ASTM E2927-23

Standard Test Method for Determination of Trace Elements in Soda-Lime Glass Samples Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry for Forensic Comparisons

SIGNIFICANCE AND USE
5.1 This test method is useful for the determination of elemental concentrations in the range of approximately 0.1 µgg-1 to 10 percent (%) (See Table X1.1) in soda-lime glass samples (7 and 8). A standard test method can aid in the interchange of data between laboratories and in the creation and use of glass databases.  
5.2 The determination of elemental concentrations in glass provides high discriminating value in the forensic comparison of glass fragments.  
5.3 This test method produces minimal destruction of the sample. Microscopic craters of 50 µm to 100 µm in diameter by 80 µm to 150 µm deep are left in the glass fragment after analysis. The mass removed per replicate is approximately 0.4 µg to 3 µg (6).  
5.4 Appropriate sampling techniques shall be used to account for natural heterogeneity of the materials at a microscopic scale.  
5.5 The precision, bias, and limits of detection of the method (for each element measured) shall be established during validation of the method. The measurement uncertainty of any concentration value used for a comparison shall be recorded with the concentration.  
5.6 Acid digestion of glass followed by either Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) can also be used for trace elemental analysis of glass, and offer similar detection levels and the ability for quantitative analysis. However, these methods are destructive, and require larger sample sizes and more sample preparation (Test Method E2330).  
5.7 Micro X-Ray Fluorescence (µ-XRF) uses comparable sample sizes to those used for LA-ICP-MS with the advantage of being non-destructive of the sample. Some of the drawbacks of µ-XRF include lower sensitivity and precision, and longer analysis time (Test Method E2926).  
5.8 Scanning Electron Microscopy with Energy Dispersive Spectrometry (SEM-EDS) is also available for elemental analysis, but it is of limited use for forensic glass source d...
SCOPE
1.1 This test method covers a procedure for the quantitative elemental analysis of the following seventeen elements: lithium (Li), magnesium (Mg), aluminum (Al), potassium (K), calcium (Ca), 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 inductively coupled plasma mass spectrometry (LA-ICP-MS) for the forensic comparison of glass fragments. The potential of these elements to provide the best discrimination among different sources of soda-lime glasses has been published elsewhere (1-5).2 Silicon (Si) is also monitored for use as a normalization standard. Additional elements may be added as needed, for example, tin (Sn) can be used to monitor the orientation of float glass fragments.  
1.2 The method only consumes approximately 0.4 µg to 3 µg of glass per replicate and is suitable for the analysis of full thickness samples as well as irregularly shaped fragments as small as 0.1 mm by 0.1 mm by 0.2 mm (6) in dimension. The concentrations of the elements listed above range from the low parts per million (µgg-1) to percent (%) levels in soda-lime glass, the most common type encountered in forensic cases. This standard method can be applied for the quantitative analysis of other glass types; however, some modifications in the reference standard glasses and the element menu may be required.  
1.3 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.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the respo...

General Information

• Status: Published
• Publication Date: 14-Nov-2023
• ICS: 07.140 - Forensic science
• ICS: 71.040.40 - Chemical analysis
• ICS: 81.040.10 - Raw materials and raw glass
• Technical Committee: E30 - Forensic Sciences
• Drafting Committee: E30.01 - Criminalistics

Relations

• Replaces: ASTM E2927-16e1 - Standard Test Method for Determination of Trace Elements in Soda-Lime Glass Samples Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry for Forensic Comparisons
• Effective Date: 15-Nov-2023
• Refers: ASTM E2917-24 - Standard Practice for Forensic Science Practitioner Training, Continuing Education, and Professional Development Programs
• Effective Date: 01-Feb-2024
• Refers: ASTM E2917-19a - Standard Practice for Forensic Science Practitioner Training, Continuing Education, and Professional Development Programs
• Effective Date: 01-Jun-2019
• Referred By: ASTM E1732-22 - Standard Terminology Relating to Forensic Science
• Effective Date: 15-Nov-2023

Overview

ASTM E2927-23 establishes a standardized test method for the determination of trace elements in soda-lime glass samples using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), with a special focus on forensic glass comparisons. This method is designed for the quantitative analysis of elements such as lithium, magnesium, aluminum, potassium, calcium, iron, titanium, manganese, rubidium, strontium, zirconium, barium, lanthanum, cerium, neodymium, hafnium, and lead. Silicon is also commonly monitored as a normalization standard. The method is intended for forensic science practitioners, enabling laboratories to exchange data and build reliable glass comparison databases with high discriminating power and minimal sample destruction.

