1、Designation: D1607 91 (Reapproved 2011)Standard Test Method forNitrogen Dioxide Content of the Atmosphere (Griess-Saltzman Reaction)1This standard is issued under the fixed designation D1607; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method
3、2covers the manual determination ofnitrogen dioxide (NO2) in the atmosphere in the range from 4to 10 000 g/m3(0.002 to 5 ppm(v) when sampling isconducted in fritted-tip bubblers.1.2 For concentrations of NO2in excess of 10 mg/m3(5ppm(v), as occur in industrial atmospheres, gas burner stacks,or autom
4、otive exhaust, or for samples relatively high in sulfurdioxide content, other methods should be applied. See forexample Test Method D1608.1.3 The maximum sampling period is 60 min at a flow rateof 0.4 L/min.1.4 The values stated in SI units are to be regarded asstandard. The values given in parenthe
5、ses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations
6、prior to use. See also 7.2.2 forother precautions.2. Referenced Documents2.1 ASTM Standards:3D1071 Test Methods for Volumetric Measurement of Gas-eous Fuel SamplesD1193 Specification for Reagent WaterD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD1357 Practice for Planning the Sam
7、pling of the AmbientAtmosphereD1608 Test Method for Oxides of Nitrogen in GaseousCombustion Products (Phenol-Disulfonic Acid Proce-dures)D3195 Practice for Rotameter CalibrationD3609 Practice for Calibration Techniques Using Perme-ation TubesD3631 Test Methods for Measuring Surface AtmosphericPressu
8、reE1 Specification for ASTM Liquid-in-Glass ThermometersE128 Test Method for Maximum Pore Diameter and Per-meability of Rigid Porous Filters for Laboratory Use3. Terminology3.1 For definitions of terms used in this test method, refer toTerminology D1356.4. Summary of Test Method4.1 The NO2is absorbe
9、d in an azo-dye-forming reagent(1).4Ared-violet color is produced within 15 min, the intensityof which is measured spectrophotometrically at 550 nm.5. Significance and Use5.1 Nitrogen dioxide plays an important role in photochemi-cal smog-forming reactions and, in sufficient concentrations, isdelete
10、rious to health, agriculture, materials, and visibility.5.2 In combustion processes, significant amounts of nitricoxide (NO) may be produced by combination of atmosphericnitrogen and oxygen; at ambient temperatures NO can beconverted to NO2by oxygen and other atmospheric oxidants.Nitrogen dioxide ma
11、y also be generated from processes involv-ing nitric acid, nitrates, the use of explosives, and welding.6. Interferences6.1 Aten-fold ratio of sulfur dioxide (SO2)toNO2producesno effect. A thirty-fold ratio slowly bleaches the color to aslight extent. The addition of acetone to the reagent retards t
12、he1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.03 on AmbientAtmospheres and Source Emissions.Current edition approved Oct. 1, 2011. Published October 2011. Originallyapproved in 1958. Last previous edition approv
13、ed in 2005 as D1607 - 91(2005).DOI: 10.1520/D1607-91R11.2Adapted from “Selected Methods for the Measurement of Air Pollutants,” PHSPublication No 999-AP-11, May 1965. A similar version has been submitted to theIntersociety Committee.3For referenced ASTM standards, visit the ASTM website, www.astm.or
14、g, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4The boldface numbers in parentheses refer to the list of references appended tothis method.1Copyright ASTM International, 100 B
15、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.fading by forming a temporary addition product with SO2. Thispermits reading the color intensity within 4 to 5 h (instead ofthe 45 min required without the acetone) without appreciablelosses.6.2 A five-fold ratio of ozone
16、 to NO2will cause a smallinterference, the maximal effect occurring in 3 h. The reagentassumes a slightly orange tint.6.3 Peroxyacetyl nitrate (PAN) can produce a color changein the absorbing reagent. However, in ordinary ambient air, theconcentration of PAN is too low to cause any significant error
17、in the measurement of NO2.6.4 Interferences may exist from other nitrogen oxides andother gases that might be found in polluted air.7. Apparatus7.1 Sampling ProbeA glass or TFE-fluorocarbon (pre-ferred) tube, 6 to 10 mm in diameter provided with adownwind facing intake (funnel or tip). The dead volu
18、me of thesystem should be kept minimal to avoid losses of NO2on thesurfaces of the apparatus.7.2 AbsorberAn all-glass bubbler with a 60-m maxi-mum pore diameter frit, similar to that illustrated in Fig. 1.7.2.1 The porosity of the fritted bubbler, as well as thesampling flow rate, affect absorption
