1、Designation: D7861 14Standard Test Method forDetermination of Fatty Acid Methyl Esters (FAME) in DieselFuel by Linear Variable Filter (LVF) Array Based Mid-InfraredSpectroscopy1This standard is issued under the fixed designation D7861; the number immediately following the designation indicates the y
2、ear 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 determines fatty acid methyl esters(
3、FAME or biodiesel) in diesel fuel oils. FAME can bequantitatively determined from 1.0 % to 30.0 % by volume.This test method uses linear variable filter (LVF) array basedmid-infrared spectroscopy for monitoring FAME concentra-tion.NOTE 1See Section 6 for a list of interferences that could affect the
4、results produced from this method.1.2 This test method uses a horizontal attenuated totalreflectance (HATR) crystal and a univariate calibration.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purp
5、ort 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-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D97
6、5 Specification for Diesel Fuel OilsD1298 Test Method for Density, Relative Density, or APIGravity of Crude Petroleum and Liquid Petroleum Prod-ucts by Hydrometer MethodD4052 Test Method for Density, Relative Density, and APIGravity of Liquids by Digital Density MeterD4057 Practice for Manual Sampli
7、ng of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsD5854 Practice for Mixing and Handling of Liquid Samplesof Petroleum and Petroleum ProductsD6299 Practice for App
8、lying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6300 Practice for Determination of Precision and BiasData for Use in Test Methods for Petroleum Products andLubricantsD6751 Specification for Biodiesel Fuel Blend Stock (B100)for M
9、iddle Distillate FuelsD7371 Test Method for Determination of Biodiesel (FattyAcid Methyl Esters) Content in Diesel Fuel Oil Using MidInfrared Spectroscopy (FTIR-ATR-PLS Method)D7467 Specification for Diesel Fuel Oil, Biodiesel Blend(B6 to B20)E168 Practices for General Techniques of Infrared Quanti-
10、tative Analysis (Withdrawn 2015)3E1655 Practices for Infrared Multivariate QuantitativeAnalysis3. Terminology3.1 Definitions:3.1.1 biodiesel, nfuel comprised of mono-alkyl esters oflong chain fatty acids derived from vegetable oils or animalfats, designated B100.3.1.2 biodiesel blend (BXX), nblend o
11、f biodiesel fuel withdiesel fuel oils.3.1.2.1 DiscussionIn the abbreviation, BXX, the XX rep-resents the volume percentage of biodiesel fuel in the blend.3.1.3 diesel fuel, npetroleum-based middle distillate fuel.3.1.4 univariate calibration, naprocess for creating acalibration model in which a sing
12、le measured variable, for1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0F on Absorption Spectroscopic Methods.Current edition approved Dec. 15, 2014. Published February 2015.
13、 DOI:10.1520/D7861-14.2For referenced 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.3The last approved version of this hist
14、orical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1example, the absorbance at a particular wavelength, is corre-lated with the concentration or property values for a set ofcalibration samples.
15、3.2 Acronyms:3.2.1 ATR, nattenuated total reflectance3.2.2 BXX, nsee 3.1.23.2.3 FAEE, nfatty acid ethyl esters3.2.4 FAME, nfatty acid methyl esters3.2.5 HATR, nhorizontal attenuated total reflectance3.2.6 LVF, nlinear variable filter4. Summary of Test Method4.1 A sample of diesel fuel or biodiesel b
16、lend (BXX) isplaced onto a HATR sample crystal. Infrared light is imagedthrough the sample, then through the LVF and finally onto adetector array. The LVF separates the infrared light intospecific wavelengths so that the response of the detector arraygenerates an infrared spectrum. Spectral correcti
17、ons are per-formed to eliminate interferences caused by diesel and bio-diesel variations. A wavelength region of the absorptionspectrum that correlates highly with biodiesel is selected foranalysis. The area of the selected region is determined. Acalibration curve converts the selected area of an un
18、knownsample to a concentration of biodiesel.4.2 This test method uses a LVF array based mid-infraredspectrometer with an HATR crystal. The absorption spectrumshall be used to calculate a calibration curve.5. Significance and Use5.1 Biodiesel is a fuel commodity primarily used as ablending component
19、with diesel fuel. It is important to checkthe concentration of biodiesel in the diesel fuel in order tomake sure it is either not below the minimum allowable limitand or does not exceed the maximum allowable limit.5.2 This test method is applicable for quality control in theproduction and distributi
20、on of diesel fuel and biodiesel blends.6. Interferences6.1 The hydrocarbon composition of diesel fuels can affectthe accuracy of the calibration. When possible it is advised thatdiesel fuels used in calibration be similar to the unknownsamples to be analyzed.6.2 Undissolved Water and ParticulatesSam
21、ples contain-ing undissolved water, particulates, or both will result inerroneous results. If the sample is cloudy or water saturatedafter it has been equilibrated between 15 C to 27 C, filter thesample through a qualitative filter paper until clear prior totheir introduction onto the instrument sam
