ASTM D6348-12(2020)

Standard Test Method for Determination of Gaseous Compounds by Extractive Direct Interface Fourier Transform Infrared (FTIR) Spectroscopy

SIGNIFICANCE AND USE
5.1 The FTIR measurements provide for multicomponent on-site analysis of source effluent.  
5.2 This test method provides the volume concentration of detected analytes. Converting the volume concentration to a mass emission rate using a particular compound’s molecular weight, and the effluent volumetric flow rate, temperature and pressure is useful for determining the impact of that compound to the atmosphere.  
5.3 Known concentrations of target analytes are spiked into the effluent to evaluate the sampling and analytical system’s effectiveness for transport and quantification of the target analytes, and to ensure that the data collected are meaningful.  
5.4 The FTIR measurement data are used to evaluate process conditions, emissions control devices, and for determining compliance with emission standards or other applicable permits.  
5.5 Data quality objectives for each specific testing program must be specified and outlined in a test plan (Annex A1).5
SCOPE
1.1 This field test method employs an extractive sampling system to direct stationary source effluent to an FTIR spectrometer for the identification and quantification of gaseous compounds. Concentration results are provided. This test method is potentially applicable for the determination of compounds that (1) have sufficient vapor pressure to be transported to the FTIR spectrometer and (2) absorb a sufficient amount of infrared radiation to be detected.  
1.2 This field test method provides near real time analysis of extracted gas samples from stationary sources. Gas streams with high moisture content may require conditioning to minimize the excessive spectral absorption features imposed by water vapor.  
1.3 This field test method requires the preparation of a source specific field test plan. The test plan must include the following: (1) the identification of the specific target analytes (2) the known analytical interferents specific to the test facility source effluent (3) the test data quality necessary to meet the specific test requirements and (4) the results obtained from the laboratory testing (see Annex A1 for test plan requirements).  
1.4 The FTIR instrument range should be sufficient to measure from high ppm(v) to ppb(v) and may be extended to higher or lower concentrations using any or all of the following procedures:  
1.4.1 The gas absorption cell path length may be either increased or decreased,  
1.4.2 The sample conditioning system may be modified to reduce the water vapor, CO2, and other interfering compounds to levels that allow for quantification of the target compound(s), and  
1.4.3 The analytical algorithm may be modified such that interfering absorbance bands are minimized or stronger/weaker absorbance bands are employed for the target analytes.  
1.5 The practical minimum detectable concentration is instrument, compound, and interference specific (see Annex A2 for procedures to estimate the achievable minimum detectable concentrations (MDCs)). The actual sensitivity of the FTIR measurement system for the individual target analytes depends upon the following:  
1.5.1 The specific infrared absorptivity (signal) and wavelength analysis region for each target analyte,  
1.5.2 The amount of instrument noise (see Annex A6), and  
1.5.3 The concentration of interfering compounds in the sample gas (in particular, percent moisture and CO2), and the amount of spectral overlap imparted by these compounds in the wavelength region(s) used for the quantification of the target analytes.  
1.5.4 Any sampling system interferences such as adsorption or outgassing.  
1.6 Practices E168 and E1252 are suggested for additional reading.  
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of thi...

General Information

• Status: Published
• Publication Date: 30-Nov-2020
• ICS: 71.040.40 - Chemical analysis
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.03 - Ambient Atmospheres and Source Emissions

Relations

• Refers: ASTM D1356-20a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Sep-2020
• Refers: ASTM D1356-20 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Mar-2020
• Refers: ASTM D1356-15a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Oct-2015
• Refers: ASTM D1356-15 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Jul-2015
• Refers: ASTM D1356-14b - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Dec-2014
• Refers: ASTM D1356-14a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-May-2014
• Refers: ASTM D1356-14 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Jan-2014
• Refers: ASTM D1356-05(2010) - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Apr-2010
• Refers: ASTM E1252-98(2007) - Standard Practice for General Techniques for Obtaining Infrared Spectra for Qualitative Analysis
• Effective Date: 01-Dec-2007
• Refers: ASTM E168-06 - Standard Practices for General Techniques of Infrared Quantitative Analysis (Withdrawn 2015)
• Effective Date: 01-Mar-2006
• Refers: ASTM D1356-05 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-May-2005
• Refers: ASTM D3195-90(2004) - Standard Practice for Rotameter Calibration
• Effective Date: 01-Oct-2004
• Refers: ASTM E168-99(2004) - Standard Practices for General Techniques of Infrared Quantitative Analysis
• Effective Date: 01-Feb-2004
• Refers: ASTM D1356-00a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 10-Nov-2000
• Refers: ASTM E168-99 - Standard Practices for General Techniques of Infrared Quantitative Analysis
• Effective Date: 10-Oct-1999

Overview

ASTM D6348-12(2020), “Standard Test Method for Determination of Gaseous Compounds by Extractive Direct Interface Fourier Transform Infrared (FTIR) Spectroscopy,” specifies a comprehensive approach for the identification and quantification of gaseous compounds in stationary source effluents. Developed by ASTM International, this field test method utilizes an extractive sampling system to transport stack gases to an FTIR spectrometer, enabling rapid, on-site, multicomponent gas analysis.

This standard is widely applicable to industrial facilities interested in assessing gaseous emissions for process control, environmental compliance, and regulatory reporting. It is adaptable to a wide range of target analytes, provided those compounds possess adequate vapor pressure and display significant infrared absorption features.

Key Topics

• FTIR-Based Gas Analysis: The method directs effluent gases through a sample interface to an FTIR spectrometer, where compounds are identified and quantified based on their unique infrared spectra.

• Multicomponent Detection: FTIR systems allow for simultaneous measurement of multiple gaseous species-ideal for environments where diverse pollutants must be assessed.

• Volume Concentration and Emission Calculations: Results are reported in volume concentration, with guidance for converting these values into mass emission rates using molecular weight, volumetric flow, temperature, and pressure.

• Data Quality Assurance (QA/QC): Strict requirements for sample spiking, instrument calibration, and response time verification are emphasized to ensure that analytical data are meaningful and verifiable.

