ASTM D7806-20

Standard Test Method for Determination of Biodiesel (Fatty Acid Methyl Ester) and Triglyceride Content in Diesel Fuel Oil Using Mid-Infrared Spectroscopy (FTIR Transmission Method)

SIGNIFICANCE AND USE
5.1 Biodiesel is a fuel 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 diesel fuel and biodiesel blends containing FAME.  
5.3 The use of triglycerides in fuels is not approved for transportation applications within any ASTM specification. This test method allows the quantification of triglyceride concentration in biodiesel blends, thus enabling detection of out-of-specification blending.  
5.4 This test method is fast, simple to run, inexpensive and requires no sample preparation.
SCOPE
1.1 This test method covers the determination of fatty acid methyl ester (FAME) biodiesel and triglyceride (TAG) concentrations in traditional diesel and renewable diesel fuel blends using a portable mid-infrared spectrometer.  
1.2 The method applies to samples with biodiesel concentrations from 3 % to 40 % by volume. Additionally, it applies to samples with biodiesel concentrations from 2 % to 27 % by volume which contain triglycerides concentrations from 1 % to 10 % by volume. Triglycerides from 2 % to 10 % by volume can be determined in samples of diesel having biodiesel concentrations from 3 % to 27 % by volume. FAME and triglyceride can be simultaneously determined outside these stated ranges, but the stated precision estimates do not apply.  
1.3 The method is not able to distinguish TAG and FAME if the TAG concentrations is below 0.142× the measured FAME concentrations.  
1.4 This procedure is not appropriate for the determination of the concentration of biodiesel in the form of fatty acid ethyl esters (FAEE), see Section 6 for further discussion of possible interferences.  
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-Jul-2020
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0F - Absorption Spectroscopic Methods

Relations

• Replaces: ASTM D7806-12 - Standard Test Method for Determination of the Fatty Acid Methyl Ester (FAME) Content of a Blend of Biodiesel and Petroleum-Based Diesel Fuel Oil Using Mid-Infrared Spectroscopy
• Effective Date: 15-Jul-2020
• Refers: ASTM D1655-24 - Standard Specification for Aviation Turbine Fuels
• Effective Date: 15-Mar-2024
• Refers: ASTM D6300-24 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Mar-2024
• Refers: ASTM D975-23a - Standard Specification for Diesel Fuel
• Effective Date: 15-Dec-2023
• Refers: ASTM D6299-23a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Dec-2023
• Refers: ASTM D6300-23a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Dec-2023
• Refers: ASTM D1655-23a - Standard Specification for Aviation Turbine Fuels
• Effective Date: 01-Oct-2023
• Refers: ASTM D6300-19a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Dec-2019
• Refers: ASTM D975-19 - Standard Specification for Diesel Fuel Oils
• Effective Date: 01-Feb-2019
• Refers: ASTM D975-18a - Standard Specification for Diesel Fuel Oils
• Effective Date: 01-Dec-2018
• Refers: ASTM D6751-18 - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 01-Oct-2018
• Refers: ASTM D1655-18 - Standard Specification for Aviation Turbine Fuels
• Effective Date: 01-Jan-2018
• Refers: ASTM D6299-17b - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Dec-2017
• Refers: ASTM D975-17a - Standard Specification for Diesel Fuel Oils
• Effective Date: 15-Dec-2017
• Refers: ASTM D1655-17a - Standard Specification for Aviation Turbine Fuels
• Effective Date: 01-Dec-2017

Overview

ASTM D7806-20 is a standard test method developed by ASTM International for the determination of biodiesel (fatty acid methyl ester, FAME) and triglyceride (TAG) content in diesel fuel oil using a mid-infrared (FTIR) transmission spectroscopy technique. This method is designed to provide fast, accurate, and cost-effective results for quality control in the production and distribution of diesel fuels and biodiesel blends, with an emphasis on quantifying both biodiesel and undesirable triglyceride content.

Biodiesel, primarily derived from vegetable oils or animal fats, is commonly used as an additive or blending component with traditional diesel fuel. Ensuring accurate quantification of FAME and detecting any excess triglycerides is critical for adherence to fuel specifications and optimal engine performance.

Key Topics

• Scope of Measurement

  • Determines FAME and triglyceride concentrations in traditional and renewable diesel fuel blends.
  • Applicable to biodiesel concentrations ranging between 3% - 40% by volume, and to triglyceride concentrations from 1% - 10% in certain ranges.
  • Suited to both laboratory and field quality control settings.

• Significance for Industry

  • Validates the correct blending of biodiesel and detects out-of-specification fuel mixing.
  • Assures end-users and regulators of fuel quality and conformance to approved limits.
  • Identifies triglyceride content, which is not permitted in transportation fuels under ASTM specifications.

• Test Method Features

  • Utilizes a portable mid-infrared FTIR spectrometer for rapid on-site or laboratory analysis.
  • Requires no sample preparation, making it efficient and easy to implement.
  • Capable of simultaneously determining FAME and TAG content within defined ranges.

• Limitations

  • Not suitable for detecting fatty acid ethyl esters (FAEE) or FAME/TAG at very low concentrations below specified ratios.
  • Interference can occur from certain compounds such as carboxylic acids, ketones, aldehydes, and undissolved water.

Applications

ASTM D7806-20 is widely used in a variety of sectors related to diesel fuel production, distribution, and regulation:

• Fuel Producers and Blenders

  • Ensures proper blending ratios for compliance with fuel specifications (such as ASTM D975 and ASTM D6751).
  • Monitors and controls production processes to avoid off-specification batches.

• Fuel Distributors and Retailers

  • Allows for quick field verification of fuel blends before reaching end-users.
  • Detects and prevents contamination or improper mixing that could affect engine performance.

• Regulatory and Compliance Laboratories

  • Acts as a fundamental method for quality assurance required by fuel standards and regulatory oversight.
  • Enables routine surveillance to ensure marketplace fuels adhere to legal and safety requirements.