22、ple crystal.6.3 The primary spectral interferences are vegetable oils oranimal fats, or both. Other means of analysis or separatecalibrations may be required if fuel is suspected to be contami-nated with vegetable oils or animal fats, or both.6.4 Due to the inherent variability in LVFs, calibrations
23、cannot be transferred between instruments. Each instrumentshall be calibrated separately prior to use.6.5 This test method is not appropriate for fatty acid ethylesters (FAEE). FAEEs will cause a negative bias.7. Apparatus7.1 Mid-Infrared Spectrometer:7.1.1 LVF Array Based Mid-Infrared SpectrometerT
24、hetype of apparatus suitable for use in this test method employsan IR source, a HATR crystal, a LVF paired to a detector array,an A/D converter, a microprocessor, and controller software.Specifications of sub parts of the analyzer listed below willdetermine the applicability of an instrument to this
25、 test method.7.1.2 The noise level shall be established by acquiring asingle beam spectrum of air. The single beam spectrum may bean average of multiple instrument scans but the total collectiontime shall not exceed 60 s. The noise of the spectrum at 100 %transmission shall be less than 0.3 % in the
26、 range of 5.50 m to5.90 m (1818 cm-1to 1725 cm-1).7.2 Detector Array/Linear Variable Filter SpecificationsThe infrared detector array shall have at least 128 detectionchannels. This detector array shall be paired to a LVF with arange that includes the region of 5.4 m to 6.0 m. At least tendetector c
27、hannels shall be within the range of 5.4 m to 6.0 m.The filter shall have a resolution of at least 50 cm-1.7.3 Horizontal Attenuated Total Reflection CrystalA hori-zontal attenuated total reflectance (ATR) crystal, with zincselenide element mounted on a horizontal plate shall be used.Any number of i
28、nternal reflections (bounces) may be used,however the absorbance at 1745 cm-1shall not exceed 1.1absorbance units for the highest concentration calibrationstandard used in the calibration range. Therefore, for higherconcentration measurements, careful consideration of elementlength and face angle sh
29、all be made to maximize sensitivitywithout exceeding 1.1 absorbance units at 1745 cm-1.7.4 Note that other spectrometer configurations can provideadequate results; however, the precision and bias data listedwith this test method was collected based on these apparatusspecifications. Any modifications
30、 can result in precision and orbias that differ from the numbers listed in this test method.8. Reagents and Materials8.1 Purity of ReagentsSpectroscopic grade (preferred) orreagent grade chemicals shall be used in tests. Unless other-wise indicated, it is intended that all reagents shall conform tot
31、he specifications of the committee on analytical reagents of theAmerican Chemical Society, where such specifications areavailable.4Other grades may be used, provided it is firstascertained that the reagent is of sufficiently high purity topermit its use without lessening the accuracy of the determi-
32、nation.8.1.1 Hexane, anhydrous 110-54-3 or Heptane 142-82-5for use as a cell cleaning agent.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, D.C. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Stand
33、ards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia andNational Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D7861 1428.1.2 B100 used for calibration, qualification, and qualitycontrol standards are recommended to be compliant withS
34、pecification D6751 or similar FAME specifications. Thebiodiesel (B100) shall be FAME.ABQ-9000 certified producerfor the biodiesel is recommended to ensure quality of product.58.1.3 Middle distillate fuel used for calibration,qualification, and quality control standards are recommendedto be compliant
35、 with Specification D975 or similar diesel fuelspecifications, be free of biodiesel or biodiesel oil precursor, orboth. If possible, middle distillate fuel shall be representativeof diesel fuels anticipated for blends to be analyzed (crudesource, 1D, 2D, blends, winter/summer cuts, low aromaticconte
36、nt, high aromatic content, and so forth).9. Sampling, Test Specimens, and Test Units9.1 General Requirements:9.1.1 Fuel samples to be analyzed by this test method shallbe sampled using procedures outlined in Practice D4057 orD4177, where appropriate. Do not use “sampling by waterdisplacement.” FAME
37、is more water-soluble than the hydro-carbon base in a biodiesel blend.9.1.2 Protect samples from excessive temperatures prior totesting.9.1.3 Do not test samples stored in leaky containers. Discardand obtain a new sample if leaks are detected.9.2 Sample Handling During Analysis:9.2.1 When analyzing
38、samples using this method, thesample temperature needs to be within the range of 15 C to27 C. Equilibrate all samples to the temperature of the test site(15 C to 27 C) prior to analysis by this test method.9.2.2 After the analysis, if the sample is to be retained,reseal the container before storage.
