ASTM E2881-2018 Standard Test Method for Extraction and Derivatization of Vegetable Oils and Fats from Fire Debris and Liquid Samples with Analysis by Gas Chromatography-Mass Spect.pdf

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1、Designation: E2881 18Standard Test Method forExtraction and Derivatization of Vegetable Oils and Fatsfrom Fire Debris and Liquid Samples with Analysis by GasChromatography-Mass Spectrometry1This standard is issued under the fixed designation E2881; the number immediately following the designation in

2、dicates 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.1. Scope1.1 This test method covers the extraction,

3、derivatization,and identification of fatty acids indicative of vegetable oils andfats in fire debris and liquid samples. This procedure will alsoextract animal oils and fats, as these are similar in chemicalcomposition to vegetable oils and fats. Herein, the phrase “oilsand fats” will be used to ref

4、er to both animal and vegetablederived oils and fats.1.2 This test method is suitable for successfully extractingoil 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 fattyacid este

5、rs and is beyond the scope of this test method.1.4 This test method cannot replace the requisiteknowledge, skills, or abilities acquired through appropriateeducation, training, and experience and should be used inconjunction with sound professional judgment.1.5 The values stated in SI units are to b

6、e regarded asstandard. No other units of measurement are included in thisstandard.1.6 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, health, and environmental

7、 practices and deter-mine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guid

8、es and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E620 Practice for Reporting Opinions of Scientific or Tech-nical ExpertsE1386 Practice for Separation of Ignitable Liquid Residuesfrom Fire Debris Samp

9、les by Solvent ExtractionE1388 Practice for Static Headspace Sampling of Vaporsfrom Fire Debris SamplesE1412 Practice for Separation of Ignitable Liquid Residuesfrom Fire Debris Samples by Passive Headspace Concen-tration With Activated CharcoalE1413 Practice for Separation of Ignitable Liquid Resid

10、uesfrom Fire Debris Samples by Dynamic Headspace Con-centrationE1492 Practice for Receiving, Documenting, Storing, andRetrieving Evidence in a Forensic Science LaboratoryE1618 Test Method for Ignitable Liquid Residues in Extractsfrom Fire Debris Samples by Gas Chromatography-MassSpectrometryE2154 Pr

11、actice for Separation and Concentration of Ignit-able Liquid Residues from Fire Debris Samples by Pas-sive Headspace Concentration with Solid Phase Microex-traction (SPME)E2451 Practice for Preserving Ignitable Liquids and Ignit-able Liquid Residue Extracts from Fire Debris Samples3. Summary of Test

12、 Method3.1 If ignitable liquid analysis is required, it shall beperformed prior to analysis for oils and fats as this test methodis a destructive technique. A fire debris sample (or sub-sample)or an aliquot of a liquid is initially analyzed for ignitable liquidresidues using standards listed in the

13、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 anorganic solvent, and a derivatizing agent is added to convert1This test method is under the jurisdiction ofASTM Committee E30 on ForensicSciences and is the

14、direct responsibility of Subcommittee E30.01 on Criminalistics.Current edition approved June 1, 2018. Published June 2018. Originallyapproved in 2013. Last previous edition approved in 2013 as E2881 131. DOI:10.1520/E2881-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcon

15、tact 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 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international stan

16、dard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1eithe

17、r 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, andconcentrated if necessary, using dry nitrogen, filtered air, o

18、rinert gas.3.4 The derivatized extract is analyzed by gaschromatography-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 Use4.1 This test method is useful when oils and fats aresuspected

19、as an ignition source or a fuel source in a fire.4.1.1 The identification of oil and fat residues in samplesfrom a fire scene can support the field investigators opinionregarding the origin and cause of the fire.4.1.2 The positive identification of fatty acid(s) does notnecessarily mean that the fir

20、e was caused by self heating.4.2 This test method specifically identifies fatty acid deriva-tives. Oils and fats are comprised primarily of triglycerides(which are fatty acids attached to a glycerol backbone), andsome free fatty acids. Free fatty acids and triglycerides are noteasily analyzed by the

21、 traditional ignitable liquid extractiontechniques. Solvent extraction and derivatization to FAME willenable identification by GC-MS.4.2.1 The identification of an individual fatty acid in firedebris samples does not confirm the presence of oils or fats;however, there are times when large quantities

