1、Designation: D 3414 98 (Reapproved 2004)Standard Test Method forComparison of Waterborne Petroleum Oils by InfraredSpectroscopy1This standard is issued under the fixed designation D 3414; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method provides a means for the identificationof waterborne oil samples by the comparison
3、of their infraredspectra with those of potential source oils.1.2 This test method is applicable to weathered or unweath-ered samples, as well as to samples subjected to simulatedweathering.1.3 This test method is written primarily for petroleum oils.1.4 This test method is written for linear transmi
4、ssion, butcould be readily adapted for linear absorbance outputs.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 appl
5、ica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 3325 Practice for Preservation of Waterborne OilSamplesD 3326 Practice f
6、or Preparation of Samples for Identifica-tion of Waterborne OilsD 3415 Practice for Identification of Waterborne OilsE 131 Terminology Relating to Molecular SpectroscopyE 168 Practices for General Techniques of Infrared Quan-titative AnalysisE 275 Practice for Describing and Measuring Performanceof
7、Ultraviolet, Visible, and Near Infrared Spectrophotom-eters3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method referto Terminology E 131 and Terminology D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 weathering of waterborne oilthe combined effectso
8、f evaporation, solution, emulsification, oxidation, biologicaldecomposition, etc.4. Summary of Test Method4.1 The spill sample and potential source oil(s) are treatedidentically to put them in an appropriate form for analysis byinfrared spectrophotometry. The oils are transferred to suitableinfrared
9、 cells and the spectra are recorded from 4000 to 600cm1for KBr cells, and to 650 cm-1 for HATR cells with ZnSecrystals. All analyses are performed on the same instrumentusing the same sample cell, which is cleaned between samples.The spectra of the sample and the potential source oil(s) arethen comp
10、ared by superimposing one upon the other, lookingat particular portions of the spectra. A high degree of coinci-dence between the spectra of the sample and a potential sourceoil indicates a common origin. This test method is recom-mended for use by spectroscopists experienced in infrared oilidentifi
11、cation or under close supervision of such qualifiedpersons.5. Significance and Use5.1 This test method provides a means for the comparison ofwaterborne oil samples with potential sources. The waterbornesamples may be emulsified in water or obtained from beaches,boats, oil-soaked debris, and so forth
12、.5.2 The unknown oil is identified by the similarity of itsinfrared spectrum with that of a potential source oil obtainedfrom a known source, selected because of its possible relation-ship to the unknown oil.5.3 The analysis is capable of comparing most oils. Diffi-culties may be encountered if a sp
13、ill occurs in an alreadypolluted area, that is, the spilled-oil mixes with another oil.5.4 In certain cases, there may be interfering substanceswhich require modification of the infrared test method or theuse of other test methods (see Practice D 3326, Method D.)1This test method is under the jurisd
14、iction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.06 on Methods forAnalysis forOrganic Substances in Water.Current edition approved June 1, 2004. Published June 2004. Originallyapproved in 1975. Last previous edition approved in 1998 as D 341498.2For reference
15、d ASTM standards, visit 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Con
16、shohocken, PA 19428-2959, United States.5.5 It is desirable, whenever possible, to apply other inde-pendent analytical test methods to reinforce the findings of theinfrared test method (see Practice D 3415).6. Apparatus6.1 Infrared SpectrophotometerAn instrument3capableof recording in the spectral r
17、ange from 4000 to 600 cm1andmeeting the specifications is shown in Table 1. Refer also toPractice E 275. Fourier transform infrared spectrophotometersmeet these specifications.NOTE 1Although this test method is written for the use of dispersiveinfrared spectroscopy, Fourier transform infrared spectr
18、oscopy can also beused for oil comparison.6.2 Sample Cells:6.2.1 Demountable CellsThe cell generally used is ademountable liquid cell using a 0.05-mm spacer. This cell isusable for all oil types, the heavy oils being analyzed assmears. For light oils, a sealed cell can be used, provided thatthe samp
19、le is known to be dry. Another type used is alow-capacity demountable cell using a silver halide windowwith a 0.025-mm depression.4Satisfactory oil spectra can beobtained with this cell with as little as 10 L of oil, comparedto the nearly 100 L required for the standard cells. This cellcan also be u