• Test Planning: The standard mandates the preparation of a source-specific field test plan, including:

  • Identification of target analytes
  • Recognition of analytical interferents
  • Data quality requirements
  • Laboratory validation results

• Dealing with Interferences: Recommendations are provided for minimizing interference from water vapor, CO₂, or other spectrally overlapping compounds-crucial for accurate quantification.

Practical Applications

ASTM D6348-12(2020) is especially valuable to:

• Industrial Environmental Managers: Ensuring continuous compliance with air emissions regulations.
• Consulting and Testing Laboratories: Supporting regulatory reporting, research studies, and process troubleshooting.
• Process Engineers: Optimizing emissions control devices and evaluating changes in process conditions.
• Regulatory Agencies: Verifying compliance with operating permits and emission limits through robust and defensible data collection.

The standard supports analysis of diverse environments, such as:

• Power plants
• Chemical manufacturing facilities
• Waste incinerators
• Refineries and petrochemical plants

Related Standards

ASTM D6348-12(2020) is designed to function alongside other ASTM and regulatory references, including:

• ASTM Practices E168 and E1252: General techniques for infrared quantitative and qualitative analysis.
• ASTM D1356: Terminology related to atmospheric sampling and analysis.
• EPA Methods (40 CFR Part 60, Appendix A):
  • Method 1: Sample and velocity traverses
  • Method 2: Stack gas velocity and volumetric flow rate
  • Method 3: Gas analysis for CO₂, O₂, excess air, and dry molecular weight
  • Method 4: Moisture content in stack gases

These references provide foundational principles for calibration, quality control, and data interpretation critical to effective use of ASTM D6348.

