ASTM D7371-2012 red 2892 Standard Test Method for Determination of Biodiesel (Fatty Acid Methyl Esters) Content in Diesel Fuel Oil Using Mid Infrared Spectroscopy (FTIR-ATR-PLS Met.pdf

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1、Designation:D737107 Designation: D7371 12Standard Test Method forDetermination of Biodiesel (Fatty Acid Methyl Esters)Content in Diesel Fuel Oil Using Mid Infrared Spectroscopy(FTIR-ATR-PLS Method)1This standard is issued under the fixed designation D7371; the number immediately following the design

2、ation 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 () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the det

3、ermination of the content of fatty acid methyl esters (FAME) biodiesel in diesel fuel oils.It is applicable to concentrations from 1.00 to 20 volume % (see Note 1). This procedure is applicable only to FAME. Biodieselin the form of fatty acid ethyl esters (FAEE) will cause a negative bias.NOTE 1Usin

4、g the proper ATR sample accessory, the range maybe expanded from 1 to 100 volume %, however precision data is not available above20 volume %.1.2 The values stated in SI units of measurement are to be regarded as the standard. The values given in parentheses are forinformation only.1.3 This standard

5、does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Sta

6、ndards:2D975 Specification for Diesel Fuel OilsD976 Test Method for Calculated Cetane Index of Distillate FuelsD1298 Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid PetroleumProducts by Hydrometer MethodD4052 Test Method for Density, Relativ

7、e Density, and API Gravity of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD4307 Practice for Preparation of Liquid Blends for Use as Analytical StandardsD4737 Test Metho

8、d for Calculated Cetane Index by Four Variable EquationD5854 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum ProductsD6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6751 Speci

9、fication for Biodiesel Fuel Blend Stock (B100) for Middle Distillate FuelsD7467 Specification for Diesel Fuel Oil, Biodiesel Blend (B6 to B20)E168 Practices for General Techniques of Infrared Quantitative AnalysisE1655 Practices for Infrared Multivariate Quantitative AnalysisE2056 Practice for Quali

10、fying Spectrometers and Spectrophotometers for Use in Multivariate Analyses, Calibrated UsingSurrogate Mixtures3. Terminology3.1 Definitions:3.1.1 biodiesel, na fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats,designated B100. D67511This test m

11、ethod is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04.0Fon Absorption Spectroscopic Methods.Current edition approved Oct. 1, 2007. Published October 2007. DOI: 10.1520/D7371-07.Current edition approvedApril

12、15, 2012. Published July 2012. Originally approved in 2007. Last previous edition approved in 2007 as D7371-07. DOI: 10.1520/D7371-12.2For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume inform

13、ation, refer to the standards Document Summary page on the ASTM website.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately de

14、pict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standard.Copyright ASTM Internat

15、ional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.2 biodiesel blend, BXX, na blend of biodiesel fuel with petroleum-based diesel fuel. D74673.1.2.1 DiscussionIn the abbreviation BXX, the XX represents the volume percentage of biodiesel fuel in the blend.D

16、67513.1.3 diesel fuel, npetroleum-based middle distillate fuel.3.1.4 multivariate calibration, nprocess for creating a model that relates component concentrations or properties to theabsorbances of a set of known reference samples at more than one wavelength or frequency. E16553.1.4.1 DiscussionThe

17、resultant multivariate calibration model is applied to the analysis of spectra of unknown samples toprovide an estimate of the component concentration or property values for the unknown sample.3.1.4.2 DiscussionThe multivariate calibration algorithm employed in this test method is partial least squa

18、re (PLS) as definedin Practices E1655.3.2 Abbreviations:ATR = attenuated total reflectanceBxx = see 3.1.2FAEE = fatty acid ethyl estersFAME = fatty acid methyl estersFTIR = Fourier transform infraredmid-IR = mid infraredPLS = partial least squareULSD = ultra low sulfur diesel4. Summary of Test Metho

19、d4.1 A sample of diesel fuel, biodiesel, or biodiesel blend is introduced into a liquid attenuated total reflectance (ATR) samplecell. A beam of infrared light is imaged through the sample onto a detector, and the detector response is determined. Wavelengthsof the absorption spectrum that correlate

