ASTM D6348-12(2020)
(Test Method)Standard Test Method for Determination of Gaseous Compounds by Extractive Direct Interface Fourier Transform Infrared (FTIR) Spectroscopy
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...
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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 service@astm.org. 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
...
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