Summary

ASTM D6348-12(2020) offers a versatile, on-site field test protocol for the accurate, multicomponent analysis of stationary source gas emissions using FTIR spectroscopy. Its structured approach to test planning, calibration, and QA/QC makes it essential for industries and regulators seeking to ensure accurate emissions measurement and environmental compliance. By following this standard, users can generate data that are both scientifically robust and suitable for regulatory reporting.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6348 − 12 (Reapproved 2020)
Standard Test Method for
Determination of Gaseous Compounds by Extractive Direct
Interface Fourier Transform Infrared (FTIR) Spectroscopy
This standard is issued under the fixed designation D6348; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This extractive FTIR based field test method is used to quantify gas phase concentrations of
multiple target analytes from stationary source effluent. Because an FTIR analyzer is potentially
capable of analyzing hundreds of compounds, this test method is not analyte or source specific. The
analytes,detectionlevels,anddataqualityobjectivesareexpectedtochangeforanyparticulartesting
situation. It is the responsibility of the tester to define the target analytes, the associated detection
limits for those analytes in the particular source effluent, and the required data quality objectives for
each specific test program. Provisions are included in this test method that require the tester to
determine critical sampling system and instrument operational parameters, and for the conduct of
QA/QC procedures. Testers following this test method will generate data that will allow an
independent observer to verify the valid collection, identification, and quantification of the subject
target analytes.
1. Scope 1.4 The FTIR instrument range should be sufficient to
measure from high ppm(v) to ppb(v) and may be extended to
1.1 This field test method employs an extractive sampling
higherorlowerconcentrationsusinganyorallofthefollowing
system to direct stationary source effluent to an FTIR spec-
procedures:
trometer for the identification and quantification of gaseous
1.4.1 The gas absorption cell path length may be either
compounds. Concentration results are provided. This test
increased or decreased,
method is potentially applicable for the determination of
compounds that (1) have sufficient vapor pressure to be
1.4.2 The sample conditioning system may be modified to
transportedtotheFTIRspectrometerand(2)absorbasufficient
reduce the water vapor, CO , and other interfering compounds
amount of infrared radiation to be detected.
to levels that allow for quantification of the target
compound(s), and
1.2 Thisfieldtestmethodprovidesnearrealtimeanalysisof
extracted gas samples from stationary sources. Gas streams 1.4.3 The analytical algorithm may be modified such that
with high moisture content may require conditioning to mini- interferingabsorbancebandsareminimizedorstronger/weaker
mize the excessive spectral absorption features imposed by absorbance bands are employed for the target analytes.
water vapor.
1.5 The practical minimum detectable concentration is
1.3 This field test method requires the preparation of a
instrument, compound, and interference specific (see Annex
source specific field test plan. The test plan must include the
A2 for procedures to estimate the achievable minimum detect-
following: (1) the identification of the specific target analytes
able concentrations (MDCs)). The actual sensitivity of the
(2) the known analytical interferents specific to the test facility
FTIR measurement system for the individual target analytes
source effluent (3) the test data quality necessary to meet the
depends upon the following:
specific test requirements and (4) the results obtained from the
1.5.1 The specific infrared absorptivity (signal) and wave-
laboratory testing (see Annex A1 for test plan requirements).
length analysis region for each target analyte,
1.5.2 The amount of instrument noise (see AnnexA6), and
1.5.3 The concentration of interfering compounds in the
ThistestmethodisunderthejurisdictionofCommitteeD22onAirQualityand
is the direct responsibility of Subcommittee D22.03 on AmbientAtmospheres and
sample gas (in particular, percent moisture and CO ), and the
Source Emissions.
amountofspectraloverlapimpartedbythesecompoundsinthe
Current edition approved Dec. 1, 2020. Published December 2020. Originally
ɛ1
wavelength region(s) used for the quantification of the target
approved in 1998. Last previous edition approved in 2012 as D6348–12 . DOI:
10.1520/D6348-12R20. analytes.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6348 − 12 (2020)
1.5.4 Anysamplingsysteminterferencessuchasadsorption 3.2.1 absorbance, n—the negative logarithm of the
or outgassing. transmission, A = –log (I/I ), where I is the transmitted
intensity of the light and I is the incident intensity.
1.6 Practices E168 and E1252 are suggested for additional
3.2.2 absorptivity,adj—theamountofinfraredradiationthat
reading.
is absorbed by each molecule.
1.7 The values stated in SI units are to be regarded as
3.2.3 analyte spiking, n—the process of quantitatively co-
standard. No other units of measurement are included in this
adding calibration standards with source effluent to determine
standard.
the effectiveness of the FTIR measurement system to quantify
1.8 This standard does not purport to address all of the
the target analytes.
safety concerns, if any, associated with its use. It is the
3.2.4 analytical algorithm, n—the method used to quantify
responsibility of the user of this standard to establish appro-
the concentration of the target analytes and interferences in
priate safety, health, and environmental practices and deter-
each FTIR Spectrum. The analytical algorithm should account
mine the applicability of regulatory limitations prior to use.
for the analytical interferences by conducting the analysis in a
Additional safety precautions are described in Section 9.
portionoftheinfraredspectrumthatisthemostuniqueforthat
1.9 This international standard was developed in accor-
particular compound.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
3.2.5 analytical interference, n—the physical effects of su-
Development of International Standards, Guides and Recom-
perimposing two or more light waves.Analytical interferences
mendations issued by the World Trade Organization Technical
occur when two or more compounds have overlapping absor-
Barriers to Trade (TBT) Committee.
bance bands in their infrared spectra.
3.2.6 apodization, v—amathematicaltransformationcarried
2. Referenced Documents
out on data received from an interferometer to reduce the side
2.1 ASTM Standards:
lobes of the measured peaks. This procedure alters the instru-
D1356Terminology Relating to Sampling and Analysis of
ment’s response function. There are various types of transfor-
Atmospheres
mation; the most common forms are boxcar, triangular, Happ-
D3195Practice for Rotameter Calibration
Genzel, and Beer-Norton functions.
E168Practices for General Techniques of Infrared Quanti-
3.2.7 background spectrum, n—the spectrum taken in the
tative Analysis
absence of absorbing species or sample gas, typically con-
E1252Practice for General Techniques for Obtaining Infra-