• Engine Manufacturers and Researchers

  • Used for research and development of new formulations and validation of compatibility with diesel engine systems.
  • Assists in investigating field issues related to fuel quality or performance.

Related Standards

The performance and application of ASTM D7806-20 are supported and referenced by several other ASTM standards, including:

• ASTM D975 - Specification for Diesel Fuel Oils
• ASTM D6751 - Specification for Biodiesel (B100) Blend Stock for Distillate Fuels
• ASTM D1298 / D4052 - Methods for Density Measurement of Petroleum Products
• ASTM D4057 / D4177 - Practices for Sampling Petroleum and Petroleum Products
• ASTM D6299 - Statistical Quality Assurance and Control Charting for Analytical Measurement
• ASTM D7418 - Set-Up and Operation of FT-IR Spectrometers

Keywords: ASTM D7806-20, biodiesel determination, fatty acid methyl ester, FAME, triglyceride analysis, FTIR spectroscopy, diesel fuel quality, fuel blend testing, mid-infrared transmission, petroleum standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7806 − 20
Standard Test Method for
Determination of Biodiesel (Fatty Acid Methyl Ester) and
Triglyceride Content in Diesel Fuel Oil Using Mid-Infrared
Spectroscopy (FTIR Transmission Method)
This standard is issued under the fixed designation D7806; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This test method covers the determination of fatty acid
methylester(FAME)biodieselandtriglyceride(TAG)concen-
2. Referenced Documents
trations in traditional diesel and renewable diesel fuel blends
2.1 ASTM Standards:
using a portable mid-infrared spectrometer.
D975Specification for Diesel Fuel
1.2 The method applies to samples with biodiesel concen-
D1298Test Method for Density, Relative Density, or API
trations from 3% to 40% by volume. Additionally, it applies
Gravity of Crude Petroleum and Liquid Petroleum Prod-
to samples with biodiesel concentrations from 2% to 27% by
ucts by Hydrometer Method
volumewhichcontaintriglyceridesconcentrationsfrom1%to
D1655Specification for Aviation Turbine Fuels
10% by volume. Triglycerides from 2% to 10% by volume
D4052Test Method for Density, Relative Density, and API
can be determined in samples of diesel having biodiesel
Gravity of Liquids by Digital Density Meter
concentrations from 3% to 27% by volume. FAME and
D4057Practice for Manual Sampling of Petroleum and
triglyceride can be simultaneously determined outside these
Petroleum Products
stated ranges, but the stated precision estimates do not apply.
D4177Practice for Automatic Sampling of Petroleum and
1.3 ThemethodisnotabletodistinguishTAGandFAMEif
Petroleum Products
the TAG concentrations is below 0.142× the measured FAME
D4307Practice for Preparation of Liquid Blends for Use as
concentrations.
Analytical Standards
D5854Practice for Mixing and Handling of Liquid Samples
1.4 This procedure is not appropriate for the determination
of Petroleum and Petroleum Products
of the concentration of biodiesel in the form of fatty acid ethyl
D6299Practice for Applying Statistical Quality Assurance
esters (FAEE), see Section 6 for further discussion of possible
and Control Charting Techniques to Evaluate Analytical
interferences.
Measurement System Performance
1.5 The values stated in SI units are to be regarded as the
D6300Practice for Determination of Precision and Bias
standard. The values given in parentheses are for information
Data for Use in Test Methods for Petroleum Products,
only.
Liquid Fuels, and Lubricants
1.6 This standard does not purport to address all of the
D6751Specification for Biodiesel Fuel Blend Stock (B100)
safety concerns, if any, associated with its use. It is the
for Middle Distillate Fuels
responsibility of the user of this standard to establish appro-
D7418Practice for Set-Up and Operation of Fourier Trans-
priate safety, health, and environmental practices and deter-
form Infrared (FT-IR) Spectrometers for In-Service Oil
mine the applicability of regulatory limitations prior to use.
Condition Monitoring
1.7 This international standard was developed in accor-
E131Terminology Relating to Molecular Spectroscopy
dance with internationally recognized principles on standard-
E168Practices for General Techniques of Infrared Quanti-
ization established in the Decision on Principles for the
tative Analysis
Development of International Standards, Guides and Recom-
E1655 Practices for Infrared Multivariate Quantitative
Analysis
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.04.0F on Absorption Spectroscopic Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 15, 2020. Published August 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2012. Last previous edition approved in 2012 as D7806–12. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7806-20. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7806 − 20
E2056Practice for Qualifying Spectrometers and Spectro- 5.2 This test method is applicable for quality control in the
photometers for Use in Multivariate Analyses, Calibrated production and distribution of diesel fuel and biodiesel blends
Using Surrogate Mixtures containing FAME.
5.3 The use of triglycerides in fuels is not approved for
3. Terminology
transportation applications within any ASTM specification.
3.1 Definitions: This test method allows the quantification of triglyceride
concentration in biodiesel blends, thus enabling detection of
3.1.1 biodiesel, n—a fuel composed of mono-alkyl esters of
out-of-specification blending.
long chain fatty acids derived from vegetable oils or animal
fats, designated B100 in Specification D6751.
5.4 This test method is fast, simple to run, inexpensive and
