1、Designation: D7371 12D7371 14Standard 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 designation indica
2、tes 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 determination o
3、f 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 1Using the proper
4、 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 does not pur
5、port 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 Standards:2D975
6、 Specification for Diesel Fuel OilsD976 Test Method for Calculated Cetane Index of Distillate FuelsD1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products byHydrometer MethodD4052 Test Method for Density, Relative Density, and API Gravity of L
7、iquids 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 Method for Calculated Cetane Index b
8、y 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 Analytical Measure-ment System PerformanceD6751 Specification for Biodiesel Fuel B
9、lend 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 Qualifying Spectrometers and Spect
10、rophotometers for Use in Multivariate Analyses, Calibrated UsingSurrogate Mixtures3. Terminology3.1 Definitions:1 This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0F on
11、 Absorption Spectroscopic Methods.Current edition approved April 15, 2012Oct. 1, 2014. Published July 2012October 2014. Originally approved in 2007. Last previous edition approved in 20072012 asD7371-07.D7371 12. DOI: 10.1520/D7371-12.10.1520/D7371-14.2 For referencedASTM standards, visit theASTM we
12、bsite, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indicat
13、ion of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict 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 cons
14、idered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.1 biodiesel, na fuel comprised of mono-alkyl esters of long chain fatty acids derived fr
15、om vegetable oils or animal fats,designated B100. D67513.1.2 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. D67513.1.3 diesel fuel, npetroleum-b
16、ased 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 resultant multivariate calibration
17、model is applied to the analysis of spectra of unknown samples to provide an estimate of thecomponent concentration or property values for the unknown sample.3.1.4.2 DiscussionThe multivariate calibration algorithm employed in this test method is partial least square (PLS) as defined in Practices E1
18、655.3.2 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 Method4.1 A sample of diesel fuel, biod
19、iesel, 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 highly with biodiesel or interfere
20、nces 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 sample cell. The absorption spectrum sh
21、all beused to calculate a partial least square (PLS) calibration algorithm.5. Significance and Use5.1 Biodiesel is a blendstock commodity primarily used as a value-added blending component with diesel fuel.5.2 This test method is applicable for quality control in the production and distribution of d
22、iesel 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 blend is represented in the calibratio
23、n 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 bands in A1.2 lie in regions where si
24、gnificant 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 should be allowed to stabilize oversever
25、al 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 measure a reference background spectrumfor
26、 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 background correction routines.D7371 14
27、2The 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 in anoverall lower concentrat
28、ion 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 will result in erroneous res
29、ults. 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 use in this test method employs
30、 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:Scan Range 4000 to 650 cm-1Resolution 4 cm-17.1.2 The noise level sh
31、all 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 dioxide is a problem, the instrument shall
32、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 followingrequirements:7.2.1 Conical Atten
33、uated 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 plate. Theabsorbance at 1745 cm-1 shal
34、l 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 without exceeding 1.2 absorbance units at 1
35、745 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 analytical reagents of theAmericanChemical So
36、ciety, where such specifications are available.3 Other 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 calibration, qualification, and quality
37、 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 animal fats, canola oil, jatrophaoil,
38、 palm oil, rapeseed oil, and yellow grease may be used. Standards made with yellow grease methyl esters should not represent3 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed bythe American C
39、hemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.TABLE 1 Attenuated Total Reflectance (ATR) ConicalCells SpecificationATR element material
40、 ZnSebeam condensing optics conical, 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 1.55in.)element diameter 3.175 mm (0.125 in.)angle of incidence at sampleinterface53.8maximum
41、range of incidenceangles 1.5standard absorbance(1428 cm-1 band of acetone)0.38 0.02 AUmaterial of construction 316 stainless steelseals Chemrez or Kalrez o-ringsAA Trademarks of Chemrez, Inc. and Dupont Performance Elastomers L.L.C.D7371 143more than 50 % of the number of the calibration standards.
42、A BQ-9000 certified producer for the biodiesel is recommended toensure quality of 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
43、precursor, or both. As far as possible, middle distillate fuel shall berepresentative 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 Di
44、esel Cetane Check FuelLow (DCCF-Low).4 (See A2.2 for alternative material.)8.1.4 Diesel 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
45、 SolventA mixture of equal parts by volume of toluene, acetone, and methanol.9. Sampling and Sample Handling9.1 General Requirements:9.1.1 Fuel samples to be analyzed by this test method shall be sampled using procedures outlined in Practice D4057 or PracticeD4177, where appropriate. Do not use “sam
46、pling by water displacement.” FAME is more water-soluble than the hydrocarbon basein a biodiesel blend.9.1.2 Protect samples from excessive temperatures prior 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 Du
47、ring 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 temperature 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
48、 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
49、, after maintenance, theinstrument calibration is repeated, the qualification procedure is also repeated.10.2 Before use, the instrument is qualified according to the procedure described in Annex A1. The qualification need only becarried out when the instrument is initially put into operation, recalibrated, or repaired.11. Quality Control Checks11.1 Confirm the in-statistical-control status of the test method each day it is used by measuring the biodiesel concentration ofat least one quality control sample that is similar in composition and
