ASTM_E_1790_-_04_2010.pdf

Designation:E179004(Reapproved 2010)Standard Practice forNear Infrared Qualitative Analysis1This standard is issued under the fixed designation E1790;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 practice covers the use of near-infrared(NIR)spectroscopy for the qualitative analysis of liquids and solids.The practice is written under the assumption that most NIRqualitative analyses will be performed with instruments de-signed specifically for this region and equipped with comput-erized data handling algorithms.In principle,however,thepractice also applies to work with liquid samples usinginstruments designed for operation over the ultraviolet(UV),visible,and mid-infrared(IR)regions if suitable data handlingcapabilities are available.Many Fourier Transform Infrared(FTIR)(normally considered mid-IR instruments)have NIRcapability,or at least extended-range beamsplitters that allowoperation to 1.2 m;this practice also applies to data fromthese instruments.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 SpectroscopyE1252 Practice for General Techniques for Obtaining Infra-red Spectra for Qualitative AnalysisE1655 Practices for Infrared Multivariate QuantitativeAnalysis3.Terminology3.1 DefinitionsFor definitions of general terms and sym-bolspertainingtoNIRspectroscopyandstatisticalcomputations,refer to Terminology E131.3.2 Definitions of Terms Specific to This Standard:3.2.1 interactance,nthe phenomenon whereby radiantenergy entering the surface of a material is scattered by thematerial back to the surface,but at a different portion of thesurface.3.2.1.1 DiscussionThis differs from diffuse reflectance,where the returning radiation exits the same portion of thesurface of the material as the illuminating radiation entered.3.2.2 training sample(otherwise called a“referencesample”or“standard”),na quantity of material of knowncomposition or properties,or both,presented to an instrumentfor measurement in order to find relationships between themeasurements and the composition or properties,or both,ofthe sample.3.2.2.1 DiscussionThis term is typically used in conjunc-tion with computerized methods for ascertaining the relation-ships.Training samples for quantitative analysis(also called“calibration samples,”as in Practices E1655)have differentrequirements than training samples used for qualitativeanalysis.4.Significance and Use4.1 NIR spectroscopy is a widely used technique for quan-titative analysis,and it is also becoming more widely used forthe identification of organic materials,that is,qualitativeanalysis.In general,however,the concept of qualitative analy-sis as used in the NIR spectral region differs from that used inthe mid-IR spectral region in that NIR qualitative analysisrefers to the process of automated comparison of the spectra ofunknown materials to the spectra of known materials in orderto identify the unknown.This approach constitutes a librarysearch method in which each user generates his own library.4.2 Historically,NIR spectroscopy as practiced with classi-cal UV-VIS-NIR instruments using methods similar to thosedescribed in Practice E1252 was not considered to be a strongtechnique for qualitative analysis.Although the positions andintensities of absorption bands in specific wavelength rangeswere used to confirm the presence of certain functional groups,1This practice is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is the direct responsibility of Subcom-mittee E13.11 on Multivariate Analysis.Current edition approved March 1,2010.Published April 2010.Originallyapproved in 1996.Last previous edition approved in 2004 as E1790 04.DOI:10.1520/E1790-04R10.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 the spectra were not considered to be specific enough to allowunequivocal identification of unknown materials.Afew impor-tant libraries of NIR spectra were developed for qualitativepurposes,but the lack of suitable data handling facilitieslimited the scope of qualitative analysis s