ASTM D5186-22

Standard Test Method for Determination of the Aromatic Content and Polynuclear Aromatic Content of Diesel Fuels By Supercritical Fluid Chromatography

SIGNIFICANCE AND USE
5.1 The aromatic hydrocarbon content of motor diesel fuels is a factor that can affect their cetane number and exhaust emissions.  
5.2 The United States Environmental Protection Agency (USEPA) regulates the aromatic content of diesel fuels. California Air Resources Board (CARB) regulations place limits on the total aromatics content and polynuclear aromatic hydrocarbon content of motor diesel fuel, thus requiring an appropriate analytical determination to ensure compliance with the regulations. Producers of diesel fuels will require similar determinations for process and quality control. This test method can be used to make such determinations.  
5.3 This test method is applicable to materials in the boiling range of motor diesel fuels and is unaffected by fuel coloration. Test Method D1319, which has been mandated by the USEPA for the determination of aromatics in motor diesel fuel, excludes materials with final boiling points greater than 315 °C (600 °F) from its scope. Test Method D2425 is applicable to the determination of both total aromatics and polynuclear aromatic hydrocarbons in diesel fuel, but is much more costly and time consuming to perform.  
5.4 Results obtained by this test method have been shown to be statistically more precise than those obtained from Test Method D1319 for typical diesel fuels, and this test method has a shorter analysis time.3 Results from this test method for total polynuclear aromatic hydrocarbons are also expected to be at least as precise as those of Test Method D2425.
SCOPE
1.1 This test method covers the determination of the total amounts of monoaromatic and polynuclear aromatic hydrocarbon compounds in motor diesel fuels and blend stocks by supercritical fluid chromatography (SFC). The range of aromatics concentration to which this test method is applicable is from 1 % to 75 % by mass. The range of polynuclear aromatic hydrocarbon concentrations to which this test method is applicable is from 0.5 % to 50 % by mass.  
1.2 This test method includes relative bias for Test Method D5186 versus Test Method D1319 and Test Method D6591 versus Test Method D5186 for diesel fuels. The applicable ranges of the correlation ranges are presented in the Relative Bias section. The correlations are applicable only in the stated ranges and only to diesel fuels.  
1.3 This test method and correlations were developed for diesel samples not containing biodiesel; the presence of biodiesel will interfere with the results. The correlation equations are only applicable between these concentration ranges and to diesel fuels that do not contain biodiesel.  
1.4 The values stated in SI units are to be regarded as standard. The values stated in inch-pound units are for information only.  
1.5 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.  
1.6 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: 31-Mar-2022
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0C - Liquid Chromatography

Relations

• Refers: ASTM D6708-24 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Mar-2024
• 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 D2425-23 - Standard Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry
• Effective Date: 01-Dec-2023
• Refers: ASTM D6708-19 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-May-2019
• Refers: ASTM D6708-18 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Apr-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 D6299-17a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Nov-2017
• Refers: ASTM D2425-17 - Standard Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry
• Effective Date: 01-Oct-2017
• Refers: ASTM D6299-17 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Jan-2017
• Refers: ASTM D6708-16a - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Apr-2016
• Refers: ASTM D6708-16 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Jan-2016
• Refers: ASTM D6708-15 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Jul-2015
• Refers: ASTM D1319-14 - Standard Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption
• Effective Date: 01-Oct-2014
• Refers: ASTM D6299-13e1 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Oct-2013
• Refers: ASTM D1319-13 - Standard Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption
• Effective Date: 01-May-2013

Overview

ASTM D5186-22 outlines the Standard Test Method for Determination of the Aromatic Content and Polynuclear Aromatic Content of Diesel Fuels by Supercritical Fluid Chromatography (SFC). This test method is a crucial tool for accurately quantifying both monoaromatic and polynuclear aromatic hydrocarbon compounds in motor diesel fuels and blend stocks within the boiling range typical of these fuels. Using SFC, this method delivers results for aromatics in the 1% to 75% by mass range and polynuclear aromatic hydrocarbons from 0.5% to 50% by mass. The primary keywords associated with this standard include aromatic hydrocarbons, diesel fuel analysis, polynuclear aromatics, and supercritical fluid chromatography.