3.1.2 biodiesel blend, BXX, n—a blend of biodiesel fuel requires no sample preparation.
with petroleum-based diesel fuel.
3.1.2.1 Discussion—In the abbreviation BXX, the XX rep- 6. Interferences
resentsthepercentagebyvolumeofbiodieselfuelintheblend.
6.1 Thepresenceofcarbonylcontainingcompoundsinclud-
3.1.3 diesel fuel oil, n—a petroleum-based diesel fuel, as ing carboxylic acids, ketones and aldehydes, as well as fatty
described in Specification D975. acid ethyl esters (FAEE), may result in spectral interference.
3.1.4 FAME, n—a biodiesel composed of long chain fatty
6.2 The hydrocarbon composition of the diesel fuel has a
acid methyl esters derived from vegetable or animal fats.
minor impact on the calibration model. The proper choice of
the evaluation routine as described in this standard can
3.1.5 mid-infrared spectroscopy, n—uses the mid-infrared
minimize interferences from the hydrocarbon composition of
region of the electromagnetic spectrum, as described inTermi-
the diesel fuel.
nology E131.
6.3 Water Vapor Interference—The calibration and analysis
3.1.6 oxygenate-free middle distillate, n—a petroleum-
bands in used for the calculations in Section 12 lie in regions
basedfuelmeetingthespecificationsofD975orE1655,freeof
where significant signals due to water vapor can appear in the
compounds containing esters, acids, or ketones.
infrared spectrum. This shall be accounted for to permit
3.1.7 renewable diesel fuel, n—a biomass-based fuel, meet-
calibration and measurements at the low end concentrations.
ing the specifications in D975.
NOTE 1—Ideally, the spectrometer should be purged with dry air or
3.1.8 triglycerides, TAG, n—a naturally occurring ester
nitrogen to remove water vapor. The purge should be allowed to stabilize
formedfromglycerolandthreefattyacidgroups,whicharethe
over several hours before analytical work is pursued, due to the rapid
main constituents of natural fats and oils, biodiesel feedstocks,
changes in the air moisture content within the spectrometer during early
stages of the purge. In cases where water vapor prevention or elimination
fats and/or oils, that have not been transesterified into bio-
is not possible using a purge, the operator should measure a reference
diesel.
background spectrum for correction of the ratioed spectrum for each
3.2 Acronyms:
sample spectrum measured. This operation is generally automated in
today’s spectrometer systems and the operator should consult the manu-
3.2.1 AU—absorption unit
facturer of the spectrometer for specific instructions for implementing
3.2.2 CLS—classical least squares
automated background correction routines. The spectrometer should be
sealedanddesiccatedtominimizetheeffectofwatervaporvariations,and
3.2.3 FAEE—fatty acid ethyl esters
any accessory should be sealed to the spectrometer.
3.2.4 FAME—fatty acid methyl esters
6.4 High Lauric Acid Methyl Esters Interference—Samples
3.2.5 FTIR—Fourier transform infrared spectrometer
with high lauric acid methyl ester (that is, coconut biodiesel)
content are known to cause a bias when used in the calibration
3.2.6 IR—infrared
model.Unlessthemethodisbeingusedtocalibratespecifically
3.2.7 PL—path length
and exclusively for samples containing high levels of lauric
3.2.8 TAG—triglyceride
acid methyl esters, feedstocks containing high levels of these
compounds should be avoided.
4. Summary of Test Method
4.1 This method utilizes a Fourier transform mid infrared 7. Apparatus
spectrometer fitted with a transmission sample cell with a
7.1 Mid-IR Spectrometric Analyzer:
specifiedpathlength.Asampleofdieselfuelorbiodieselblend
7.1.1 Fourier Transform Mid-IR Spectrometer (FT-IR)—
is introduced into the sample cell. A beam of infrared light is
The type of apparatus suitable for use in this test method
passed through the sample and the motion of the spectrometer
employs an IR source, a liquid transmission cell, a scanning
mirrors enables determination of the sample absorption spec-
interferometer, a detector, an analog-to-digital converter, a
trum. Specific regions of the spectrum where FAME and
microprocessor, and a method to introduce the sample. The
triglycerides show strong absorption are used for the analysis.
following performance specifications must be met:
-1
spectral resolution 4 cm
5. Significance and Use
NOTE 2—The noise of the single beam spectrum at 100% transmission
-1
5.1 Biodiesel is a fuel commodity primarily used as a
shall be less than 0.3% peak-to-peak in the region from 1725cm to
-1
value-added blending component with diesel fuel. 1765cm . The single beam spectrum obtained can be the average of
D7806 − 20
multiple of FTIR scans but the total collection time shall not exceed
10. Calibration of the Apparatus
60seconds.
10.1 Calibrate the instrument according to the procedure
7.2 Absorption Cell—The cell shall be a transmission cell
described in AnnexA1. This calibration may be performed by
made from non-hygroscopic materials having a significant
theinstrumentmanufacturerpriortodeliveryoftheinstrument
-1
transmission in the relevant spectral range (1050cm to
to the end user.
-1
1850cm ). The nominal path length of the cell shall be
0.10mm 6 0.015mm, appropriate to measure the relevant
11. Quality Control Checks
peaks involved in the spectral analysis without going into
11.1 Eachdaythattheinstrumentistobeused,confirmitis
saturation.Thepathlengthshouldbedeterminedinaccordance
in statistical control by measuring the biodiesel concentration
to Practice D7418.
using the procedure outlined in Section 12 on at least one
quality control sample of known biodiesel content. The prepa-
8. Reagents and Materials
ration of samples with known biodiesel concentration is
