1、Designation:E231004(Reapproved 2015)Standard Guide forUse of Spectral Searching by Curve Matching Algorithmswith Data Recorded Using Mid-Infrared Spectroscopy1This standard is issued under the fixed designation E2310;the number immediately following the designation indicates the year oforiginal adop
2、tion 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 Spectral searching is the process whereby a spectrum ofan unknown material is e
3、valuated against a library(database)of digitally recorded reference spectra.The purpose of thisevaluation is classification of the unknown and,wherepossible,identification of the unknown.Spectral searching isintended as a screening method to assist the analyst and is notan absolute identification te
4、chnique.Spectral searching is notintended to replace an expert in infrared spectroscopy.Spectralsearching should not be used without suitable training.1.2 The user of this guide should be aware that the results ofa spectral search can be affected by the following factorsdescribed in Section 5:(1)bas
5、elines,(2)sample purity,(3)Absorbance linearity(Beers Law),(4)sample thickness,(5)sample technique and preparation,(6)physical state of thesample,(7)wavenumber range,(8)spectral resolution,and(9)choice of algorithm.1.2.1 Many other factors can affect spectral searching re-sults.1.3 The scope of this
6、 guide is to provide a guide for the useof search algorithms for mid-infrared spectroscopy.The meth-ods described herein may be applicable to the use of thesealgorithms for other types of spectroscopic data,but each typeof data search should be assessed separately.1.4 The Euclidean distance algorith
7、m and the first derivativeEuclidean distance algorithm are described and their usediscussed.The theory and common assumptions made whenusing search algorithms are also discussed,along with guide-lines for the use and interpretation of the search results.1.5 The values stated in SI units are to be re
8、garded asstandard.No other units of measurement are included in thisstandard.2.Referenced Documents2.1 ASTM Standards:2E131 Terminology Relating to Molecular SpectroscopyE334 Practice for General Techniques of Infrared Micro-analysisE573 Practices for Internal Reflection SpectroscopyE1252 Practice f
9、or General Techniques for Obtaining Infra-red Spectra for Qualitative AnalysisE1642 Practice for General Techniques of Gas Chromatog-raphy Infrared(GC/IR)AnalysisE2105 Practice for General Techniques of Thermogravimet-ric Analysis(TGA)Coupled With Infrared Analysis(TGA/IR)E2106 PracticeforGeneralTec
10、hniquesofLiquidChromatography-Infrared(LC/IR)and Size ExclusionChromatography-Infrared(SEC/IR)Analyses3.Terminology3.1 DefinitionsFor general definitions of terms andsymbols,refer to Terminology E131.3.1.1 Euclidean distance algorithmthe Euclidean distancealgorithm measures the Euclidean distance be
11、tween eachlibrary spectrum and the unknown spectrum by treating thespectra as normalized vectors.The closeness of the match,orhit quality index(HQI),is calculated from the square root ofthe sum of the squares of the difference between the vectors forthe unknown spectrum and each library spectrum.3.1
12、.2 first derivative Euclidean distance algorithmin thefirst derivative Euclidean distance algorithm the Euclideandistance is also computed,except the derivative of eachspectrum is calculated prior to the Euclidean distance calcula-tion.3.1.3 hit quality index(HQI)a table which ranks thelibrary spect
13、ra in the database according to their hit qualityvalues(see 7.5).3.1.4 hit quality valuethe spectral search software com-pares each spectrum in the database to that of the unknown and1This guide is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is th
14、e direct responsibility of Subcom-mittee E13.03 on Infrared and Near Infrared Spectroscopy.Current edition approved May 1,2015.Published June 2015.Originallyapproved in 2004.Last previous edition approved in 2009 as E2310 04(2009).DOI:10.1520/E2310-04R15.2For referenced ASTM standards,visit the ASTM
15、 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 a
16、ssigns a numeric value for each library entry demonstratinghow similar the two spectra are.3.1.4.1 DiscussionThere are several methods for assign-ing hit quality values and either a high or low value can beassigned as the best match.Refer to the software manufacturersdocumentation.3.1.5 normalizationthe mathematical technique used tocompensate for an intensity difference between two spectra(see 5.1).3.1.6 peak searchingthe process whereby the peak tableof the spectrum of an unknown material is e