Key Topics

• Regulatory Compliance: The aromatic content of diesel fuels directly influences cetane number and exhaust emissions. Both the United States Environmental Protection Agency (USEPA) and California Air Resources Board (CARB) impose strict regulations on total aromatics and polynuclear aromatic hydrocarbons in diesel fuels. Accurate determination is essential for compliance with environmental regulations.

• Precision and Efficiency: Compared to alternative test methods such as ASTM D1319 and D2425, ASTM D5186-22 provides statistically improved precision and faster analysis times for typical diesel fuels, enabling more efficient laboratory workflows and better process control for fuel producers.

• Scope and Limitations: The method is applicable to diesel fuels and blend stocks not containing biodiesel, as the presence of biodiesel can interfere with results. The test is independent of fuel coloration, an advantage over some other methods.

• System Requirements: Implementation requires instrumentation capable of SFC, equipped with a flame ionization detector (FID), temperature and pressure controls, and precision sample injection systems, along with high-purity reagents to ensure reliable results.

Applications

• Fuel Quality Control: Refineries and fuel producers use ASTM D5186-22 for routine monitoring and quality assurance. The method provides accurate profiling of monoaromatics and polynuclear aromatic hydrocarbons, supporting consistent product quality and process optimization.

• Regulatory Testing: Laboratories rely on this test to ensure motor diesel fuels meet federal and state regulatory requirements for aromatic hydrocarbon content. The method supports reporting, compliance audits, and certification of products for environmental standards.

• Research and Development: The method proves valuable in the analysis of new fuel formulations and additives, especially when researching their impact on aromatics-related properties.

• Interlaboratory Consistency: ASTM D5186-22 includes procedures for assessing accuracy and precision through reference standards and quality control samples, establishing reliable and repeatable results across laboratories.

Related Standards

The following ASTM standards are referenced and closely related to ASTM D5186-22:

• ASTM D1319: Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption. Historically mandated for some regulatory purposes.
• ASTM D2425: Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry. Suitable for detailed hydrocarbon analysis but more costly and time-consuming.
• ASTM D6591: Test Method for Determination of Aromatic Hydrocarbon Types in Middle Distillates by High Performance Liquid Chromatography.
• ASTM D6299: Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance.
• ASTM D6708: Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods That Purport to Measure the Same Property of a Material.

Practical Value

Implementing ASTM D5186-22 enables laboratories and fuel producers to:

• Accurately measure aromatic and polynuclear aromatic hydrocarbons in diesel fuels
• Ensure regulatory compliance with USEPA and CARB standards
• Improve quality control and process consistency
• Achieve faster, more precise, and reliable test results compared to traditional methods

By utilizing supercritical fluid chromatography, this standard delivers robust and repeatable aromatic content determinations, helping the fuel industry meet quality and environmental demands efficiently.