8.1 Standards for Calibration, Qualification, and Quality
described in 11.1.1 and 11.1.2. For details on quality control
Control Check Standards—Because this method is intended to
testing and control charting refer to Practice D6299.
quantify FAME and triglyceride content in commercial bio-
11.1.1 Standard(s) of known biodiesel and triglyceride con-
diesel blends there are no high purity standard chemical
centration shall be prepared by mass and converted to volume
reference materials that are appropriate for development of
percentusingthemeasureddensityasoutlinedinSection13.1.
multivariate calibration models.
At least one standard shall be prepared for each calibration
8.1.1 B100 (Neat Biodiesel) used for calibration, qualifica-
range.Additionalstandardsincluding0%byvolumemayalso
tionandqualitycontrolstandardsmustbeSpecificationD6751
be prepared and used for quality control checks.
compliant. If the origin of FAME is known, this type shall be
11.1.2 Standard(s) should be prepared in sufficient volume
used for calibration. If the type of biodiesel is not known, use
to allow for a minimum of 30 quality control measurements to
soy methyl ester or the FAME most commonly used in the
be made on one batch of material. Properly package and store
geographical area where the samples are obtained.
thequalitycontrolsamplestoensurethatallanalysesofquality
8.1.2 The triglycerides shall be food grade oils liquid at
control samples from a given lot are performed on essentially
room temperature, preferably soy oil or the type of oil most
identical material.
commonly found in the local market, available for purchase
11.2 If the biodiesel volume percent value estimated for the
commercially.SeeAnnexA2forfurtherdiscussionondifferent
quality control sample exceeds the action limits described
biodiesel and triglyceride varieties.
specified in Practice D6299 or equivalent, then the measure-
8.1.3 Middledistillatefuelusedforcalibration,qualification
ment system is out-of-control and cannot be used to measure
and quality control standards must be Specification D975
biodiesel concentrations until the cause of the out-of-control
compliant, free of biodiesel or biodiesel precursor compounds
behavior is identified and corrected.
andshouldasfaraspossibleberepresentativeofthepetroleum
basestocksanticipatedforblendstobeanalyzed(thatis,crude
12. Procedure
source, 1D, 2D, blends, winter/summer cuts, etc). See Annex
A2 for further discussion on calibration fuels. 12.1 Equilibrate all samples to the temperature of the
laboratory (15°C to 27°C) prior to analysis by this test
9. Sampling and Sample Handling method.
12.2 Background Spectrum—Record a single beam infrared
9.1 General Requirements:
spectrum of dry air or nitrogen.
9.1.1 Fuel samples to be analyzed by the test method shall
be sampled using procedures outlined in Practices D4057 or
12.3 Priortotheanalysisofunknowntestsamples,establish
D4177,whereappropriate.Donotusethe“SamplingbyWater
that the equipment is running properly by collecting the
Displacement” procedure.
spectrum of the quality control standard(s) and comparing the
9.1.2 Protect samples from excessive (<0°C and >60°C)
estimated biodiesel concentration to the known value for the
temperatures prior to testing.
QC standard(s).
9.1.3 Until test samples are known to contain <4.0% by
12.4 Rinse the absorption cell according to the manufactur-
volume TAG, avoid storage of samples in refrigerated condi-
er’s instructions. Biodiesel and high concentrations biodiesel
tions (< ≈10°C).
blends are difficult to remove from the cell. Flush the cell with
9.1.4 Do not test samples stored in leaking containers.
sample or use a solvent rinse between measurements to ensure
Discard and obtain a new sample if leaks are detected.
that carry-over between measurements is minimal. Measuring
a blank (oxygenate-free middle distillate or jet fuel) after the
9.2 Sample Handling During Analysis:
measurement of the high range quality control sample can be
9.2.1 Equilibrate all samples to the temperature of the
used to verify adequate rinsing.
laboratory (15°C to 27°C) prior to analysis by this test
method.
12.5 Introducetheunknownsampleintothesamplecelland
9.2.2 After analysis, if the sample is to be saved, reseal the obtain the digitized absorption spectrum (AS) of the fuel
-1 -1
container before storing. sampleoverthefrequencyrangefrom1050cm to1850cm .
D7806 − 20
12.6 Normalize the absorption spectrum to 0.1mm path V 5 M D ⁄ D (2)
~ !
b b f b
length, that is, multiply the spectrum with the factor 0.1/PL,
where:
where PL is the path length of the cell in mm. The absorption
V = biodiesel volume percent,
b
spectrumafternormalizationshouldbeusedforthesubsequent
M = biodiesel mass percent,
b
analysis.
D = relative density at 15.56°C of the calibration or
f
12.7 Perform a classical least squares (CLS) (A1.1.8)fitof
qualification standard being tested as determined by
the spectrum of the unknown sample as described in A1.1.7
Practice D1298 or Test Method D4052, and
and A1.1.8. Determine the respective concentrations using the
D = B100biodieselblendstockrelativedensityat15.56°C
b
CLS calibration (A1.1.9).
ofthecalibrationorqualificationstandardbeingtested
as determined by Practice D1298 or Test Method
12.8 Determine the relative contribution of biodiesel and
D4052.
triglycerides.
13.2 Conversion to Volume Percent of Triglyceride—To
c
i
X 5 ,iϵ FAMEandTAG (1)
i convert the calibration and qualification standards to volume
c
( i
i
percent, use Eq 3:
If X < 0.14, set X = 0 and X =1.
TAG TAG FAME
V 5 M D ⁄ D (3)
~ !
t t f t
If X < 0.14, set X = 0 and X =1.
FAME FAME TAG
where:
12.9 Let P be the maximum of the absorption spectrum
-1 -1
betw
...

