1、Designation: E2927 13Standard Test Method forDetermination of Trace Elements in Soda-Lime GlassSamples Using Laser Ablation Inductively Coupled PlasmaMass Spectrometry for Forensic Comparisons1This standard is issued under the fixed designation E2927; the number immediately following the designation
2、 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.INTRODUCTIONOne objective of a forensic glass exa
3、mination is to compare glass samples to determine if they canbe discriminated using their physical, optical or chemical properties (for example, color, refractiveindex (RI), density, elemental composition). If the samples are distinguishable in any of theseobserved and measured properties, it may be
4、 concluded that they did not originate from the samesource of broken glass. If the samples are indistinguishable in all of these observed and measuredproperties, the possibility that they originated from the same source of glass cannot be eliminated. Theuse of an elemental analysis method such as la
5、ser ablation inductively coupled plasma massspectrometry yields high discrimination among sources of glass.1. Scope1.1 This test method covers a procedure for the quantitativeelemental analysis of the following seventeen elements:lithium (Li), magnesium (Mg), aluminum (Al), potassium (K),calcium (Ca
6、), iron (Fe), titanium (Ti), manganese (Mn),rubidium (Rb), strontium (Sr), zirconium (Zr), barium (Ba),lanthanum (La), cerium (Ce), neodymium (Nd), hafnium (Hf)and lead (Pb) through the use of Laser Ablation InductivelyCoupled Plasma Mass Spectrometry (LA-ICP-MS) for theforensic comparison of glass
7、fragments. The potential of theseelements to provide the best discrimination among differentsources of soda-lime glasses has been published elsewhere(1-5).2Silicon (Si) is also monitored for use as an internalstandard. Additional elements can be added as needed, forexample, tin (Sn) can be used to m
8、onitor the orientation of floatglass fragments.1.2 The method only consumes approximately 0.4 to2gofglass per replicate and is suitable for the analysis of fullthickness samples as well as irregularly shaped fragments assmall as 0.1 mm by 0.4 mm in dimension. The concentrationsof the elements listed
9、 above range from the low parts permillion (gg-1) to percent (%) levels in soda-lime-silicate glass,the most common type encountered in forensic cases. Thisstandard method may be applied for the quantitative analysis ofother glass types; however, some modifications in the referencestandard glasses a
10、nd the element menu may be required.1.3 This standard does not replace knowledge, skill, ability,experience, education or training and should be used inconjunction with professional judgment.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included i
11、n thisstandard.1.5 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.
12、2. Referenced Documents2.1 ASTM Standards:3E2330 Test Method for Determination of Concentrations ofElements in Glass Samples Using Inductively CoupledPlasma Mass Spectrometry (ICP-MS) for Forensic Com-parisonsE177 Practice for Use of the Terms Precision and Bias inASTM Test Methods1This test method
13、is under the jurisdiction ofASTM Committee E30 on ForensicSciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.Current edition approved June 1, 2013. Published July 2013. DOI: 10.1520/E2927-13.2The boldface numbers in parentheses refer to a list of references at the end
14、 ofthis standard.3For 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 Harbo
15、r Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Summary of Test Method3.1 The glass fragments usually do not require samplepreparation prior to the LA-ICP-MS analysis. However, theymay be washed with solvents or pre-ablated if necessary.3.2 The glass fragment is placed insid
16、e an ablation chamberand a laser beam is focused on the surface of the sample. Whenthe ablation is started, the interaction between the pulsed laserand the sample surface produces a cloud of very smallparticles, which are transported from the ablation cell by acarrier gas into the ICP-MS for analysi
17、s.3.3 An ICP-MS is used to quantify the elements of interest.3.4 Quantitative analysis is accomplished using well-characterized glass standards whose major elemental compo-sition is similar to the material to be analyzed.4. Significance and Use4.1 This test method is useful for the determination ofe
18、lemental concentrations in the microgram per gram (gg-1)topercent (%) levels in soda-lime glass samples. A standard testmethod can aid in the interchange of data between laboratoriesand in the creation and use of glass databases.4.2 The determination of elemental concentrations in glassprovides high
19、 discriminating value in the forensic comparisonof glass fragments.4.3 This test method produces minimal destruction of thesample. Microscopic craters of 50 to 100 m in diameter by 80to 150-m deep are left in the glass fragment after analysis. Themass removed per replicate is approximately 0.4 to 3.