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: D5186 − 22
Standard Test Method for
Determination of the Aromatic Content and Polynuclear
Aromatic Content of Diesel Fuels By Supercritical Fluid
Chromatography
This standard is issued under the fixed designation D5186; 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* mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This test method covers the determination of the total
amounts of monoaromatic and polynuclear aromatic hydrocar-
2. Referenced Documents
bon compounds in motor diesel fuels and blend stocks by
2.1 ASTM Standards:
supercritical fluid chromatography (SFC). The range of aro-
D1319 Test Method for Hydrocarbon Types in Liquid Petro-
matics concentration to which this test method is applicable is
leum Products by Fluorescent Indicator Adsorption
from1%to75%by mass. The range of polynuclear aromatic
D2425 Test Method for Hydrocarbon Types in Middle Dis-
hydrocarbon concentrations to which this test method is
tillates by Mass Spectrometry
applicable is from 0.5 % to 50 % by mass.
D6299 Practice for Applying Statistical Quality Assurance
1.2 This test method includes relative bias for Test Method
and Control Charting Techniques to Evaluate Analytical
D5186 versus Test Method D1319 and Test Method D6591
Measurement System Performance
versus Test Method D5186 for diesel fuels. The applicable
D6591 Test Method for Determination of Aromatic Hydro-
ranges of the correlation ranges are presented in the Relative
carbon Types in Middle Distillates—High Performance
Bias section. The correlations are applicable only in the stated
Liquid Chromatography Method with Refractive Index
ranges and only to diesel fuels.
Detection
D6708 Practice for StatisticalAssessment and Improvement
1.3 This test method and correlations were developed for
of Expected Agreement Between Two Test Methods that
diesel samples not containing biodiesel; the presence of bio-
Purport to Measure the Same Property of a Material
diesel will interfere with the results. The correlation equations
are only applicable between these concentration ranges and to
3. Terminology
diesel fuels that do not contain biodiesel.
3.1 Definitions of Terms Specific to This Standard:
1.4 The values stated in SI units are to be regarded as
3.1.1 critical pressure, n—that pressure needed to condense
standard. The values stated in inch-pound units are for infor-
a gas at the critical temperature.
mation only.
3.1.2 critical temperature, n—the highest temperature at
1.5 This standard does not purport to address all of the
which a gaseous fluid may be converted to a liquid by means
safety concerns, if any, associated with its use. It is the
of compression.
responsibility of the user of this standard to establish appro-
3.1.3 mononuclear aromatic hydrocarbons,
priate safety, health, and environmental practices and deter-
n—hydrocarbon compounds containing exactly one aromatic
mine the applicability of regulatory limitations prior to use.
ring. This group includes benzene, alkyl-substituted benzenes,
1.6 This international standard was developed in accor-
indans, tetralins, alkyl-substituted indans, and alkyl-substituted
dance with internationally recognized principles on standard-
tetralins.
ization established in the Decision on Principles for the
3.1.4 polynuclear aromatic hydrocarbons, n—all hydrocar-
Development of International Standards, Guides and Recom-
bon compounds containing two or more aromatic rings. These
rings may be fused as in naphthalene and phenanthrene, or
separate as in biphenyl.
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 D02.04.0C on Liquid Chromatography. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2022. Published May 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1991. Last previous edition approved in 2020 as D5186 – 20. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D5186-22. 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
D5186 − 22
3.1.5 restrictor, n—a device, attached to the outlet of a 6. Apparatus
chromatographic column, to restrict the mobile phase flow
6.1 Supercritical Fluid Chromatograph (SFC)—Any SFC
such that the mobile phase is maintained in the supercritical
instrumentation can be used that has the following capabilities
state throughout the chromatographic column.
and meets the performance requirements in Section 8.
3.1.6 supercritical fluid, n—a fluid maintained in a thermo-
6.1.1 Pump—The SFC instrumentation must include a
dynamic state above its critical temperature and critical pres-
pump capable of delivering supercritical carbon dioxide to the
sure.
column without pressure fluctuations and at constant flow. The