This 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. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: D7806 − 12 D7806 − 20
Standard Test Method for
Determination of the FattyBiodiesel (Fatty Acid Methyl Ester
(FAME) Content of a Blend of Biodiesel and Petroleum-
Based Ester) and Triglyceride Content in Diesel Fuel Oil
Using Mid-Infrared Spectroscopy (FTIR Transmission
Method)
This standard is issued under the fixed designation D7806; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This test method covers the determination of fatty acid methyl ester (FAME) biodiesel and triglyceride (TAG)
concentrations in traditional diesel and renewable diesel fuel blends using a portable mid-infrared spectrometer.
1.2 The method applies to samples with biodiesel concentrations from 3 % to 40 % by volume. Additionally, it applies to
samples with biodiesel concentrations from 2 % to 27 % by volume which contain triglycerides concentrations from 1 % to 10 %
by volume. Triglycerides from 2 % to 10 % by volume can be determined in samples of diesel having biodiesel concentrations from
3 % to 27 % by volume. FAME and triglyceride can be simultaneously determined outside these stated ranges, but the stated
precision estimates do not apply.
1.3 The method is not able to distinguish TAG and FAME if the TAG concentrations is below 0.142× the measured FAME
concentrations.
1.4 This test method covers the determination of the content of biodiesel (fatty acid methyl esters—FAME) in diesel fuel oils.
It is applicable to concentrations from 1 to 30 volume %. This procedure is applicable only to FAME. This test method is procedure
is not appropriate for the determination of the concentration of biodiesel that is in the form of fatty acid ethyl esters
(FAEE).(FAEE), see Section 6 for further discussion of possible interferences.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D975 Specification for Diesel Fuel
D1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products by
Hydrometer Method
D1655 Specification for Aviation Turbine Fuels
D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.04.0F on Absorption Spectroscopic Methods.
Current edition approved Sept. 1, 2012July 15, 2020. Published November 2012August 2020. Originally approved in 2012. Last previous edition approved in 2012 as
D7806 – 12. DOI: 10.1520/D7806-1210.1520/D7806-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7806 − 20
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
D5854 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and
Lubricants
D6751 Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
D7418 Practice for Set-Up and Operation of Fourier Transform Infrared (FT-IR) Spectrometers for In-Service Oil Condition
Monitoring
E131 Terminology Relating to Molecular Spectroscopy
E168 Practices for General Techniques of Infrared Quantitative Analysis
E1655 Practices for Infrared Multivariate Quantitative Analysis
E2056 Practice for Qualifying Spectrometers and Spectrophotometers for Use in Multivariate Analyses, Calibrated Using
Surrogate Mixtures
3. Terminology
3.1 Definitions:
3.1.1 biodiesel, n—a fuel composed of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats,
designated B100 in Specification D6751.
3.1.2 biodiesel blend, BXX, n—a blend of biodiesel fuel with petroleum-based diesel fuel.
3.1.2.1 Discussion—
In the abbreviation BXX, the XX represents the percentage by volume of biodiesel fuel in the blend.
3.1.3 diesel fuel oil, n—a petroleum-based diesel fuel, as described in Specification D975.
3.1.4 FAME, n—a biodiesel composed of long chain fatty acid methyl esters derived from vegetable or animal fats.
3.1.5 Mid-Infrared Spectroscopy,mid-infrared spectroscopy, n—uses the mid-infrared region of the electromagnetic spectrum,
as described in Terminology E131.
3.1.6 oxygenate-free middle distillate, n—a petroleum-based fuel meeting the specifications of D975 or E1655, free of
compounds containing esters, acids, or ketones.
3.1.7 renewable diesel fuel, n—a biomass-based fuel, meeting the specifications in D975.
3.1.8 triglycerides, TAG, n—a naturally occurring ester formed from glycerol and three fatty acid groups, which are the main
constituents of natural fats and oils, biodiesel feedstocks, fats and/or oils, that have not been transesterified into biodiesel.
3.2 Acronyms:
3.2.1 AU—absorption unit
3.2.2 CLS—classical least squares
3.2.3 FAEE—fatty acid ethyl esters
3.2.4 FAME—fatty acid methyl esters
3.2.5 FTIR—Fourier transform infrared spectrometer
3.2.6 IR—infrared
3.2.7 PL—path length
3.2.8 TAG—triglyceride
4. Summary of Test Method
4.1 This method utilizes a Fourier transform mid infrared spectrometer fitted with a transmission sample cell with a specified
path length. A sample of diesel fuel or biodiesel blend is introduced into a liquid sample cell having a specified path length. the
sample cell. A beam of infrared light is imagedpassed through the sample onto a detector, and the detector response is determined.
Wavelengths of the absorption spectrum that correlate highly with biodiesel or interferences are selected for analysis. Mathematical
analysis converts the detector response for the selected areas or peaks and the motion of the spectrometer mirrors enables
determination of the sample absorption spectrum. Specific regions of the spectrum of an unknown to a concentration of
biodiesel.where FAME and triglycerides show strong absorption are used for the analysis.
4.2 This test method can utilize two different types of spectrometers.
D7806 − 20
4.2.1 A Fourier Transform Mid-IR Spectrometer fitted with a transmission sample cell can be used. The absorbance spectrum
is baseline corrected to eliminate linear and constant background from the spectrum. Linear regression calibration is calculated
without considering the influence of interferences.
4.2.2 A filter-based Mid-IR spectrometer fitted with a transmission cell can be used. The absorbance values at specified
wavenumbers are used to develop a multiple linear regression calibration.
5. Significance and Use
5.1 Biodiesel is a fuel commodity primarily used as a value-added blending component with diesel fuel.
5.2 This test method is fast and simple to run.
5.2 This test method is applicable for quality control in the production and distribution of diesel fuel and biodiesel blends
containing FAME.
5.3 The use of triglycerides in fuels is not approved for transportation applications within any ASTM specification. This test
method allows the quantification of triglyceride concentration in biodiesel blends, thus enabling detection of out-of-specification
blending.
5.4 This test method is fast, simple to run, inexpensive and requires no sample preparation.
6. Interferences
6.1 The primary spectral interferences are vegetable oils, or animal fats, or both.presence of carbonyl containing compounds