22、 of the oil or fatmay be extracted. In such cases a more positive identificationcan be made.4.2.2 Oils and fats containing fatty acids with no doublebonds will generally have no tendency to self-heat. Withincreasing unsaturation (1, 2, and 3 double bonds), the ten-dency to self-heat also increases,

23、such that polyunsaturatedfatty acids (PUFAs), such as C18:3, have a high tendency toself-heat.4.3 This test method is a sensitive separation technique andcan detect quantities as small as 3 L of oil or fat residue in anextract from a debris sample.4.4 This test method shall be performed after all re

24、quiredtraditional testing for ignitable liquid residues is completed.4.5 This test method extracts liquids and residues fromporous and nonporous materials of various sizes.4.6 This test method can be hampered by coincident extrac-tion of interfering compounds present in the fire debrissamples.4.7 Th

25、is is a destructive technique and whenever possiblethe entire sample should not be used for the procedure. It isrecommended that visual inspection be used to locate portionsor areas exhibiting potential oily residue for sub-samplingwhich would preserve remaining portions for further analysesand also

26、 minimize solvent waste. The solvent extracted por-tions of the sample are not suitable for resampling.4.8 Alternate methods of extraction, derivatization, oranalysis exist and may be suitable for use in obtaining similarresults and conclusions.4.9 Biodiesel, an ignitable liquid, is a trans-esterifi

27、ed prod-uct containing FAMEs. The FAME compounds in biodiesel canbe detected in fire debris using many fire debris extractiontechniques followed directly by GC-MS analysis. Derivatiza-tion is not necessary to identify the FAMEs in biodiesel.4.10 For more information on oils, FAME, and fire debrisana

28、lysis, see the references listed.3, 4, 5, 65. Apparatus5.1 Gas ChromatographA chromatograph capable of us-ing capillary columns and being interfaced to a mass spectrom-eter.5.1.1 Sample Inlet SystemA sample inlet system that canbe operated in either split or splitless mode with capillarycolumns; the

29、 inlet system may use on-column technology.5.1.2 ColumnAcapillary, bonded phase, methylsilicone orphenylmethylsilicone column or equivalent, or a polarcapillary, bonded phase, such as a cyanopropyl-based fatty acidspecific column, may be used to determine the presence of fattyacids.5.1.2.1 A polar c

30、apillary, bonded phase, such as acyanopropyl-based fatty acid specific column shall be used toperform comparative analysis between neat liquid samples, orfire debris samples, or both. Any column length or temperatureprogram conditions may be used provided that each componentof the reference mixture

31、(see 6.8) is adequately separated onthe polar column.5.1.3 GC OvenA column oven capable of reproducibletemperature program operation in the range from 50 to 300C.5.2 Mass SpectrometerCapable of acquiring mass spectrafrom m/z 40 to m/z 400 with unit resolution or better, withcontinuous data output.5.

32、2.1 Sensitivity and ResolutionThe system shall be ca-pable of detecting each component of the reference mixture(see 6.8) and providing sufficient ion intensity data to identifyeach component, either by computer library search or bycomparison with reference spectra.5.3 Data StationA computerized data

33、 station capable ofstoring time sequenced mass spectral data from sample runs.5.3.1 Data HandlingThe data system shall be capable ofperforming, either through its operating system or by userprogramming, various data handling functions, including inputand storage of sample data files, generation of e

34、xtracted ion3Gambrel, A. K., and Reardon, M. R., “Extraction, Derivatization, and Analysisof Vegetable Oils from Fire Debris,” Journal of Forensic Sciences, Vol 53, No. 6,2008, pp. 13721380.4Schwenk, L. M., and Reardon, M. R., “Practical Aspects of AnalyzingVegetable Oils in Fire Debris,” Journal of

35、 Forensic Sciences, Vol 54, No. 4, 2009,pp. 874880.5Stauffer, E., “A Review of the Analysis of Vegetable Oil Residues from FireDebris Samples: Spontaneous Ignition, Vegetable Oils, and the ForensicApproach,”Journal of Forensic Sciences, Vol 50, No. 5, 2005, pp. 10911100.6Stauffer, E., “A Review of t