pump is typically a single-stroke-type (syringe) pump or a
3.1.7 supercriticalfluidchromatography,n—aclassofchro-
matography that employs supercritical fluids as mobile phases. highly dampened reciprocating pump with pressure fluctua-
tions not exceeding 60.3 % of the operating pressure.
4. Summary of Test Method
6.1.2 Detector—This test method is limited to the use of the
flame ionization detector (FID). The detector must have
4.1 A small aliquot of the fuel sample is injected onto a
sufficient sensitivity to detect 0.1 % by mass toluene in
packed silica adsorption column and eluted using supercritical
hexadecane under instrument conditions employed in this test
carbon dioxide mobile phase. Monoaromatics and polynuclear
method.
aromatics in the sample are separated from nonaromatics and
6.1.3 Column Temperature Control—The chromatograph
detected using a flame ionization detector.
must be capable of column temperature control of at least
4.2 The detector response to hydrocarbons is recorded
60.5 °C (1 °F) at the operating temperature.
throughout the analysis time. The chromatographic areas
6.1.4 Sample Inlet System—A liquid sample injection valve
corresponding to the monoaromatic, polynuclear aromatic, and
is required, capable of reproducibly introducing samples in the
nonaromatic components are determined and the % by mass
0.05 µL to 0.50 µL liquid volume range. The inlet system
content of each of these groups in the fuel is calculated by area
should be operated at between 25 °C and 30 °C. The sample
normalization.
inlet system must be connected to the chromatographic column
so that loss of chromatographic efficiency is avoided.
5. Significance and Use
6.1.5 Post-column Restrictor—A device capable of main-
5.1 The aromatic hydrocarbon content of motor diesel fuels
taining mobile phase supercritical conditions within the col-
is a factor that can affect their cetane number and exhaust
umn and up to the detector inlet must be connected to the end
emissions.
of the column.
5.2 The United States Environmental Protection Agency
6.1.6 Column—Any liquid or supercritical fluid chromato-
(USEPA) regulates the aromatic content of diesel fuels. Cali-
graphic column may be used that provides separation of
forniaAirResourcesBoard(CARB)regulationsplacelimitson
nonaromatic, monoaromatic, and polynuclear aromatic hydro-
the total aromatics content and polynuclear aromatic hydrocar-
carbons and meets the performance requirements of Section 8.
bon content of motor diesel fuel, thus requiring an appropriate
6.1.7 Integrator—Means must be provided for the determi-
analytical determination to ensure compliance with the regu-
nation of both discrete chromatographic peak areas and the
lations. Producers of diesel fuels will require similar determi-
accumulated area under the chromatogram. This can be done
nationsforprocessandqualitycontrol.Thistestmethodcanbe
by means of a computer or electronic integrator. The computer
used to make such determinations.
or integrator must have the capability of correcting for baseline
shifts during the run.
5.3 This test method is applicable to materials in the boiling
rangeofmotordieselfuelsandisunaffectedbyfuelcoloration. 6.1.8 Sample Filter—Amicrofilter of a porosity of 0.20 µm,
Test Method D1319, which has been mandated by the USEPA which is chemically-inert to hydrocarbon solvents, may be
for the determination of aromatics in motor diesel fuel, usedfortheremovalofmicroscopicparticulatematterfromthe
excludesmaterialswithfinalboilingpointsgreaterthan315 °C sample solution that potentially may harm the injection valve
(600 °F) from its scope. Test Method D2425 is applicable to and affect system performance.
the determination of both total aromatics and polynuclear
aromatic hydrocarbons in diesel fuel, but is much more costly 7. Reagents and Materials
and time consuming to perform.
7.1 Purity of Reagents—Reagent-grade chemicals shall be
5.4 Resultsobtainedbythistestmethodhavebeenshownto
used in all tests. Unless otherwise indicated, it is intended that
be statistically more precise than those obtained from Test
all reagents conform to the specifications of the Committee on
MethodD1319fortypicaldieselfuels,andthistestmethodhas
Analytical Reagents of the American Chemical Society where
a shorter analysis time. Results from this test method for total
such specifications are available. Other grades may be used,
polynuclear aromatic hydrocarbons are also expected to be at
least as precise as those of Test Method D2425.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
Supporting data (obtained in a comparison study of Test Methods D1319 and DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
