you may sample using the ``3-
point short line.''
11.5.1.6 If the concentration at any traverse point differs from
the mean by more than 10%, the gas stream is considered stratified,
and you must sample using the stratification check procedure
specified in section 11.5.1.1 of this method.
11.5.2 Assign a unique filename to each spectrum and separately
to each corresponding interferogram. Spectra and interferograms must
be providable in ``.spc'' format upon request.
11.5.3 Temperature. The temperature of the gas cell must be
measured directly. The temperature measurement device must be
calibrated to within 0.1 [deg]C every 12 months.
11.5.4 Pressure. The gas cell pressure must be measured
empirically. The measurement device must be calibrated to within
1 mmHg every 12 months.
11.5.5 Inspect the sample spectra immediately after the run to
verify that the gas matrix composition was close to the expected
(assumed) gas matrix. Additionally, look at the residual spectra for
each sample spectrum to confirm interferences have been accounted
for.
11.6 Post-Test CTS. At the end of each test, record another CTS
spectrum. Compare the pre- and post-test CTS spectra. The peak
absorbance in pre- and post-test CTS must be 5% of the
mean value.
11.7 Record and Report.
11.7.1 The following must be documented and reported for each
sample spectrum: sampling conditions, sampling time (# of scans per
average and amount of time per scan), instrumental conditions
(pathlength, temperature, pressure, resolution, laser frequency,
instrument make and model), and spectral filename.
11.7.2 Test Report. You must prepare a test report following the
guidance in EPA Guidance Document 043 (Preparation and Review of
Test Reports. December 1998). Additional minimum reporting
requirements are listed here:
11.7.2.1 Instrument and sampling system related items.
a. Instrument make and model.
b. Sampling line length, material, and temperature.
c. Instrument resolution.
d. Cell pathlength, pressure, and temperature.
e. Laser frequency.
f. Cylinder regulator type.
11.7.2.2 Software/Algorithm related items.
a. Gases included in the analysis (interferences + analytes of
interest).
b. Concentration values of reference spectra, as well as
temperature and pressure. information for all interferences and
analytes of interest.
c. Analysis wavelength regions for each compound (interferences
+ analytes of interest).
11.7.2.3 CTS, QA/QC and validation related items.
a. A list of compounds that are being spiked. Note that Method
320 allows for use of qualified surrogates. Qualified surrogates
should be appropriate for the compound actually being measured. It
is preferable that the compound of interest always be spiked if it
is available as a certified standard.
b. Is/are the spike(s) being performed dynamically?
c. Are spikes being introduced at the back of the sample probe
and travelling through the entire sampling system?
d. Are standards being used for QA spiking of appropriate
quality? For example, (2% for Protocol gases where
available and 5% for other certified gases?
[[Page 15115]]
e. Has FTIR been validated for the source under consideration?
11.8 Digital Data Storage. All field test data must be
electronically stored, readily available, and provided to the
regulatory authority upon request. Stored information must include:
sample interferograms, background interferograms, CTS sample
interferograms, processed sample absorbance spectra, and processed
CTS absorbance spectra.
12.0 Data Analysis and Calculations
12.1 Analyte concentrations must be measured using reference
spectra as they are described in section 10.5 of this method. Use
the algorithm developed in section 8.3 of this method to calculate
the concentration of each species in the sample matrix as well as
their respective residuals. Classical least squares, augmented
classical least squares, or partial least squares algorithms must
meet the following criteria:
12.1.1 The algorithm must be capable of correcting for
differences in gas cell pathlength, temperature, and cell pressure
between sample and reference spectra. If the algorithm does not have
this capability, perform this correction using equation 12:
[GRAPHIC] [TIFF OMITTED] TP01MR24.047
12.1.2 The algorithm must be capable of reporting spectral
residuals for all compounds being analyzed as a function of its
spectral fit using the techniques in section 11.1 of this method.
13.0 Method Performance
13.1 Detection Level (DL). The DL of this method is defined as
the SAR value where the SAR is greater than three times the residual
value of the corresponding standard addition elevated concentration
(MCspiked). The DL for this method must be less than or
equal to 20% of the applicable compliance limit for the compound
being measured. If this is not the case, Method 320 cannot be used
for such an application.
13.2 Background Deviation. Deviations in absorption greater than
5% in an analytical region are unacceptable, and Method
320 cannot be used under this condition.
14.0 Pollution Prevention
The extracted sample gas is vented outside the enclosure
containing the FTIR system and gas manifold after the analysis. In
typical method applications, the vented sample volume is a small
fraction of the source volumetric flow and its composition is
identical to that emitted from the source. When analyte spiking is
used, spiked pollutants are vented with the extracted sample gas.
Minimize emissions by keeping the spike flow off when not in use.
15.0 Waste Management
Small volumes of laboratory gas standards can be vented through
a laboratory hood. Neat samples must be packed and disposed of
according to applicable regulations. Surplus materials may be
returned to supplier for disposal.
16.0 References
1. Protocol for the Use of Extractive Fourier Transform Infrared
(FTIR) Spectrometry in Analyses of Gaseous Emissions from Stationary
Sources, https://www3.epa.gov/ttn/emc/ftir/FTIRProtocol.pdf.
2. U.S. EPA. Method 301--Field Validation of Pollutant Measurement
Methods from Various Waste Media, 40 CFR part 63, appendix A.
3. EPA Traceability Protocol for Assay and Certification of Gaseous
Calibration Standards, https://www.epa.gov/air-research/epa-traceability-protocol-assay-and-certification-gaseous-calibration-standards.
17.0 Tables, Diagrams, Flowcharts, and Validation Data
[GRAPHIC] [TIFF OMITTED] TP01MR24.048
Figure 1. Schematic of FTIR Sampling System
* * * * *
[FR Doc. 2024-04359 Filed 2-29-24; 8:45 am]
BILLING CODE 6560-50-P