ASTM D3608-95(2000)e1
(Test Method)Standard Test Method for Nitrogen Oxides (Combined) Content in the Atmosphere by the Griess-Saltzman Reaction
Standard Test Method for Nitrogen Oxides (Combined) Content in the Atmosphere by the Griess-Saltzman Reaction
SCOPE
1.1 This test method covers the manual determination of the combined nitrogen dioxide (NO2) and nitric oxide (NO) content, total NOx; in the atmosphere in the range from 4 to 10000 ug/m3 (0.002 to 5 ppm (v)).
1.2 The maximum sampling period is 60 min at a flow rate of 0.4 L/min.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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.
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e1
Designation:D3608–95(Reapproved2000)
Standard Test Method for
Nitrogen Oxides (Combined) Content in the Atmosphere by
the Griess-Saltzman Reaction
This standard is issued under the fixed designation D 3608; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Footnote was removed from 7.2 in September 2000
1. Scope E 1 Specification for ASTM Thermometers
E 128 Test Method for Maximum Pore Diameter and Per-
1.1 This test method covers the manual determination of the
meability of Rigid Porous Filters for Laboratory Use
combined nitrogen dioxide (NO ) and nitric oxide (NO)
content, total NO ; in the atmosphere in the range from 4 to
x
3. Terminology
10 000 µg/m (0.002 to 5 ppm (v)).
3.1 Definitions—For definitions of terms used in this test
1.2 The maximum sampling period is 60 min at a flow rate
method, refer to Terminology D 1356.
of 0.4 L/min.
1.3 The values stated in SI units are to be regarded as the
4. Summary of Test Method
standard. The values given in parentheses are for information
4.1 The NO is quantitatively (1) converted to NO by a
only.
chromicacidoxidizer.TheresultingNO ,plustheNO already
2 2
1.4 This standard does not purport to address all of the
present, are absorbed in an azo-dye-forming reagent (2). A
safety concerns, if any, associated with its use. It is the
red-violet color is produced within 15 min, the intensity of
responsibility of the user of this standard to establish appro-
which is measured spectrophotometrically at 550 nm.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
5. Significance and Use
5.1 Both NO and NO play an important role in
2. Referenced Documents
photochemical-smog-forming reactions. In sufficient concen-
2.1 ASTM Standards:
trations NO is deleterious to health, agriculture, materials,
D 1071 Test Methods for Volumetric Measurement of Gas-
and visibility.
eous Fuel Samples
3 5.2 In combustion processes, significant amounts of NO
D 1193 Specification for Reagent Water
may be produced by combination of atmospheric nitrogen and
D 1356 Terminology Relating to Sampling and Analysis of
4 oxygen; at ambient temperatures, NO can be converted to NO
Atmospheres
by oxygen and other atmospheric oxidants. Nitrogen dioxide
D 1357 Practice for Planning the Sampling of the Ambient
4 also may be generated from processes involving nitric acid,
Atmosphere
nitrates, the use of explosives, and welding.
D 3195 Practice for Rotameter Calibration
D 3609 Practice for Calibration Techniques Using Perme-
6. Interferences
ation Tubes
6.1 Anysignificantinterferencesduetosulfurdioxide(SO )
D 3631 Test Methods for Measuring Surface Atmospheric
4 should be negated by the oxidation step. The addition of
Pressure
acetone to the reagent retards color-fading by forming a
temporary addition product with SO . This will protect the
reagent from incidental exposure to SO and will permit
readingthecolorintensitywithin4to5h(insteadofthe45min
This test method is under the jurisdiction of ASTM Committee D22 on
required without acetone) without appreciable losses.
Sampling and Analysis of Atmospheres and is the direct responsibility of Subcom-
mittee D22.03 on Ambient Atmospheres and Source Emissions.
Current edition approved Sept. 10, 1995. Published November 1995. Originally
published as D 3608 – 77T. Last previous edition D 3608 – 91.
Annual Book of ASTM Standards, Vol 14.03.
Annual Book of ASTM Standards, Vol 05.05.
Annual Book of ASTM Standards, Vol 14.02.
3 7
Annual Book of ASTM Standards, Vol 11.01. The boldface numbers in parentheses refer to the list of references appended to
Annual Book of ASTM Standards, Vol 11.03. this test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D3608–95 (2000)
6.2 A five-fold ratio of ozone to NO will cause a small 7.3.2 Measure the porosity of an absorber in accordance
interference, the maximal effect occurring in 3 h. The reagent with Test Method E 128. If the frit is clogged or visibly
assumes a slightly orange tint. discolored, carefully clean with concentrated chromic-sulfuric
6.3 The interferences from nitrous oxide and nitrogen pen- acid mixture, rinse well with water, and redetermine the
toxide, and other gases that might be found in polluted air are maximum pore diameter.
considered to be negligible. 7.3.3 Rinse the bubbler thoroughly with water and allow to
dry before using.
7.4 Mist Eliminator or Gas Drying Tube filled with acti-
vated charcoal or soda lime is used to prevent damage to the
flowmeter and pump.