D5186) have been filed at ASTM International Headquarters and may be obtained Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
by requesting Research Report RR:D02-1276. Contact ASTM Customer Service at U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
[e-mail]. copeial Convention, Inc. (USPC), Rockville, MD.
D5186 − 22
provided it is first ascertained that the reagent is of sufficiently 2 3 t 2 t
~ !
2 1
R 5 (1)
NM
high purity to permit its use without lessening the accuracy of 1.699 3 y 1y
~ !
2 1
the determination.
2 3 t 2 t
~ !
4 3
R 5 (2)
MD
7.2 Air—Zero grade (hydrocarbon-free) is used as the FID
1.699 3 y 1y
~ 4 3!
oxidant. (Warning—Air is usually supplied as a compressed
where:
gas under high pressure and supports combustion.)
t = time for the n-C peak apex, s,
1 16
7.3 Carbon Dioxide (CO )—Supercritical fluid chromato-
t = time for the toluene peak apex, s,
graphic grade, 99.99 % minimum purity, supplied pressurized
t = time for the tetralin peak apex, s,
in a cylinder equipped with a dip tube for removal of liquid
t = time for the naphthalene peak apex, s,
CO.(Warning—Liquid at high pressure. Release of pressure
y = peak width at half height of n-C peak, s,
1 16
results in production of extremely cold solid CO and gas,
y = peak width at half height of toluene, s,
which can dilute available atmospheric oxygen.)
y = peak width at half height of tetralin, s, and
y = peak width at half height of naphthalene, s.
7.4 Check Standard—A commercial standard reference
material, which has accepted reference values, in accordance
8.2.2 Retention Time Reproducibility—Repeated injections
with Section 6 on Reference Materials in Practice D6299.
of the performance mixture must show a retention time
Alternatively, samples subjected to round robin may be used as
repeatability (maximum difference between duplicate runs) of
check standards. It is important that the standard deviation of not more than 0.5 % for n-C and toluene peaks.
the values of the laboratory exchange program not be statisti-
8.2.3 Detector Accuracy Test—This test method assumes
cally greater than the reproducibility for the test method.
that the FID response approximates the theoretical unit carbon
response. To verify this assumption, analyze the performance
7.5 Hydrogen—Hydrogen of high quality (hydrocarbon-
mixture and calculate the response factors, relative to hexade-
free) is used as the fuel for the flame ionization detector.
cane (RRF), for each of the components in the performance
(Warning—Hydrogen is usually supplied under high pressure i
mix, using the following equations:
and is extremely flammable.)
A
i
7.6 Performance Mixture—A quantitative mixture of ap-
RF 5 (3)
i
M
i
proximately 75 % by mass hexadecane (n-C ), 20 % by mass
toluene,3%by mass tetralin (1,2,3,4-tetrahydronaphthalene), RF
i
RRF 5 (4)
i
and2%by mass naphthalene is used for performance checks.
RF
C16
7.7 Quality Control Sample—Ahomogeneous material hav-
where:
ing similar physical and chemical properties to the samples to
A = Component i in performance mix, % by area,
i
be analyzed. The choice of such material should be guided by
M = Component i in performance mix, known % by
i
Section 6 on Reference Materials in Practice D6299. Examples
mass,
of such material can be motor diesel fuel or other typical
RF = response factor of Component i,
i
samples containing aromatics and polynuclear aromatics simi-
RF = response factor of hexadecane in performance mix,
C16
lar to the samples to be analyzed.
and
RRF = relative response factor of Component i.
i
8. Preparation of Apparatus
These values can then be compared to the theoretical
8.1 Install the SFC instrumentation in accordance with the
response factor for each component in the performance mix as
manufacturer’s instructions. System operating conditions will
calculated by the following equation:
depend upon the column used and optimization of perfor-
12.01 3n 226.4
RRF 5 3 (5)
mance. If the performance characteristics in terms of retention
S D S D
theo
MW 12.01 316
and resolution, specified in 8.2, are not achieved, modify the
where:
temperature, pressure, or mobile phase flow rate to achieve
compliance. A column of low activity may be reactivated by
12.01 = atomic mass of carbon,
solvent rinsing using established liquid chromatography acti- n = number of carbon atoms in component molecule,
MW = molecular mass of component,
vation techniques.
226.4 = molecular mass of hexadecane, and
NOTE 1—This temperature can be increased (up to 40 °C) if the
16 = number of carbon atoms in hexadecane molecule.
resolution between the monoa
...