Key Topics

• Trace Element Analysis: Quantifies elements in soda-lime glass in the range of 0.1 µg/g to around 10% by mass, providing a robust scientific basis for forensic casework.
• Forensic Discrimination: High sensitivity and precision make LA-ICP-MS especially valuable for distinguishing between unrelated glass fragments.
• Minimal Sample Destruction: Typically removes only 0.4 µg to 3 µg per replicate, leaving microscopic craters (~50-100 µm in diameter) that are minimally destructive, preserving valuable evidence.
• Sampling and Heterogeneity: Emphasizes appropriate sampling techniques to account for the natural heterogeneity of glass at the microscopic level, ensuring reliable results.
• Calibration and Quality Control: Requires laboratories to validate precision, bias, limits of detection, and to use matrix-matched calibration standards and quality control materials such as those from NIST or FGS.
• Comparison to Other Methods:
  • ICP-MS/ICP-OES (after acid digestion): Similar detection levels, but are more destructive and require larger sample quantities.
  • Micro X-ray Fluorescence (μ-XRF): Non-destructive and uses similar sample sizes but with lower sensitivity and precision.
  • SEM-EDS: Offers elemental analysis but is less effective for trace discrimination due to detection limits.

Applications

• Forensic Investigations: Critical for comparing glass fragments in criminal cases, such as burglaries, car accidents, and violent crime scenes, by determining whether glass samples share a common origin.
• Data Interchange and Databasing: Standardized results support reliable data sharing between laboratories and the creation of large-scale glass composition databases.
• Quality Control in Analytical Laboratories: Ensures that forensic laboratories can validate their procedures to meet accreditation and evidentiary standards.
• Adaptability: While developed for soda-lime glass, the methodology may be adapted for other glass types with modifications to reference standards and the menu of elements analyzed.

Related Standards

• ASTM E2330: Standard method for glass elemental analysis using traditional ICP-MS following acid digestion.
• ASTM E2926: Standard for glass comparison using micro X-ray fluorescence spectrometry (µ-XRF).
• ASTM E2917: Practice for forensic science practitioner training and validation, ensuring competency in the use of LA-ICP-MS and related techniques.
• ASTM C162: Terminology for glass and glass products, providing foundational definitions for glass analysis.

---

Keywords: ASTM E2927-23, trace elemental analysis, soda-lime glass, LA-ICP-MS, forensic glass comparison, minimal destruction, forensic science standards, glass database, calibration standards, laboratory validation.

By implementing ASTM E2927-23, forensic laboratories enhance their analytical capabilities, leverage robust scientific methods for glass comparison, and ensure data integrity across the forensic science community.

Standards Content (Sample)

