ASTM E2143-2001(2006)e1 Standard Practice for Using Field-Portable Fiber Optics Synchronous Fluorescence Spectrometer for Quantification of Field Samples for Aromatic and Polycycli.pdf

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1、Designation: E 2143 01 (Reapproved 2006)e1Standard Test Method forUsing Field-Portable Fiber Optics SynchronousFluorescence Spectrometer for Quantification of FieldSamples for Aromatic and Polycyclic AromaticHydrocarbons1This standard is issued under the fixed designation E 2143; the number immediat

2、ely following the designation indicates 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 (e) indicates an editorial change since the last revision or reapproval.e1NOTEChanged the s

3、tandard category in September 2006.1. Scope1.1 This test method covers a rapid method for the screeningof environmental samples for aromatic hydrocarbons (AHs)and polycyclic aromatic hydrocarbons (PAHs). The screeningtakes place in the field and provides immediate feedback onlimits of contamination

4、by substances containing AHs andPAHs. Quantification is obtained by the use of appropriatelycharacterized, site-specific calibration curves. Remote sensingby use of optical fibers is useful for accessing difficult to reachareas or potentially dangerous materials or situations. Whencontamination of f

5、ield personnel by dangerous materials is apossibility, use of remote sensors may minimize or eliminatethe likelihood of such contamination taking place.1.2 This test method is applicable to AHs and PAHs presentin samples extracted from soils or in water. This test method isapplicable for field scree

6、ning or, with an appropriate calibra-tion, quantification of total AHs and PAHs.1.3 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 det

7、ermine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 4489 Practices for Sampling of Waterborne OilsD 5412 Test Method for Quantification of Complex Poly-cyclic Aromatic Hydrocarbon Mixtures or Petroleum Oils

8、in WaterE 131 Terminology Relating to Molecular SpectroscopyE 388 Test Method for Wavelength Accuracy of SpectralBandwidth of Fluorescence SpectrometersE 578 Test Method for Linearity of Fluorescence MeasuringSystemsE 579 Test Method for Limit of Detection of Fluorescenceof Quinine Sulfate in Soluti

9、on3. Terminology3.1 For definitions of terms used in this test method refer toTerminology D 1129 and E 131.4. Summary of Test Method4.1 This test method consists of extracting the AHs andPAHs from soil samples or preparation of water samplesfollowed by synchronous fluorescence analysis with a field-

10、portable instrument. The samples require serial dilutions ofsamples to establish a linear response. These measurements aremade using standard fluorescence cuvettes. While some opti-mization of selectivity can be accomplished by varying thewavelength difference between excitation and emission mono-ch

11、romators, generally spectra generated from petroleum con-taminants with a wavelength difference such as 6 or 18 nmprovide good results and no preliminary spectra are required(see Test Method D 5412).4.2 Different soils have varying partition coefficients.Therefore, representative samples of a subset

12、 of the extracts orthe water samples should be analyzed by gas chromatography(GC) or other appropriate methods. The purpose is to establisha site-specific calibration curve to be used for quantification oftotal AHs and PAHs in the environmental samples of interest.1This test method is under the juri

13、sdiction of ASTM Committee E13 onMolecular Spectroscopy and is the direct responsibility of Subcommittee E13.09 onOptical Fibers and Wave Lengths.Current edition approved Sept. 1, 2006. Published September 2006. Originallyapproved in 2001. Last previous edition approved in 2001 as E 2143 01.2For ref

14、erenced 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, We

15、st Conshohocken, PA 19428-2959, United States.4.3 When desirable, determination of AHs and PAHs maybe made remotely using an optical fiber.5. Significance and Use5.1 This technique is designed for on-site rapid screeningand characterization of environmental soil and water samplesresulting in signifi

16、cant cost savings for environmental reme-diation projects. Remote analysis can be made with opticalfibers when situations warrant or demand use of this option.5.2 Quantification of total AHs and PAHs in these environ-mental samples is accomplished by having a subset of thesamples analyzed by an alte

17、rnate technique and generating asite-specific calibration curve.5.3 Synchronous fluorescence provides sufficient spectralinformation to characterize the AHs and PAHs present asbenzene, toluene, ethylbenzene and xylene(s) (BTEX), thearomatic portion of total petroleum hydrocarbons (TPH), orlarge arom

18、atic ring systems up to at least seven fused rings,such as might be found in creosote.6. Interferences6.1 The synchronous fluorescence spectrum can be distortedor quantification may be affected if there is a contaminantpresent that produces a synchronous peak in the same vicinityas the material of i

