ASTM_E_1865_-_97_2013.pdf

Designation:E186597(Reapproved 2013)Standard Guide forOpen-Path Fourier Transform Infrared(OP/FT-IR)Monitoringof Gases and Vapors in Air1This standard is issued under the fixed designation E1865;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 guide covers active open-path Fourier transforminfrared(OP/FT-IR)monitors and provides guidelines forusing active OP/FT-IR monitors to obtain concentrations ofgases and vapors in air.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 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.2.Referenced Documents2.1 ASTM Standards:2E131 Terminology Relating to Molecular SpectroscopyE168 Practices for General Techniques of Infrared Quanti-tative Analysis(Withdrawn 2015)3E1421 Practice for Describing and Measuring Performanceof Fourier Transform Mid-Infrared(FT-MIR)Spectrom-eters:Level Zero and Level One TestsE1655 Practices for Infrared Multivariate QuantitativeAnalysis3.Terminology3.1 For definitions of terms relating to general molecularspectroscopy used in this guide refer to Terminology E131.Acomplete glossary of terms relating to optical remote sensing isgiven in Ref(1).43.2 Definitions:3.2.1 background spectrum,na single-beam spectrum thatdoes not contain the spectral features of the analyte(s)ofinterest.3.2.2 bistatic system,na system in which the IR source issome distance from the detector.For OP/FT-IR monitoring,this implies that the IR source and the detector are at oppositeends of the monitoring path.3.2.3 monitoring path,nthe location in space over whichconcentrations of gases and vapors are measured and averaged.3.2.4 monitoring pathlength,nthe distance the opticalbeam traverses through the monitoring path.3.2.5 monostatic or unistatic system,na system with theIR source and the detector at the same end of the monitoringpath.For OP/FT-IR systems,the beam is generally returned bya retroreflector.3.2.6 open-path monitoring,nmonitoring over a path thatis completely open to the atmosphere.3.2.7 parts per million meters,nthe units associated withthe quantity path-integrated concentration and a possible unitof choice for reporting data from OP/FT-IR monitors becauseit is independent of the monitoring pathlength.3.2.8 path-averaged concentration,nthe result of dividingthe path-integrated concentration by the pathlength.3.2.8.1 DiscussionPath-averaged concentration gives theaverage value of the concentration along the path,and typically1This guide is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is the direct responsibility of Subcom-mittee E13.03 on Infrared and Near Infrared Spectroscopy.Current edition approved Jan.1,2013.Published January 2013.Originallyapproved in 1997.Last previous edition approved in 2007 as E1865 97(2007).DOI:10.1520/E1865-97R13.2For 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.4The boldface numbers in parentheses refer to a list of references at the end ofthis standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 is expressed in units of parts per million(ppm),parts perbillion(ppb),or micrograms per cubic meter(gm3).3.2.9 path-integrated concentration,nthe quantity mea-sured by an OP/FT-IR monitor over the monitoring path.It hasunits of concentration times length,for example,ppmm.3.2.10 plume,nthe gaseous and aerosol effluents emittedfrom a stack or other pollutant source and the volume of spacethey occupy.3.2.11 retroreflector,nan optical device that returns radia-tion in directions close to the direction from which it came.3.2.11.1 DiscussionRetroreflectors come in a variety offorms.The retroreflector commonly used in OP/FT-IR moni-toring uses reflection from three mutually perpendicular sur-faces.This kind of retroreflector is usually called a cube-cornerretroreflector.3.2.12 single-beam spectrum,nthe radiant power mea-sured by the instrument detector as a function of frequency.3.2.12.1 DiscussionIn FT-IR absorption spectrometry thesingle-beam spectrum is obtained after a fast Fourier transformof the interferogram.3.2.13 synthetic background spectrum,na backgroundspectrum made by choosing points along the envelope