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.
Designation: E2927 − 23 An American National Standard
Standard Test Method for
Determination of Trace Elements in Soda-Lime Glass
Samples Using Laser Ablation Inductively Coupled Plasma
Mass Spectrometry for Forensic Comparisons
This standard is issued under the fixed designation E2927; 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.
INTRODUCTION
One objective of a forensic glass examination is to compare glass samples to determine if they can
be discriminated by their physical, optical, or chemical properties (for example, color, refractive index
(RI), density, elemental composition). If the samples are distinguishable in any of these observed and
measured properties, it can be determined that they did not originate from the same source of broken
glass. If the samples are indistinguishable in all these observed and measured properties, the
possibility exists that they originated from the same source of glass. The use of an elemental analysis
method such as laser ablation inductively coupled plasma mass spectrometry yields high discrimina-
tion among sources of glass.
1. Scope small as 0.1 mm by 0.1 mm by 0.2 mm (6) in dimension. The
concentrations of the elements listed above range from the low
1.1 This test method covers a procedure for the quantitative
-1
parts per million (μgg ) to percent (%) levels in soda-lime
elemental analysis of the following seventeen elements:
glass, the most common type encountered in forensic cases.
lithium (Li), magnesium (Mg), aluminum (Al), potassium (K),
This standard method can be applied for the quantitative
calcium (Ca), iron (Fe), titanium (Ti), manganese (Mn),
analysis of other glass types; however, some modifications in
rubidium (Rb), strontium (Sr), zirconium (Zr), barium (Ba),
the reference standard glasses and the element menu may be
lanthanum (La), cerium (Ce), neodymium (Nd), hafnium (Hf)
required.
and lead (Pb) through the use of laser ablation inductively
coupled plasma mass spectrometry (LA-ICP-MS) for the 1.3 This standard is intended for use by competent forensic
science practitioners with the requisite formal education,
forensic comparison of glass fragments. The potential of these
elements to provide the best discrimination among different discipline-specific training (see Practice E2917), and demon-
strated proficiency to perform forensic casework.
sources of soda-lime glasses has been published elsewhere
(1-5). Silicon (Si) is also monitored for use as a normalization
1.4 The values stated in SI units are to be regarded as
standard. Additional elements may be added as needed, for
standard. No other units of measurement are included in this
example, tin (Sn) can be used to monitor the orientation of float
standard.
glass fragments.
1.5 This standard does not purport to address all of the
1.2 The method only consumes approximately 0.4 μg to
safety concerns, if any, associated with its use. It is the
3 μg of glass per replicate and is suitable for the analysis of full
responsibility of the user of this standard to establish appro-
thickness samples as well as irregularly shaped fragments as
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1 1.6 This international standard was developed in accor-
This test method is under the jurisdiction of ASTM Committee E30 on Forensic
dance with internationally recognized principles on standard-
Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.
Current edition approved Nov. 15, 2023. Published January 2024. Originally
ization established in the Decision on Principles for the
ɛ1
approved in 2013. Last previous edition approved in 2016 as E2927 – 16 . DOI:
Development of International Standards, Guides and Recom-
10.1520/E2927-23.
mendations issued by the World Trade Organization Technical
The boldface numbers in parentheses refer to a list of references at the end of
this standard. Barriers to Trade (TBT) Committee.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2927 − 23
-1
2. Referenced Documents 0.1 μgg to 10 percent (%) (See Table X1.1) in soda-lime glass
3 samples (7 and 8). A standard test method can aid in the
2.1 ASTM Standards:
interchange of data between laboratories and in the creation
C162 Terminology of Glass and Glass Products
and use of glass databases.
E177 Practice for Use of the Terms Precision and Bias in
ASTM Test Methods 5.2 The determination of elemental concentrations in glass
E2330 Test Method for Determination of Concentrations of provides high discriminating value in the forensic comparison
Elements in Glass Samples Using Inductively Coupled of glass fragments.
Plasma Mass Spectrometry (ICP-MS) for Forensic Com-
5.3 This test method produces minimal destruction of the
parisons
sample. Microscopic craters of 50 μm to 100 μm in diameter by
E2917 Practice for Forensic Science Practitioner Training,
80 μm to 150 μm deep are left in the glass fragment after
Continuing Education, and Professional Development
analysis. The mass removed per replicate is approximately
Programs
0.4 μg to 3 μg (6).
E2926 Test Method for Forensic Comparison of Glass Using
5.4 Appropriate sampling techniques shall be used to ac-
Micro X-ray Fluorescence (μ-XRF) Spectrometry
count for natural heterogeneity of the materials at a micro-
3. Terminology
scopic scale.
3.1 Definitions: 5.5 The precision, bias, and limits of detection of the
3.1.1 calibration standard, n—a reference material used to
method (for each element measured) shall be established
determine the concentrations of the analyte elements in the during validation of the method. The measurement uncertainty
