1、Designation: D5739 06 (Reapproved 2013)Standard Practice forOil Spill Source Identification by Gas Chromatography andPositive Ion Electron Impact Low Resolution MassSpectrometry1This standard is issued under the fixed designation D5739; the number immediately following the designation indicates the
2、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 practice covers the use of gas chromatography a
3、ndmass spectrometry to analyze and compare petroleum oil spillsand suspected sources.1.2 The probable source for a spill can be ascertained by theexamination of certain unique compound classes that alsodemonstrate the most weathering stability. To a greater orlesser degree, certain chemical classes
4、can be anticipated tochemically alter in proportion to the weathering exposure timeand severity, and subsequent analytical changes can be pre-dicted. This practice recommends various classes to be ana-lyzed and also provides a guide to expected weatheringinduced analytical changes.1.3 This practice
5、is applicable for moderately to severelydegraded petroleum oils in the distillate range from dieselthrough Bunker C; it is also applicable for all crude oils withcomparable distillation ranges. This practice may have limitedapplicability for some kerosenes, but it is not useful forgasolines.1.4 The
6、values stated in SI units are to be regarded as thestandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-b
7、ility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD3325 Practice for Preservation of Waterborne Oil SamplesD3326 Practice for Preparation of Samples for Identificationof Waterborne OilsD3328 Test Methods for Comparison of Water
8、borne Petro-leum Oils by Gas ChromatographyD3414 Test Method for Comparison of Waterborne Petro-leum Oils by Infrared SpectroscopyD3415 Practice for Identification of Waterborne OilsD3650 Test Method for Comparison of Waterborne Petro-leum Oils By Fluorescence AnalysisD5037 Test Method for Compariso
9、n of Waterborne Petro-leum Oils by High Performance Liquid Chromatography(Withdrawn 2002)3E355 Practice for Gas Chromatography Terms and Relation-ships3. Summary of Practice3.1 The recommended chromatography column is a capil-lary directly interfaced to the mass spectrometer (either qua-drupole or m
10、agnetic).3.2 The low-resolution mass spectrometer is operated in thepositive ion electron impact mode, 70 eV nominal.3.3 Mass spectral data are acquired, stored, and processedwith the aid of commercially available computer-based datasystems.4. Significance and Use4.1 This practice is useful for asse
11、ssing the source for an oilspill. Other less complex analytical procedures (Test MethodsD3328, D3414, D3650, and D5037) may provide all of thenecessary information for ascertaining an oil spill source;however, the use of a more complex analytical strategy may benecessary in certain difficult cases,
12、particularly for significantlyweathered oils. This practice provides the user with a means tothis end.4.1.1 This practice presumes that a “screening” of possiblesuspect sources has already occurred using less intensive1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the
13、direct responsibility of Subcommittee D19.06 on Methods for Analysis forOrganic Substances in Water.Current edition approved Feb. 15, 2013. Published March 2013. Originallyapproved in 1995. Last previous edition approved in 2006 as D5739 06. DOI:10.1520/D5739-06R13.2For referenced ASTM standards, vi
14、sit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright A
15、STM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1techniques. As a result, this practice focuses directly on thegeneration of data using preselected targeted compoundclasses. These targets are both petrogenic and pyrogenic andcan constitute both m
16、ajor and minor fractions of petroleumoils; they were chosen in order to develop a practice that isuniversally applicable to petroleum oil identification in generaland is also easy to handle and apply. This practice canaccommodate light oils and cracked products (exclusive ofgasoline) on the one hand
17、, as well as residual oils on the other.4.1.2 This practice provides analytical characterizations ofpetroleum oils for comparison purposes. Certain classes ofsource-specific chemical compounds are targeted in this quali-tative comparison; these target compounds are both uniquedescriptors of an oil a
18、nd chemically resistant to environmentaldegradation. Spilled oil can be assessed in this way as beingsimilar or different from potential source samples by the directvisual comparison of specific extracted ion chromatograms(EICs). In addition, other, more weathering-sensitive chemicalcompound classes