20、highly with biodiesel or interferences are selected for analysis. A multivariatemathematical analysis converts the detector response for the selected areas of the spectrum from an unknown to a concentrationof biodiesel.4.2 This test method uses Fourier transform mid-IR spectrometer with an ATR sampl

21、e cell. The absorption spectrum shall beused to calculate a partial least square (PLS) calibration algorithm.5. Significance and Use5.1 Biodiesel is a fuelblendstock commodity primarily used as a value-added blending component with diesel fuel.5.2 This test method is applicable for quality control i

22、n the production and distribution of diesel fuel and biodiesel blendscontaining FAME.6. Interferences6.1 The hydrocarbon composition of diesel fuel has a significant impact on the calibration model. Therefore, for a robustcalibration model, it is important that the diesel fuel in the biodiesel fuel

23、blend is represented in the calibration set.6.2 Proper choice of the apparatus, design of a calibration matrix, utilization of multivariate calibration techniques, andevaluation routines as described in this standard can minimize interferences.6.3 Water Vapor InterferenceThe calibration and analysis

24、 bands in A1.2 lie in regions where significant signals due to watervapor can appear in the infrared spectrum. This shall be accounted for to permit calibration at the low end concentrations.NOTE 2Ideally, the spectrometer should be purged with dry air or nitrogen to remove water vapor. The purge sh

25、ould be allowed to stabilize overseveral hours before analytical work is pursued, due to the rapid changes in the air moisture content within the spectrometer during early stages of thepurge. In cases where water vapor prevention or elimination is not possible using a purge, the operator should meas

26、ure a reference background spectrumfor correction of the ratioed spectrum for each sample spectrum measured. This operation is generally automated in todays spectrometer systems andthe operator should consult the manufacturer of the spectrometer for specific instructions for implementing automated b

27、ackground correction routines.The spectrometer should be sealed and desiccated to minimize the affect of water vapor variations, and any accessory should be sealed to the spectrometer.6.4 Fatty Acid Ethyl Esters (FAEE) InterferenceThe presence of FAEE in the composition of the biodiesel will result

28、in anoverall lower concentration measurement of biodiesel content. Outlier statistical results may be a useful tool for determining highconcentration FAEE content (for additional FAEE information, see research report referenced in Section 15).6.5 Undissolved WaterSamples containing undissolved water

29、 will result in erroneous results. Filter cloudy or water saturatedsamples through a dry filter paper until clear prior to their introduction into the instrument sample cell.7. Apparatus7.1 Mid-IR Spectrometric Analyzer:7.1.1 Fourier Transform Mid-IR SpectrometerThe type of apparatus suitable for us

30、e in this test method employs an IR source,a liquid attenuated total internal reflection cell, a scanning interferometer, a detector, an A-D converter, a microprocessor, and amethod to introduce the sample. The following performance specifications shall be met:D7371 122Scan Range 4000 to 650 cm-1Res

31、olution 4 cm-17.1.2 The noise level shall be established by acquiring a single beam spectrum using air or nitrogen. The single beam spectrumobtained can be the average of multiple of FTIR scans but the total collection time shall not exceed 60 seconds. If interferencefrom water vapor or carbon dioxi

32、de is a problem, the instrument shall be purged with dry air or nitrogen. The noise of the spectrumat 100 % transmission shall be less than 0.3 % in the region from 1765 to 1725 cm-1.7.2 Absorption Cell, multi-bounce (multi-reflections) attenuated total reflectance cell. It shall meet one of the fol

33、lowingrequirements:7.2.1 Conical Attenuated Total Reflectance (ATR) Cell, having similar specifications defined in Table 1. This cell is suitable forthe low, medium, and high concentration ranges.7.2.2 Horizontal Attenuated Total Reflectance (ATR) Cell, with ZnSe element ATR mounted on a horizontal

34、plate. Theabsorbance at 1745 cm-1shall not exceed 1.2 absorbance units for the highest concentration calibration standard used in thecalibration range. Therefore, for higher concentration measurements, careful consideration of element length and face angle shallbe made to maximize sensitivity withou