ducted using dry nitrogen or zero air in the gas cell.
red Spectra for Qualitative Analysis
3.2.8 bandwidth, adj—the width of a spectral feature as
2.2 EPA Methods (40 CFR Part 60 Appendix A):
recorded by a spectroscopic instrument. This width is listed as
Method 1Sample and Velocity Traverses for Stationary
the full width at the half maximum of the feature or as the half
Sources
width at the half maximum of the spectral feature. This is also
Method 2 SeriesDetermination of Stack Gas Velocity and 4
referred to as the line width (1).
Volumetric Flow Rate (Type S Pitot Tube)
3.2.9 beamsplitter,n—adevicelocatedintheinterferometer
Method 3 SeriesGasAnalysis for Carbon Dioxide, Oxygen,
that splits the incoming infrared radiation into two separate
Excess Air, and Dry Molecular Weight
beams that travel two separate paths before recombination.
Method4SeriesDeterminationofMoistureContentinStack
3.2.10 Beer’s law, n—the principal by which FTIR spectra
Gases
are quantified. Beer’s law states that the intensity of a mono-
chromatic plane wave incident on an absorbing medium of
3. Terminology
constant thickness diminishes exponentially with the number
3.1 Definitions—See Terminology D1356 for definition of
of absorbers in the beam. Strictly speaking, Beer’s law holds
terms related to sampling and analysis of atmospheres.
only if the following conditions are met: (1) perfectly mono-
3.2 Definitions of Terms Specific to This Standard—This
chromatic radiation (2) no scattering (3) a beam that is strictly
section contains the terms and definitions used in this test
collimated (4) negligible pressure-broadening effects (2, 3).
method and those that are relevant to extractive FTIR based
For an excellent discussion of the derivation of Beer’s law, see
sampling and analysis of stationary source effluent. When
(4).
possible, definitions of terms have been drawn from authori-
3.2.11 calibration transfer standard, n—a certified calibra-
tative texts or manuscripts in the fields of air pollution
tion standard that is used to verify the instrument stability on a
monitoring, spectroscopy, optics, and analytical chemistry.
daily basis when conducting sampling.
3.2.12 classical least squares, n—a common method of
2 analyzing multicomponent infrared spectra by scaled absor-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
bance subtraction.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:// Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
www.access.gpo.gov. the standard.
D6348 − 12 (2020)
3.2.13 condenser system,(dryer), n—a moisture removal sample spectra. The instrument specific reference spectra are
system that condenses water vapor from the source effluent to used in the analytical algorithm.
provide a dry sample to the FTIR gas cell. Part of the sample
3.2.25 intensity, n—the radiant power per unit solid angle.
conditioning system.
Whentheterm spectral intensityisused,theunitsarewattsper
3.2.14 cooler, n—a device into which a quantum detector is
steradian per nanometre. In most spectroscopic literature, the
placed for maintaining it at a low temperature in an IR system. term intensity is used to describe the power in a collimated
Atalowtemperature,thedetectorprovidesthehighsensitivity
beam of light in terms of power per unit area per unit
that is required for the IR system. The two primary types of wavelength. However, in the general literature, this definition
coolers are a liquid nitrogen Dewar and a closed-cycle Stirling
is more often used for the term irradiance,or normal irradi-
cycle refrigerator. ance (9, 10).
3.2.15 electromagnetic spectrum, n—the total set of all
3.2.26 interferogram, n—the effects of interference that are
possible frequencies of electromagnetic radiation. Different detected and recorded by an interferometer, the output of the
sources may emit over different frequency regions. All elec-
FTIR and the primary data are collected and stored (8, 10).
tromagnetic waves travel at the same speed in free space (5).
3.2.27 interferometer, n—any of several kinds of instru-
3.2.16 extractive FTIR, n—a means of employing FTIR to
ments used to produce interference effects. The Michelson
quantify concentrations of gaseous components in stationary
interferometer used in FTIR instruments is the most famous of
sourceeffluent.ItconsistsofdirectinggassamplestotheFTIR
a class of interferometers that produce interference by the
cell without collection on sample media.
division of amplitude (11).
3.2.17 fingerprint region, n—the region of the absorption
3.2.28 irradiance, n—radiant power per unit projected area
spectrum of a molecule that essentially allows its unequivocal
of a specified surface. This has units of watts per square
identification. For example, the organic fingerprint region
centimetre.Theterm spectral irradianceisusedtodescribethe
–1
covers the wave number range from 650 to 1300 cm (6).
irradianceasafunctionofwavelength.Ithasunitsofwattsper
square centimetre per nanometre (9).
3.2.18 Fourier transform, v—a mathematical transform that
allowsanaperiodicfunctiontobeexpressedasanintegralsum
3.2.29 laser, n—an acronym for the term light amplification
over a continuous range of frequencies (7). The interferogram
by stimulated emission of radiation. A source of light that is
represents the detector response (intensity) versus time, the
highly coherent, both spatially and temporally (1).
Fourier transform function produces intensity as a function of
3.2.30 light, n—strictly,lightisdefinedasthatportionofthe
frequency.
electromagneticspectrumthatcausesthesensationofvision.It
–1 –1
3.2.19 frequency position, n—the accepted exact spectral
extends from about 25 000 cm to about 14 300 cm (5).
linepositionforaspecificanalyte.Awavenumberorfractional
3.2.31 minimum detectable concentration, n—the minimum
wavenumber is used to determine whether spectral shifts have
concentration of a compound that can be detected by an
occurred with time.
instrument with a given statistical probability. Usually the
3.2.20 FTIR, n—an abbreviation for Fourier transform in-
detection limit is given as three times the standard deviation of
frared.Aspectroscopicinstrumentusingtheinfraredportionof
the noise in the system. In this case, the minimum concentra-
the electromagnetic spectrum. The working component of this
tion can be detected with a probability of 99.7% (9, 12). See
system is an interferometer. To obtain the absorption spectrum
AnnexA2ofthisstandardforaseriesofprocedurestomeasure
as a function of frequency, a Fourier transform of the output of
MDC.
theinterferometer mustbeperformed.Foranin-depthdescrip-
3.2.32 native effluent concentration, n—the underlying ef-
tion of the FTIR, see (8).
fluent concentration of the target analytes.
3.2.21 fundamental CTS, n—a NIST traceable reference
3.2.33 noise equivalent absorbance (NEA), n—the peak-to-
spectrum with known temperature and pressure, that has been
peak noise in the spectrum resulting from the acquisition of
recorded with an absorption cell that has been measured using
two successive background spectra.
either a laser or other suitably accurate physical measurement
3.2.34 path length, n—the distance that the sample gas
device.
interacts with the infrared radiation.
3.2.22 infrared spectrum, n—thatportionoftheelectromag-
–1
3.2.35 peak-to-peak noise, n—the absolute difference from
