ASTM E2224-10
(Guide)Standard Guide for Forensic Analysis of Fibers by Infrared Spectroscopy
Standard Guide for Forensic Analysis of Fibers by Infrared Spectroscopy
SIGNIFICANCE AND USE
Fiber samples may be prepared and mounted for microscopical infrared analysis by a variety of techniques. Infrared spectra of fibers are obtained using an IR spectrophotometer coupled with an IR microscope. Fiber polymer identification is made by comparison of the fiber spectrum with reference spectra.
Consideration should be given to the potential for additional compositional information that may be obtained by IR spectroscopy over polarized light microscopy alone (see Microscopy Guidelines). The extent to which IR spectral comparison is indicated will vary with specific sample and case evaluations.
The recommended point for IR analysis in a forensic fiber examination is following visible and ultraviolet (UV) comparison microscopy (fluoresence microscopy), polarized light microscopy, and UV/visible spectroscopy, but before dye extraction for thin-layer chromatography. This list of analytical techniques is not meant to be totally inclusive or exclusive.
The following generic types of fiber are occasionally encountered in routine forensic examinations: Anidel, Fluorocarbon, Lastrile, Novoloid, Nytril, Polycarbonate, PBI, Sulfar, Vinal, and Vinyon.
Exemplar data, reference standards, or examiner experience, or combination thereof, may be inadequate for characterization of these fibers by optical microscopical and microchemical techniques. For these fiber types, IR spectroscopic confirmation of polymer type is advisable.
Because of the large number of subgeneric classes, forensic examination of acrylic fibers is likely to benefit significantly from IR spectral analysis (11).
Colorless manufactured fibers are lacking in the characteristics for color comparison available in dyed or pigmented fibers. The forensic examination of these fibers may, therefore, benefit from the additional comparative aspect of IR spectral analysis.
If polymer identification is not readily apparent from optical data alone, an additional method of analysis should be used such as mi...
SCOPE
1.1 Infrared (IR) spectrophotometery is a valuable method of fiber polymer identification and comparison in forensic examinations. The use of IR microscopes coupled with Fourier transform infrared (FT-IR) spectrometers has greatly simplified the IR analysis of single fibers, thus making the technique feasible for routine use in the forensic laboratory.
1.2 This guideline is intended to assist individuals and laboratories that conduct forensic fiber examinations and comparisons in the effective application of infrared spectroscopy to the analysis of fiber evidence. Although this guide is intended to be applied to the analysis of single fibers, many of its suggestions are applicable to the infrared analysis of small particles in general.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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Designation: E2224 − 10
Standard Guide for
1
Forensic Analysis of Fibers by Infrared Spectroscopy
This standard is issued under the fixed designation E2224; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2.1 absorbance (A)—the logarithm to the base 10 of the
reciprocal of the transmittance, (T):
1.1 Infrared (IR) spectrophotometery is a valuable method
of fiber polymer identification and comparison in forensic A 5 log ~1/T!52log T
10 10
examinations.The use of IR microscopes coupled with Fourier
3.2.2 absorption band—a region of the absorption spectrum
transforminfrared(FT-IR)spectrometershasgreatlysimplified
in which the absorbance passes through a maximum.
the IR analysis of single fibers, thus making the technique
3.2.3 absorption spectrum—a plot, or other representation,
feasible for routine use in the forensic laboratory.
of absorbance, or any function of absorbance, against
1.2 This guideline is intended to assist individuals and
wavelength, or any function of wavelength.
laboratories that conduct forensic fiber examinations and
comparisons in the effective application of infrared spectros- 3.2.4 absorptivity (a)—absorbance divided by the product
of the sample pathlength (b) and the concentration of the
copy to the analysis of fiber evidence. Although this guide is
intended to be applied to the analysis of single fibers, many of absorbing substance (c):
its suggestions are applicable to the infrared analysis of small
a 5 A/bc
particles in general.
3.2.5 attenuated total reflection (ATR)—reflection that oc-
1.3 The values stated in SI units are to be regarded as
curs when an absorbing coupling mechanism acts in the
standard. No other units of measurement are included in this
process of total internal reflection to make the reflectance less
standard.
than unity.
3.2.6 background—apparent absorption caused by anything
2. Referenced Documents
other than the substance for which the analysis is being made.
2
2.1 ASTM Standards:
D123 Terminology Relating to Textiles 3.2.7 cellulosic fiber—fiber composed of polymers formed
E1421 Practice for Describing and Measuring Performance from glucose subunits.
of Fourier Transform Mid-Infrared (FT-MIR) Spectrom-
3.2.8 far-infrared—pertaining to the infrared region of the
eters: Level Zero and Level One Tests
electromagnetic spectrum with wavelength range from ap-
E1459 Guide for Physical Evidence Labeling and Related
-1
proximately25to300 µm(wavenumberrange400to30 cm ).
