ASTM E2881-13
(Test Method)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
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
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 L 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 n...
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E2881 − 13
StandardTest 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.
1. Scope E1388 Practice for Sampling of HeadspaceVapors from Fire
Debris Samples
1.1 This test method covers the extraction, derivatization,
E1412 Practice for Separation of Ignitable Liquid Residues
and identification of fatty acids indicative of vegetable oils and
from Fire Debris Samples by Passive Headspace Concen-
fats in fire debris and liquid samples. This procedure will also
tration With Activated Charcoal
extract animal oils and fats, as these are similar in chemical
E1413 Practice for Separation of Ignitable Liquid Residues
composition to vegetable oils and fats. Herein, the phrase “oils
from Fire Debris Samples by Dynamic Headspace Con-
and fats” will be used to refer to both animal and vegetable
centration
derived oils and fats.
E1492 Practice for Receiving, Documenting, Storing, and
1.2 This test method is suitable for successfully extracting
Retrieving Evidence in a Forensic Science Laboratory
oil and fat residues having 8 to 24 carbon atoms.
E1618 TestMethodforIgnitableLiquidResiduesinExtracts
from Fire Debris Samples by Gas Chromatography-Mass
1.3 The identification of a specific type of oil (for example,
olive, corn, linseed) requires a quantitative analysis of the fatty Spectrometry
E2154 Practice for Separation and Concentration of Ignit-
acid esters and is beyond the scope of this test method.
able Liquid Residues from Fire Debris Samples by Pas-
1.4 This test method cannot replace the requisite
sive Headspace Concentration with Solid Phase Microex-
knowledge, skills, or abilities acquired through appropriate
traction (SPME)
education, training, and experience and should be used in
E2451 Practice for Preserving Ignitable Liquids and Ignit-
conjunction with sound professional judgment.
able Liquid Residue Extracts from Fire Debris Samples
1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
3. Summary of Test Method
standard.
3.1 If ignitable liquid analysis is required, it shall be
1.6 This standard does not purport to address all of the
performed prior to analysis for oils and fats as this test method
safety concerns, if any, associated with its use. It is the
is a destructive technique.Afire debris sample (or sub-sample)
responsibility of the user of this standard to establish appro-
or an aliquot of a liquid is initially analyzed for ignitable liquid
priate safety and health practices and determine the applica-
residues using standards listed in referenced documents.
bility of regulatory limitations prior to use.
3.2 The same sample of fire debris (or different sub-sample)
2. Referenced Documents
or an additional aliquot of a liquid is then extracted with an
organic solvent, and a derivatizing agent is added to convert
2.1 ASTM Standards:
either the free fatty acids and some triglycerides (for acid-
E620 Practice for Reporting Opinions of Scientific or Tech-
catalyzed derivatization) or just the triglycerides (for base-
nical Experts
catalyzed derivatization) to fatty acid methyl esters (FAMEs).
E1386 Practice for Separation of Ignitable Liquid Residues
from Fire Debris Samples by Solvent Extraction
3.3 The organic layer of solvent is removed, filtered, and
concentrated if necessary, using dry nitrogen, filtered air, or
inert gas.
ThistestmethodisunderthejurisdictionofASTMCommitteeE30onForensic
Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.
3.4 The derivatized extract is analyzed by gas
Current edition approved June 1, 2013. Published October 2013. DOI: 10.1520/
E2881-13. chromatography-mass spectrometry (GC-MS).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2881 − 13
3.5 Specific chemical components (fatty acid methyl esters) 5. Apparatus
are identified by their retention times and mass spectra.
5.1 Gas Chromatograph—A chromatograph capable of us-
ing capillary columns and being interfaced to a mass spectrom-
4. Significance and Use
eter.
5.1.1 Sample Inlet System—A sample inlet system that can
4.1 This test method is useful when oils and fats are
be operated in either split or splitless mode with capillary
suspected as an ignition source or a fuel source in a fire.
columns; the inlet system may use on-column technology.
4.1.1 The identification of oil and fat residues in samples
5.1.2 Column—Acapillary,bondedphase,methylsiliconeor
from a fire scene can support the field investigator’s opinion
phenylmethylsilicone column or equivalent, or a polar
regarding the origin and cause of the fire.
capillary,bondedphase,suchasacyanopropyl-basedfattyacid
4.1.2 The positive identification of fatty acid(s) does not
specificcolumn,maybeusedtodeterminethepresenceoffatty
necessarily mean that the fire was caused by self heating.
acids.