19、nterest. Often spectroquality solventscontain impurities that produce background signals. Solventblanks should be used to verify a low fluorescence backgroundso the background can be subtracted from the samplesspectrum.6.2 There are naturally occurring compounds that fluoresce,which may interfere wi

20、th the detection of petroleum com-pounds, present in the sample. Humic acid from leaf mold is anexample of such a compound. Its strongest emission occurs inthe near ultraviolet range.6.3 Absorption of the exciting light by the sample itself(self-filtering effect) produces erroneous results. Analysis

21、 ofserial dilutions of the sample detects this effect and ensures anaccurate analysis is made. Once linearity is established, thenintegration of the spectrum produces accurate results.6.4 Certain solvents used for extraction of the soil samplescould quench or absorb the fluorescence and raise the li

22、mit ofdetection. Care should be taken to avoid halogenated solventsor solvents containing other quenchers. The user of this testmethod should bear this in mind when selecting an appropriatesolvent.NOTE 1Storage of samples in improper containers, such as plasticsother than polytetrafluoroethylene (or

23、 TFE-fluorocarbon), may result incontamination.NOTE 2This test method is normally used without an internal stan-dard due to possible interference by the internal standard.6.5 Certain optical fibers may generate a fluorescence back-ground. These should be avoided whenever possible. If theymust be use

24、d, a background spectrum should be generated andsubtracted from any samples measured.7. Apparatus7.1 Fluorescence SpectrometerAn instrument recordingin the spectral range of at least 250 to 650 nm is required forboth excitation and emission spectrum measurements andcapable of scanning both monochrom

25、ators at a constant speedwith a constant wavelength offset between them for synchro-nous scanning. The bandwidth of the monochromators shouldbe less than one half the wavelength offset between themonochromators or smaller. The spectrometer should be ca-pable of remote sensing via optic fiber. The de

26、tector should bea photomultiplier tube or a device with similar sensitivity andresponse time. Occasionally field work requires the spectrom-eter to be battery powered. The instrument should meet thespecifications in Table 1.7.2 Excitation SourceA pulsed (9.9 W) Xenon lamp orother source having suffi

27、cient intensity throughout the ultra-violet and visible regions can be used.7.3 Cuvette Sample HolderSample holders should befabricated to hold commercially available, fluorescence-free,fused silica cuvettes.7.4 Optical Fiber HolderA stage that allows correctpositioning of the optical fiber with res

28、pect to the emission andexcitation monochromators. The device may also be used tooptically match each fiber and the respective monochromator.7.5 Computer SystemThe instrument should be interfacedto a computer system that is compatible with the instrumentand has suitable software for spectral data ma

29、nipulation.7.6 CuvetteA standard 12 by 12 by 31 mm fluorescence-free fused silica cuvette. Four sides of the cuvette should bepolished.7.7 Optical FiberFused silica fiber (preferably a highhydroxide) is required for transmission of the ultravioletwavelengths required for accurate spectroscopic analy

30、sis. Ingeneral, this material has good thermal characteristics, can beobtained with low fluorescence background, and is readilyavailable commercially.7.8 GlasswareA 10 mL and 2 mL disposable pipet, bothmarked with 0.1 mL gradations. A glass disposable test tube,capable of holding volumes of liquid g

31、reater than 15 mL. Thetest tube caps should be polytetrafluoroethylene lined to reducepotential contamination.7.9 ScaleAportable scale capable of measuring 2 g of soilto the nearest 0.1 g.7.10 CentrifugeA portable centrifuge, capable of holdingthe test tubes described in 7.8.7.11 ShakerA portable sh

32、aker, capable of mixing the soiland solvent in the test tubes described in 7.8.TABLE 1 Desirable Performance Standards of a Field PortableFluorescence SpectrometerCharacteristic Desirable Range TypicalMonochromatorBandwidth 15 nm 3 nmWavelength accuracy 6 0.52 nm 6 1.0 nmReproducibility 6 0.1 1 % 6

33、0.2 %InterfaceData collection computerized laptop PCInstrument control control and dataSourceBroad band 2001000 nm Xenon lampLow-power consumption 575 W 10 WE 2143 01 (2006)e127.12 Filter ApparatusA syringe with disposable 100-mglass detachable filters.8. Reagents and Materials8.1 Purity of Reagents

34、Spectroquality grade reagentsshould be used in all instances unless otherwise stated.8.2 Purity of WaterASTM Grade 3 or Grade 4 watershould be used.8.3 SolventsHigh purity solvents should be used. Solventsshould be of sufficient purity so as to not generate a back-ground fluorescence spectrum when a