19、efficiency. An efficiencyof over 95 % may be expected with a flow rate of 0.4 L/min orless and a maximum pore diameter of 60 m. Frits having amaximum pore diameter less than 60 m will have a higherefficiency but will require an inconvenient pressure drop forsampling. Considerably lower efficiencies
20、are obtained withcoarser frits.7.2.2 Measure the porosity of an absorber in accordancewith Test Method E128. If the frit is clogged or visiblydiscolored, carefully clean with concentrated chromic-sulfuricacid mixture, and rinse well with water and redetermine themaximum pore diameter.NOTE 1Caution:
21、Do not dispose of this reagent in the drain system.7.2.3 Rinse the bubbler thoroughly with water and allow todry before using.7.3 Mist Eliminator or Gas Drying Tube, filled with acti-vated charcoal or soda lime is used to prevent damage to theflowmeter and pump.7.4 Air-Metering DeviceA calibrated, g
22、lass, variable-areaflowmeter, or dry gas meter coupled with a flow indicatorcapable of accurately measuring a flow of 0.4 L/min.7.5 ThermometerASTM Thermometer 33C, meeting therequirements of Specification E1, will be suitable for mostapplications of this test method.7.6 Manometer, accurate to 670 P
23、a (0.20 in. Hg). See TestMethods D3631.7.7 Air PumpA suction pump capable of drawing therequired sample flow for intervals of up to 60 min is suitable.7.8 Spectrophotometer or Colorimeter An instrumentsuitable for measuring the intensity of absorption at 550 nm,with stoppered tubes or cuvettes. The
24、wavelength band-widthis not critical for this determination.7.9 Stopwatch or Timer.8. Reagents and Materials8.1 Reagent grade chemicals shall be used in all tests. Allreagents shall conform to the specifications of the Committeeon Analytical Reagents of the American Chemical Society,where such speci
25、fications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, watershall be deionized water in accordance with Speci
26、ficationD1193 for Type I or II reagent water. Water shall be free ofnitrite.8.3 Absorbing ReagentDissolve5gofanhydrous sulfa-nilic acid (or 5.5 g of sulfanilic acid monohydrate) in almost aL of water containing 140 mL of glacial acetic acid. Gentleheating is permissible to speed up the process. To t
27、he cooledmixture, add 20 mL of the 0.1 % stock solution of N-(1-naphthyl)-ethylenediamine dihydrochloride, and 10 mL ofacetone. Dilute to 1 L. The solution will be stable for severalmonths if kept well-stoppered in a brown bottle in therefrigerator. The absorbing reagent shall be at room tempera-tur
28、e before use. Avoid lengthy contact with air during prepa-ration and use since discoloration of reagent will result becauseof absorption of NO2.8.4 N-(1-Naphthyl)-Ethylenediamine Dihydrochloride,Stock Solution (0.1 %)Dissolve 0.1 g of the reagent in 100mL of water. Solution will be stable for severa
29、l months if keptwell-stoppered in a brown bottle in the refrigerator. (Alterna-tively, preweighed amounts of the solid reagent may be stored.)8.5 Sodium Nitrite, Standard Solution (0.0246 g/L)OnemL of this working solution of sodium nitrite (NaNO2)5Reagent Chemicals, American Chemical Society Specif
30、ications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Conven
31、tion, Inc. (USPC), Rockville,MD.FIG. 1 Fritted Bubbler for Sampling Nitrogen DioxideD1607 91 (2011)2produces a color equivalent to that of 20 g of NO2in1Lofair at 101 kPa (29.92 in. Hg) and 25C (see 10.1). Prepare freshjust before use by dilution from a stock solution containing2.46 g of the reagent
32、 grade granular solid per litre. Assay thesolid reagent. The stock solution is stable for 90 days at roomtemperature, and for 1 year in a brown bottle under refrigera-tion.8.6 NO2Permeation DeviceWith a permeation rate of 0.1to 0.2 g/min.9. Sampling9.1 Sampling procedures are described in Section 11
33、. Dif-ferent combinations of sampling rates and time may be chosento meet specific needs, but sample volumes and air flow ratesshall be adjusted so that linearity is maintained betweenabsorbance and concentration over the dynamic range.9.2 See Practice D1357 for sampling guidelines.10. Calibration a
34、nd Standardization10.1 Sampling Equipment:10.1.1 FlowmeterCalibrate flowmeter prior to use, usingPractice D3195.10.1.2 Gas MeterCalibrate gas meter prior to use, usingTest Method D1071.10.2 Analysis:10.2.1 Recommended Procedure:10.2.1.1 The recommended procedure for preparation ofcalibration standar
35、ds is by the use of permeation devices (3).Analysis of known concentrations gives calibration curves thatsimulate all of the operational conditions performed duringsampling and analytical procedures.10.2.1.2 Using the apparatus described in Practice D3609,generate a gas stream of known concentration