36、he Analysis of Vegetable Oil Residues from FireDebris Samples: Analytical Scheme, Interpretation of the Results, and FutureNeeds,” Journal of Forensic Sciences, Vol 51, No. 5, 2006, pp. 117.E2881 182profiles, searching data files for selected compounds, andqualitative and semi-quantitative compound

37、analysis.5.3.2 Mass Spectral LibrariesThe system shall be capableof retrieving a specified mass spectrum from a data file andcomparing it against a library of mass spectra available to thedata system. This capability is considered an aid to the analyst,who will use it in conjunction with chromatogra

38、phic data andknown reference materials to identify unknown components.5.4 SyringesA syringe capable of introducing a samplesize in the range from 0.1 to 10.0 L.5.5 Steam bath, for use in warming sample extracts incontainers used during evaporation steps.6. Reagents and Materials6.1 Purity of Reagent

39、sReagent grade chemicals shall beused in all tests. It is intended that all reagents conform to thespecifications of the Committee on Analytical Reagents of theAmerican Chemical Society. Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permi

40、t its use without lessening the accuracy ofthe determination.6.2 SolventA suitable solvent, such as n-pentane,n-hexane, or n-heptane.6.2.1 Solvent purity can be verified by evaporating to atleast twice the extent used in the analysis and analyzing theevaporated solvent in accordance with Test Method

41、 E1618.6.3 Derivatization ReagentThere are two types of deriva-tization processes: (1) acid-catalyzed, which will act on bothtriglycerides and free fatty acids; and (2) base-catalyzed, whichwill only trans-esterify triglycerides. A suitable derivatizationreagent, such as a 2N potassium hydroxide (KO

42、H) in methanolsolution (base-catalyzed) or a 10 % boron trifluoride inmethanol solution (acid-catalyzed), will be chosen to convertthe fatty acids and triglycerides to FAMEs.6.4 Drying AgentA suitable drying agent, such as anhy-drous sodium sulfate.6.5 Filter Apparatus, free of extractable hydrocarb

43、ons, oils,and fats.6.6 Evaporation AccelerantsCompressed dry nitrogen,filtered air, or inert gas used in the concentration of solventextracts.6.7 Carrier GasHelium or hydrogen of purity 99.995 %or higher.6.8 Reference MixtureThe reference mixture shall consistof a minimum of the following FAMEs: C16

44、:0, C18:0, C18:1,C18:2, C18:3. Additional compounds may be included at thediscretion of the analyst. The mixture should contain approxi-mately equal parts by weight of the required fatty acids methylesters in the chosen solvent or a traceable commerciallyavailable reference mixture. The final soluti

45、on is prepared bydiluting the above mixture such that the concentration of eachcomponent is no greater than 0.005 % weight/volume (0.05micrograms/milliliter) in the chosen solvent. A typical chro-matogram including components of the reference mixture on atypical non-polar fire debris column is shown

46、 in Fig. 1.Atypical chromatogram including components of the referencemixture on a fatty acid specific column is shown in Fig. 2.6.9 Reference Oils and FatsOils and fats should beavailable for comparison and identification purposes.6.9.1 Typically, FAMEs derived from reference oils and fatsare dilut

47、ed approximately 1:200 in an appropriate solvent andderivatized using the same procedure that will be used on thedebris and liquid samples. Depending on the column capacityand injection technique, derivatized oil and fat solutions can beconcentrated to ensure detection of minor compounds.6.10 Glassw

48、are or LabwareClean glassware (beakers, testtubes, and vials) or disposable labware free of extractablehydrocarbons, oils, and waxes.7. Equipment Calibration and Maintenance7.1 Verify the consistent performance of the chromato-graphic instrument by using blanks and a known concentrationof the refere

49、nce mixture (see 6.8). Optimize gas flow periodi-cally.7.2 Tune and Calibrate Mass Spectrometer:7.2.1 Ensure proper operation of the mass spectrometerusing perfluorotributylamine (PFTBA), or another appropriatecalibration standard, according to the instrument manufactur-ers specifications, prior to use. This should be done at leastevery day that the instrument is used or in accordance withmanufacturers recommendations.7.2.2 Maintain tuning documentation as a portion of thequality control documentation.7.3 Equipment Maintenance:7.3.1 Change septa and cle