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: D5186 − 20 D5186 − 22
Standard Test Method for
Determination of the Aromatic Content and Polynuclear
Aromatic Content of Diesel Fuels By Supercritical Fluid
Chromatography
This standard is issued under the fixed designation D5186; 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*
1.1 This test method covers the determination of the total amounts of monoaromatic and polynuclear aromatic hydrocarbon
compounds in motor diesel fuels and blend stocks by supercritical fluid chromatography (SFC). The range of aromatics
concentration to which this test method is applicable is from 1 % to 75 % by mass. The range of polynuclear aromatic hydrocarbon
concentrations to which this test method is applicable is from 0.5 % to 50 % by mass.
1.2 This test method includes relative bias for Test Method D5186 versus Test Method D1319 and Test Method D6591 versus Test
Method D5186 for diesel fuels. The applicable ranges of the correlation ranges are presented in the Relative Bias section. The
correlations are applicable only in the stated ranges and only to diesel fuels.
1.3 This test method and correlations were developed for diesel samples not containing biodiesel; the presence of biodiesel will
interfere with the results. The correlation equations are only applicable between these concentration ranges and to diesel fuels that
do not contain biodiesel.
1.4 The values stated in SI units are to be regarded as standard. The values stated in inch-pound units are for information only.
1.5 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.
1.6 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:
D1319 Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption
D2425 Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry
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
D02.04.0C on Liquid Chromatography.
Current edition approved July 1, 2020April 1, 2022. Published July 2020May 2022. Originally approved in 1991. Last previous edition approved in 20192020 as
D5186 – 19.D5186 – 20. DOI: 10.1520/D5186-20.10.1520/D5186-22.
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
D5186 − 22
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6591 Test Method for Determination of Aromatic Hydrocarbon Types in Middle Distillates—High Performance Liquid
Chromatography Method with Refractive Index Detection
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport
to Measure the Same Property of a Material
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 critical pressure, n—that pressure needed to condense a gas at the critical temperature.
3.1.2 critical temperature, n—the highest temperature at which a gaseous fluid may be converted to a liquid by means of
compression.
3.1.3 mononuclear aromatic hydrocarbons, n—hydrocarbon compounds containing exactly one aromatic ring. This group
includes benzene, alkyl-substituted benzenes, indans, tetralins, alkyl-substituted indans, and alkyl-substituted tetralins.
3.1.4 polynuclear aromatic hydrocarbons, n—all hydrocarbon compounds containing two or more aromatic rings. These rings may
be fused as in naphthalene and phenanthrene, or separate as in biphenyl.
3.1.5 restrictor, n—a device, attached to the outlet of a chromatographic column, to restrict the mobile phase flow such that the
mobile phase is maintained in the supercritical state throughout the chromatographic column.
3.1.6 supercritical fluid, n—a fluid maintained in a thermodynamic state above its critical temperature and critical pressure.
3.1.7 supercritical fluid chromatography, n—a class of chromatography that employs supercritical fluids as mobile phases.
4. Summary of Test Method
4.1 A small aliquot of the fuel sample is injected onto a packed silica adsorption column and eluted using supercritical carbon
dioxide mobile phase. Monoaromatics and polynuclear aromatics in the sample are separated from nonaromatics and detected
using a flame ionization detector.
4.2 The detector response to hydrocarbons is recorded throughout the analysis time. The chromatographic areas corresponding to
the monoaromatic, polynuclear aromatic, and nonaromatic components are determined and the % by mass content of each of these
groups in the fuel is calculated by area normalization.
5. Significance and Use
5.1 The aromatic hydrocarbon content of motor diesel fuels is a factor that can affect their cetane number and exhaust emissions.
5.2 The United States Environmental Protection Agency (USEPA) regulates the aromatic content of diesel fuels. California Air
