ASTM D2914-01(2007)
(Test Method)Standard Test Methods for Sulfur Dioxide Content of the Atmosphere (West-Gaeke Method)
Standard Test Methods for Sulfur Dioxide Content of the Atmosphere (West-Gaeke Method)
SIGNIFICANCE AND USE
Sulfur dioxide is a major air pollutant, commonly formed by the combustion of sulfur-bearing fuels. The Environmental Protection Agency (EPA) has set primary and secondary air quality standards (7) that are designed to protect the public health and welfare.
The Occupational Safety and Health Administration (OSHA) has promulgated exposure limits for sulfur dioxide in workplace atmospheres (8).
These methods have been found satisfactory for measuring sulfur dioxide in ambient and workplace atmospheres over the ranges pertinent in 5.1 and 5.2.
Method A has been designed to correspond to the EPA-Designated Reference Method (7) for the determination of sulfur dioxide.
SCOPE
1.1 These test methods cover the bubbler collection and colorimetric determination of sulfur dioxide (SO2) in the ambient or workplace atmosphere.
1.2 These test methods are applicable for determining SO2 over the range from approximately 25 g/m3 (0.01 ppm(v)) to 1000 μg/m 3 (0.4 ppm(v)), corresponding to a solution concentration of 0.03 g SO2/mL to 1.3 g SO2/mL. Beer's law is followed through the working analytical range from 0.02 g SO2/mL to 1.4 g SO2/mL.
1.3 The lower limit of detection is 0.075 g SO2/mL(1), representing an air concentration of 25 g SO2/m3 (0.01 ppm(v)) in a 30-min sample, or 13 g SO2/m3 (0.005 ppm(v)) in a 24-h sample.
1.4 These test methods incorporate sampling for periods between 30 min and 24 h.
1.5 These test methods describe the determination of the collected (impinged) samples. A Method A and a Method B are described.
1.6 Method A is preferred over Method B, as it gives the higher sensitivity, but it has a higher blank. Manual Method B is pH-dependent, but is more suitable with spectrometers having a spectral band width greater than 20 nm. Note 1These test methods are applicable at concentrations below 25 g/m 3 by sampling larger volumes of air if the absorption efficiency of the particular system is first determined, as described in Annex A4. Note 2
Concentrations higher than 1000 g/m 3 can be determined by using smaller gas volumes, larger collection volumes, or by suitable dilution of the collected sample with absorbing solution prior to analysis.
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 this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see 8.3.1, Section 9, and A3.11.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D2914 − 01(Reapproved 2007)
Standard Test Methods for
Sulfur Dioxide Content of the Atmosphere (West-Gaeke
Method)
This standard is issued under the fixed designation D2914; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 These test methods cover the bubbler collection and
bility of regulatory limitations prior to use. For specific
colorimetric determination of sulfur dioxide (SO)inthe
precautionary statements, see 8.3.1, Section 9, and A3.1.1.
ambient or workplace atmosphere.
1.2 These test methods are applicable for determining SO
2. Referenced Documents
over the range from approximately 25 µg/m (0.01 ppm(v)) to
2.1 ASTM Standards:
1000 µg/m (0.4 ppm(v)), corresponding to a solution concen-
D1071Test Methods for Volumetric Measurement of Gas-
tration of 0.03 µgSO /mL to 1.3 µgSO /mL. Beer’s law is
2 2
eous Fuel Samples
followed through the working analytical range from 0.02 µg
D1193Specification for Reagent Water
SO /mL to 1.4 µgSO /mL.
2 2
D1356Terminology Relating to Sampling and Analysis of
1.3 The lower limit of detection is 0.075 µgSO /mL(1) ,
Atmospheres
representing an air concentration of 25 µgSO /m (0.01
D1357Practice for Planning the Sampling of the Ambient
ppm(v)) in a 30–min sample, or 13 µgSO /m (0.005 ppm(v))
Atmosphere
in a 24–h sample.
D1605Practices for Sampling Atmospheres for Analysis of
Gases and Vapors (Withdrawn 1992)
1.4 These test methods incorporate sampling for periods
D1914PracticeforConversionUnitsandFactorsRelatingto
between 30 min and 24 h.