glass matrix. The calibration standard(s) shall have a known
of any concentration value used for a comparison shall be
elemental composition including a known uncertainty for the recorded with the concentration.
reported analytes.
5.6 Acid digestion of glass followed by either Inductively
3.1.2 glass, n—an inorganic product of fusion that has been
Coupled Plasma-Optical Emission Spectrometry (ICP-OES) or
cooled to a rigid condition without crystallization. C162
Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) can
also be used for trace elemental analysis of glass, and offer
3.1.3 normalization standard, n—an element that is present
similar detection levels and the ability for quantitative analysis.
in the glass matrix at elevated and relatively homogeneous
However, these methods are destructive, and require larger
concentration that may be used to normalize the laser ablation
sample sizes and more sample preparation (Test Method
signal to compensate for any variation on the ablated mass or
E2330).
instrumental drift.
5.7 Micro X-Ray Fluorescence (μ-XRF) uses comparable
4. Summary of Test Method
sample sizes to those used for LA-ICP-MS with the advantage
4.1 The glass fragments usually do not require sample
of being non-destructive of the sample. Some of the drawbacks
preparation prior to the LA-ICP-MS analysis. However, they
of μ-XRF include lower sensitivity and precision, and longer
can be washed with solvents or pre-ablated if necessary.
analysis time (Test Method E2926).
4.2 The glass fragment is placed inside an ablation chamber
5.8 Scanning Electron Microscopy with Energy Dispersive
and a laser beam is focused on the surface of the sample. When
Spectrometry (SEM-EDS) is also available for elemental
the ablation is started, the interaction between the pulsed laser
analysis, but it is of limited use for forensic glass source
and the sample surface produces a cloud of very small
discrimination due to poor detection limits for higher atomic
particles, which are transported from the ablation cell by a
number elements present in glass at trace concentration levels.
carrier gas into the ICP-MS for analysis.
However, distinguishing between sources having similar RIs
and densities is sometimes possible.
4.3 An ICP-MS is used to quantify the elements of interest.
4.4 Quantitative analysis is accomplished using well-
6. Apparatus
characterized glass standards whose major elemental compo-
6.1 LA-ICP-MS—A Laser Ablation system coupled to an
sition is similar to the material to be analyzed.
ICP-MS instrument is employed. Since there are several
4.5 A comparison between the reported elemental composi-
manufacturers for both laser ablation units and ICP-MS
tions of the known and questioned glass fragments may result
instruments, the instrument maker, model, configuration, and
in a decision on whether the samples are distinguishable or
major operational parameters (that is, laser wavelength for the
indistinguishable by elemental composition.
laser and mass selective detector type for the ICP-MS) of both
instruments shall be noted within the analysis results. The most
5. Significance and Use
common laser wavelengths used for glass analysis are 266 nm,
5.1 This test method is useful for the determination of
213 nm, and 193 nm. Either quadrupole or magnetic sector
elemental concentrations in the range of approximately
ICP-MS instruments are suitable for this test method.
6.2 Prior to analysis, the ICP-MS shall be tuned according
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
to the manufacturer’s recommendations covering the mass
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
range of the elements to be measured. Detector cross calibra-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. tions (pulse/analog) shall be performed when two detector
E2927 − 23
modes are used in the analysis. The instrument shall be CFGS3 evaluated by the NIJ Glass Interpretation Working
adjusted for maximum sensitivity, best precision, and to Group and distributed by Florida International University,
minimize oxides and doubly charged ion interferences. The use USA (8, 10).
of a glass reference material, such as NIST 612, is recom-
8.2 In addition to the calibration standard, at least one
mended during the tuning and performance check.
additional glass standard reference material (that is, “calibra-
6.3 In order to prepare for data acquisition, the signals of the tion verification standard”) shall be measured with each sample
following isotopes are monitored in the ICP-MS; lithium ( Li), set as a quality control check for the accuracy and precision of
24 or 25 27 29
magnesium ( Mg), aluminum ( Al), silicon ( Si), the method. The quality control specifications shall be set by
39 42 57 49
potassium ( K), calcium ( Ca), iron ( Fe), titanium ( Ti), each Forensic Science Service Provider (FSSP). The quality
55 85 88
manganese ( Mn), rubidium ( Rb), strontium ( Sr), zirco- control check standard should be a well-characterized glass and
90 118 137 139
nium ( Zr), tin ( Sn), barium ( Ba), lanthanum ( La), one not used to calibrate the instrument.
140 146 180
cerium ( Ce), neodymium ( Nd), hafnium ( Hf) and lead
8.3 As a minimum, calibration standards are required at the
( Pb). This procedure can be applicable to other elements and
beginning and the end of the analytical sequence in order to
206, 207
other isotopes (for example, Pb); however, those ele-
adjust for instrument drift over time. Acceptance criteria for the
ments listed above are considered to provide the most discrimi-
calibration shall be defined by validation protocols and shall