4.2 This test method specifically identifies fatty acid deriva- 5.1.2.1 A polar capillary, bonded phase, such as a
tives. Oils and fats are comprised primarily of triglycerides cyanopropyl-based fatty acid specific column shall be used to
(which are fatty acids attached to a glycerol backbone), and perform comparative analysis between neat liquid samples, or
some free fatty acids. Free fatty acids and triglycerides are not fire debris samples, or both.Any column length or temperature
easily analyzed by the traditional ignitable liquid extraction programconditionsmaybeusedprovidedthateachcomponent
techniques.SolventextractionandderivatizationtoFAMEwill of the reference mixture (see 6.8) is adequately separated on
enable identification by GC-MS. the polar column.
5.1.3 GC Oven—A column oven capable of reproducible
4.2.1 The identification of an individual fatty acid in fire
temperature program operation in the range from 50 to 300°C.
debris samples does not confirm the presence of oils or fats;
however, there are times when large quantities of the oil or fat
5.2 Mass Spectrometer—Capable of acquiring mass spectra
may be extracted. In such cases a more positive identification
from m/z 40 to m/z 400 with unit resolution or better, with
can be made.
continuous data output.
4.2.2 Oils and fats containing fatty acids with no double
5.2.1 Sensitivity and Resolution—The system shall be ca-
bonds will generally have no tendency to self-heat. With
pable of detecting each component of the reference mixture
increasingunsaturation(1,2and3doublebonds),thetendency
(see 6.8) and providing sufficient ion intensity data to identify
toself-heatalsoincreases,suchthatpolyunsaturatedfattyacids each component, either by computer library search or by
(PUFAs), such as C18:3, have a high tendency to self-heat.
comparison with reference spectra.
5.3 Data Station—A computerized data station capable of
4.3 This test method is a sensitive separation technique and
storing time sequenced mass spectral data from sample runs.
can detect quantities as small as 3 L of oil or fat residue in an
5.3.1 Data Handling—The data system shall be capable of
extract from a debris sample.
performing, either through its operating system or by user
4.4 This test method shall be performed after all required
programming, various data handling functions, including input
traditional testing for ignitable liquid residues is completed.
and storage of sample data files, generation of extracted ion
profiles, searching data files for selected compounds, and
4.5 This test method extracts liquids and residues from
qualitative and semi-quantitative compound analysis.
porous and nonporous materials of various sizes.
5.3.2 Mass Spectral Libraries—The system shall be capable
4.6 This test method can be hampered by coincident extrac-
of retrieving a specified mass spectrum from a data file and
tion of interfering compounds present in the fire debris
comparing it against a library of mass spectra available to the
samples.
data system. This capability is considered an aid to the analyst,
who will use it in conjunction with chromatographic data and
4.7 This is a destructive technique and whenever possible
known reference materials to identify unknown components.
the entire sample should not be used for the procedure. It is
recommended that visual inspection be used to locate portions
5.4 Syringes—A syringe capable of introducing a sample
or areas exhibiting potential oily residue for sub-sampling
size in the range from 0.1 to 10.0 µm.
which would preserve remaining portions for further analyses
5.5 Steam bath, for use in warming sample extracts in
and also minimize solvent waste. The solvent extracted por-
containers used during evaporation steps.
tions of the sample are not suitable for resampling.
4.8 Alternate methods of extraction, derivatization, or
6. Reagents and Materials
analysis exist and may be suitable for use in obtaining similar
6.1 Purity of Reagents—Reagent grade chemicals shall be
results and conclusions.
used in all tests. It is intended that all reagents conform to the
4.9 Biodiesel, an ignitable liquid, is a trans-esterified prod- specifications of the Committee on Analytical Reagents of the
uctcontainingFAMEs.TheFAMEcompoundsinbiodieselcan American Chemical Society. Other grades may be used,
be detected in fire debris using many fire debris extraction provided it is first ascertained that the reagent is of sufficiently
techniques followed directly by GC-MS analysis. Derivatiza- high purity to permit its use without lessening the accuracy of
tion is not necessary to identify the FAMEs in biodiesel the determination.
E2881 − 13
6.2 Solvent—A suitable solvent, such as n-pentane, 6.7 Carrier Gas—Helium or hydrogen of purity 99.995 %
n-hexane, or n-heptane. or higher.