Sampling and Analysis of Atmospheres
1.5 These test methods describe the determination of the
D3195Practice for Rotameter Calibration
collected(impinged)samples.AMethodAandaMethodBare
D3609Practice for Calibration Techniques Using Perme-
described.
ation Tubes
1.6 Method A is preferred over Method B, as it gives the
D3631Test Methods for Measuring Surface Atmospheric
higher sensitivity, but it has a higher blank. Manual Method B
Pressure
is pH-dependent, but is more suitable with spectrometers
E1Specification for ASTM Liquid-in-Glass Thermometers
having a spectral band width greater than 20 nm.
E275PracticeforDescribingandMeasuringPerformanceof
Ultraviolet and Visible Spectrophotometers
NOTE 1—These test methods are applicable at concentrations below 25
2.2 Other Standards:
µg/m bysamplinglargervolumesofairiftheabsorptionefficiencyofthe
particular system is first determined, as described in Annex A4.
40 CFR Part 58 Probe and Monitoring Path Siting Criteria
NOTE 2—Concentrations higher than 1000 µg/m can be determined by
from Ambient Air Quality Monitoring, Appendix E
using smaller gas volumes, larger collection volumes, or by suitable
dilution of the collected sample with absorbing solution prior to analysis.
3. Terminology
1.7 This standard does not purport to address all of the
3.1 For definitions of terms used in this method, refer to
safety concerns, if any, associated with its use. It is the
Terminology D1356.
1 3
These test methods are under the jurisdiction ofASTM Committee D22 on Air For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Quality and are the direct responsibility of Subcommittee D22.03 on Ambient contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Atmospheres and Source Emissions. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved April 1, 2007. Published June 2007. Originally the ASTM website.
approved in 1970. Last previous edition approved in 2001 as D2914–01. The last approved version of this historical standard is referenced on
DOI:10.1520/D2914-01R07. www.astm.org.
2 5
The boldface numbers in parentheses refer to a list of references at the end of AvailablefromU.SGovernmentPrintingOffice,SuperintendentofDocuments,
this standard. 732 North Capitol Street, NW, Mail Stop: SDE, Washington, DC 20401.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2914 − 01 (2007)
4. Summary of Test Methods absorbing reagent can react with the stopper to yield errone-
ously high SO concentrations, and cause high and variable
4.1 Sulfur dioxide (SO ) is absorbed by aspirating a mea-
blank values). Insert a glass impinger stem, 6 mm inside
sured air sample through a tetrachloromercurate (TCM)
diameter and 158 mm long, into one port of the absorber cap.
solution, resulting in the formation of a dichlorosulfonatomer-
Taper the tip of the stem to a small diameter orifice (0.4 6 0.1
curate complex (2,3). Ethylenediaminetetraacetic acid diso-
mm)suchthataNo.79jeweler’sdrillbitwillpassthroughthe
dium salt (EDTA) is added to this solution to complex heavy
opening but a No. 78 drill bit will not. Clearance from the
metals that interfere with this method (4).
bottomoftheabsorbertothetipofthestemshallbe6 62mm.
Dichlorosulfonatomercurate, once formed, is stable to strong
Perform the orifice test before use to verify the orifice size.
oxidants(forexample,ozoneandoxidesofnitrogen) (2).After
Permanentlymarkthe50mLvolumelevelontheabsorber.See
the absorption is completed, any ozone in the solution is
Fig. 1.
allowed to decay (5). The liquid is treated first with a solution
7.1.3 Air Sample Probe—A sample probe meeting the re-
of sulfamic acid to destroy the nitrite anion formed from the
quirements of Section 7 of 40 CFR Part 58, Appendix E,
absorption of oxides of nitrogen present in the atmosphere (6).
