ASTM_D_1608_-_98_2009.pdf

Designation:D160898(Reapproved 2009)Standard Test Method forOxides of Nitrogen in Gaseous Combustion Products(Phenol-Disulfonic Acid Procedures)1This standard is issued under the fixed designation D1608;the number immediately following the designation indicates the year oforiginal adoption or,in the case 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 describes the phenol-disulfonic acidcolorimetric procedure(1)2for the determination of totaloxides of nitrogen nitrous oxide(N2O)excepted in gaseouseffluents from combustion and other nitrogen oxidation pro-cesses.1.2 It is applicable to a concentration range of oxides ofnitrogen as nitrogen dioxide(NO2)of 5 ppm to severalthousand parts per million by volume(four to several thousandmilligrams per dry standard cubic metre).1.3 Since the grab sampling technique used takes a rela-tively small sample over a very short period of time,the resultobtained will be an instantaneous measure of the nitrogenoxides and,therefore,will be representative of the emissionsonly if the gas stream is well mixed and the concentrationconstant with time.Multiple samples are recommended.1.4 The values stated in SI units are to be regarded asstandard.The SI equivalents are in parentheses and may beapproximate.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 prior to use.(For more specificsafety precautionary information see 8.5 and Section 3.)2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD1357 Practice for Planning the Sampling of the AmbientAtmosphereD1605 Practices for Sampling Atmospheres for Analysis ofGases and Vapors(Withdrawn 1992)33.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology D1356.4.Summary of Test Method4.1 The gas sample is admitted into an evacuated flaskcontaining an oxidizing absorbing solution consisting of hy-drogen peroxide in dilute sulfuric acid.The oxides of nitrogenare converted to nitric acid by gas phase oxidation due tooxygen in the sample and by the absorbent solution.Theresulting nitrate ion is reacted with phenol disulfonic acid toproduce a yellow compound(the tri-ammonium salt of 6-nitro-1-phenol-2,4-disulfonic acid),which is measured colorimetri-cally.Calibration curves,prepared from samples of knownnitrate content,are used to determine the amount of nitrate inthe sample with results expressed as nitrogen dioxide.5.Significance and Use5.1 This test method provides a means to measure the totalnitrogen oxides(NOx)content of gaseous emissions for pur-poses such as determining compliance with regulations,study-ing the effect of various abatement procedures on NOxemissions,and checking the validity of instrumental measure-ments.6.Interferences(1,2)6.1 Inorganic nitrates,nitrites,or organic nitrogen com-pounds that are easily oxidized to nitrates interfere with the testmethod and give erroneously high results.The presence ofcertain reducing agents,for example,sulfur dioxide(SO2),may interfere by consuming part of the hydrogen peroxide inthe absorbing solution to leave an inadequate amount forreaction with the oxides of nitrogen.Halides lower the results,1This 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 March 1,2009.Published March 2009.Originallyapproved in 1958.Last previous edition approved in 2003 as D1608 98(2003).DOI:10.1520/D1608-98R09.2For 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 last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 but interference from halide ion(and lead)are negligible in theconcentration usually encountered in combustion sources.6.2 The role of some of the constituents of combustioneffluents as possible interfering substances has not been thor-oughly investigated.7.Apparatus7.1 The assembled sampling apparatus is shown in Fig.1.7.2 Barometer,capable of measuring atmospheric pressureto 6250 Pa 62 mm Hg.7.3 Bottles,120-mL or 4-oz,glass or polyethylene,withleak-free noncontaminating caps.7.4 Evaporating Dishes,new condition,unetched borosili-cate glass or porcelain,about 200-mL capacity.Do not useplatinum ware(3).7.5 Mercury Manometer,op