nation power for soda-lime glass comparisons. Alternatively,
include the use of calibration verification standards.
other isotopes such as Fe may be monitored using ICP-MS
8.4 A normalization standard, preferably silicon ( Si), shall
with advanced technology to remove interferences (for
be used to normalize the signal. The use of a normalization
example, sector field ICP-MS or reaction cells).
standard is needed to adjust for differences in ablation yield
6.4 Helium is used as the carrier gas to transport the
between the ablated materials. Since silicon is present as a
particles from the ablation cell to the plasma. The use of helium
major component in all soda-lime glass (~70 % to 72 % as
carrier gas has been reported to result in fewer fractionation 29
SiO ) (3, 11), a low abundance isotope ( Si) is commonly
effects than the use of argon as a carrier (9).
used as the normalization standard for this method.
7. Hazards
9. Procedure
7.1 Commercial laser ablation units are enclosed type I
9.1 If necessary, clean the samples to remove any surface
lasers. However, laser systems typically used for analysis of
contamination by washing or pre-ablation, or both, prior to
glass generate high energy radiation that can pose serious risks
analysis.
to eye safety if exposed to the eye. Interlocks shall not be
NOTE 1—Cleaning can include washing samples in soap or water,
bypassed or disconnected.
ultrasonication, or additional rinses in deionized water then acetone,
7.2 The argon plasma shall not be observed directly without
methanol, or ethanol, before drying. In addition, soaking in dilute
concentrations of nitric acid for at least 30 minutes and rinsing in
protective eyewear. Potentially hazardous UV light can be
deionized water and ethanol removes most surface contamination without
emitted.
affecting the elemental concentrations of interest. However, nitric acid can
7.3 ICP-MS instruments generate high amounts of radiof-
unintentionally remove surface coatings on the sample.
requency energy (RF) in their RF power supply and torch
9.2 Multiple samples and standards can be placed together
boxes that is potentially hazardous if allowed to escape. Safety
in the ablation cell as long as their positions are documented.
devices and safety interlocks shall not be bypassed or discon-
9.3 Secure the samples or standards, or both, in the ablation
nected.
cell using double-sided tape, other adhesive, or putty. Orient
the sample to avoid an original surface of the glass. The
8. Calibration and Standardization
following steps shall be followed:
8.1 A calibration curve using multiple glass standards or
9.3.1 After opening the ablation cell for sample exchange,
using a single glass standard is used for quantitation for
purge the cell with the carrier gas to avoid any contamination.
LA-ICP-MS analysis of glass. Any calibration standard shall
9.3.2 If pre-ablation cleaning is performed, it can be done at
be matrix-matched to the sample and well-characterized. The
this point.
calibration standard(s) shall be traceable to an accepted stan-
9.3.3 Focus the laser beam at the surface of the sample. Spot
dard. For glass analysis there are several standards that are
sizes of ~50 μm to 100 μm and a repetition rate of 10 Hz are
available. They include the NIST Standard Reference Materials
recommended.
NIST 610, NIST 612, and NIST 614; the float glass standard
9.3.4 Initiate the acquisition of the analytical signals using
glasses FGS1 and FGS2, evaluated by the European group
the ICP-MS software. Each data acquisition consists of a
NITECRIME (5) and distributed by the Bundeskriminalamt,
transient signal of intensity versus time for each element. Each
Germany; and the calibration standards CFGS1, CFGS2, and
transient signal shall include a background (gas blank) mea-
surement (typically 20 s to 40 s), followed by the ablation of
the sample (typically 30 s to 60 s). A washout delay (typically
30 s to 60 s) shall be applied between two measurements to
Available from National Institute of Standards and Technology (NIST), 100
Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
avoid carryover.
Available from Bundeskriminalamt, Section KI 42, 65173 Wiesbaden,
Germany, http://www.bka.de. NOTE 2—The background, ablation and washout delay intervals will
E2927 − 23
vary depending upon instrumental configurations and the needs of the analytical sequence can be as follows:
analysis. Specific intervals should be determined by validation procedures. (1) Calibration standard(s) (spots 1-3)
(2) “Known” fragment #1 (spots 1-3)
9.4 Conduct replicate ablations at different locations within
(3) “Questioned” fragment #1 (spots 1-3)
the fragment(s). If the size allows, space the fragments
(4) Quality Control Standard(s) (spots 1-3)
sufficiently apart to avoid re-ablating possible debris from
(5) “Questioned” fragment #1 (spots 4-6)
(6) “Known” fragment #2 (spots 4-6)
other ablation halos.
(7) Calibration standard(s) (spots 4-6)
9.5 Collect replicate measurements to ensure that the ques-
(8) “Known” fragment #3 (spots 7-9)
tioned glass fragments and known glass source(s) are ad- (9) “Questioned” fragment #2 (spots 1-3)
(10) Quality Control Standard(s) (spots 4-6)
equately characterized in all dimensions (7). Analyze a mini-
(11) “Questioned” fragment #2 (spots 4-6)
mum of three replicates on each questioned sample examined
(12) “Known” fragment #4 (spots 10-12)
and nine replicates on known glass sources.
(13) Calibration standard(s) (spots 7-9)
9.5.1 If the size of the questioned samples allows, perform
NOTE 5—A symmetrical arrang
...

