ASTM E2937-2018 Standard Guide for Using Infrared Spectroscopy in Forensic Paint Examinations《在法医检验中使用红外光谱的标准指南》.pdf
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1、Designation: E2937 13E2937 18Standard Guide forUsing Infrared Spectroscopy in Forensic PaintExaminations1This standard is issued under the fixed designation E2937; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONInfrared (IR) spectroscopy is commonly used by forensic laboratories for the analysis of paints andcoatings received in the f
3、orm of small chips, residues, particles, or smears, and serves as a staplecomparative technique in the assessment of whether or not questioned paint could have come from aparticular source. IR spectroscopy provides molecular structure information on many of the organicand inorganic constituents cont
4、ained within a single paint layer. This information can be used toclassify both binders and pigments in coating materials. The classification information maycan thenbe utilizedused to identify probable types of paint such as architectural, automotive, or maintenance.Additionally, the use of automoti
5、ve paint databases may allow for the determination of informationsuch as potential vehicle year, make and model. Databases maycan also aid in the interpretation of thesignificance (for example, how limited is the group of potential donor sources) of a questioned paint.1. Scope1.1 This guide applies
6、to the forensic IR analysis of paints and coatings and is intended to supplement information presentedin the Forensic Paint Analysis and Comparison Guidelines (1)2 written by Scientific Working Group on Materials Analysis(SWGMAT).This guideline is limited to the discussion of FourierTransform Infrar
7、ed (FTIR) instruments and provides informationon FTIR instrument setup, performance assessment, sample preparation, analysis and data interpretation. It is intended to providean understanding of the requirements, benefits, limitations and proper use of IR accessories and sampling methods available f
8、oruse by forensic paint examiners. The following accessory techniques will be discussed: FTIR microspectroscopy (transmission andreflectance), diamond cell and attenuated total reflectance. The particular methods employed by each examiner or laboratory, orboth, are dependent upon available equipment
9、, examiner training, specimen size or suitability, and purpose of examination. Thisguideline does not cover the theoretical aspects of many of the topics presented. These can be found in texts such as An InfraredSpectroscopy Atlas for the Coatings Industry (Federation of Societies for Coatings, 1991
10、) (2) and Fourier Transform InfraredSpectrometry (Griffiths and de Haseth, 1986) (3).1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associa
11、ted with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationa
12、lly recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3D16 Terminolog
13、y for Paint, Related Coatings, Materials, and Applications1 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 Sept. 1, 2013Feb. 1, 2018. Published October 2013February 201
14、8. Originally approved in 2013. Last previous edition approved in 2013 as E2937 13. DOI: 10.1520/E2937-13.10.1520/E2937-18.2 The boldface numbers in parentheses refer to the list of references at the end of this standard.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contact
15、ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been m
16、ade to the previous version. Becauseit 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 versionof the standard as published by ASTM is to be considered the official document.Co
17、pyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E131 Terminology Relating to Molecular SpectroscopyE1421 Practice for Describing and Measuring Performance of Fourier Transform Mid-Infrared (FT-MIR) Spectrometers: LevelZero and Level One
18、 TestsE1492 Practice for Receiving, Documenting, Storing, and Retrieving Evidence in a Forensic Science LaboratoryE1610 Guide for Forensic Paint Analysis and Comparison3. Terminology3.1 DefinitionsFor definitions of terms used in this guide other than those listed here, see Terminologies D16 and E13
19、1.3.2 Definitions of Terms Specific to This Standard:3.2.1 100 % linecalculated by ratioing two background spectra taken under identical conditions; the slope and noise of 100% lines are used to measure the performance of the instrument.3.2.2 absorbance (A)the logarithm to the base 10 of the recipro
20、cal of transmittance T, written as A = log 10 (1/T) = log10T.3.2.3 absorbance spectruma representation of the infrared spectrum in which the ordinate is defined in absorbance units (A);absorbance is linearly proportional to concentration and is therefore used in quantitative analysis.3.2.1 additive
21、(modifier)(modifier), nany substance added in a small quantity to improve properties; additives may includesubstances such as driers, corrosion inhibitors, catalysts, ultraviolet absorbers, and plasticizers.3.2.5 attenuated total reflectance (ATR)a method of spectrophotometric analysis based on the
22、reflection of energy at theinterface of two media that have different refractive indices and are in intimate contact with each other.3.2.6 aperturean opening in an optical system that controls the amount of light passing through a system.3.2.2 backgroundbackground, nthe signal produced by the entire
23、 analytical system apart from the material of interest.3.2.8 beam condensera series of mirrors that focus the infrared beam in the sample compartment to permit the examinationof smaller specimens.3.2.9 beam splitteran optical component that partially reflects and partially transmits radiation from t
24、he source in such amanner as to direct part to a fixed mirror and the other part to a moving mirror.3.2.3 binderbinder, na nonvolatile portion of the liquid vehicle of a coating, which serves to bindbond or cement thepigment particles together.3.2.4 coatingcoating, na generic term for paint, lacquer
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