(TFE-fluorocarbon, polypropylene, or glass with a residence
It is treated next with solutions of formaldehyde and specially
time less than 20 sec), used to transport ambient air to the
purified acid-bleached pararosaniline containing phosphoric
acid(H PO )tocontrolpH.Pararosaniline,formaldehyde,and sampling train location. Design or orient the end of the probe
3 4
to preclude the sampling of precipitation, large particles, etc.
the bisulfite anion react to form the intensely colored pararo-
saniline methyl sulfonic acid which behaves as a two-color pH
7.1.4 Moisture Trap—Glass or polypropylene trap as shown
indicator (2). The pH of the final solution is adjusted to the
in Fig. 1, placed between the absorber tube and flow control
desired value by the addition of prescribed amounts of 3 N
device to prevent entrained liquid from reaching the flow
H PO to the pararosaniline reagent (5).
control device. Pack the tube with coconut charcoal and glass
3 4
wool or with indicating silica gel. Charcoal is preferred when
5. Significance and Use
collecting long-term samples (1 h or more) if flow changes are
5.1 Sulfur dioxide is a major air pollutant, commonly routinely encountered.
formed by the combustion of sulfur-bearing fuels. The Envi-
7.1.5 Cap Seals—Seal the absorber and moisture trap caps
ronmental Protection Agency (EPA) has set primary and
securely to prevent leaks during use, by using heat-shrink
secondary air quality standards (7) that are designed to protect
material to prevent the caps coming loose during sampling,
the public health and welfare.
shipment, or storage.
5.2 The Occupational Safety and Health Administration 7.1.6 Filter,membrane,of0.8to2.0 µmporosity,withfilter
holder, to protect the flow controller from particles during
(OSHA) has promulgated exposure limits for sulfur dioxide in
workplace atmospheres (8). long-term sampling. This item is optional for short-term
sampling.
5.3 These methods have been found satisfactory for mea-
7.1.7 Pump,equippedwithvacuumgauge,capableofmain-
suring sulfur dioxide in ambient and workplace atmospheres
taining a vacuum greater than 70 kPa (0.7 atm) at the specified
over the ranges pertinent in 5.1 and 5.2.
flow rate across the flow control device.
5.4 Method A has been designed to correspond to the
7.1.8 Flow Control and Measurement Devices:
EPA-Designated Reference Method (7) for the determination
7.1.8.1 Flow Control Device—A calibrated rotameter and
of sulfur dioxide.
needle valve combination capable of maintaining and measur-
6. Interferences ing air flow to within 62 percent is suitable for short-term
sampling but shall not be used for long-term sampling. A
6.1 The interferences of oxides of nitrogen are eliminated
critical orifice can be used for regulating flow rate for both
bysulfamicacid (5,6),ofozonebytimedelay (5),andofheavy
long-termandshort-termsampling.Usea22-gagehypodermic
metals by EDTA and phosphoric acid (4,5). At least 60 µgof
needle 25 mm long as a critical orifice (10) to yield a flow rate
Fe(III), 10 µg of Mn(II), and 10 µg of Cr(III), 10 µg of Cu(II)
ofapproximately1L/minfora30–minsamplingperiod.When
and 22 µg of V(V) in 10 mL of absorbing reagent can be
sampling for 1 h, use a 23-gage hypodermic needle 16 mm in
tolerated in the procedure. No significant interference was
length to provide a flow rate of approximately 0.5 L/min.
found with 2.3 µgofNH (9).
Provide a flow control for a 24–h sample by a 27–gage
hypodermic needle critical orifice that is 9.5 mm in length so
7. Apparatus
that the flow rate is in the range of 0.18 to 0.22 L/min.
7.1 For Sampling:
7.1.8.2 Flow Measurement Device—calibrated as specified
7.1.1 Absorber, Short–Term Sampling—An all-glass midget
in 11.1.1, and used to measure sample flow rate at the
impinger having a solution capacity of 30 mL and a stem
monitoring site.
clearance of 4 6 1 mm from the bottom of the vessel is used
7.1.9 Thermometer—ASTMThermometer33C,meetingthe
for sampling periods of 30 min and 1 h (or any period
requirementsofSpecificationE1willmeettherequirementsof
considerably less than 24 h).
most applications in this method.
7.1.2 Absorber, 24-h Sampling—A glass or polypropylene
tube 32 mm in diameter and 164 mm long with a polypropyl- 7.1.10 Barograph or Barometer, capable of measuring at-
enetwo-portcap(rubberstoppersareunacceptablebecausethe mospheric pressure to 60.5 kPa (5 torr).