20、1 g.4.4 Appropriate sampling techniques should be used toaccount for natural heterogeneity of the materials at a micro-scopic scale.4.5 The precision, accuracy, and limits of detection of themethod (for each element measured) should be established ineach laboratory that employs the method. The measu
21、rementuncertainty of any concentration value used for a comparisonshould be recorded with the concentration.4.6 Acid digestion of glass followed by either InductivelyCoupled Plasma-Optical Emission Spectrometry (ICP-OES) orInductively Coupled Plasma-Mass Spectrometry (ICP-MS)may also be used for tra
22、ce elemental analysis of glass, and offersimilar detection levels and the ability for quantitative analysis.However, these methods are destructive, and require largersample sizes and much longer sample preparation times (TestMethod E2330).4.7 Micro X-Ray Fluorescence (-XRF) uses comparablesample siz
23、es to those used for LA-ICP-MS with the advantageof being non-destructive of the sample. Some of the drawbacksof -XRF are poorer sensitivity and precision, and longeranalysis time.4.8 Scanning Electron Microscopy with EDS (SEM-EDS) isalso available for elemental analysis, but it is of limited use fo
24、rforensic glass source discrimination due to poor detectionlimits for higher atomic number elements present in glass attrace concentration levels. However, distinguishing betweensources having similar RIs and densities is possible.5. Apparatus5.1 LA-ICP-MSA Laser Ablation system coupled to anICP-MS
25、instrument is employed. Since there are severalmanufacturers for both laser ablation units and ICP-MSinstruments, the instrument maker, model, configuration andmajor operational parameters (that is, laser wavelength for thelaser and mass selective detector type for the ICP-MS) of bothinstruments sho
26、uld be noted within the analysis results. Themost common laser wavelengths used for glass analysis are266 nm, 213 nm, and 193 nm. Either quadrupole or magneticsector ICP-MS instruments are suitable for this test method.5.2 Prior to the analysis on the day it is used, the ICP-MSshould be tuned accord
27、ing to the manufacturers recommenda-tions covering the mass range of the elements to be measured.The instrument should be adjusted for maximum sensitivity,best precision, and to minimize oxides and doubly charged ioninterferences. The use of a well-characterized glass standard,such as NIST 612,4is r
28、ecommended during the tuning andperformance check. Detector cross calibrations (pulse/analog)should be performed before any measurements when twodetector modes are used in the analysis.5.3 In order to prepare for data acquisition, the signals of thefollowing isotopes are monitored in the ICP-MS; lit
29、hium (7Li),magnesium (24 or 25Mg), aluminum (27Al), silicon (29Si),potassium (39K), calcium (42Ca), iron (57Fe), titanium (49Ti),manganese (55Mn), rubidium (85Rb), strontium (88Sr), zirco-nium (90Zr), tin (118Sn), barium (137Ba), lanthanum (139La),cerium (140Ce), neodymium (146Nd), hafnium (180Hf) a
30、nd lead(208Pb). This procedure may be applicable to other elementsand other isotopes (for example,206, 207Pb); however, thoseelements listed above are considered to provide the mostdiscrimination power for soda-lime glass comparisons.Alternatively, other isotopes such as56Fe can be monitoredusing IC
31、P-MS with advanced technology to remove interfer-ences (for example, sector field ICP-MS or reaction cells).5.4 Either argon or helium can be used as a carrier gas totransport the particles from the ablation cell to the plasma. Theuse of helium carrier gas has been reported to result in fewerfractio
32、nation effects than the use of argon as a carrier (6).6. Hazards6.1 Commercial laser ablation units are enclosed type Ilasers. However, laser systems typically used for analysis ofglass generate high energy radiation that can pose serious risksto eye safety if exposed to the eye. Interlocks should n
33、ot bebypassed or disconnected.6.2 The argon plasma should not be observed directlywithout protective eyewear. Potentially hazardous UV lightmay be emitted.6.3 ICP-MS instruments generate high amounts of radiof-requency energy in their RF power supply and torch boxes thatis potentially hazardous if a
34、llowed to escape. Safety devicesand safety interlocks should not be bypassed or disconnected.4Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.E2927 1327. Calibration and Standardization7.1 A calibration c
35、urve using multiple glass standards orusing a single glass standard can be used for quantitation forLA-ICP-MS analysis of glass. Any standard used to create thecalibration should be matrix-matched to the sample and well-characterized. The calibration standard(s) must be traceable toan accepted stand
36、ard. For glass analysis there are severalstandards that are available such as the NIST Standard Refer-ence Materials (that is, NIST 610, NIST 612, NIST 614) andthe float glass standard glasses (FGS1, FGS2) evaluated by theEuropean group NITECRIME (5) and distributed by theBundeskriminalamt, Germany.
