1、Designation:D360895(Reapproved 2011)Standard Test Method forNitrogen Oxides(Combined)Content in the Atmosphere bythe Griess-Saltzman Reaction1This standard is issued under the fixed designation D3608;the number immediately following the designation indicates the year oforiginal adoption or,in the ca
2、se of revision,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.1.Scope1.1 This test method covers the manual determination of thecombined nitrogen dioxide(NO2)and nitric
3、oxide(NO)content,total NOx;in the atmosphere in the range from 4 to10 000 g/m3(0.002 to 5 ppm(v).1.2 The maximum sampling period is 60 min at a flow rateof 0.4 L/min.1.3 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.4 This stand
4、ard 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 prior to use.2.Referenced Documents2.1 ASTM S
5、tandards:2D1071 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 Sampling of the AmbientAtmosphereD3195 Practice for Rotameter CalibrationD3609 Practic
6、e for Calibration Techniques Using Perme-ation TubesD3631 Test Methods for Measuring Surface AtmosphericPressureE1 Specification for ASTM Liquid-in-Glass ThermometersE128 Test Method for Maximum Pore Diameter and Perme-ability of Rigid Porous Filters for Laboratory Use3.Terminology3.1 DefinitionsFor
7、 definitions of terms used in this testmethod,refer to Terminology D1356.4.Summary of Test Method4.1 The NO is quantitatively(1)3converted to NO2by achromic acid oxidizer.The resulting NO2,plus the NO2alreadypresent,are absorbed in an azo-dye-forming reagent(2).Ared-violet color is produced within 1
8、5 min,the intensity ofwhich is measured spectrophotometrically at 550 nm.5.Significance and Use5.1 Both NO2and NO play an important role inphotochemical-smog-forming reactions.In sufficient concen-trations NO2is deleterious to health,agriculture,materials,andvisibility.5.2 In combustion processes,si
9、gnificant amounts of NOmay be produced by combination of atmospheric nitrogen andoxygen;at ambient temperatures,NO can be converted to NO2by oxygen and other atmospheric oxidants.Nitrogen dioxidealso may be generated from processes involving nitric acid,nitrates,the use of explosives,and welding.6.I
10、nterferences6.1 Any significant interferences due to sulfur dioxide(SO2)should be negated by the oxidation step.The addition ofacetone to the reagent retards color-fading by forming atemporary addition product with SO2.This will protect thereagent from incidental exposure to SO2and will permitreadin
11、g the color intensity within 4 to 5 h(instead of the 45 minrequired without acetone)without appreciable losses.6.2 A five-fold ratio of ozone to NO2will cause a smallinterference,the maximal effect occurring in 3 h.The reagentassumes a slightly orange tint.1This test method is under the jurisdiction
12、 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 1977.Last previous edition approved in 2005 as D3608 95(2005).DOI:10.1520/D3608-95R
13、11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The boldface numbers in parentheses refer to the list of refer
14、ences appended tothis test method.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.3 The interferences from nitrous oxide and nitrogenpentoxide,and other gases that might be found in polluted airare considered to be negligible.7.Apparatu
15、s7.1 Sampling ProbeA glass or TFE-fluorocarbon(pre-ferred)tube,6 to 10 mm in diameter,provided with adownward-facing intake(funnel or tip).The dead volume ofthe system should be kept minimal,to avoid loss of NOxon thesurfaces of the apparatus.7.2 Oxidizer TubeSoak 14 to 16-mesh firebrick or116-in.(1
16、.5 mm molecular sieve pellets in a 17%aqueous solution ofchromium trioxide(CrO3)for 10 to 30 min.After draining theexcess solution and drying in an oven at 105C for 30 min,thesolid oxidizer has a dull pink color.This color changes to richyellow(active color)after 24-h equilibration with ambient airat 40 to 70%relative humidity,or after drawing ambient airthrough at a flow rate of 0.5 L/min for 1 h.A change in colorto a greenish brown indicates the exhaustion of oxidizingability,and progresses wi