D2914 − 01 (2007)
FIG. 1 Sampling System
7.1.11 Temperature Control Device—To maintain the tem- 7.2.1 Shipping Container—tomaintainatemperatureof5 6
perature of the absorbing solution during sampling at 15 6 5°C while transporting the sample from the collection site to
10°C. Maintain the temperature of the collected sample at 5 6 the analytical laboratory. Ice coolers or refrigerated shipping
5°C,assoonaspossiblefollowingsamplinganduntilanalysis.
containers have been found to be satisfactory. The use of
Where an extended period of time may elapse before the eutectic cold packs instead of ice will give a more stable
collected sample can be moved to the lower storage
temperature control.
temperature, use a collection temperature near the lower limit
7.3 Analysis:
of the 15 6 10°C range to minimize losses during this period.
7.3.1 Spectrophotometer or Colorimeter—The instrument
Thermoelectric coolers specifically designed for this tempera-
shall be suitable for measurement of color at 548 nm for
ture control are available commercially and normally operate
MethodAor575nmforMethodB.ForMethodA,aneffective
in the range of 5 to 15°C. Small refrigerators can be modified
spectralbandwidthoflessthan15nmisrequiredsincereagent
to provide the required temperature control; however, insulate
blank problems may otherwise result. Verify the wavelength
the inlet lines from the lower temperatures to prevent conden-
calibration of the spectrophotometer in accordance with Prac-
sationwhensamplingunderhumidconditions.Asmallheating
tice E275 upon initial receipt of the instrument and after each
pad may be necessary when sampling at low temperatures
160 h or normal use or every 6 months, whichever occurs first,
(<7°C) to prevent the absorbing solution from freezing(11).
using a standard wavelength filter traceable to the National
7.1.12 Sampling Train Container—a light-proof box to
Institute of Standards and Technology.
shield the absorbing solution from light during and after
sampling.
7.3.2 Spectrophotometer Cells—A set of 1–cm path length
7.1.13 Timer—to initiate and to stop sampling for the 24–h
cells suitable for use in the visible region. If the cells are
sampling period. This is not a required piece of equipment;
unmatched, determine the matching correction factor in accor-
however, without the timer it will be necessary to manually
dance with 11.2.
startandstopthesampling.Anelapsedtimemetermayalsobe
7.3.3 Temperature Control Device—Conduct the color de-
used to determine the sampling period.
velopmentstepsduringanalysisinanenvironmentthatisinthe
7.1.14 The arrangement of the component parts for sam-
range of 20 to 30°C and controlled to 61°C. Perform both
pling is shown in Fig. 1.
calibration and sample analysis under identical conditions
7.2 Shipping: (within 1°C). Adequate temperature control may be obtained
D2914 − 01 (2007)
by means of constant temperature baths, water baths with 8.3.3 1-Butanol—Certain batches of 1-butanol contain oxi-
manual temperature control, or temperature controlled rooms. dants that create a sulfur dioxide (SO ) demand. Check by
7.3.4 TCM Waste Receptacle—A glass waste receptacle for shaking 20 mL of 1-butanol with 5 mL of 15% potassium
the storage of spent TCM solution. Store the vessel stoppered iodide (KI) solution. If a yellow color appears in the alcohol
in a hood at all times. phase, redistill the 1-butanol from silver oxide.
8.3.4 Formaldehyde (0.2%) —Dilute 5 mL of 36 to 38%
8. Reagents and Materials
formaldehyde (HCHO) to 1 L. Prepare this solution daily.
8.1 Purity of Reagents—Reagent grade chemicals shall be
8.3.5 Hydrochloric Acid (1 N)—Slowly and while stirring,
used in all tests.All reagents shall conform to the specification
add 86 mL of concentrated hydrochloric acid to 500 mL of
of the Committee on Analytical Reagents of the American
distilled water. Allow to cool and dilute to 1000 mL with
Chemical Society, where such specifications are available.
distilled water. This is stable for one year.
Other grades may be used, provided it is first ascertained that
8.3.6 Pararosaniline, Stock Solution (PRA), 0.2 %—
the reagent is of sufficiently high purity to permit its use
Dissolve 0.2 g of pararosaniline in 100 mLof water.The stock
without lessening the accuracy of the determination.
pararosaniline solution shall meet the following specifications:
8.3.6.1 The sol
...
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