39、9.2.3 Avoid using plastic materials for sampling and do notuse rubber caps or plastic bottles for storage of the sample.10. Preparation of Apparatus10.1 Before use, the instrument needs to be calibratedaccording to the procedure described in Annex A1. Thiscalibration may be performed by the instrume
40、nt manufacturerprior to delivery of the instrument to the end user. If, aftermaintenance, the instrument calibration is repeated, the quali-fication procedure shall also be repeated.10.2 Before use, the instrument shall be qualified accordingto the procedure described in AnnexA1. The qualification n
41、eedonly be carried out when the instrument is initially put intooperation, recalibrated, or repaired.11. Calibration and Standardization11.1 Information on calibration and qualification of theapparatus can be found in Annex A1.11.2 Confirm the in-statistical-control status of the testmethod each day
42、 it is used by measuring the biodieselconcentration of at least one quality control sample that issimilar in composition and matrix to samples routinely ana-lyzed. For details on quality control sample selection,preparation, testing, and control charting, refer to PracticeD6299.11.3 A system that is
43、 found to be out of statistical controlcannot be used until the root cause(s) of out-of-control isidentified and corrected.11.4 If correction of out-of-control behavior requires repairto the instrument or recalibration of the instrument, thequalification of instrument performance described in A1.3 s
44、hallbe performed and the in-statistical control status shall beconfirmed.12. Procedure12.1 Equilibrate the samples to between 15 C and 27 Cbefore analysis.12.2 Clean the sample crystal of any residual fuel or othercontamination according to the manufacturers recommenda-tion. Hexane or heptane has be
45、en determined to be suitable forcleaning the sample cell. It is recommended that the samplecrystal be cleaned at least twice before a baseline spectrum isobtained since a clean baseline spectrum is critical for ensuringcorrect results.12.3 Obtain a baseline spectrum in the manner establishedby the m
46、anufacturer of the equipment.12.4 Prior to the analysis of unknown test samples, establishthat the equipment is running properly by collecting thespectrum of the quality control standard(s) and comparing theestimated biodiesel concentration(s) to the known value(s) forthe QC standard(s).12.5 Introdu
47、ce the unknown fuel sample in the mannerestablished by the manufacturer. Ensure that the entire crystalsurface is covered with fuel.12.6 Obtain the digitized spectral response of the fuelsample in the manner established by the manufacturer of theequipment in a spectral range containing 5.4 m to 6.0
48、m.12.7 Determine and record the biodiesel concentration ac-cording to the calibration curve generated in Annex A1.12.8 Wipe the sample off of the sample crystal and cleanthoroughly according to manufacturers specification.12.9 Biodiesel and biodiesel blends containing high concen-trations of biodies
49、el are difficult to remove from the ATRcrystal surface. The sample crystal should be cleaned thor-oughly between each sample. When in doubt, repeat steps 12.5 12.8 and compare the results to ensure adequate cleaningoccurred.13. Report13.1 Report the following information:13.1.1 Volume Percent Biodiesel by Test Method D7861, tothe nearest 0.1 %.14. Precision and Bias14.1 The precision of this test method is based on aninterlaboratory study conducted in 2011. A total of twelve5A current list of BQ9000 producers can be found at the National Biodies