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 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.
´1
Designation: E2927 − 16 E2927 − 23 An American National Standard
Standard Test Method for
Determination of Trace Elements in Soda-Lime Glass
Samples Using Laser Ablation Inductively Coupled Plasma
Mass Spectrometry for Forensic Comparisons
This standard is issued under the fixed designation E2927; 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.
ε NOTE—Editorial corrections were made to 11.1 in December 2017.
INTRODUCTION
One objective of a forensic glass examination is to compare glass samples to determine if they
maycan be discriminated usingby their physical, optical, or chemical properties (for example, color,
refractive index (RI), density, elemental composition). If the samples are distinguishable in any of
these observed and measured properties, it may be concludedcan be determined that they did not
originate from the same source of broken glass. If the samples are indistinguishable in all of these
observed and measured properties, the possibility exists that they originated from the same source of
glass may not be eliminated. glass. The use of an elemental analysis method such as laser ablation
inductively coupled plasma mass spectrometry yields high discrimination among sources of glass.
1. Scope
1.1 This test method covers a procedure for the quantitative elemental analysis of the following seventeen elements: lithium (Li),
magnesium (Mg), aluminum (Al), potassium (K), calcium (Ca), 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 Inductively Coupled Plasma Mass Spectrometrylaser ablation inductively coupled plasma mass
spectrometry (LA-ICP-MS) for the forensic comparison of glass fragments. The potential of these elements to provide the best
discrimination among different sources of soda-lime glasses has been published elsewhere ((1-5).). Silicon (Si) is also monitored
for use as a normalization standard. Additional elements may be added as needed, for example, tin (Sn) can be used to monitor
the orientation of float glass fragments.
1.2 The method only consumes approximately 0.4 to 2 μg 0.4 μg to 3 μg of glass per replicate and is suitable for the analysis of
full thickness samples as well as irregularly shaped fragments as small as 0.1 mm by 0.4 mm 0.1 mm by 0.2 mm (6) in dimension.
-1
The concentrations of the elements listed above range from the low parts per million (μgg ) to percent (%) levels in
soda-lime-silicatesoda-lime glass, the most common type encountered in forensic cases. This standard method maycan be applied
for the quantitative analysis of other glass types; however, some modifications in the reference standard glasses and the element
menu may be required.
1.3 This standard does not replace knowledge, skill, ability, experience, education or training is intended for use by competent
This test method 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 Dec. 1, 2016Nov. 15, 2023. Published April 2017January 2024. Originally approved in 2013. Last previous edition approved in 20132016 as
ɛ1
E2927 – 13.16 . DOI: 10.1520/E2927-16E01.10.1520/E2927-23.
The boldface numbers in parentheses refer to a list of references at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2927 − 23
forensic science practitioners with the requisite formal education, discipline-specific training (see Practice E2917and should be
used in conjunction with professional judgment.), and demonstrated proficiency to perform forensic casework.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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 and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
1.6 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.
E2927 − 23
2. Referenced Documents
2.1 ASTM Standards:
C162 Terminology of Glass and Glass Products
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E2330 Test Method for Determination of Concentrations of Elements in Glass Samples Using Inductively Coupled Plasma Mass
Spectrometry (ICP-MS) for Forensic Comparisons
E177E2917 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsForensic Science Practitioner Training,
Continuing Education, and Professional Development Programs
C162E2926 Terminology of Glass and Glass ProductsTest Method for Forensic Comparison of Glass Using Micro X-ray
Fluorescence (μ-XRF) Spectrometry
3. Terminology
3.1 Definitions:
3.1.1 calibration standard, n—a reference material used to determine the quantitative analysis for concentrations of the analyte
elements of interest in the glass matrix. The calibration standard(s) shall have a known elemental composition including a known
uncertainty for the reported analytes.
3.1.2 glass, n—an inorganic product of fusion that has been cooled to a rigid condition without crystallization. C162
3.1.3 normalization standard, n—an element that is present in the glass matrix at elevated and relatively homogeneous
concentration that may be used to normalize the laser ablation signal to compensate for any variation on the ablated mass or
instrumental drift.
4. Summary of Test Method
4.1 The glass fragments usually do not require sample preparation prior to the LA-ICP-MS analysis. However, they maycan be
washed with solvents or pre-ablated if necessary.
4.2 The glass fragment is placed inside an ablation chamber and a laser beam is focused on the surface of the sample. When the
ablation is started, the interaction between the pulsed laser and the sample surface produces a cloud of very small particles, which
are transported from the ablation cell by a carrier gas into the ICP-MS for analysis.
4.3 An ICP-MS is used to quantify the elements of interest.
4.4 Quantitative analysis is accomplished using well-characterized glass standards whose major elemental composition is similar
to the material to be analyzed.
4.5 A comparison between the reported elemental compositions of the known and recoveredquestioned glass fragments may result
in a decision on whether the samples are distinguishable by elemental composition or indistinguishable by elemental composition.
5. Significance and Use
5.1 This test method is useful for the determination of elemental concentrations in the microgram per gram (μggrange of
-1
approximately 0.1 μgg ) to percent (%) levels 10 percent (%) (See Table X1.1) in soda-lime glass samples. samples (7 and 8). A