netic spectrum that spans the region from about 10 cm to
–1
the highest positive peak to the lowest negative peak in a
about 12 500 cm . It is divided (6) into (1) the near-infrared
–1
defined spectral region.
region(from12500to4000cm ),(2)themid-infraredregion
–1
(from 4000 to 650 cm ), and (3) the far-infrared region (from
3.2.36 primary particulate matter filter, n—filter of 0.3
–1
650 to 10 cm ).
microns or less to remove particulate matter and thus protect
the sample interface. The analyte spike must be delivered
3.2.23 instrument function, n—the function superimposed
on the actual absorption line shape by the instrument. This is upstream(thatis,onthe“dirtyside”)oftheprimaryparticulate
matter filter (if used).
sometimes referred to as the slit function; a term taken from
instruments that use slits to obtain resolution.
3.2.37 reactive compounds, n—compound(s) available in
3.2.24 instrument specific reference spectra, n—reference compressed gas form with a certified concentration within
spectra collected on the instrument that collects the actual 610%accuracy.Thecompoundisusedasanoverallsurrogate
D6348 − 12 (2020)
for the test program target analytes for the purpose of conduct- 3.2.50 spectral interference, n—when the absorbance fea-
ing analyte spikes and for QA purposes. The test program tures from two or more gases cover the same wave number
manager, client, or regulator agency is responsible for deter- regions, the gases are said to exhibit spectral interference.
mining the reactive compounds to be used for this purpose.
3.2.51 system mechanical response time, n—the amount of
time that is required to obtain a stable instrument response
3.2.38 reference library—the available reference spectra for
use in developing the analytical algorithm. when directing a non-retained calibration standard through the
entire sampling system.
3.2.39 reference spectra, n—spectra of the absorbance ver-
3.2.52 system zero, n—a system zero is conducted by
sus wave number for a pure sample of a set of gases. These
directing nitrogen or zero air through the entire sampling
spectra are obtained under controlled conditions of pressure
system to demonstrate whether any target analytes or interfer-
and temperature, pathlength, and known concentration. The
ences are present.
spectraareusedtoobtaintheunknownconcentrationsofgases
in stationary source effluent samples.
3.2.53 transmittance, n—percent transmittance is defined as
the amount of infrared radiation that is not absorbed by the
3.2.40 resolution, n—the minimum separation that two
sample, % T = (I/Io) × 100.
spectral features can have and still, in some manner, be
distinguishedfromoneanother.Acommonlyusedrequirement
3.2.54 truncation, v—the act of stopping a process before it
for two spectral features to be considered just resolved is the
iscomplete.InFTIRspectrometers,thefinitemovementofthe
Raleighcriterion.Thisstatesthattwofeaturesarejustresolved
interferometer mirror truncates the theoretically infinite scale
when the maximum intensity of one falls at the first minimum
of the interferogram.
of the other (11, 13). This definition of resolution and the
3.2.55 volumetric flowrate, n—see 40 CFR part 60 Appen-
Raleigh criterion are also valid for the FTIR, although there is
dix A, Method 2. The flowrate is necessary when calculating
another definition in common use for this technique. This
stationary source emissions in terms of mass per unit of time.
definition states that the minimum separation in wave numbers
3.2.56 wave number, n—the number of electromagnetic
oftwospectralfeaturesthatcanberesolvedisthereciprocalof
waves per centimetre. This term has units of reciprocal
the maximum optical path difference (in centimetres) of the
–1
centimetres (cm ).
two-interferometer mirrors employed. (8, 14)
3.2.41 root mean square (RMS) noise, n—the root mean
4. Summary of Test Method
square difference between the absorbance values that form a
4.1 Sampling—Stationary source effluent is extracted from
segment in a spectrum and the mean absorbance value of that
the stack or duct at a constant rate, filtered and conditioned (if
segment.
required),andtransportedtotheFTIRgascellforanalysis.For
3.2.42 sample conditioning system, n—the part of the sam-
sampling hot/wet sample effluent, all sample extraction and
plingsystemthatremoveswatervapor,CO ,orotherspectrally
measurement system components shall be maintained at tem-
interfering compounds before analysis.
peratures that prevent sample condensation. If sample condi-
3.2.43 sample interface, n—the entire sampling system
tioning is used, then the condenser system (or other device)
consisting of the sample probe, sample transport line, and all
should minimize the contact between the condensed water
other components necessary to direct effluent to the FTIR gas
vapor and the effluent.
cell.
4.2 Analysis—Stationary source effluent is directed to the
3.2.44 sampling system, n—see sample interface.
Fourier transform infrared (FTIR) spectrometer gas cell. Indi-
vidual compounds in the effluent absorb characteristic infrared
3.2.45 sampling system interference, n—aninterferencethat
radiation that is proportional to their concentration. The FTIR
prohibitsorpreventsdeliveryofthetargetanalytestotheFTIR
system identifies and quantifies multiple compounds simulta-
gas cell. Examples of potential sampling system interferences
neously.
are unwanted moisture condensation within the sampling
system, heavy deposition of particulate matter or aerosols
NOTE1—AnFTIRinterferometermodulatesthepolychromaticinfrared
within the sampling system components, or reactive gases. source so that individual wavelengths in the infrared beam can be
differentiated. This is accomplished using a beam splitter which divides
3.2.46 sampling system recovery, n—the amount of calibra-
the infrared radiation emanating from the source, and forces the two
tion standard that is recovered through the sampling system
beamstotraversetwoseparatepaths(oneofwhichremainsconstantwhile
during the analyte spiking procedure. theotherchangeslengthwithtimeusingamovingmirrororotherdevice).
The two beams are recombined at the beam splitter to produce a variable
3.2.47 signal-to-noise, n—in general terms, the signal-to-
phasedifferencebetweenthetwoinfraredbeams.Itistheresponsibilityof
noise is defined as the area of the target analyte peaks divided
the tester to develop or employ the appropriate analytical algorithms (see
by the NEA area in the same spectroscopic region. Annex A7).
NOTE 2—The modulated infrared radiation produced by the interfer-
3.2.48 source, n—the device that supplies the electromag-
ometerisfocusedthroughthegasabsorptioncellcontainingthesampleto
netic energy for the various instruments used to measure
be analyzed. A single interferometer scan is defined as the detector
atmospheric gases. These generally are a Nernst glower or response over the time required to perform a single interferometer motion
(that is, allowing the moving mirror or other device to traverse its
globar for the infrared region or a xenon arc lamp for the
minimum to maximum path length). Co-addition of numerous sequential
ultraviolet region.
interferometer scans produces an averaged interferogram with higher
3.2.49 spectral intensity, n—see intensity. signal-to-noise than a single scan alone.
D6348 − 12 (2020)
