ASTM_E_2224_-_10.pdf

Designation:E222410Standard Guide forForensic Analysis of Fibers by Infrared Spectroscopy1This standard is issued under the fixed designation E2224;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 Infrared(IR)spectrophotometery is a valuable methodof fiber polymer identification and comparison in forensicexaminations.The use of IR microscopes coupled with Fouriertransform infrared(FT-IR)spectrometers has greatly simplifiedthe IR analysis of single fibers,thus making the techniquefeasible for routine use in the forensic laboratory.1.2 This guideline is intended to assist individuals andlaboratories that conduct forensic fiber examinations andcomparisons in the effective application of infrared spectros-copy to the analysis of fiber evidence.Although this guide isintended to be applied to the analysis of single fibers,many ofits suggestions are applicable to the infrared analysis of smallparticles in general.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.2.Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesE1421 Practice for Describing and Measuring Performanceof Fourier Transform Mid-Infrared(FT-MIR)Spectrom-eters:Level Zero and Level One TestsE1459 Guide for Physical Evidence Labeling and RelatedDocumentationE1492 Practice for Receiving,Documenting,Storing,andRetrieving Evidence in a Forensic Science Laboratory3.Terminology3.1 DefinitionsFor definitions of terms used in this guide,refer to Terminology D123.3.2 Definitions of Terms Specific to This Standard:3.2.1 absorbance(A)the logarithm to the base 10 of thereciprocal of the transmittance,(T):A 5 log101/T!5 2log10T3.2.2 absorption banda region of the absorption spectrumin which the absorbance passes through a maximum.3.2.3 absorption spectruma plot,or other representation,of absorbance,or any function of absorbance,against wave-length,or any function of wavelength.3.2.4 absorptivity(a)absorbance divided by the productof the sample pathlength(b)and the concentration of theabsorbing substance(c):a 5 A/bc3.2.5 attenuated total reflection(ATR)reflection that oc-curs when an absorbing coupling mechanism acts in theprocess of total internal reflection to make the reflectance lessthan unity.3.2.6 backgroundapparent absorption caused by anythingother than the substance for which the analysis is being made.3.2.7 cellulosic fiberfiber composed of polymers formedfrom glucose subunits.3.2.8 far-infraredpertaining to the infrared region of theelectromagnetic spectrum with wavelength range from ap-proximately 25 to 300 m(wavenumber range 400 to 30 cm-1).3.2.9 Fourier transforma mathematical operation thatconverts a function of one independent variable to one of adifferent independent variable.3.2.9.1 DiscussionIn FT-IR spectroscopy,the Fouriertransform converts a time function(the interferogram)to afrequency function(the infrared absorption spectrum).Spectraldata are collected through the use of an interferometer,whichreplaces the monochrometer found in the dispersive infraredspectrometer.3.2.10 Fourier transform infrared(FT-IR)spectrometryaform of infrared spectrometry in which an interferogram isobtained;this interferogram is then subjected to a Fouriertransformation to obtain an amplitude-wavenumber(or wave-length)spectrum.3.2.11 generic classa group of fibers having similar(butnot necessarily identical)chemical composition;a generic1This guide is under the jurisdiction of ASTM Committee E30 on ForensicSciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.Current edition approved Sept.15,2010.Published October 2010.Originallyapproved in 2002.Last previous edition approved in 2002 as E2224 02.DOI:10.1520/E2224-10.2For 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 name applies to all members of a group and is not protected bytrademark registration.3.2.11.1 DiscussionGeneric names for manufactured fi-bers include,for example,rayon,nylon,and polyester.Genericnames to be used in the United States for manufactured fiberswere established as part of the Textile Fiber Products Identifi-cation Act enacted by Congress in 1954(1).33.2.12 infraredpertaining to the region of the electromag-netic spectrum with wavelength range from approximately0.78 to 1000 m(wavenumber range 12 800 to 10 cm-1).3.2.13 infrared spectroscopypertaining to spectroscopy inthe infrared region of the electromagnetic spectrum.3.2.14 intern