including carboxylic acids, ketones and aldehydes, as well as fatty acid ethyl esters (FAEE), may result in spectral interference.
6.2 The hydrocarbon composition of the diesel fuel has a significantminor impact on the calibration model. Therefore, for a
robust calibration model, it is important that the diesel fuel in the biodiesel fuel blend is represented in the calibration set.The
proper choice of the evaluation routine as described in this standard can minimize interferences from the hydrocarbon composition
of the diesel fuel.
6.3 Proper design of a calibration matrix, utilization of multivariate calibration techniques, and evaluation routines as described
in this standard can minimize interferences.
6.3 Water Vapor Interference—This procedure is applicable only The calibration and analysis bands in used for the calculations
in Section 12to FAME. The concentration of fatty acid ethyl esters (FAEE) cannot be determined using this test method. lie in
regions where significant signals due to water vapor can appear in the infrared spectrum. This shall be accounted for to permit
calibration and measurements at the low end concentrations.
NOTE 1—Ideally, the spectrometer should be purged with dry air or nitrogen to remove water vapor. The purge should be allowed to stabilize over
several hours before analytical work is pursued, due to the rapid changes in the air moisture content within the spectrometer during early stages of the
purge. In cases where water vapor prevention or elimination is not possible using a purge, the operator should measure a reference background spectrum
for correction of the ratioed spectrum for each sample spectrum measured. This operation is generally automated in today’s spectrometer systems and
the operator should consult the manufacturer of the spectrometer for specific instructions for implementing automated background correction routines.
The spectrometer should be sealed and desiccated to minimize the effect of water vapor variations, and any accessory should be sealed to the spectrometer.
6.4 Undissolved Water—High Lauric Acid Methyl Esters Interference—Samples containing undissolved water will result in
erroneous results. Filter cloudy or water saturated samples through a dry filter paper until clear prior to their introduction into the
instrument sample cell.with high lauric acid methyl ester (that is, coconut biodiesel) content are known to cause a bias when used
in the calibration model. Unless the method is being used to calibrate specifically and exclusively for samples containing high
levels of lauric acid methyl esters, feedstocks containing high levels of these compounds should be avoided.
7. Apparatus
7.1 Mid-IR Spectrometric Analyzer:
7.1.1 Fourier Transform Mid-IR Spectrometer (FT-IR)—The type of apparatus suitable for use in this test method employs an
IR source, a liquid transmission cell, a scanning interferometer, a deuterated triglycine sulfate detector, an analog-to-digital
converter, a microprocessor, and a method to introduce the sample. The following performance specifications must be met:
-1
scan range 4000 to 650 cm
-1
spectral resolution 4 cm
-1
digital resolution 1 cm
-1
NOTE 2—To obtain a digital resolution of 1 cmThe noise of the single for a beam spectrum recorded at 4 cmat 100 % transmission shall be less than
-1 -1
0.3 % peak-to-peak in the region from 1725 cm requires thatto 1765 cm the interferogram be zero filled prior to Fourier transformation. Consult the
FT-IR manufacturer’s instructions for the appropriate zero fill parameter settings to achieve this digital resolution. The single beam spectrum obtained
can be the average of multiple of FTIR scans but the total collection time shall not exceed 60 seconds.
7.1.1.1 The noise level shall be established by taking and ratioing two successive single beam spectra of dry air. The single beam
spectra obtained can be the average of multiple of FTIR scans. The noise of the spectrum at 100 % transmission shall be less than
-1
0.3 % peak-to-peak in the region from 1765 to 1725 cm .
D7806 − 20
7.1.2 Filter-based Mid-IR Test Apparatus—The type of apparatus suitable for use in this test method minimally employs an IR
source, an infrared transmission cell, wavelength discriminating filters, a chopper wheel, a lithium tantalate detector, an
analog-to-digital converter, a microprocessor, and a method to introduce the sample. The frequencies and bandwidths of the filters
are specified in Table 1.
7.2 TransmissionAbsorption Cell—The cell shall be a transmission cell made from non-hygroscopic materials having a
-1 -1
significant transmission in the appropriate IR wavelength region.relevant spectral range (1050 cm to 1850 cm ). The nominal
path length of the cell shall be 0.10 (6 0.01) mm, 0.10 mm 6 0.015 mm, appropriate to measure the peak regions (as defined
relevant peaks involved in Table 1) of samples in scope the spectral analysis without going into saturation. If path length
information from the manufacturer is not available,The path length should be determined in accordance to Practice D7418use
cyclohexane as a path length check sample (see . A1.2).
8. Reagents and Materials
8.1 Standards for Calibration, Qualification, and Quality Control Check Standards—AsBecause this test method is intended to
quantify FAME and triglyceride content in commercial biodiesel blends there are no high purity standard chemical reference
materials that are appropriate for development of multivariate calibration models.
8.1.1 B100 (Neat Biodiesel) used for calibration, qualification and quality control standards must be Specification D6751
compliant. The B100 shall be a methyl fatty acid ester derived from soy. The B100 used to generate the precision of this test
method was derived from soy. SeeIf the origin of FAME is known, this type shall be used for calibration. If the type of biodiesel
is not known, use soy methyl ester Annex A2 for further discussion.or the FAME most commonly used in the geographical area
where the samples are obtained.
8.1.2 The triglycerides shall be food grade oils liquid at room temperature, preferably soy oil or the type of oil most commonly
found in the local market, available for purchase commercially. See Annex A2 for further discussion on different biodiesel and
triglyceride varieties.
8.1.3 Middle distillate fuel used for calibration, qualification and quality control standards must be Specification D975
compliant, free of biodiesel or biodiesel oil precursor, or both, and so precursor compounds and should as far as possible should
be representative of the petroleum base stocks anticipated for blends to be analyzed (that is, crude source, 1D, 2D, blends,
winter/summer cuts, etc). See Annex A2 for calibration set.further discussion on calibration fuels.