NOTE 3—A Fourier transform of these data convert them from an of such potential sampling system interferences. Specific provisions and
interferogram to a single beam infrared spectrum. Transmittance or performancecriteriaareincludedinthistestmethodtodetectthepresence
absorbance double beam spectra are produced by ratioing the single beam of sampling system interferences.
spectrum to the background absorbance spectrum. Target analytes are
7. Apparatus
identifiedandquantifiedby(1)visualinspectionoftheinfraredspectra(2)
comparing sample spectra to infrared reference spectra and (3) computer
7.1 Analytical Instrumentation:
identification and quantification of infrared spectral patterns using classi-
7.1.1 Fourier Transform Infrared (FTIR) Spectrometer,with
cal least squares or other comparable techniques.
gas absorption cell (having either an adjustable or fixed path
4.3 Quality Assurance—Calibration standard gases, and ni-
length), interferometer response time, and signal-to-noise ratio
trogenorzeroair(systemblanks)mustbeanalyzeddirectlyby
that are sufficient to perform the analysis called for in the data
the FTIR instrumentation and through the entire sampling
quality objectives. The FTIR gas cell must have provisions to
system at the beginning and at the end of each test day to
monitor the pressure and temperature of the contained sample
ensure measurement system integrity. Specific QA/QC proce-
gas.
dures are detailed in Annex A1 – Annex A8.
7.1.2 Computer/Data Acquisition System, with compatible
FTIR software for control of the FTIR system, acquisition of
5. Significance and Use
the infrared data, and analysis of the resulting spectra. This
5.1 The FTIR measurements provide for multicomponent
systemmusthavealsoadequateharddiskstoragetoarchiveall
on-site analysis of source effluent.
necessary data, and back-up media storage.
5.2 This test method provides the volume concentration of
7.2 Sampling System:
detected analytes. Converting the volume concentration to a
7.2.1 Sampling Probe, glass, stainless steel or other appro-
mass emission rate using a particular compound’s molecular
priate material of sufficient length and physical integrity to
weight, and the effluent volumetric flow rate, temperature and
sustainheating,preventadsorptionofanalytes,andtoreachthe
pressureisusefulfordeterminingtheimpactofthatcompound
gas sampling point.
to the atmosphere.
7.2.2 Calibration Assembly, to introduce calibration stan-
5.3 Known concentrations of target analytes are spiked into dardsintothesamplingsystemattheprobeoutlet,upstreamof
the effluent to evaluate the sampling and analytical system’s the primary particulate filter.
effectiveness for transport and quantification of the target
NOTE 6—If condensation could occur, then provisions must be made to
analytes, and to ensure that the data collected are meaningful.
deliver the calibration standards at the same temperature as that of the
effluent samples.
5.4 The FTIR measurement data are used to evaluate
process conditions, emissions control devices, and for deter- 7.2.3 Particulate Filters, (recommended) rated at 0.3 µm,
miningcompliancewithemissionstandardsorotherapplicable placedimmediatelyaftertheheatedprobeandafterthesample
permits. condenser system.
7.2.4 Pump, leak-free, with heated head, capable of main-
5.5 Dataqualityobjectivesforeachspecifictestingprogram
5 taining an adequate sample flow rate (typically 15 L/min).
must be specified and outlined in a test plan (Annex A1).
7.2.5 Sampling Line, heated to prevent sample
condensation, made of stainless steel, TFE-fluorocarbon, or
6. Interferences
other material that minimizes adsorption of analytes, and of
6.1 Analytical (Spectral) Interferences—Analytical interfer-
minimal length to reach the sampling point(s) of concern.
ences occur when the target analyte infrared absorbance
7.2.6 Sample Conditioning System, (if used) a refrigeration
features overlap with those of other components present in the
unit, permeation dryer, or other device capable of reducing the
sample gas matrix.
moisture of the sample gas to a level acceptable for analysis.
NOTE 4—These interferences can make detection of the target analytes
NOTE 7—Additional sample conditioning components such as a CO
difficultorimpossibledependinguponthestrength(concentrationrelative
scrubber may be also required to quantify certain analytes at low
to the target analyte(s)) of the interfering absorption features. High
concentration levels.
concentrationsofinterferents(suchaswatervaporandCO )canabsorbso
strongly in the target analyte(s) analysis region that quantification of the
7.2.7 Sample Flow Rotameters, capable of withstanding
target analytes may be prohibited. In many cases, interferences may be
sample gas and measurement conditions, calibrated according
overcome using the appropriate analytical algorithms.
to Practice D3195, or equivalent.
6.2 Sampling System Interferences—Sampling system inter-
7.3 Auxiliary Equipment:
ferencesoccurwhentargetanalytesarenottransportedfullyto
7.3.1 Calibration Gas Manifold, capable of delivering ni-
the instrumentation when compounds damage the measure-
trogen or calibration gases through the sampling system or
ment system components, or when the sampling system out-
directly to the instrumentation. The calibration gas manifold
gases the target analytes or interfering compounds.
should have provisions to (1) provide for accurate dilution of
NOTE 5—Condensed water, reactive particulate matter, adsorptive sites
thecalibrationgasesasnecessary(2)tomonitorcalibrationgas
within the sampling system components, and reactive gases are examples
pressure and (3) introduce analyte spikes into the sample
stream (before the particulate filter) at a precise and known
flowrate.
Supporting data have been filed atASTM International Headquarters and may
7.3.2 Mass Flow Meters or Controllers, (optional) with a
beobtainedbyrequestingResearchReportRR:D22-1027.ContactASTMCustomer
Service at [e-mail]. stated accuracy and calibrated range (for example 62% of
D6348 − 12 (2020)
scalefrom0to500mL/minor0to5L/min)appropriateforthe field-testing. The procedures in these annexes need only be
concentrations of calibration or spike gases, or both. Calibrate conducted once before any testing using this measurement
using Practice D3195 or equivalent. system. Thereafter, these procedures are to be conducted
7.3.3 Digital Bubble Meter (or equivalent), NIST-traceable during the testing. Results from these annexes should be kept
with an accuracy of 62% of reading, with an adequate range with the measurement system so that system performance can
to calibrate the mass flow meters, controllers and rotameters at be determined relative to past performance.
the specific flow rates (within 610%) required to perform the 11.2.2 Measure and record the following:
method. 11.2.2.1 The system pathlength using the CTS (AnnexA4),
7.3.4 Tubing,TFC316stainlesssteelorotherinertmaterial, 11.2.2.2 The sampling system mechanical response time
of suitable diameter and length. using the CTS (Annex A4),
7.3.5 Gas Regulators, appropriate for individual gas
NOTE 8—The analytical algorithm results from the system pathlength
cylinders, constructed of materials that minimize adsorption of
check and from the sampling system mechanical response time check
analytes. should agree to within 65%.
11.2.2.3 The sampling system response time for the target