19、 can also be examined in order to crudelyassess the degree of weathering undergone by an oil spillsample.4.2 This practice simply provides a means of makingqualitative comparisons between petroleum samples; quantita-tion of the various chemical components is not addressed.5. Apparatus5.1 Gas Chromat
20、ograph Interfaced to a Mass Spectrometer,with a 70-eV electron impact ionization source. The systemshall include a computer for the control of data acquisition andreduction.5.2 Capillary Column, with a high-resolution, 30 m by0.25-mm or 0.32-mm inside diameter (0.25-m df) (such as J however, theresu
21、lting mass spectra may be distorted significantly so that MS computer searchroutines for the identification of unknowns by comparison to conventionallyacquired mass spectral libraries may be impaired significantly.BAdjust the entrance lens voltage.CAdjust the ion focus voltage.7.2.2 Retune every 12
22、h of mass spectrometer operation.7.3 Resolution CheckUnder the instrumental conditionslisted (7.1), pristane and phytane usually display 80 % orgreater resolution from C17and C18, respectively. If theresolution is less than 50 %, take corrective action such asreplacement of the injector liner and se
23、als and removal of thefront of the analytical column. Report the degree of resolutionin Section 10. Refer to Practice E355 for calculation ofresolution values.7.4 Mass Discrimination Check:7.4.1 Use the gas chromatographic instrumental parametersenumerated in 8.3.1; operate the mass spectrometer, bu
24、t in thelinear scan mode from m/e 45 to 360 in 1 s.7.4.2 Inject a 1-L solution of naphthalene, fluoranthene,and benzo (g,h,i) perylene in equal concentrations (from 50 to150 ng/L) in cyclohexane.7.4.3 Integrate the total ion chromatogram (TIC).7.4.4 Calculate the following ratios:(1) Area of naphtha
25、lene to area of fluoranthene, and(2) Area of benzo (g,h,i) perylene to area of fluoranthene.7.4.5 The ratio of (1) must be less than or equal to 2, and theratio of (2) must be greater than or equal to 0.2. Report thisvalue in Section 10.7.4.6 A high molecular weight response can sometimes beimproved
26、 by changing the penetration of the chromatographiccolumn into the injector body or using silanized glass wool orquartz as injector packing material, or both. Electronic flowcontrol (instead of constant column head pressure) has recentlybecome available for Capillary GC. It can be used to provide ah
27、igh molecular weight response by increased flow duringsplitless injection.7.5 Retention Time CheckThe absolute retention times forthe mass discrimination check compounds (7.4.2) must berecorded. The batch-to-batch retention time reproducibility canbe documented in this way. Report these retention ti
28、mes inSection 10.8. Procedure8.1 Refer to Terminology D1129 for terms relating to waterand Practice D3415 for identification of waterborne oils. Referto Practice D3325 for the preservation of oil samples andPractice D3326 for preparation of the neat oil sample. (PracticeD3326 includes Procedure F fo
29、r recovering oil from thin filmson water and Procedure G for recovering oil from sand anddebris.) It is the responsibility of the user to validate thismethod for use with these types of matrices since oil recoveredfrom them may contain contamination derived from the sub-strate material.8.2 Sample Pr
30、eparationWeigh 100 to 200 mg of oil into ascrew-cap glass vial, and add 10 mL cyclohexane. Sonicationmay be necessary, as well as centrifugation, to remove particu-lates if the sample does not dissolve completely.8.3 Instrumental Parameters:8.3.1 Gas ChromatographUse the following parameters:1-L spl
31、itless injection for 45 s; an initial column temperatureof 55C for 2 min; a temperature ramp at 6C/min to 270C; atemperature ramp of 3C/min to 300C; a final columntemperature of 300C for 17 min; an injection temperature of290C; and a mass spectrometer (MS) interface temperature of300C. A total run t
32、ime of approximately 65 min will beachieved using these parameters.8.3.2 Mass Spectrometer Data Acquisition ParametersOperate the mass spectrometer in selected ion monitoring(SIM) for the 24 ions listed in Table 2. Since all of the ions willbe scanned every second, the dwell time for each is 70 ms.A
33、llow a solvent delay time of 4 min before the start of MSscanning.NOTE 1It is recognized that the different monitored classes of analyteselute only in certain regions of the chromatogram; consequently, not allions need be monitored continuously. However, no effort has been madeto segment the chromat
34、ogram by using different SIM masses at differenttimes for the sake of maintaining simplicity. It is also recognized that thesignal-to-noise ratio is improved by an increase in the dwell time;however, this improvement is directly proportional to the square root ofthe proportional dwell time increase.