Documentation
3.2.9 Fourier transform—a mathematical operation that
E1492 Practice for Receiving, Documenting, Storing, and
converts a function of one independent variable to one of a
Retrieving Evidence in a Forensic Science Laboratory
different independent variable.
3. Terminology
3.2.9.1 Discussion—In FT-IR spectroscopy, the Fourier
transform converts a time function (the interferogram) to a
3.1 Definitions—For definitions of terms used in this guide,
frequencyfunction(theinfraredabsorptionspectrum).Spectral
refer to Terminology D123.
data are collected through the use of an interferometer, which
3.2 Definitions of Terms Specific to This Standard:
replaces the monochrometer found in the dispersive infrared
spectrometer.
1 3.2.10 Fourier transform infrared (FT-IR) spectrometry—a
This guide is under the jurisdiction of ASTM Committee E30 on Forensic
Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.
form of infrared spectrometry in which an interferogram is
Current edition approved Sept. 15, 2010. Published October 2010. Originally
obtained; this interferogram is then subjected to a Fourier
approved in 2002. Last previous edition approved in 2002 as E2224 – 02. DOI:
transformation to obtain an amplitude-wavenumber (or wave-
10.1520/E2224-10.
2
length) spectrum.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3.2.11 generic class—a group of fibers having similar (but
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. not necessarily identical) chemical composition; a generic
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E2224 − 10
name applies to all members of a group and is not protected by infrared microspectroscopy. It is intended to be applicable to a
trademark registration. wide range of infrared spectrophotometery and microscope
3.2.11.1 Discussion—Generic names for manufactured fi- configurat
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E2224–02 Designation: E2224 – 10
Standard Guide for
1
Forensic Analysis of Fibers by Infrared Spectroscopy
This standard is issued under the fixed designation E2224; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 Infrared (IR) spectrophotometery is a valuable method of fiber polymer identification and comparison in forensic
examinations.The use of IR microscopes coupled with Fourier transform infrared (FT-IR) spectrometers has greatly simplified the
IR analysis of single fibers, thus making the technique feasible for routine use in the forensic laboratory.
1.2 This guideline is intended to assist individuals and laboratories that conduct forensic fiber examinations and comparisons
in the effective application of infrared spectroscopy to the analysis of fiber evidence.Although this guide is intended to be applied
to the analysis of single fibers, many of its suggestions are applicable to the infrared analysis of small particles in general.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
2. Referenced Documents
2
2.1 ASTM Standards:
D123 Terminology Relating to Textiles
E1421 Practice for Describing and Measuring Performance of FourierTransform Mid-Infrared (FT-MIR) Spectrometers: Level
Zero and Level One Tests
E1459 Guide for Physical Evidence Labeling and Related Documentation
E1492 Practice for Receiving, Documenting, Storing, and Retrieving Evidence in a Forensic Science Laboratory
3. Terminology
3.1
3.1 Definitions—For 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 the reciprocal of the transmittance, (T); A = log (1/T) = -log T.
10 10
3.2):
A 5 log ~1/T! 5 –log T
10 10
3.2.2 absorption band—a region of the absorption spectrum in which the absorbance passes through a maximum.
3.3
3.2.3 absorption spectrum—a plot, or other representation, of absorbance, or any function of absorbance, against wavelength,
or any function of wavelength.
3.4
3.2.4 absorptivity (a)—absorbance divided by the product of the sample pathlength (b) and the concentration of the absorbing
substance (c); a = A/bc
3.5):
a 5 A/bc
3.2.5 attenuated total reflection (ATR)—reflection that occurs when an absorbing coupling mechanism acts in the process of
total internal reflection to make the reflectance less than unity.
3.6
3.2.6 background—apparent absorption caused by anything other than the substance for which the analysis is being made.
3.7
3.2.7 cellulosic fiber—fiber composed of polymers formed from glucose subunits.
3.8
1
This guide is under the jurisdiction of ASTM Committee E30 on Forensic Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.
Current edition approved July 10, 2002. Published September 2002. DOI: 10.1520/E2224-02.
Current edition approved Sept. 15, 2010. Published October 2010. Originally approved in 2002. Last previous edition approved in 2002 as E2224 – 02. DOI:
10.1520/E2224-10.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
E2224 – 10
3.2.8 far-infrared—pertaining to the infrared region of the electromagnetic spectrum with wavelength range from approxi-
-1
mately 25 to 300 µm (wavenumber range 400 to 30 cm ).
3.9
3.2.9 Fourier transform—a mathematical operation that converts a function of one independent variable to one of a different
independent variable.
3.2.9.1 Discussion—In FT-IR spectroscopy, the Fourier transform converts a time function (the interferogram) to a frequency
function (the infrared absorption spectrum). Spectral data are collected through the use of an interferometer, which replaces the
monochrometer found in the dispersive infrared spectrometer.
3.2.10 Fouriertransforminfrared(FT-IR)spectrometry—aformofinfraredspectrometryinwhichaninterferogramisobtained;
this interferogram is then subjected to a Fourier tr
...
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