ASTM_E_1588_-_10e1.pdf

Designation:E1588101Standard Guide forGunshot Residue Analysis by Scanning ElectronMicroscopy/Energy Dispersive X-Ray Spectrometry1This standard is issued under the fixed designation E1588;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.1NOTESections 7.1.5.2 and 7.2.1.2 were editorially corrected in July 2010.1.Scope1.1 This guide covers the analysis of gunshot residue(GSR)by scanning electron microscopy/energy-dispersive X-rayspectrometry(SEM/EDS)by manual and automated methods.The analysis may be performed manually,with the operatormanipulating the microscope controls and the EDS systemsoftware,or in an automated fashion,where some amount ofthe analysis is controlled by pre-set software functions.1.2 Since software and hardware formats vary among com-mercial systems,guidelines will be offered in the most generalterms possible.For proper terminology and operation,consultthe SEM/EDS system manuals for each system.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Summary of Practice2.1 From the total population of particles collected,thosethat are detected by SEM to be within the limits of certainparameters(for example,atomic number,size,or shape)areanalyzed by EDS(1-3).2Typically,particles composed of highmean atomic number elements are detected by their SEMbackscattered electron signals and an EDS spectrum is ob-tained from each.The EDS spectrum is evaluated for constitu-ent elements that may identify the particle as being consistentwith or characteristic of GSR,or both.3.Significance and Use3.1 This document will be of use to forensic laboratorypersonnel who are involved in the analysis of GSR samples bySEM/EDS(4).3.2 SEM/EDS analysis of GSR is a non-destructive methodthat provides(5,6)both morphological information and theelemental profiles of individual particles.3.3 Particle analysis contrasts with bulk sample methods,such as atomic absorption spectrophotometry(AAS)(7),neu-tron activation analysis(NAA)(8),inductively coupled plasmaatomic emission spectrometry(ICP-AES),and inductivelycoupled plasma mass spectrometry(ICP-MS),where thesampled material is dissolved or extracted prior to the deter-mination of total element concentrations,thereby sacrificingmorphological information and individual particle identifica-tion.3.4 X-ray fluorescence spectrometry(XRF)is a techniquethat has been used to map the placement and distribution ofGSR particles surrounding bullet holes in order to establishshooting distances(9).Unlike the solution-based bulk methodsof analysis,XRF is non-destructive;however,XRF still doesnot provide morphological information and is incapable ofindividual GSR particle identification.4.Sample Preparation4.1 Once the evidence seal is broken,care should be takenso that no object touches the surface of the adhesive SEM/EDSsample collection stub and that the stub is not left uncoveredany longer than is reasonable for transfer,mounting,orlabeling.4.2 Label the sample collection stub in such a manner that itis distinguishable from other sample collection stubs withoutcompromising the sample;for example,label the bottom orside of the stub.4.3 If a non-conductive adhesive was used in the samplecollection stub,the sample will need to be coated to increase itselectrical conductivity,unless an environmental SEM orvariable-pressure/low-vacuum SEM is used for the analysis.Carbon is a common choice of coating material,since it will1This 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 June 1,2010.Published June 2010.Originallyapproved in 1994.Last previous version approved in 2008 as E1588 08.DOI:10.1520/E1588-10E01.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 not interfere with X-ray lines of interest.For high-vacuumSEM,coat the sample sufficiently to eliminate charging of thesample.5.Sample Area5.1 Sample collection stubs for SEMs typically come in oneof two diameters:12.7 mm or 25.4 mm,which yield surfaceareas of 126.7 mm2and 506.7 mm2respectively.5.2 Manual analysis of the total surface area of the stub isprohibitively time-consuming.Because the particles are col-lected onto an adhesive surface in a random manner and theparticles do