TABLE 1 Filter Frequencies and Bandwidths
Center Bandwidth
Wave (in
Number wavelength
(±0.15 % units)
of wave (full width
number) at half
height)
1 % of λc
-1
1745 cm
-1
1605 cm 1 % of λc
-1
1159 cm 1 % of λc
-1
915 cm 1 % of λc
-1
769 cm 1 % of λc
-1
698 cm 1 % of λc
TABLE 1 Precision Estimate Examples for FAME in Diesel / no
TAG Detected, FAME in Diesel / TAG Detected, and TAG / FAME
Detected for Different Concentrations
FAME / no TAG FAME / TAG TAG / FAME
C (%
Detected Detected Detected
Vol)
r R r R r R
2 0.10 0.20 0.11 0.37
3 0.06 0.37 0.17 0.33 0.20 0.67
5 0.12 0.56 0.31 0.60 0.41 1.38
7 0.19 0.74 0.45 0.90 0.67 2.22
10 0.31 0.99 0.69 1.36
15 0.53 1.38 1.12 2.20
20 0.78 1.75 1.57 3.09
25 1.04 2.10 2.04 4.02
30 1.33 2.44
40 1.95 3.08
D7806 − 20
8.1.3 Diesel Cetane Check Fuel—Low (DCCF-Low).
8.1.4 Diesel Cetane Check Fuel—High (DCCF-High).
8.1.5 n-Hexane [110-54-3]—Reagent grade. (Warning—Flammable.)
8.1.6 Hexadecane [544-76-3]—With a minimum purity of 99.0 volume percent.
8.1.7 Acetone [67-64-1]—Reagent grade. (Warning—Flammable.)
8.1.8 Toluene [108-88-3]—Reagent grade. (Warning—Flammable.)
8.1.9 Cyclohexane [110-82-7]—Reagent grade. (Warning—Flammable.)
8.1.10 Methanol [67-56-1]—Reagent grade. (Warning—Flammable.)
8.1.11 Triple Solvent—A mixture of equal parts by volume of toluene, acetone, and methanol. (Warning—Flammable.)
9. Sampling and Sample Handling
9.1 General Requirements:
9.1.1 Fuel samples to be analyzed by the test method shall be sampled using procedures outlined in Practices D4057 or D4177,
where appropriate. Do not use the “Sampling by Water Displacement” procedure.
9.1.2 Protect samples from excessive (<0 °C and >60 °C) temperatures prior to testing.
9.1.3 Until test samples are known to contain <4.0 % by volume TAG, avoid storage of samples in refrigerated conditions (<
≈10 °C).
9.1.4 Do not test samples stored in leaking containers. Discard and obtain a new sample if leaks are detected.
9.2 Sample Handling During Analysis:
9.2.1 Equilibrate all samples to the typical temperature of the laboratory (15(15 °C to 27°C)27 °C) prior to analysis by this test
method.
9.2.2 After analysis, if the sample is to be saved, reseal the container before storing.
10. Calibration and Qualification of the Apparatus
10.1 Calibrate the instrument according to the procedure described in Annex A1. This calibration canmay be performed by the
instrument manufacturer prior to delivery of the instrument to the end user. Perform this qualification procedure anytime the
instrument is calibrated.
10.2 Perform this qualification procedure when an instrument is initially put into operation, when it is recalibrated, or when it
is repaired. The qualification procedure is described in Annex A1.
11. Quality Control Checks
11.1 Each day it that the instrument is to be used, confirm that the instrument it is in statistical control by measuring the biodiesel
concentration using the procedure outlined in Section 12 on at least one quality control sample of known biodiesel content. The
preparation of samples with known biodiesel concentration is described in 11.1.1 and 11.1.2. For details on quality control testing
and control charting refer to Practice D6299.
11.1.1 Standard(s) of known biodiesel and triglyceride concentration shall be prepared by mass according to A1.1.1and
converted to volume % volume percent using the measured density as outlined in Section 1313.1. At least one standard shall be
prepared for each calibration range. For example, 2 volume % may be used for the low calibration range, 20 volume % for high
calibration range. Additional standards including 0 0 % by volume percent may also be prepared and used for quality control
checks.
11.1.2 Standard(s) should be prepared in sufficient volume to allow for a minimum of 30 quality control measurements to be
made on one batch of material. Properly package and store the quality control samples to ensure that all analyses of quality control
samples from a given lot are performed on essentially identical material.
11.2 If the biodiesel volume % volume percent value estimated for the quality control sample exceeds the action limits described
specified in Practice D6299 or equivalent, then the measurement system is out-of-control and cannot be used to estimatemeasure
biodiesel concentrations until the cause of the out-of-control behavior is identified and corrected.
11.3 If correction of out-of-control behavior requires repair to the instrument or recalibration of the instrument, the qualification
of instrument performance described in A1.4 shall be performed before the system is used to measure biodiesel content on samples.
12. Procedure
12.1 Equilibrate all samples to the temperature of the laboratory (15 °C to 27 °C) prior to analysis by this test method.
12.2 Background Spectrum—Record a single beam infrared spectrum of dry air or nitrogen.
The sole source of supply of the apparatus known to the committee at this time is Chevron Phillips Chemical Company LP, 10001 Six Pines Drive, The Woodlands, TX
77380. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at
aSupporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-2002meeting of the responsible technical
committee,. Contact ASTM Customer Service at which you may [e-mail].
D7806 − 20
12.3 FTIR Procedure: Prior to the analysis of unknown test samples, establish that the equipment is running properly by
collecting the spectrum of the quality control standard(s) and comparing the estimated biodiesel concentration to the known value
for the QC standard(s).
12.1.1 If the FTIR instrument is used, remove the fuel by flushing the cell and inlet-outlet lines with sufficient solvent, described
in 8.1.11. Evaporate the residual solvent with dry air.
12.1.2 Background Spectrum—Record a single beam infrared spectrum of dry air. This spectrum can be used as a background
spectrum for 6 h.
12.1.3 Prior to the analysis of unknown test samples, establish that the equipment is running properly by collecting the spectrum
of the quality control standard(s) and comparing the estimated biodiesel concentration to the known value for the QC standard(s).
Introduce enough standard to the cell to ensure that the cell is washed by a volume of at least three times the dead volume of the
sample introduction system.
12.1.4 Equilibrate the unknown fuel sample to the typical temperature of the laboratory (15 to 27°C) before analysis.
12.1.5 Introduce enough of the fuel sample to the cell to ensure the cell is washed by a volume of at least three times the dead
volume of the sample introduction system.
-1
12.1.6 Obtain the digitized spectral response of the fuel sample over the frequency region from 4000 to 650 cm .
-1
12.1.7 Measure the absorption spectrum and note the maximum absorption value of the peak in the region 1765 to 1720 cm .