standard test method maycan aid in the interchange of data between laboratories and in the creation and use of glass databases.
5.2 The determination of elemental concentrations in glass provides high discriminating value in the forensic comparison of glass
fragments.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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5.3 This test method produces minimal destruction of the sample. Microscopic craters of 5050 μm to 100 μm in diameter by 80
to 150-μm80 μm to 150 μm deep are left in the glass fragment after analysis. The mass removed per replicate is approximately 0.4
to 3.1 μg.0.4 μg to 3 μg (6).
5.4 Appropriate sampling techniques shall be used to account for natural heterogeneity of the materials at a microscopic scale.
5.5 The precision, accuracy,bias, and limits of detection of the method (for each element measured) shall be established in each
laboratory that employs during validation of the method. The measurement uncertainty of any concentration value used for a
comparison shall be recorded with the concentration.
5.6 Acid digestion of glass followed by either Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) or
Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) maycan also be used for trace elemental analysis of glass, and offer
similar detection levels and the ability for quantitative analysis. However, these methods are destructive, and require larger sample
sizes and much longer more sample preparation times (Test Method E2330).
5.7 Micro X-Ray Fluorescence (μ-XRF) uses comparable sample sizes to those used for LA-ICP-MS with the advantage of being
non-destructive of the sample. Some of the drawbacks of μ-XRF are poorerinclude lower sensitivity and precision, and longer
analysis time. time (Test Method E2926).
5.8 Scanning Electron Microscopy with EDS Energy Dispersive Spectrometry (SEM-EDS) is also available for elemental
analysis, but it is of limited use for forensic glass source discrimination due to poor detection limits for higher atomic number
elements present in glass at trace concentration levels. However, distinguishing between sources having similar RIs and densities
is sometimes possible.
6. Apparatus
6.1 LA-ICP-MS—A Laser Ablation system coupled to an ICP-MS instrument is employed. Since there are several manufacturers
for both laser ablation units and ICP-MS instruments, the instrument maker, model, configuration, and major operational
parameters (that is, laser wavelength for the laser and mass selective detector type for the ICP-MS) of both instruments shall be
noted within the analysis results. The most common laser wavelengths used for glass analysis are 266 nm, 213 nm, and 193 nm.
Either quadrupole or magnetic sector ICP-MS instruments are suitable for this test method.
6.2 Prior to the analysis on the day it is used, the analysis, the ICP-MS shall be tuned according to the manufacturer’s
recommendations covering the mass range of the elements to be measured. Detector cross calibrations (pulse/analog) shall be
performed when two detector modes are used in the analysis. The instrument shall be adjusted for maximum sensitivity, best
precision, and to minimize oxides and doubly charged ion interferences. The use of a glass reference material, such as NIST 612,
is recommended during the tuning and performance check. Detector cross calibrations (pulse/analog) shall be performed before
any measurements when two detector modes are used in the analysis.
6.3 In order to prepare for data acquisition, the signals of the following isotopes are monitored in the ICP-MS; lithium ( Li),
24 or 25 27 29 39 42 57 49
magnesium ( Mg), aluminum ( Al), silicon ( Si), potassium ( K), calcium ( Ca), iron ( Fe), titanium ( Ti), manganese
55 85 88 90 118 137 139 140
( Mn), rubidium ( Rb), strontium ( Sr), zirconium ( Zr), tin ( Sn), barium ( Ba), lanthanum ( La), cerium ( Ce),
146 180 208
neodymium ( Nd), hafnium ( Hf) and lead ( Pb). This procedure maycan be applicable to other elements and other isotopes
206, 207
(for example, Pb); however, those elements listed above are considered to provide the most discrimination power for
soda-lime glass comparisons. Alternatively, other isotopes such as Fe may be monitored using ICP-MS with advanced technology
to remove interferences (for example, sector field ICP-MS or reaction cells).
6.4 Either argon or helium may be used as aHelium is used as the carrier gas to transport the particles from the ablation cell to
the plasma. The use of helium carrier gas has been reported to result in fewer fractionation effects than the use of argon as a carrier
((69).).
Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
E2927 − 23
7. Hazards
7.1 Commercial laser ablation units are enclosed type I lasers. However, laser systems typically used for analysis of glass generate
high energy radiation that maycan pose serious risks to eye safety if exposed to the eye. Interlocks shall not be bypassed or
disconnected.
7.2 The argon plasma shall not be observed directly without protective eyewear. Potentially hazardous UV light maycan be
emitted.
7.3 ICP-MS instruments generate high amounts of radiofrequency energy (RF) in their RF power supply and torch boxes that is
potentially hazardous if allowed to escape. Safety devices and safety interlocks shall not be bypassed or disconnected.
8. Calibration and Standardization
8.1 A calibration curve using multiple glass standards or using a single glass standard may be is used for quantitation for
LA-ICP-MS analysis of glass. Any calibration standard shall be matrix-matched to the sample and well-characterized. The
calibration standard(s) shall be traceable to an accepted standard. For glass analysis there are several standards that are available
such asavailable. They include the NIST Standard Reference Materials (that is, NIST 610, NIST 612, NIST 614) and and NIST
614; the float glass standard glasses (FGS1, FGS2) FGS1 and FGS2, evaluated by the European group NITECRIME ((5)) and
5 29
distributed by the Bundeskriminalamt, Germany.Germany; A normalization standard, preferably silicon (and Si), shall be used
to normalize the signal. The use of a normalization standard is needed to adjust for differences in ablation yield between the ablated