36、. Sample it asdescribed in 11.1, five times, adjusting the sample times so thatthe amount of NO2in each collected sample solution covers thedynamic range of the method. Analyze each as described in11.2, and prepare a calibration curve using regression analysisby the method of least squares. Determin
37、e the reciprocal of theslope of the line, and denote it as K, the volume of NO2,inL,intercepted at an absorbance of 1.0.10.2.2 Alternate Procedure:10.2.2.1 Standardization is based upon the empirical obser-vation (1, 2, 5) that 0.82 mol of NaNO2produces the samecolor as 1 mol of NO2. One mL of the w
38、orking standardsolution contains 24.6 g of NaNO2. Since the molecularweight of NaNO2is 69.1, this is equivalent to (24.6/69.1) 3 (46.0/0.82) = 20 g NO2.10.2.2.2 For convenience, standard conditions are taken as101 kPa (29.92 in. Hg) and 25C, at which the molar gasvolume is 24.47 L. This is very clos
39、e to the standard conditionsused for air-handling equipment101 kPa (29.92 in. Hg), 70F(21.1C), and 50 % relative humidity, at which the molar gasvolume is 24.76 L, or 1.2 % greater. Ordinarily, the correctionof the sample volume to these standard conditions is slight andmay be omitted, however, for
40、greatest bias, it may be made bymeans of the perfect gas equation.10.2.2.3 Add graduated amounts of NaNO2solution up to 1mL(measured accurately in a graduated pipet or small buret) toa series of 25-mL volumetric flasks, and dilute to the markswith absorbing reagent. Mix, allow 15 min for complete co
41、lordevelopment, and read the absorbance (see 11.2).10.2.2.3.1 Good results can be obtained with these smallvolumes of standard solution if they are carefully measured.Making the calibration solutions up to 25-mL total volume,rather than the 10-mL volume used for samples, increasesaccuracy.10.2.2.3.2
42、 Plot absorbances of the standards against micro-grams of NO2per mL of absorbing reagent. The plot followsBeers law. Find the standardization factor, K, as described in10.2.1.1.11. Procedure11.1 Assemble in order as shown in Fig. 2, a sampling probe(optional), fritted-tip absorber, mist eliminator o
43、r trap, flow-meter, and pump. Measure temperature and pressure differencefrom atmospheric so that corrections for gas volume may beFIG. 2 Sampling TrainD1607 91 (2011)3applied. Keep the flowmeter free from spray or dust. Useground-glass connections. Butt-to-butt glass connections withvinyl tubing al
44、so may be used for connections without losses iflengths are kept minimal.11.2 Pipet 10.0 mL of absorbing reagent into a dry frittedbubbler. Draw an air sample through it at the rate of 0.4 L/min,long enough to develop sufficient final color (about 10 to 60min). Note the total air volume sampled. Mea
45、sure and recordair temperature and pressure. After using the bubbler, rinsewell with water and dry. If fritted tip is visibly discolored, cleanin accordance with the procedure in 7.2.2.11.3 After sampling, development of the red-violet color iscomplete within 15 min at room temperatures. Transfer to
46、 astoppered cuvette and read in a spectrophotometer at 550 nm,using distilled water as a reference. Deduct the absorbance ofthe reagent blank from that of the sample.11.4 Colors too dark to read may be quantitatively dilutedwith unexposed absorbing reagent. Then multiply the mea-sured absorbance by
47、the dilution factor.12. Calculation12.1 Air VolumeConvert the volume of air sampled to thevolume at standard conditions of 25 C and 101.3 kPA (1 atm),as follows:VR5 V 3 P/101.3 3 298.15/T (1)where:VR= volume of air sampled at standard conditions, LV = volume of air sampled at ambient conditions, LP
48、= average ambient atmospheric pressure, kPaT = average ambient atmospheric temperature, K101.3 = pressure of standard atmosphere, kPa, and290.15 = temperature of standard atmosphere, K.12.2 Compute the concentrations of NO2in the sample asfollows:NO2, g/m35 absorbance 3 K 3 1033 v!/V (2)where:K = st
49、andardization factor (micrograms of NO2per mLof absorbing solution/absorbance),Vr= volume of air sample, L (see 12.1),103= L/m3, andv = volume of absorbing reagent, mL.13. Precision and Bias13.1 The information in this section is derived from the datacollected and analyzed as part of ASTM “Project Threshold”(4).13.2 Repeatability (Single-Analyst)The standard devia-tion of results obtained by a single analyst on separate samplesfrom the same flowing air stream is also shown in Fig. 3 as afunction of the mean value of NO2determined. The range of