35、t exceeding 1.2 absorbance units at 1745 cm-1.8. Reagents and Materials8.1 Purity of ReagentsSpectroscopic grade (preferred) or reagent grade chemicals shall be used in tests. Unless otherwiseindicated, it is intended that all reagents shall conform to the specifications of the committee on analytic

36、al reagents of theAmericanChemical Society, where such specifications are available.3Other grades may be used, provided it is first ascertained that thereagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.8.1.1 B100 (Neat Biodiesel)Used for cal

37、ibration, qualification, and quality control standards shall be compliant withSpecification D6751. The B100 shall be fatty acid methyl esters. Soy methyl ester (SME) was used in calibration standards fordeveloping the precision of this test method. Esters derived from other feedstocks, for example a

38、nimal fats, canola oil, jatrophaoil, palm oil, rapeseed oil, and yellow grease may be used. Standards made with yellow grease methyl esters should not representmore than 50 % of the number of the calibration standards. A BQ-9000 certified producer for the biodiesel is recommended toensure quality of

39、 product. See Annex A2 for further discussion.8.1.2 Middle Distillate FuelUsed for calibration, qualification, and quality control standards shall be compliant withSpecification D975, free of biodiesel or biodiesel oil precursor, or both. As far as possible, middle distillate fuel shall berepresenta

40、tive of petroleum base stocks anticipated for blends to be analyzed (crude source, 1D, 2D, blends, winter/summer cuts,low aromatic content, high aromatic content, and the like). See Annex A2 for calibration set.8.1.3 Diesel Cetane Check FuelLow (DCCF-Low).4(See A2.2 for alternative material.)8.1.4 D

41、iesel Cetane Check FuelHigh (DCCF-High).8.1.5 Diesel Cetane Check FuelUltra High (DCCF-Ultra High).8.1.6 Acetone 67-64-1Reagent grade.8.1.7 Toluene 108-88-3Reagent grade.8.1.8 Methanol 67-56-1Reagent grade.8.1.9 Triple SolventA mixture of equal parts by volume of toluene, acetone, and methanol.3Reag

42、ent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed bythe American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia

43、and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.4The sole source of supply of the material known to the committee at this time is Chevron Phillips Chemical Company LLC, 10001 Six Pines Drive, The Woodlands,TX 77380. If you are aware of alternative suppliers, please p

44、rovide this information to ASTM International Headquarters. Your comments will receive careful considerationat a meeting of the responsible technical committee, which you may attend.TABLE 1 Attenuated Total Reflectance (ATR) ConicalCells SpecificationATR element material ZnSebeam condensing optics c

45、onical, non-focusing opticsintegral to cell bodyelement configuration circular cross section withcoaxial conical endscone half angle 60element length 36.83 to 39.37 mm (1.45 to 1.55 in.)element diameter 3.175 mm (0.125 in.)angle of incidence at sample interface 53.8maximum range of incidence angles

46、6 1.5standard absorbance(1428 cm-1band of acetone)0.38 6 0.02 AUmaterial of construction 316 stainless steelseals Chemrez or Kalrez o-ringsAATrademarks of Chemrez, Inc. and Dupont Performance Elastomers L.L.C.D7371 1239. Sampling and Sample Handling9.1 General Requirements:9.1.1 Fuel samples to be a

47、nalyzed by this test method shall be sampled using procedures outlined in Practice D4057 or PracticeD4177, where appropriate. Do not use “sampling by water displacement.” FAME is more water-soluble than the hydrocarbon basein a biodiesel blend.9.1.2 Protect samples from excessive temperatures prior

48、to testing.9.1.3 Do not test samples stored in leaky containers. Discard and obtain a new sample if leaks are detected.9.2 Sample Handling During Analysis:9.2.1 When analyzing samples using the FTIR, the sample temperature needs to be within the range of 15 to 27C. Equilibrateall samples to the temp

49、erature of the laboratory (15 to 27C) prior to analysis by this test method.9.2.2 After analysis, if the sample is to be retained, reseal the container before storing.10. Calibration and Qualification of the Apparatus10.1 Before use, the instrument needs to be calibrated according to the procedure described in Annex A1. This calibration canbe performed by the instrument manufacturer prior to delivery of the instrument to the end user. If, after maintenance, theinstrument calibration is repeated, the qualification procedure is also repeated.10.2 Be