7.5 Air-Metering Device—A calibrated glass variable-area
flowmeter, or dry gas meter coupled with a flow indicator
capableofaccuratelymeasuringaflowof0.4L/minissuitable.
7.6 Thermometer—ASTM Thermometer 33C, meeting the
requirements of Specification E 1, will be suitable for most
applications of the method.
7.7 Manometer, accurate to 670 Pa (0.20 in Hg).
7.8 Air Pump—A suction pump capable of drawing the
required sample flow for intervals of up to 60 min.
7.9 Spectrophotometer or Colorimeter— A laboratory in-
strument suitable for measuring the intensity of the red-violet
color at 550 nm, with stoppered tubes or cuvettes. The
wavelength band-width is not critical for this determination.
7.10 Stopwatch or Timer.
8. Reagents and Materials
8.1 Purity of Reagents—Reagent grade chemicals shall be
usedinalltests.Allreagentsshallconformtothespecifications
FIG. 1 Fritted Bubbler for Sampling Combined Nitrogen Oxides
of the Committee on Analytical Reagents of the American
Chemical Society, where such specifications are available.
Other grades may be used, provided it is first ascertained that
7. Apparatus
the reagent is of sufficiently high purity to permit its use
7.1 Sampling Probe—A glass or TFE-fluorocarbon (pre-
without lessening the accuracy of the determination.
ferred) tube, 6 to 10 mm in diameter, provided with a
8.2 Purity of Water—Water shall be deionized water in
downward-facing intake (funnel or tip). The dead volume of
accordance with Specification D 1193 forType I and II reagent
the system should be kept minimal, to avoid loss of NO on the
x water. Water must be nitrite-free.
surfaces of the apparatus.
8.3 Absorbing Reagent—Dissolve5gof anhydrous sulfa-
7.2 Oxidizer Tube—Soak 14 to 16-mesh firebrick or ⁄16-in.
nilic acid (or 5.5 g of the monohydrate) in almost a litre of
(1.5 mm) molecular sieve pellets in a 17 % aqueous solution of
water containing 140 mL of glacial acetic acid. Gentle heating
chromium trioxide (CrO ) for 10 to 30 min.After draining the
3 is permissible to speed up the process. To the cooled mixture,
excess solution and drying in an oven at 105°C for 30 min, the
add 20 mL of the 0.1 % stock solution of N-(1-naphthyl)-
solid oxidizer has a dull pink color. This color changes to rich
ethylenediamine dihydrochloride and 10-mLacetone. Dilute to
yellow (active color) after 24-h equilibration with ambient air
1 L. The solution will be stable for several months if kept
at 40 to 70 % relative humidity, or after drawing ambient air
well-stoppered in a brown bottle in the refrigerator. The
through at a flow rate of 0.5 L/min for 1 h. A change in color
absorbing reagent must be at room temperature before use.
to a greenish brown indicates the exhaustion of oxidizing
Avoidlengthycontactwithairduringbothpreparationanduse,
ability, and progresses with a sharp boundary. Place about 3 g
since absorption of nitrogen dioxide will discolor the reagent.
of the oxidizer in a 30-mLmidget impinger, or fill a 5-mm tube
8.4 Chromic Acid Oxidant—Dissolve 17 g of chromium
to a height of 80 mm and plug each end with glass wool.
trioxide (CrO ) in 100 mL of water.
7.3 Absorber—An all-glass bubbler with a 60-µm maxi-
8.5 N-(1-Naphthyl)-Ethylenediamine Dihydrochloride,
mum pore diameter frit, commonly labeled “coarse,” similar to
Stock Solution (0.1 %)—Dissolve 0.1 g of the reagent in 100
that illustrated in Fig. 1.
mL of water. The solution will be stable for several months if
7.3.1 The porosity of the fritted bubbler, as well as the
sampling flow rate, affect absorption efficiency. An efficiency
of over 95 % may be expected with a flow rate of 0.4 L/min or
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
less and a maximum pore diameter of 60 µm. Frits having a
listed by the American Chemical Society, see Analar Standards for Laboratory
maximum pore diameter less than 60 µm will have a higher
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
efficiency but will require an inconvenient pressure drop for
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
sampling. MD.
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D3608–95 (2000)
kept well-stoppered in a brown bottle in the refrigerator. measured to an accuracy of 1 to 2 %. With a tube permeating
(Alternatively,weighedsmallamountsofthesolidreagentmay NO at a rate of 0.1 µL/min (0.19 µg/min), the range of
be stored.) concentration of NO will be between 20 to 1000 µg/m (0.01
8.6 Sodium Nitrite (NaNO ), Standard Solution (0.0246 to 0.50 ppm (v)), a generally satisfactory range for ambient air
g/L)—One mL of this working solution of NaNO produces a conditions. When higher concentrations are desired, calibrate
colorequivalenttothatof20µgofNO in1Lofairat101kPa using longer permeation tubes.