6.2.1 Solvent purity can be verified by evaporating to at
6.8 Reference Mixture—The reference mixture shall consist
least twice the extent used in the analysis and analyzing the
of a minimum of the following FAMEs: C16:0, C18:0, C18:1,
evaporated solvent in accordance with Test Method E1618.
C18:2, C18:3. Additional compounds may be included at the
6.3 Derivatization Reagent—There are two types of deriva-
discretion of the analyst. The mixture should contain approxi-
tization processes: (1) acid-catalyzed, which will act on both
mately equal parts by weight of the required fatty acids methyl
triglyceridesandfreefattyacids;and(2)base-catalyzed,which
esters in the chosen solvent or a traceable commercially
only trans-esterify triglycerides. A suitable derivatization
available reference mixture. The final solution is prepared by
reagent, such as a 2N potassium hydroxide (KOH) in methanol
diluting the above mixture such that the concentration of each
solution (base-catalyzed) or a 10 % boron trifluoride in
component is no greater than 0.005 % weight/volume (0.05
methanol solution (acid-catalyzed), will be chosen to convert
micrograms/milliliter) in the chosen solvent. A typical chro-
the fatty acids and triglycerides to FAMEs.
matogram including components of the reference mixture on a
typical non-polar fire debris column is shown in Fig. 1.A
6.4 Drying Agent—A suitable drying agent, such as anhy-
typical chromatogram including components of the reference
drous sodium sulfate.
mixture on a fatty acid specific column is shown in Fig. 2.
6.5 Filter apparatus, free of extractable hydrocarbons, oils,
and fats.
6.9 Reference Oils and Fats—Oils and fats should be
available for comparison and identification purposes.
6.6 Evaporation Accelerants—Compressed dry nitrogen,
filtered air, or inert gas used in the concentration of solvent 6.9.1 Typically, FAMEs derived from reference oils and fats
extracts. are diluted approximately 1:200 in an appropriate solvent and
Instrument: HP 6890 Gas Chromatograph
Detector: HP 5972 Mass Selective Detector
Column: 30m×0.25mm×0.25µm,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
E2881 − 13
Instrument: HP 6890 Gas Chromatograph
Detector: HP 5973 Mass Selective Detector
A
Column: 30m×0.25mm×0.25µm, Supelco SP-2380 poly (90 % biscyanopropyl/10 %
cyanopropylphenyl siloxane)
Mobile Phase: Helium, 1.0 mL/min
Sample: 1 µL
Injector: 250°C
Initial Temperature: 105°C for 0 min
Rate: 4°C/min to 200°C for 0 min
20°C/min to 260°C for 0 min
Total Run Time: 26.75 min
Split: 20:1
A
A trademark by Sigma-Aldrich Co., LLC.
FIG. 2 Total Ion Chromatogram (TIC) of a FAME Reference Mixture on a SP-2380 Capillary Column Using a Program Optimized for Oil
and Fat Analysis
derivatized using the same procedure that will be used on the 7.2.2 Maintain tuning documentation as a portion of the
debris and liquid samples. Depending on the column capacity quality control documentation.
and injection technique, derivatized oil and fat solutions can be
7.3 Equipment Maintenance:
concentrated to ensure detection of minor compounds.
7.3.1 Change septa and clean or replace injector liners on a
6.10 Glassware or Labware—Cleanglassware(beakers,test
periodic basis to avoid sample contamination by carryover of
tubes, and vials) or disposable labware free of extractable
residual material from previous sample injections.
hydrocarbons, oils, and waxes.
8. Sample Handling Procedure
7. Equipment Calibration and Maintenance
8.1 Onlysamplesofappropriatedilutionshouldbeanalyzed
7.1 Verify the consistent performance of the chromato-
on a GC-MS system
graphic instrument by using blanks and a known concentration
8.2 Care must be taken to ensure that samples and extracts
of the reference mixture (see 6.8). Optimize gas flow periodi-
containing a small quantity of triglycerides and free fatty acids
cally.
are not subjected to heat or evaporated to dryness prior to
7.2 Tune and Calibrate Mass Spectrometer:
derivatization, as both of these may change the composition of
7.2.1 Ensure proper operation of the mass spectrometer
the extract.
using perfluorotributylamine (PFTBA), or another appropriate
calibration standard, according to the instrument manufactur- 8.3 Analyze solvent blanks at
...
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