20、sed to screen for the presence of water in oilsamples.6.2.2 Horizontal Attentuated Reflectance Apparatus(HATR), may be used instead of demountable cells. If so, allanalyses must be performed with the same HATR apparatus.6.3 Cell Windows:6.3.1 Potassium or silver bromide should be used fordemountable
21、 cells. Silver chloride may be substituted for thebromide.NOTE 2Sodium chloride should not be used; results obtained usingthis window material, although consistent with each other, are not directlycomparable to those from the other window materials. Sodium chloridewas shown by Brown, et al5to give r
22、esults significantly different fromthose obtained with potassium bromide or silver chloride, based onquantitative comparisons.6.3.2 Zinc selenide is the material of choice for the HATRapparatus.6.4 Accessories:6.4.1 Reference Beam Attenuator, for setting baseline withthe low-capacity silver halide c
23、ell.6.4.2 Disposable Pasteur Pipets and Hypodermic Syringes.6.4.3 Window-Polishing Kit.6.4.4 Centrifuge.6.4.5 Vortex Mixer.6.4.6 Hot Plate.6.4.7 Light-Box, for viewing spectra.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests unless otherwise indicated. It is intende
24、d thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.6For sample treatmentand for cleaning cells, special spectroquality reagents arerequired. Other grades may be used, provided it is
25、firstestablished that the reagent is of sufficiently high purity topermit its use without decreasing the accuracy of the determi-nation.7.2 Purity of Water Unless otherwise indicated referencesto water shall be understood to mean reagent water conformingto Specification D 1193, Type II.7.3 Magnesium
26、 Sulfateanhydrous, reagent grade, for dry-ing samples.7.4 SolventsSpectroquality solvents for sample treatmentand cleaning cells include cyclohexane, pentane, hexane,methylene chloride, and methanol.8. Precautions8.1 Take normal safety precautions when handling organicsolvents.Take precautions to en
27、sure that wet oil samples do notcome in contact with water-soluble cell window materials.Most spectrophotometers require humidity control (to about45 %), particularly if they have humidity-sensitive detectorssuch as those with cesium iodide optics. The primary precau-tion which must be taken to prov
28、ide the best possible results isthat all samples analyzed should be treated in an identicalfashion, run in the same cell, on the same instrument andpreferably on the same day by the same operator.NOTE 3If the samples cannot be analyzed the same day, one of thefirst samples must be repeated to ensure
29、 that the spectra are notsignificantly different.9. Sampling9.1 On-SceneA representative sample of the waterborneoil is collected in a glass jar (precleaned with cyclohexane anddried) having a TFE-fluorocarbon-lined cap. In the same timeframe, samples are collected of potential source samples thatar
30、e to be compared to the waterborne sample.9.2 LaboratorySee Annex A1.10. Preservation of Sample10.1 Refer to Practice D 3325.3Consult the manufacturers operating manual for specific instructions on usingthis apparatus.4The Mini-cell made by Wilks Scientific Corp., S. Norwalk, CT, has been foundto be
31、 satisfactory for this purpose.5Brown, C. W., Lynch, P. F., and Ahmadjian, M. “Identification of Oil Slicks byInfrared Spectroscopy,” NTIS Accession No. ADA 040975, 1976.6“Reagent Chemicals, American Chemical Society Specifications,” AmericanChemical Society, Washington, DC. For suggestions on the t
32、esting of reagents notlisted by the American Chemical Society, see Rosin, J.,“ Reagent Chemicals andStandards,” D. Van Nostrand Co., New York, NY, and the “United StatesPharmacopeia”.TABLE 1 Specifications for Infrared SpectrophotometersAbscissa accuracy Better than 6 5cm1from 4000 to 2000cm1range;
33、better than 6 3cm1from 2000 to 600 cm1(or below).Abscissa repeatability 2.5 cm1from 4000 to 2000 cm1;1.5cm1from 2000 to 600 cm1(or below).Ordinate accuracy 6 1 % of full scale.Ordinate repeatability within 1 % of full scale.D 3414 98 (2004)211. Analytical Procedures11.1 Recording Spectra for Dispers
34、ive Instruments:11.1.1 Operate the instrument in accordance with the manu-facturers instructions. Refer to Practices E 168 for moreinformation on handling cells.11.1.2 Check the calibration daily by scanning a 0.05-mmpolystyrene film in accordance with Practice E 275. Observewhether the test spectra
