Standard Guide for Forensic Examination of Dyes in Textile Fibers by Thin-Layer Chromatography

SIGNIFICANCE AND USE
5.1 TLC is an inexpensive and simple technique that could be used to complement other analytical techniques within a general analytical scheme related to forensic fiber examination.  
5.2 Consider the forensic analysis of fiber colorants using TLC for single fiber comparisons only when the sample size is adequate (that is, enough colorant can be extracted for analysis) and it is not possible to discriminate between the fibers of interest using other techniques, such as comparison microscopy and MSP. Larger fibrous units (for example, thread or tuft) can be treated as an individual sample if determined to be homogeneous. Do not treat fibers that cannot be directly related to each other as a collective sample for the purposes of TLC.  
5.3 The extraction procedures carried out prior to TLC analysis can provide useful information about dye classification. TLC can provide qualitative information about dye components. Similar colors made up of different dye components can be differentiated using this technique. The application of TLC may serve to discriminate between fibers or it may support the possibility of fibers sharing a common source.  
5.4 TLC can be prohibitively difficult or undesirable in some circumstances. Short lengths of fibers or pale-colored fibers can lack adequate amounts of colorant necessary to be examined by TLC. Dye extraction from some fibers can be impossible (2, 3). Some fiber types do not truly extract, but change or lose color. Reactive dyes are covalently bonded to the fiber and typically cannot be removed by conventional extraction methods, but can be released from cotton and wool by disrupting the fiber by enzymatic or chemical digestion, respectively (1). The desire to preserve evidence from deleterious change or for possible analysis by another examiner can preclude removing the color or employing a destructive method for analysis.
SCOPE
1.1 This guide is intended as an overview of the Thin-Layer Chromatography (TLC) of fiber colorants (or individual dye components) present in dyed fibers. It is intended to be applied within the scope of a broader analytical scheme for the forensic analysis of fiber samples. TLC could provide information that cannot be obtained through other color analyses (such as microspectrophotometry (MSP)) (1).2  
1.2 This standard is intended for use by competent forensic science practitioners with the requisite formal education, discipline-specific training (see Practice E2917), and demonstrated proficiency to perform forensic casework (see Practice E3255).  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

Status
Published
Publication Date
30-Apr-2023
Technical Committee
Drafting Committee
Current Stage
Ref Project

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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: E2227 − 23 An American National Standard
Standard Guide for
Forensic Examination of Dyes in Textile Fibers by Thin-
1
Layer Chromatography
This standard is issued under the fixed designation E2227; 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
ε NOTE—Editorially updated 6.2.1 in June 2023.
1. Scope 2. Referenced Documents
3
2.1 ASTM Standards:
1.1 This guide is intended as an overview of the Thin-Layer
E620 Practice for Reporting Opinions of Scientific or Tech-
Chromatography (TLC) of fiber colorants (or individual dye
nical Experts
components) present in dyed fibers. It is intended to be applied
E1459 Guide for Physical Evidence Labeling and Related
within the scope of a broader analytical scheme for the forensic
Documentation
analysis of fiber samples. TLC could provide information that
E1492 Practice for Receiving, Documenting, Storing, and
cannot be obtained through other color analyses (such as
2
Retrieving Evidence in a Forensic Science Laboratory
microspectrophotometry (MSP)) (1).
E1732 Terminology Relating to Forensic Science
1.2 This standard is intended for use by competent forensic
E2224 Guide for Forensic Analysis of Fibers by Infrared
science practitioners with the requisite formal education,
Spectroscopy
discipline-specific training (see Practice E2917), and demon-
E2228 Guide for Microscopical Examination of Textile Fi-
strated proficiency to perform forensic casework (see Practice
bers
E3255).
E2917 Practice for Forensic Science Practitioner Training,
1.3 The values stated in SI units are to be regarded as
Continuing Education, and Professional Development
standard. No other units of measurement are included in this
Programs
standard.
E3255 Practice for Quality Assurance of Forensic Science
Service Providers Performing Forensic Chemical Analysis
1.4 This standard does not purport to address all of the
2.2 Other Standards:
safety concerns, if any, associated with its use. It is the
ISO/IEC 17025 General Requirements for the Competence
responsibility of the user of this standard to establish appro-
4
of Testing and Calibration Laboratories
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3. Terminology
1.5 This international standard was developed in accor-
3.1 Definitions—For definitions of terms used in this guide,
dance with internationally recognized principles on standard-
refer to Terminology E1732.
ization established in the Decision on Principles for the
3.2 Definitions of Terms Specific to This Standard:
Development of International Standards, Guides and Recom-
3.2.1 adsorbent, n—the stationary phase for adsorption
mendations issued by the World Trade Organization Technical
TLC.
Barriers to Trade (TBT) Committee.
3.2.2 band, n—one or more colored areas (circular to
elongated shape) on a TLC plate produced by the separation of
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This guide is under the jurisdiction of ASTM Committee E30 on Forensic
3
Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2023. Published May 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2002. Last previous edition approved in 2013 as E2227 – 13, which was Standards volume information, refer to the standard’s Document Summary page on
withdrawn in January 2022 and reinstated in May 2023. DOI: 10.1520/E2227- the ASTM website.
4
23E01. Available from International Organization for Standardization (ISO), ISO
2
The boldface numbers in parentheses refer to a list of references at the end of Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
this standard. Switzerland, https://www.iso.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E2227 − 23
the dye components for a particular combination of solvent and and interpretation of the resulting chromatograms. The proto-
stationary phase. Bands are created as the solvent (mobile cols and equipment mentioned in this document are not meant
phase) moves past and reacts with the solute, migrating from to be totally inclusive or exclusive.
the origin.
4.3 Not all fiber type/dye class combinations are covered in
3.2.2.1 Discussion—“
...

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