8. Reagents and Materials
analytes or similar compound (Annex A4),
11.2.2.4 The time required to achieve a system zero after
8.1 Calibration Standards, compressed gases, permeation
exposure to the analytes (Annex A4),
tubes and so forth, certified for the CTS measurements (2%
11.2.2.5 The sampling system recovery for the analytes or
accuracy), instrument calibrations and for conducting analyte
similarcompoundsusingtheanalytespikingtechnique(Annex
spiking (2% to 10%).
A5),
8.2 High Purity (HP) Nitrogen or Zero Air, for collection of
11.2.2.6 The noise equivalent absorbance (Annex A6), and
FTIR background, for purging sample lines and sampling
11.2.2.7 The selected water vapor frequency position and
system components, for diluting sample and calibration gas,
instrument resolution (AnnexA6).Water vapor and instrument
and for conducting blank measurements.
resolutionbandpositionscanbeselectedbythetester,butmust
8.3 Liquid Nitrogen (if required), for cooling quantum
remain constant so that instrument stability may be demon-
detectors.
strated.
11.3 Field Sampling and Analysis—Conduct the calcula-
9. Hazards
tions as detailed in Annex A2 for the particular test matrix.
9.1 Target Analytes—Many of the compounds that will be
11.3.1 Flow Rate and Moisture Determination—If effluent
analyzed using this test method are toxic and carcinogenic.
volumetric flow rates are required, perform EPA Methods 1
Therefore,avoidexposuretothesechemicals.Becausesomeof
through 3. Determine the source effluent moisture content to
the calibration standards are contained in compressed gas
within 2% using the FTIR analytical algorithm, Method 4,
cylinders, exercise appropriate safety precautions to avoid
wet-bulb dry-bulb measurements, saturation calculations, or
accidents in their transport and use.
other applicable means.
9.2 Sampling Location—Thistestmethodmayinvolvesam-
NOTE 9—If the moisture content of the flue gas is greater than
pling at locations having a high positive or negative pressure, appropriate for the instrument, condition the gas sample before introduc-
tion into the FTIR analyzer.
high temperatures, elevated heights, or high concentrations of
hazardous or toxic pollutants.
11.3.2 Sample Interface Preparation—Assemble the sam-
pling system.
9.3 Mobile or Remote Laboratory—To avoid exposure to
11.3.2.1 Allow the sample interface system components to
hazardouspollutantsandtoprotectpersonnelinthelaboratory,
reach stable operating temperatures and flow rates.
perform a leak check of the sampling system and inspect the
11.3.2.2 Conduct a sample interface leak check. This pro-
sample exhaust equipment before sampling the calibration
cedure is not mandatory if a system mechanical response time
standards or effluent. Properly vent the exhaust gases.
check is conducted in the field (see A4.5).
10. Reference Spectra
NOTE 10—Conduct the leak check under the same pressure or partial
vacuum conditions identical to the conditions anticipated during a test.
10.1 Prepareoracquirereferencespectraforallofthetarget
Operate the sampling system at a constant flow rate during the entire test.
analytes and interfering compounds that are expected in the
11.3.3 FTIRBackground—Flownitrogenorzeroairthrough
source effluent. (Follow the procedures detailed in Annex A3
the FTIR gas cell directly.
for preparation and acquisition of reference spectra.)
11.3.3.1 Acquire a background spectrum (Io) according to
manufacturers’s instructions. Use the same gas cell conditions
11. Procedure
(that is, temperature, pressure, and pathlength) as used for
11.1 Complete the procedures identified in Annex A1 –
sample analysis. Use the same number (or greater) of interfer-
Annex A3.
ometer scans as that used during sample analysis.
11.2 Pretest Preparations and Evaluations: 11.3.4 Pre-Test Calibration Transfer Standard (CTS)—Flow
11.2.1 Pre-Test—Determine the sampling system perfor- the calibration transfer standard gas through the FTIR gas cell,
manceinthelaboratoryinaccordancewithproceduresdetailed AnalyzetheCTSgasandverifytheresultsarewithin 65%of
inAnnexA4,AnnexA5,andAnnexA6beforeconductingany the certified value.
D6348 − 12 (2020)
11.3.5 System Recovery—Perform the analyte spiking pro- squares, inverse least squares, and so forth) that contain all
cedure for the selected analytes according to procedures target analytes and interferences, appropriate for the antici-
detailed in Annex A5. patedeffluentconditions.FollowproceduresdetailedinAnnex
11.3.5.1 Analyze and verify that the analyte recoveries are A7.
within the stated test data quality objectives for accuracy
NOTE 13—The analytical algorithm program(s) shall perform the
before proceeding.
analysesforalltestplanspecifiedanalytesandinterferentsbaseduponthe
11.3.5.2 Recordthemeasurementresultsandpercentrecov-
selected analytical infrared absorbance regions and the reference spectra
to be used for quantification.
ery for each of the spiked analytes.
11.3.6 System Zero Analysis—Flow nitrogen or zero air
12.2 CalculatetheMDCfollowingtheproceduresidentified
through the entire sampling system.
in Annex A2.
11.3.6.1 Analyze the gas sample and record the time re-
12.3 Report the specific target analyte and interferent con-
quired for the measured concentrations of residual calibration
centrations based upon the specific reference absorption path
gases to fall to 65% of their original value or to a value that
length, temperature, and pressure.
is acceptable to initiate sampling.
11.3.7 Acquire FTIR Spectra—Extract effluent sample gas 12.4 Report the error estimated for the measurement values
for a period equal to or greater than the system response time based upon residual absorbance or other appropriate statistical
before acquiring the first FTIR sample spectrum. means (follow procedures detailed in Annex A2).
NOTE 11—Extract the effluent continuously between successive sample
13. Post Test QA/QC
analysis to ensure constant equilibration within the sample interface
system.
13.1 Conduct the procedures detailed in Annex A8.
11.3.7.1 Obtain the requisite number of co-added interfer-
ometer scans and save data to a unique file name.
14. Reporting
11.3.8 Sample Analysis—Analyze the sample spectra ac-
14.1 Report the concentration results for the target analytes
cording to procedures outlined in Annex A7.
provided by the FTIR analysis.
11.3.8.1 Identify and quantify the concentrations of the
14.1.1 Include also the minimum detectable concentration
target analytes according to Section 12.
and the associated error of the measurement for each analyte.
11.3.9 Test Run—Typical test run durations are 60 min
14.1.2 The temperature, pressure, and pathlength of the
unless otherwise specified in the test plan.
FTIR gas sample cell, and
11.3.9.1 For test run durations longer than 60 min, continue
14.1.3 The source of the reference spectra used to prepare
to acquire and analyze additional samples.
the analytical algorithm.
11.4 Post-test CTS—Attheendofeachtest,(orattheendof
14.2 Include in the test report the results of all CTS
eachday)flowthecalibrationtransferstandardgasthroughthe
analyses, the results of all analyte spiking runs and the results
FTIR gas cell.
of all test method QA/QC activities conducted. Use the table
11.4.1 Analyze the CTS gas and verify that the pathlength
format in Fig. A4.1 or similar.
