ASTM E2881-18

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Designation: E2881 − 13 E2881 − 18
Standard Test Method for
Extraction and Derivatization of Vegetable Oils and Fats
from Fire Debris and Liquid Samples with Analysis by Gas
Chromatography-Mass Spectrometry
This standard is issued under the fixed designation E2881; 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 throughout in January 2015.
1. Scope
1.1 This test method covers the extraction, derivatization, and identification of fatty acids indicative of vegetable oils and fats
in fire debris and liquid samples. This procedure will also extract animal oils and fats, as these are similar in chemical composition
to vegetable oils and fats. Herein, the phrase “oils and fats” will be used to refer to both animal and vegetable derived oils and
fats.
1.2 This test method is suitable for successfully extracting oil and fat residues having 8 to 24 carbon atoms.
1.3 The identification of a specific type of oil (for example, olive, corn, linseed) requires a quantitative analysis of the fatty acid
esters and is beyond the scope of this test method.
1.4 This test method cannot replace the requisite knowledge, skills, or abilities acquired through appropriate education, training,
and experience and should be used in conjunction with sound professional judgment.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 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.
2. Referenced Documents
2.1 ASTM Standards:
E620 Practice for Reporting Opinions of Scientific or Technical Experts
E1386 Practice for Separation of Ignitable Liquid Residues from Fire Debris Samples by Solvent Extraction
E1388 Practice for Static Headspace Sampling of Vapors from Fire Debris Samples
E1412 Practice for Separation of Ignitable Liquid Residues from Fire Debris Samples by Passive Headspace Concentration With
Activated Charcoal
E1413 Practice for Separation of Ignitable Liquid Residues from Fire Debris Samples by Dynamic Headspace Concentration
E1492 Practice for Receiving, Documenting, Storing, and Retrieving Evidence in a Forensic Science Laboratory
E1618 Test Method for Ignitable Liquid Residues in Extracts from Fire Debris Samples by Gas Chromatography-Mass
Spectrometry
E2154 Practice for Separation and Concentration of Ignitable Liquid Residues from Fire Debris Samples by Passive Headspace
Concentration with Solid Phase Microextraction (SPME)
E2451 Practice for Preserving Ignitable Liquids and Ignitable Liquid Residue Extracts from Fire Debris Samples
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 June 1, 2013June 1, 2018. Published October 2013June 2018. Originally approved in 2013. Last previous edition approved in 2013 as E2881
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– 13 . DOI: 10.1520/E2881-13E01.10.1520/E2881-18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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3. Summary of Test Method
3.1 If ignitable liquid analysis is required, it shall be performed prior to analysis for oils and fats as this test method is a
destructive technique. A fire debris sample (or sub-sample) or an aliquot of a liquid is initially analyzed for ignitable liquid residues
using standards listed in the referenced documents.
3.2 The same sample of fire debris (or different sub-sample) or an additional aliquot of a liquid is then extracted with an organic
solvent, and a derivatizing agent is added to convert either the free fatty acids and some triglycerides (for acid-catalyzed
derivatization) or just the triglycerides (for base-catalyzed derivatization) to fatty acid methyl esters (FAMEs).
3.3 The organic layer of solvent is removed, filtered, and concentrated if necessary, using dry nitrogen, filtered air, or inert gas.
3.4 The derivatized extract is analyzed by gas chromatography-mass spectrometry (GC-MS).
3.5 Specific chemical components (fatty acid methyl esters) are identified by their retention times and mass spectra.
4. Significance and Use
4.1 This test method is useful when oils and fats are suspected as an ignition source or a fuel source in a fire.
4.1.1 The identification of oil and fat residues in samples from a fire scene can support the field investigator’s opinion regarding
the origin and cause of the fire.
4.1.2 The positive identification of fatty acid(s) does not necessarily mean that the fire was caused by self heating.
4.2 This test method specifically identifies fatty acid derivatives. Oils and fats are comprised primarily of triglycerides (which
are fatty acids attached to a glycerol backbone), and some free fatty acids. Free fatty acids and triglycerides are not easily analyzed
by the traditional ignitable liquid extraction techniques. Solvent extraction and derivatization to FAME will enable identification
by GC-MS.