12.1.8 Biodiesel and high concentrations of biodiesel in biodiesel blends are difficult to remove from the cell surface. Flush
several times with sample or use a solvent rinse between samples. When in doubt, repeat steps 12.1.6 through 12.1.8 and compare
result to ensure adequate rinsing occurred.
12.1.9 For FTIR instruments using a baseline correction step and a linear regression calibration, determine the biodiesel
concentration using the calibration models developed in A1.3 by following the steps outlined as follows.
12.1.9.1 If the absorption value (determined in 12.1.8) is smaller or equal to 1.0, calculate the baseline corrected absorption
-1
spectrum. The baseline is defined through the absorption values at the wavenumber 1708 and 1785 cm . Calculate the area from
-1
the wavenumber 1713 to 1784 cm . Estimate the biodiesel concentration by applying the low concentration linear regression
calibration (see A1.3.3.1).
12.1.9.2 If the absorption value (determined in 12.1.7) is greater than 1.0, calculate the baseline corrected absorption spectrum.
-1
The baseline is defined through the absorption values at the wavenumber 1126 and 1225 cm . Calculate the area from the
-1
wavenumber 1126 to 1220 cm . Estimate the biodiesel concentration by applying the high concentration linear regression
calibration (see A1.3.3.2).
12.4 Rinse the absorption cell according to the manufacturer’s instructions. Biodiesel and high concentrations biodiesel blends
are difficult to remove from the cell. Flush the cell with sample or use a solvent rinse between measurements to ensure that
carry-over between measurements is minimal. Measuring a blank (oxygenate-free middle distillate or jet fuel) after the
measurement of the high range quality control sample can be used to verify adequate rinsing.
12.5 Introduce the unknown sample into the sample cell and obtain the digitized absorption spectrum (AS) of the fuel sample
-1 -1
over the frequency range from 1050 cm to 1850 cm .
12.6 Normalize the absorption spectrum to 0.1 mm path length, that is, multiply the spectrum with the factor 0.1/PL, where
PL is the path length of the cell in mm. The absorption spectrum after normalization should be used for the subsequent analysis.
12.7 Perform a classical least squares (CLS) (A1.1.8) fit of the spectrum of the unknown sample as described in A1.1.7 and
A1.1.8. Determine the respective concentrations using the CLS calibration (A1.1.9).
12.8 Determine the relative contribution of biodiesel and triglycerides.
c
i
X 5 ,iϵ FAME and TAG (1)
i
c
( i
i
If X < 0.14, set X = 0 and X = 1.
TAG TAG FAME
If X < 0.14, set X = 0 and X = 1.
FAME FAME TAG
-1 -1
12.9 Let P be the maximum of the absorption spectrum between 1735 cm and 1758 cm without any baseline correction.
12.10 If X > 0 and X = 0, the sample contains only biodiesel.
FAME TAG
-1 -1 -1
12.10.1 If P > 1.55 AU, calculate the peak area from 1230 cm to 1288 cm using the baseline points at 1105 cm and
-1
1330 cm and use the high range FAME calibration to determine the biodiesel concentration (A1.1.11). Report the triglyceride
concentration as zero.
-1 -1 -1
12.10.2 If P ≤ 1.55 AU, calculate the peak area from 1730 cm to 1766 cm using the baseline points at 1673 cm and
-1
1838 cm and use the low concentration FAME calibration to determine the biodiesel concentration (A1.1.10). Report the
triglyceride concentration as zero.
12.11 If X = 0 and X > 0, the sample contains only triglycerides.
FAME TAG
12.11.1 If P > 1.55 AU, report the concentration determined by the CLS calibration, c (A1.1.9). Report the biodiesel
TAG
concentration as zero.
D7806 − 20
-1 -1 -1
12.11.2 If P ≤ 1.55 AU, calculate the peak area from 1730 cm to 1766 cm using the baseline points at 1673 cm and
-1
1838 cm and use the low concentration TAG calibration to determine the triglyceride concentration (A1.1.10). Report the
biodiesel concentration as zero.
12.12 Filter-Based Mid-IR Instruments: If X > 0 and X > 0, the sample contains a mixture of biodiesel and
FAME TAG
triglycerides.
12.2.1 Equilibrate the unknown fuel sample to the typical temperature of the laboratory (15 to 27°C) before analysis.
12.12.1 Introduce enough of the fuel sample to the cell to ensureIf P > 1.55 AU, report the biodiesel and triglyceride
concentrations determined by the CLS calibration, c the celland c is (A1.1.9washed by a volume of at least three times
TAG FAME
the dead volume of the sample introduction system.).
-1 -1
12.12.2 For the filter-based Mid-IR test apparatusIf P ≤ 1.55 AU, calculate the peak area from 1730 cm to 1766 cm , using
-1 -1
the baseline points at 1673 cm and 1838 cm determine the biodiesel concentration using the calibration models developed in and
use the low concentration FAME calibration to determine the sum of triglyceride and biodiesel concentrations, C (A1.4A1.1.10
by following the steps outlined as follows.). Calculate the biodiesel and triglyceride concentrations as C·X and C·X
FAME TAG
respectively.
12.2.3.1 Estimate the FAME concentration using the universal equation developed in A1.4.2.
12.2.3.2 If the estimated FAME concentration is ≤6.0 volume percent use the low concentration equation developed in A1.4.3
to determine the FAME concentration.
12.2.3.3 If the estimated FAME concentration is >6.0 volume percent but ≤30.0 volume percent use the high concentration
equation developed in A1.4.4 determine the FAME concentration.
12.2.3.4 The precision of the analysis may cause the result obtained from the narrow range calibration to not correspond to the
result obtained from the universal calibration at the interface between the narrow calibrations (6.00 volume percent). If the result
from the universal calibration and the result from the indicated narrow calibration agree to within the cross method reproducibility
then the result using the narrow calibration is the accepted result. If the two results do not agree then check the instrument
performance using a check standard.
13. Calculation
13.1 Conversion to Volume % Volume Percent of Biodiesel—To convert the calibration and qualification standards to volume %
volume percent use Eq 12:
V 5 M D ⁄ D (2)
~ !
b b f b
V 5 M D ⁄ D (2)
~ !
b b f b
where:
V = biodiesel volume %,
b
M = biodiesel mass %,
b
D = relative density at 15.56°C of the calibration or qualification standard being tested as determined by Practice D1298 or Test
f
Method D4052, and
D = B100 biodiesel blend stock relative density at 15.56°C of the calibration or qualification standard being tested as
b
determined by Practice D1298 or Test Method D4052.
V = biodiesel volume percent,
b
M = biodiesel mass percent,
b
D = relative density at 15.56 °C of the calibration or qualification standard being tested as determined by Practice D1298 or Test
f
Method D4052, and
D = B100 biodiesel blend stock rel
...