materials. Since silicon is present as a major component in all soda-lime glass (~70 to 72 % as SiOthe calibration standards CFGS1,
CFGS2, and CFGS3 evaluated by the NIJ Glass Interpretation Working Group and distributed by Florida International University,
USA ( ) (38, 710), a low abundance isotope (). Si) is commonly used as the normalization standard for this method. If this method
is used for the analysis of other glass types, the concentration of the normalization standard shall be determined prior to quantitative
analysis.
8.2 In addition to the calibration standard, at least one additional glass standard reference material shall should (that is, “calibration
verification standard”) shall be measured with each sample set as a quality control check for the accuracy and precision of the
method. The quality control specifications shall be set by each laboratory. Forensic Science Service Provider (FSSP). The quality
control check standard should be a well-characterized glass and one not used to calibrate the instrument.
8.3 As a minimum, calibration standards are required at the beginning and the end of the analytical sequence in order to adjust
for instrument drift over time. Acceptance criteria for the calibration shall be defined by each laboratoryvalidation protocols and
shall include the use of calibration verification standards.
8.4 A normalization standard, preferably silicon ( Si), shall be used to normalize the signal. The use of a normalization standard
is needed to adjust for differences in ablation yield between the ablated materials. Since silicon is present as a major component
in all soda-lime glass (~70 % to 72 % as SiO ) (3, 11), a low abundance isotope ( Si) is commonly used as the normalization
standard for this method.
9. Procedure
9.1 If necessary, samples may be cleaned clean the samples to remove any surface contamination by washing or pre-ablation, or
both, prior to analysis. Cleaning
NOTE 1—Cleaning can include washing samples in soap or water, ultrasonication, or additional rinses in deionized water then acetone, methanol, or
ethanol, before drying. In addition, soaking in dilute concentrations of nitric acid for at least 30 minutes and rinsing in deionized water and ethanol
removes most surface contamination without affecting the elemental concentrations of interest. However, nitric acid can unintentionally remove surface
coatings on the sample. may include washing samples with soap and water, with or without ultrasonication, and rinsing in deionized
water, followed by rinsing in acetone, methanol, or ethanol, and drying. Soaking in various concentrations of nitric acid for 30
minutes or longer, rinsing with deionized water and ethanol, and drying prior to analysis removes most surface contamination
without affecting the measured concentrations of elements inherent in the glass. However, the use of nitric acid may remove some
surface coatings that may be present.
Available from Bundeskriminalamt, Section KI 35,42, 65173 Wiesbaden, Germany, http://www.bka.de.
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9.2 Multiple samples and standards maycan be placed together in the ablation cell as long as their positions are documented.
9.3 The Secure the samples or standards, or both, shall be secured in the ablation cell using double-sided tape or other adhesive.
tape, other adhesive, or putty. Orient the sample to avoid an original surface of the glass. The known and questioned samples shall
be treated equally. The following steps shall be followed:
9.3.1 Purge After opening the ablation cell for sample exchange, purge the cell with the carrier gas between samples to avoid any
contamination.
9.3.2 If pre-ablation cleaning is performed it mayperformed, it can be done at this point.
9.3.3 Focus the laser beam at the surface of the sample. Single spot (or depth profile) ablation modes are recommended at a spot
size of ~50 to 100 μm Spot sizes of ~50 μm to 100 μm and a repetition rate of 10 Hz. Program the laser parameters.10 Hz are
recommended.
9.3.4 Initiate the acquisition of the analytical signals using the ICP-MS software. Each data acquisition shall be comprised consists
of a transient signal of intensity versus time for each element; each transient shall include 20–30 seconds of element. Each transient
signal shall include a background (gas blank) measurement, followed by 50–60 seconds of measurement (typically 20 s to 40 s),
followed by the ablation of the sample, followed by 10–30 seconds of post-ablation blank measurement.sample (typically 30 s to
60 s). A washout delay (typically 30 s to 60 s) shall be applied between two measurements to avoid carryover.
NOTE 2—The background, ablation and washout delay intervals will vary depending upon instrumental configurations and the needs of the analysis.
Specific intervals should be determined by validation procedures.
9.4 Conduct replicate ablations at different locations within the fragment(s). If the size allows, space the fragments sufficiently
apart to avoid re-ablating possible debris from other ablation halos.
9.5 Collect replicate measurements to ensure that the questioned glass fragments and known glass source(s) are adequately
characterized in all dimensions (7). Analyze a minimum of three replicates on each questioned sample examined and nine replicates
on known glass sources.
9.5.1 If the size of the questioned samples allows, perform four to six measurements on each questioned sample.
9.5.2 If the number and size allow, analyze at least three replicate measurements on four different fragments of each known sample
(that is, 12 replicate measurements total) for tempered glass sources, or at least nine replicate measurements spaced over separate
areas of one adequately-sized fragment of a non-tempered source. For smaller fragments, the nine replicate measurements can be
accomplished with more samples and fewer replicates per sample.
NOTE 3—If it is not possible to analyze the minimum recommended number of known replicates (see 9.5.2) the elemental heterogeneity may not be
captured in the source. This could potentially increase the false exclusion rate.
9.6 Analyze at least one calibration standard at the beginning and the end of a sequence. Additional standards can be added.
9.7 M
...