37、5An internal standard, prefer-ably silicon (29Si), must be used to normalize the signal. Theuse of an internal standard is needed to adjust for differences inablation yield between the ablated materials. Since silicon ispresent as a major component in all soda-lime glass (70 to 72%asSiO2) (3), a low
38、 abundance isotope (29Si) is commonlyused as the internal standard for this method. If this method isused for the analysis of other glass types, the concentration ofthe internal standard must be determined prior to quantitativeanalysis.7.2 In addition to the calibration standard, at least one glassv
39、erification standard should be measured with each sample setas a quality control check for the accuracy and precision of themethod. The quality control specifications should be set byeach laboratory.7.3 As a minimum, calibration standards are required at thebeginning and the end of the analytical se
40、quence in order toadjust for instrument drift over time.Acceptance criteria for thecalibration must be defined by each laboratory and shouldinclude the use of calibration verification standards.8. Procedure8.1 If necessary, samples may be cleaned to remove anysurface contamination by washing or pre-
41、ablation, or both,prior to analysis. Cleaning may include washing samples withsoap and water, with or without ultrasonication, and rinsing indeionized water, followed by rinsing in acetone, methanol, orethanol, and drying. Soaking in various concentrations of nitricacid for 30 minutes or longer, rin
42、sing with deionized water andethanol, and drying prior to analysis removes most surfacecontamination without affecting the measured concentrationsof elements inherent in the glass. However, the use of nitricacid may remove some surface coatings that may be present.8.2 Multiple samples and standards
43、can be placed togetherin the ablation cell as long as their positions are documented.8.3 The samples or standards, or both, must be secured inthe ablation cell using double-sided tape or other adhesive.Orient the sample to avoid an original surface of the glass. Theknown and questioned samples shoul
44、d be treated equally.8.4 Purge the ablation cell with the carrier gas betweensamples to avoid any contamination.8.5 If pre-ablation cleaning is performed it can be done atthis point.8.6 Focus the laser beam at the surface of the sample. Singlespot (or depth profile) ablation modes are recommended at
45、 aspot size of 50 to 100 m and a repetition rate of 10 Hz.Program the laser parameters.8.7 Initiate the acquisition of the analytical signals using theICP-MS software. Each data acquisition will be comprised ofa transient signal of intensity versus time for each element;each transient will include 2
46、0-30 seconds of background (gasblank) measurement, followed by 50-60 seconds of ablation ofthe sample, followed by 10-30 seconds of post-ablation blankmeasurement.8.8 Conduct replicate ablations at different locations withinthe fragment(s). Locations should be spaced sufficiently toavoid possible de
47、bris from other ablation halos. Collect repli-cate measurements to ensure that the questioned glass frag-ments and known glass source(s) are adequately characterized.Analyze a minimum of three replicates on each questionedsample examined and nine replicates on known glass sources.8.9 It is recommend
48、ed that the entire sequence be completedin a single session (a single day). As an example, when aknown sample with 3 fragments is compared to a singlerecovered fragment, the analytical sequence may be as follows:(1) Calibration standard (1st,2nd, and 3rdspot)(2) “Known” fragment #1 (1st,2nd, and 3rd
49、spot)(3) “Recovered” fragment (1st,2nd, and 3rdspot)(4) Calibration verificationstandard(1st,2nd, and 3rdspot)(5) “Known” fragment #2 (1st,2nd, and 3rdspot)(6) “Known” fragment #3 (1st,2nd, and 3rdspot)(7) Calibration standard (4th,5th, and 6thspot)8.9.1 A symmetrical arrangement of the analytical sequenceof standards and samples is advantageous in minimizing theeffects that may result from instrumental drift.8.10 Once the acquisition is completed, use the software ofchoice to integrate the transient signals and determine theelement concentrations of the samples. Some dat