4.2.1 The identification of an individual fatty acid in fire debris samples does not confirm the presence of oils or fats; however,
there are times when large quantities of the oil or fat may be extracted. In such cases a more positive identification can be made.
4.2.2 Oils and fats containing fatty acids with no double bonds will generally have no tendency to self-heat. With increasing
unsaturation (1, 2, and 3 double bonds), the tendency to self-heat also increases, such that polyunsaturated fatty acids (PUFAs),
such as C18:3, have a high tendency to self-heat.
4.3 This test method is a sensitive separation technique and can detect quantities as small as 3 μL of oil or fat residue in an
extract from a debris sample.
4.4 This test method shall be performed after all required traditional testing for ignitable liquid residues is completed.
4.5 This test method extracts liquids and residues from porous and nonporous materials of various sizes.
4.6 This test method can be hampered by coincident extraction of interfering compounds present in the fire debris samples.
4.7 This is a destructive technique and whenever possible the entire sample should not be used for the procedure. It is
recommended that visual inspection be used to locate portions or areas exhibiting potential oily residue for sub-sampling which
would preserve remaining portions for further analyses and also minimize solvent waste. The solvent extracted portions of the
sample are not suitable for resampling.
4.8 Alternate methods of extraction, derivatization, or analysis exist and may be suitable for use in obtaining similar results and
conclusions.
4.9 Biodiesel, an ignitable liquid, is a trans-esterified product containing FAMEs. The FAME compounds in biodiesel can be
detected in fire debris using many fire debris extraction techniques followed directly by GC-MS analysis. Derivatization is not
necessary to identify the FAMEs in biodieselbiodiesel.
3, 4, 5, 6
4.10 For more information on oils, FAME, and fire debris analysis, see the references listed.
5. Apparatus
5.1 Gas Chromatograph—A chromatograph capable of using capillary columns and being interfaced to a mass spectrometer.
5.1.1 Sample Inlet System—A sample inlet system that can be operated in either split or splitless mode with capillary columns;
the inlet system may use on-column technology.
5.1.2 Column—A capillary, bonded phase, methylsilicone or phenylmethylsilicone column or equivalent, or a polar capillary,
bonded phase, such as a cyanopropyl-based fatty acid specific column, may be used to determine the presence of fatty acids.
Gambrel, A. K., and Reardon, M. R., “Extraction, Derivatization, and Analysis of Vegetable Oils from Fire Debris,” Journal of Forensic Sciences, Vol 53, No. 6, 2008,
pp. 1372–1380.
Schwenk, L. M., and Reardon, M. R., “Practical Aspects of Analyzing Vegetable Oils in Fire Debris,” Journal of Forensic Sciences, Vol 54, No. 4, 2009, pp. 874–880.
Stauffer, E., “A Review of the Analysis of Vegetable Oil Residues from Fire Debris Samples: Spontaneous Ignition, Vegetable Oils, and the Forensic Approach,” Journal
of Forensic Sciences, Vol 50, No. 5, 2005, pp. 1091–1100.
Stauffer, E., “A Review of the Analysis of Vegetable Oil Residues from Fire Debris Samples: Analytical Scheme, Interpretation of the Results, and Future Needs,” Journal
of Forensic Sciences, Vol 51, No. 5, 2006, pp. 1–17.
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5.1.2.1 A polar capillary, bonded phase, such as a cyanopropyl-based fatty acid specific column shall be used to perform
comparative analysis between neat liquid samples, or fire debris samples, or both. Any column length or temperature program
conditions may be used provided that each component of the reference mixture (see 6.8) is adequately separated on the polar
column.
5.1.3 GC Oven—A column oven capable of reproducible temperature program operation in the range from 50 to 300°C.
5.2 Mass Spectrometer—Capable of acquiring mass spectra from m/z 40 to m/z 400 with unit resolution or better, with
continuous data output.
5.2.1 Sensitivity and Resolution—The system shall be capable of detecting each component of the reference mixture (see 6.8)
and providing sufficient ion intensity data to identify each component, either by computer library search or by comparison with
reference spectra.
5.3 Data Station—A computerized data station capable of storing time sequenced mass spectral data from sample runs.
5.3.1 Data Handling—The data system shall be capable of performing, either through its operating system or by user
programming, various data handling functions, including input and storage of sample data files, generation of extracted ion profiles,
searching data files for selected compounds, and qualitative and semi-quantitative compound analysis.