35、 A signal-to-noise ratio increase ofonly two would thus result from a four-fold increase in the dwell (from 70to 280 ms). This increased dwell time would permit only 3 ions/s to bemonitored. Nevertheless, the experienced analyst who is working with awell-characterized oil source, such as monitoring
36、degradation over time,may choose to monitor fewer ions in order to maximize the signal-to-noiseratios and consequently improve the sensitivity for a subset of the ionslisted in the table. Similarly, users of certain older model mass spectrom-eters may also choose to modify SIM acquisition by monitor
37、ing fewer ionssimultaneously in order to offset lowered MS sensitivity.8.4 Sample Analysis Batching RequirementsEvery timethe mass spectrometer is used, bracket all samples by aTABLE 2 SIM Acquisitionm/e Dwell/ms Elution range/min85 70 4 to 60113 70 4 to 60156 70 4 to 60166 70 4 to 60170 70 4 to 601
38、77 70 4 to 60178 70 4 to 60183 70 4 to 60184 70 4 to 60191 70 4 to 60192 70 4 to 60198 70 4 to 60202 70 4 to 60205 70 4 to 60206 70 4 to 60208 70 4 to 60212 70 4 to 60216 70 4 to 60217 70 4 to 60218 70 4 to 60220 70 4 to 60226 70 4 to 60231 70 4 to 60234 70 4 to 60D5739 06 (2013)3duplicate analysis,
39、 and specifically prepare an oil sample induplicate (8.2). Also, the first and last samples to be analyzedmust be these duplicates. Generate the resulting EICs inaccordance with 9.1.1, and compare them visually in accor-dance with 9.1.2; any variations observed will serve to definethe analytical err
40、or for the entire batch.9. Interpretation9.1 Evaluation of EICs:9.1.1 Data PresentationEICs will be generated for eachoil sample. These EICs are as follows: (1)C2through C4homologs of naphthalene, (2) dibenzothiophene and its C1C3homologs, (3) anthracene and phenanthrene and their C1C3homologs, (4)
41、triterpanes, (5) steranes, and (6) alkanes, (7)benzonaphthothiophene, (8) tri-aromatic steranes, (9) hopanes,(10) pyrene/fluoranthene, (11) fluorene and (12) bicyclonaph-thalenes. The EICs and their approximate time intervals aresummarized in Table 1. The method can be extended to includeother suita
42、ble ions, if necessary. (With this in mind, the usermay desire to include naphthalene and C1naphthalene ho-mologs for light, minimally weathered spills or chrysene andits C1to C2homologous series for heavily weathered residualoils, or both.9.1.2 Direct Visual Comparison of EICsThe EICs for eachsuspe
43、ct source oil will be compared to the appropriate EICs ofthe spilled oil; evaluation of the patterns (EICs) will beperformed as a peak-to-peak comparison simply by placing theEICs one over the other. Since the y axis will be normalized at100 %, automatically, the EICs from identical oils will haveid
44、entical plots (although not necessarily identical scale, whichis dependent on the absolute weight of the injected sample),and they will therefore overlay each other completely (withinthe confines of analytical error defined in 8.4). This uniformpresentation of the EICs makes visual comparison by ove
45、rlaya straightforward procedure, regardless of differences in injec-tion amounts.9.1.3 Weathering Stability:9.1.3.1 The more highly alkylated homologs are preferredfor characterization purposes over the unsubstituted parentcompound, or even its monomethylated forms, since bothsolubility in water and
46、 biodegradation are related inversely tothe degree of alkylation.9.1.3.2 In similar fashion, biodegradation and water solu-bility are also related inversely to the number of fused rings.Dibenzothiophene and anthracene/phenanthrene are thereforeinherently more resistant than naphthalenes.9.1.3.3 Ster
47、anes and triterpanes are relatively water in-soluble and are extraordinarily resistant to biodegradation.9.1.3.4 The most stable EICs should be examined first,progressing toward the less stable ones. This order from moreweathering stable to less weathering stable is shown in Fig. 1.9.1.4 Susceptibil
48、ity of the Various Compound Classes toWeathering ExposureIt may be best to first examine thehighest molecular weight homologous series with the greatestdegree of substitution, since weathering results in progressivelosses greatest for the lowest molecular weight homologousseries with the least degre
49、e of substitution, progressing towardthe highest molecular weight series with the greatest degree ofsubstitution. In those cases in which weathering has notprogressed sufficiently to eradicate an entire substituted seriescompletely, the remnants will continue to reflect the originalratios of the unweathered oil. The EICs for a weathered oilversus its unweathered source will thus remain qualitatively thesame, that is, the EICs will not change.NOTE 2A signal-to-noise ratio of 3:1 is used to ascertain the remnantpresence of a peak for those weathered oil EICs