35、nalyzed as a blank.Solvents such as hexane, cyclohexane and methylcyclohexane,ethanol, methanol, etc. must not absorb in the spectral region ofinterest.9. Sampling and Sample Preparation9.1 Water SamplesCollect water samples in accordancewith Practice D 4489, as applicable.9.1.1 If the water samples

36、 contain visible particles, then thesamples may be either centrifuged or filtered depending on thenature of the particles. Large, dense particles can usually becentrifuged to the bottom of the sample container, while finerparticles must be filtered. The water samples should becentrifuged in the cont

37、ainers in which they are sampled, inorder to avoid volatilization of the organic hydrocarbons. Thewater samples should be filtered into the cuvette for analysis.9.1.2 Add approximately 2.5 mL of the water sample intothe cuvette using a disposable pipet and place the cuvette intothe instrument sample

38、 holder. The sample is ready for analysis.9.2 Soil SamplesCollect the sample using accepted pro-cedures already established by ASTM Committee D18.9.2.1 Obtain a representative 2-g soil sample from thesample container. The sample should be weighed directly in thetest tube.9.2.2 Add 10 mL of the appro

39、priate solvent to the soilsample in the test tube using a disposable pipet.9.2.3 Shake the sample until greater than 90 % of thesample is suspended in the solvent. Follow this shaking processby centrifuging the sample in order to separate the solvent fromthe soil.9.2.4 Pour the extract into a second

40、 test tube. At this pointsome particles may be present in the extract, thus filtration willbe required to remove them.9.2.5 If the quality check in 13.6 indicates a need foradditional extraction, then the additional extraction will beperformed at this time.10. Preparation of Apparatus10.1 Prior to m

41、obilization for field use, set up and calibratethe fluorescence spectrometer according to the manufacturersinstructions and Test Methods E 388, E 578, and E 579. Oncein the field, include in the calibration procedures, a check of thewavelength accuracy of the instrument using an appropriateline-sour

42、ce such as a mercury lamp or xenon lamp. In addition,check the baseline of the instrument by analyzing a solventblank. Other options for calibration may include the use ofplastic standards, sealed solutions of anthracene or othercommercially available standards.11. Procedure11.1 Water SamplesAnalyze

43、 the water sample over anappropriate wavelength region using a synchronous scan witha wavelength offset between the monochromators of 18 nm.Other wavelength offset between the monochromators valuesmay be used when appropriate.11.1.1 Subtract the spectrum of a distilled water blank fromthe spectrum o

44、f the water sample.11.1.2 Integrate the area under the spectrum of the sampleover the appropriate wavelength region to determine therelative value.11.1.3 Determine if the sample is in the linear range. Thedetermination of linear range is done by performing a 1:1dilution. Subtract the spectrum of a d

45、istilled water blank fromthe spectrum of the 1:1 dilution. Integrate the area under thespectrum of the sample over the appropriate wavelengthregion. If the integrated value is half of the original value, thenthe sample is in the linear range; otherwise, perform subse-quent dilutions until the linear

46、 range is established.11.2 Soil SamplesAnalyze the soil sample extract over theappropriate wavelength region using a synchronous scan witha wavelength offset between the monochromators of 18 nm.11.2.1 Subtract the spectrum of a solvent blank from thespectrum of the soil sample.11.2.2 Integrate the a

47、rea under the spectrum of the sampleover the appropriate wavelength region to determine therelative value.11.2.3 Determine whether the sample is in the linear rangeaccording to 11.1.3.11.3 Quantitative AnalysisAfter several soil or watersamples have been analyzed by the instrument, pick severalsampl

48、es representing a range of concentrations (at least three:high, medium, and low) and include solvent blanks andsamples of known composition. These samples should beanalyzed by the laboratory using the appropriate method, suchas total petroleum hydrocarbons using the EnvironmentalProtection Agency (E

49、PA), gasoline range organics (GRO), anddiesel range organics (DRO) methods or total polycyclicaromatic hydrocarbons. Many of the approved EPA methodsalso include aliphatic hydrocarbons in the analysis. If therelative proportion of aromatic hydrocarbons to aliphatichydrocarbons remains constant then the correlation graphsdescribed in 11.3.1 can be developed.11.3.1 For each sample analyzed by the laboratory, plot thelaboratory concentration versus the instrument concentrationon a scatter plot. Apply a trend line to the data set and performlinear regressio