(29.92 in Hg) and 25°C (see 10.2.2). Prepare fresh just before
10.2.1.4 Procedure for Preparing Simulated Calibration
use by diluting from a stock solution containing 2.460 g/L of Curves—A multitude of curves may be prepared by selecting
NaNO (calculated as 100 %). It is desirable to assay the solid
differentcombinationsofsamplingrateandsamplingtime.The
reagent (3). The stock solution is stable for 90 days at room following description represents a typical procedure for ambi-
temperatures, and for a year in a brown bottle under refrigera-
ent air sampling of short duration. The system is designed to
tion. provideanaccuratemeasureofNO inthe40to10 000µg/m
8.7 NO Permeation Device—See Practice D 3609.
(0.02 to 5 ppm (v)) range. It can be modified to meet special
needs.
9. Sampling
10.2.1.5 The dynamic range of the colorimetric procedure
9.1 Sampling procedures are described in Section 11. Dif-
fixes the total volume of the sample at 24 L, then to obtain
ferent combinations of sampling rates and time may be chosen
linearity between the absorbance of the solution and the
to meet special needs, but sample volumes and air flow rates
concentration of NO in parts per million by volume, select a
must be adjusted so that linearity is maintained between
constant sampling time. This fixing of sampling time is also
absorbance and concentration over the dynamic range.
desireable from a practical standpoint. In this case, select a
9.2 See Practices D 1357 for sampling guidelines.
sampling time of 60 min. Then, to obtain a 24-L sample
requiresaflowrateof0.4L/min.Calculatetheconcentrationof
10. Calibration and Standardization
standard NO in air as follows:
10.1 Sampling Equipment—If a flowmeter is used to mea-
P~1000!
sure sample air, calibrate it prior to use using Practice D 3195.
C 5 (1)
R 1 r
If a gas meter is used, calibrate it prior to use according to
Method D 1071.
where:
10.2 Analysis:
C = concentration of NO µg/m ,
10.2.1 Recommended Procedure: P = permeation rate, µg/min,
R = flow rate of diluent air, L/min,
10.2.1.1 Calibrated permeation tubes that contain liquefied
r = flow rate of diluent nitrogen, L/min, and
NO can be used to prepare standard concentrations of NO in
2 2
1000 = conversion factor to convert L to m .
air (4). See Practice D 3609 for details. Analyses of these
10.2.1.6 AplotoftheconcentrationofNO inµg/m (x-axis)
known concentrations give calibration curves that simulate all 2
against absorbance of the final solution (y-axis) will yield a
the operational conditions performed during the sampling and
straight line, the inverse or the slope of which is the factor for
chemical procedures. This calibration curve includes the im-
conversion of absorbance to µg/m . This factor includes the
portant correction for collection efficiency at various concen-
correction for collection efficiency. Any deviation from linear-
trations of NO .
ity at the lower concentration range indicates a change in
10.2.1.2 Prepare or obtain a TFE-fluorocarbon permeation
collection efficiency of the sampling system. Actually, the
tube that emits NO at a rate of 0.1 to 0.2 µg/min (0.05 to 0.1µ
standard concentration of 20 µg/m is slightly below the
L/min at standard conditions of 25°C and 101.3 kPa (29.92 in
dynamicrangeofthemethod.Ifthisistherangeofinterest,the
Hg).Calibratepermeationtubesunderastreamofdrynitrogen,
total volume of air collected should be increased to obtain
using Practice D 3609.
sufficient color within the dynamic range of the colorimetric
10.2.1.3 To prepare standard concentrations of NO as-
procedure. Also, once the calibration factor has been estab-
semble the apparatus, as shown in Practice D 3609, consisting
lished under simulated conditions, the conditions can be
of a water-cooled condenser; constant-temperature water bath
modified so that the concentration of NO is a simple multiple
maintained at 20°C; cylinders containing pure dry nitrogen and
of the absorbance of the colored solution.
pure dry air, with appropriate pressure regulators; needle
10.2.2 Alternate Procedure:
valves and flowmeters for the nitrogen and dry air diluent gas
streams. Bring the diluent gases to temperature by passage 10.2.2.1 Standardization is based upon the empirical obser-
vation (5) that 0.82 mol of NaNO produces the same color as
through a 2-m long copper coil immersed in the water bath.
Insert a calibrated permeation tube into the central tube of the 1 mol of NO . One mL of the working standard contains 24.6
µg of NaNO . Since the molecular weight of NaNO is 69.1,
condenser maintained at 20°C by circulating water from the
2 2
constant-temperature bath and pass a stream of nitrogen over this is equivalent to: (24.6/69.1) 3 (46.0/0.82) = 20 µg of NO .
thetubeatafixedrateofapproximately50mL/min.Dilutethis 10.2.2.2 For convenience, standard conditions are taken as
gasstreamtothedesiredconcentrationbyvaryingtheflowrate 101 kPa (29.92 in. Hg) and 25°C, at which the molar gas
of the “clean dry air.” This flow rate can n
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