results agree to within 65% of the certified value of the CTS.
Record the measurement results.
14.3 Include records of the manufacturer’s certificates of
analysis for calibration transfer standards and all other calibra-
NOTE 12—If the results do not agree to within 65% of the expected
tion and analyte-spiking standards used during the test.
value, then the results from the run may be suspect. Identify and include
the source of error in the test report.
11.5 Data Storage—Identify all samples with a unique file 15. Precision and Bias
name.
15.1 Data Quality Objectives—A statement of the overall
11.5.1 Save the most fundamental data practical (interfero-
test data quality objectives must be included in each test plan
grams or single beam spectra) for a period that is determined
(see Annex A1).
by the test program (that is, for one to five years).
15.1.1 In general, an accuracy of 620% and a precision of
11.5.2 Ensure that appropriate sample information (for
610% for each measurement value should be possible when
example, sample pressure, temperature, and cell path length
procedures detailed in this standard are followed. In practice,
andsoforth)isincludedintheheaderrecordofthedatafile,or
an accuracy of 610% and precision of 65% are routinely
otherwise saved, so that it may be correlated with the data.
achieved.
Storage of data files to backup media is recommended.
16. Keywords
12. Calculations – Data Quantification
12.1 Prepare a computer analysis program or set of pro- 16.1 Fourier transform infrared spectroscopy; stack gas
grams (for example, classical least squares, partial least analysis; stationary source
D6348 − 12 (2020)
ANNEXES
(Mandatory Information)
A1. TEST PLAN REQUIREMENTS
A1.1 The purpose of the test plan is to define the test A1.3 The form in Fig.A1.1 (or similar) must be included in
objectivesintermsofrequireddataqualityobjectives.Thedata
each test plan.
qualityrequirementsaredeterminedbytheenduseofthedata.
A1.4 Additional information that should be included in the
For example, qualitative data are sufficient in many cases
test plan are (1) a generalized facility specific process descrip-
where determining the presence or absence of compounds is
tion and airflow schematic (2) a schematic of the sampling
desired. Other test scenarios, however, require quantitative
system (3) the sampling location pressure, temperature, and
results with a known degree of accuracy.
approximate volumetric flow rate (4) the percent moisture and
A1.2 The following are required for inclusion in all FTIR
CO content of the effluent (these can be estimated) (5) the
test plans: (1) a statement of the test data quality objectives (2)
height from grade or the approximate distance from the
the number of test runs that will be conducted and their
samplinglocationtothemobilelaboratoryoranalyticalsystem
duration (3) the averaging period(s) for each sample spectrum
location and (6) any health and safety concerns.
collected during each test run, (4) the results provided by
AnnexA4 (Fig.A4.1 provides an example format), and (5) the
results provided by Annex A2.
FIG. A1.1 Test Specific Target Analytes and Data Quality Objectives
A2. DETERMINATION OF FTIR MEASUREMENT SYSTEM MINIMUM DETECTABLE CONCENTRATIONS (MDC) AND
OVERALL CONCENTRATION UNCERTAINTIES
target analyte is a function of the three main components: (1) instrument
A2.1 Determination of FTIR Measurement System Mini-
noise, (2) analytical algorithm error, and (3) sampling system influences.
mum Detectable Concentration
NOTE A2.2—The instrument noise is the most fundamental noise and
A2.1.1 The minimum detectable concentration (MDC) for
includes only the FTIR instrument itself. The analytical algorithm error
each target analyte in the sample matrix must be determined
consists of the error imparted on the “true value” of the measurement by
thesoftwareanduseofreferencespectratoanalyzethedata.Thesampling
before and after the test program using the methods described
system influences are defined by the ability of the sample probe, heated
below.
extractive sample line and other associated components to deliver the
NOTE A2.1—The FTIR extractive measurement system MDC for each target analytes to the instrumentation.
D6348 − 12 (2020)
A2.2 Pre-Test Estimate of Instrument Noise-Limited Mini- A2.3.1.1 Quantify the blank samples using the analytical
mum Detectable Concentration. MDC#1 algorithm that will be used to quantify the field test data.
A2.2.1 MeasuretheNoiseEquivalentAbsorbance(NEA)in NOTE A2.9—The analytical algorithm should be able to produce both
positive and negative analyte concentrations.
eachoftheregionsusedforanalysisaccordingtoSectionA6.1.
Determine the RMS value of NEAfor analyte m in its analysis
A2.3.1.2 Quantifytheconcentrationforeachfieldtesttarget
region in accordance with:
analyte using a minimum of eight independent spectra, and
calculate the mean in accordance with the following equation:
N
m
m m 2
NEA 5ΠNEA (A2.1) P
~ !
rms ( i
n
j51
m m
C 5 C (A2.3)
ave ( p
P
p51
where:
where:
N = the number of absorbance points in the analysis
m
C = averageconcentrationforanalytemrepresentingthe
region for analyte m, and
ave
m
NEA = the individual absorbance values of the noise Analytical Bias for this compound,
i
spectruminthe analysis regionusedforanalytem. P = number of sample spectra used, and
m
C = concentration results produced by the analytical
p
m
A2.2.2 Convert the NEA for each of the analytes to a
rms
algorithm for target analyte m on spectrum p of the
noise limited concentration using:
set.
m
NEA C *L
NOTE A2.10—This method produces the average analytical algorithm
rms ref ref
MDC#1 5 * (A2.2)
m
error. Ideally, this number should be zero because the target analytes are
REF L
rms cell
not present in these spectra.
where:
A2.3.1.3 Refinetheanalyticalalgorithmuntiltheisasclose
MDC#1 = the noise limited minimum detectable concen-
to zero as possible for each target analyte.
tration for analyte m (ppm),
A2.3.1.4 Calculate the pre-test MDC#2 using the following
m
NEA = the root mean square absorbance value obtained
rms
equation:
on the reference spectrum for the same analysis
P
region as used in evaluating A2.1,
m m 2
MDC ppm 5 3 C 2 C (A2.4)
@ # Π~ !
C = theconcentrationthatwasusedingeneratingthe
2 ( ave p
ref P
p51
reference spectrum for analyte m,
NOTE A2.11—This number is three times the root mean square
D
L = the path length that was used in generating the
deviation (3 × RMS ) for each target analyte.
ref
reference spectrum of analyte m, and
A2.3.2 Determine the analytical algorithm error using re-
L = the path length of the cell which is to be used to
cell
sidual equivalent absorbance, MDC#3.
perform the measurements.
NOTE A2.3—The instrument noise defines the lower boundary for the NOTE A2.12—This MDC estimate is evaluated in an identical manner
measurementsystemMDC.TheactualmeasurementsystemMDCwillbe as the noise limited detection of A2.2, but is based on the residual
above this value. See Note A2.2 above.
equivalent absorbance (REA) in the spectra.
NOTE A2.13—The residual equivalent absorbance (REA) is the absor-
A2.3 Pre-Test Estimate of Analytical Algorithm Error
bance left after the analysis routines have accounted for all analytes
Minimum Detectable Concentrations. MDC#2 & (absorbances) in the spectrum. Many Classical Least Square (CLS)
algorithms return this residual spect
...