35、 are within the limits of the instrumentspecifications. This calibration check should be performedbefore every oil spill set and the spectrum retained with spectrafrom the spill and suspects as part of the case record.11.1.3 Test the resolution by observing the sidebands in thepolystyrene spectrum a
36、t 2850.7 and 1583.1 cm1which shouldbe distinct and well defined.7This is also true for the sidebandat 3100 cm1which should have a clear inflection with adisplacement of at least 1 to 3 % T where T = transmittance.11.1.4 Place the sample in a liquid cell (see Annex A2 orAnnex A3) and insert cell into
37、 the infrared beam. Set theabsorbance to read 0.02 A (95 % T) at 1975 6 20 cm1.NOTE 4The absorbance is set at a fixed value so that the resultantspectra can be compared from a common baseline.11.1.5 Scan the spectrum from 4000 to 600 cm1usingnormal operating conditions and slit settings.11.2 FTIR In
38、struments:11.2.1 Collect data from a background scan (air only) underconditions identical to those under which the sample will berun, that is, with the cell in the instrument and all instrumentparameters the same.11.2.2 Normalize the absorbance before comparing thespectra.11.2.3 Collect data from 65
39、0 cm-1 for HATR cells withZnSe, due to the sprectral absorbance cutoff for ZnSe.11.3 Preparation of SampleRefer to Annex A1 and Prac-tice D 3326 for sample preparation.NOTE 5The primary objective in sample preparation is the removal ofwater to protect the sample cells and get a “clean” spectrum of t
40、he oil. Ifat all possible, the use of solvent should be avoided. It is sometimesnecessary to use solvent in order to break refractory emulsions or toextract the oil from solid substrates. It must be remembered that for validcomparisons of spectra, both oils being compared must have beenprepared the
41、same way, that is, if one is deasphalted with pentane, theother must be also (see Practices D 3326 for the deasphalting procedure.It should be noted that 15 parts of solvent (versus 40) is all that isnecessary for quantitative precipitation of the asphaltene fraction.)12. Interpretation of Spectra12
42、.1 Ultimately, oil identification is based on a peak-by-peak comparison of the spill spectrum with those of the variouspotential sources. A light-box is convenient for superimposingthese spectra. When the results are to be used for forensicpurposes, comparisons must be made on spectra obtained byusi
43、ng the same sample preparation, sample cell, and the sameinstrumental conditions, preferably with the same operator onthe same day.12.2 Sample Spectra12.2.1 Fig. 1 shows the infrared spectrum of a No. 2 fuel oilto illustrate the general spectral characteristics of an oilanalyzed by infrared transmis
44、sion through KBr windows. Thisparticular illustration is actually a superposition of threeindependent spectra which graphically show how reproduciblethe triplicates are, even with a demountable cell, if propertechniques are used. The “oil fingerprint” region between 900to 700 cm1can be seen to have
45、a large amount of fine detailcharacteristic of a light oil.12.2.2 Figs. 2-5 show spectra from 2000 to 600 cm1forfour oils weathered over 4 days. They show the general effectsof weathering on baselines between 1300 and 900 cm1andrelative changes of individual peaks in the“ fingerprint” region.The fig
46、ures are, respectively: No. 2, No. 4, No. 6 fuel oils, anda Louisiana crude with curves at 0, 1, 2, 3, and 4 days outdoorweathering.12.2.3 Fig. 6 and Fig. 7 show details of weathering ofvarious oil types as described in 12.3.7.12.3 Overlay Method:12.3.1 The overlay method consists of a visual compar
47、isonof the spectrum of a spill with that of a potential source in thesequence as follows and outlined in Fig. 8. This may beaccomplished using a light-box or even recording two spectraon the same chart.12.3.1.1 First ensure that the spectra have comparablebaselines at 1975 cm1, that is, that they we
48、re set at anabsorbance of 0.02 (95 % T).12.3.1.2 Next, examine the absorbance at 1377 cm1toobtain qualitative assurance that the samples were analyzed atthe same thickness, that is, same cell path length (see 12.3.2).12.3.1.3 Then examine the curve for overall similarities inshape from 4000 to 600 c
49、m1. For petroleum oils, the baseline7Tables of Wavenumbers For The Calibration of Infrared Spectrometers,IUPAC, Commission on Molecular Structure and Spectroscopy, Butterworth andCo., Toronto, Canada, 1961.FIG. 1 Complete Spectrum of a No. 2 Fuel Oil, Analyzed in TriplicateD 3414 98 (2004)3will tend to move downward with weathering (to higherabsorbance between 1350 to 900 cm1) but with little relativechange of the peaks in that range.12.3.1.4 Examine the 1770 to 1685 cm1region to deter-mine the extent of weatheringparticularly in the 1708 cm
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