5.3.2 Mass Spectral Libraries—The system shall be capable of retrieving a specified mass spectrum from a data file and
comparing it against a library of mass spectra available to the data system. This capability is considered an aid to the analyst, who
will use it in conjunction with chromatographic data and known reference materials to identify unknown components.
5.4 Syringes—A syringe capable of introducing a sample size in the range from 0.1 to 10.0 μm.μL.
5.5 Steam bath, for use in warming sample extracts in containers used during evaporation steps.
6. Reagents and Materials
6.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. It is intended that all reagents conform to the
specifications of the Committee on Analytical Reagents of the American Chemical Society. Other grades may be used, provided
it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the
determination.
6.2 Solvent—A suitable solvent, such as n-pentane, n-hexane, or n-heptane.
6.2.1 Solvent purity can be verified by evaporating to at least twice the extent used in the analysis and analyzing the evaporated
solvent in accordance with Test Method E1618.
6.3 Derivatization Reagent—There are two types of derivatization processes: (1) acid-catalyzed, which will act on both
triglycerides and free fatty acids; and (2) base-catalyzed, which will only trans-esterify triglycerides. A suitable derivatization
reagent, such as a 2N potassium hydroxide (KOH) in methanol solution (base-catalyzed) or a 10 % boron trifluoride in methanol
solution (acid-catalyzed), will be chosen to convert the fatty acids and triglycerides to FAMEs.
6.4 Drying Agent—A suitable drying agent, such as anhydrous sodium sulfate.
6.5 Filter Apparatus, free of extractable hydrocarbons, oils, and fats.
6.6 Evaporation Accelerants—Compressed dry nitrogen, filtered air, or inert gas used in the concentration of solvent extracts.
6.7 Carrier Gas—Helium or hydrogen of purity 99.995 % or higher.
6.8 Reference Mixture—The reference mixture shall consist of a minimum of the following FAMEs: C16:0, C18:0, C18:1,
C18:2, C18:3. Additional compounds may be included at the discretion of the analyst. The mixture should contain approximately
equal parts by weight of the required fatty acids methyl esters in the chosen solvent or a traceable commercially available reference
mixture. The final solution is prepared by diluting the above mixture such that the concentration of each component is no greater
than 0.005 % weight/volume (0.05 micrograms/milliliter) in the chosen solvent. A typical chromatogram including components of
the reference mixture on a typical non-polar fire debris column is shown in Fig. 1. A typical chromatogram including components
of the reference mixture on a fatty acid specific column is shown in Fig. 2.
6.9 Reference Oils and Fats—Oils and fats should be available for comparison and identification purposes.
6.9.1 Typically, FAMEs derived from reference oils and fats are diluted approximately 1:200 in an appropriate solvent and
derivatized using the same procedure that will be used on the debris and liquid samples. Depending on the column capacity and
injection technique, derivatized oil and fat solutions can be concentrated to ensure detection of minor compounds.
6.10 Glassware or Labware—Clean glassware (beakers, test tubes, and vials) or disposable labware free of extractable
hydrocarbons, oils, and waxes.
7. Equipment Calibration and Maintenance
7.1 Verify the consistent performance of the chromatographic instrument by using blanks and a known concentration of the
reference mixture (see 6.8). Optimize gas flow periodically.
7.2 Tune and Calibrate Mass Spectrometer:
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Instrument: HP 6890 Gas Chromatograph
Detector: HP 5972 Mass Selective Detector
Column: 30 m × 0.25 mm × 0.25 μm, DB-1MS (polydimethylsiloxane)
Mobile Phase: Helium, 0.5 mL/min
Sample: 1 μL
Injector: 250°C
Initial Temperature: 60°C for 3 min
Rate: 5°C/min to 120°C for 0 min
12°C/min to 300°C for 5 min
Total Run Time: 35 min
Split: 20:1
FIG. 1 Total Ion Chromatogram (TIC) of a FAME Reference Mixture on a DB-1MS Capillary Column Using Test Method E1618 GC-MS
Conditions
7.2.1 Ensure proper operation o
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