Resources Board (CARB) regulations place limits on the total aromatics content and polynuclear aromatic hydrocarbon content
of motor diesel fuel, thus requiring an appropriate analytical determination to ensure compliance with the regulations. Producers
of diesel fuels will require similar determinations for process and quality control. This test method can be used to make such
determinations.
5.3 This test method is applicable to materials in the boiling range of motor diesel fuels and is unaffected by fuel coloration. Test
Method D1319, which has been mandated by the USEPA for the determination of aromatics in motor diesel fuel, excludes materials
with final boiling points greater than 315 °C (600 °F) from its scope. Test Method D2425 is applicable to the determination of both
total aromatics and polynuclear aromatic hydrocarbons in diesel fuel, but is much more costly and time consuming to perform.
5.4 Results obtained by this test method have been shown to be statistically more precise than those obtained from Test Method
D5186 − 22
D1319 for typical diesel fuels, and this test method has a shorter analysis time. Results from this test method for total polynuclear
aromatic hydrocarbons are also expected to be at least as precise as those of Test Method D2425.
6. Apparatus
6.1 Supercritical Fluid Chromatograph (SFC)—Any SFC instrumentation can be used that has the following capabilities and
meets the performance requirements in Section 8.
6.1.1 Pump—The SFC instrumentation must include a pump capable of delivering supercritical carbon dioxide to the column
without pressure fluctuations and at constant flow. The pump is typically a single-stroke-type (syringe) pump or a highly dampened
reciprocating pump with pressure fluctuations not exceeding 60.3 % of the operating pressure.
6.1.2 Detector—This test method is limited to the use of the flame ionization detector (FID). The detector must have sufficient
sensitivity to detect 0.1 % by mass toluene in hexadecane under instrument conditions employed in this test method.
6.1.3 Column Temperature Control—The chromatograph must be capable of column temperature control of at least 60.5 °C (1 °F)
at the operating temperature.
6.1.4 Sample Inlet System—A liquid sample injection valve is required, capable of reproducibly introducing samples in the 0.05 μL
to 0.50 μL liquid volume range. The inlet system should be operated at between 25 °C and 30 °C. The sample inlet system must
be connected to the chromatographic column so that loss of chromatographic efficiency is avoided.
6.1.5 Post-column Restrictor—A device capable of maintaining mobile phase supercritical conditions within the column and up
to the detector inlet must be connected to the end of the column.
6.1.6 Column—Any liquid or supercritical fluid chromatographic column may be used that provides separation of nonaromatic,
monoaromatic, and polynuclear aromatic hydrocarbons and meets the performance requirements of Section 8.
6.1.7 Integrator—Means must be provided for the determination of both discrete chromatographic peak areas and the accumulated
area under the chromatogram. This can be done by means of a computer or electronic integrator. The computer or integrator must
have the capability of correcting for baseline shifts during the run.
6.1.8 Sample Filter—A microfilter of a porosity of 0.20 μm, which is chemically-inert to hydrocarbon solvents, may be used for
the removal of microscopic particulate matter from the sample solution that potentially may harm the injection valve and affect
system performance.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent-grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such
specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity
to permit its use without lessening the accuracy of the determination.
7.2 Air—Zero grade (hydrocarbon-free) is used as the FID oxidant. (Warning—Air is usually supplied as a compressed gas under
high pressure and supports combustion.)
7.3 Carbon Dioxide (CO )—Supercritical fluid chromatographic grade, 99.99 % minimum purity, supplied pressurized in a
cylinder equipped with a dip tube for removal of liquid CO . (Warning—Liquid at high pressure. Release of pressure results in
production of extremely cold solid CO and gas, which can dilute available atmospheric oxygen.)
7.4 Check Standard—A commercial standard reference material, which has accepted reference values, in accordance with Section
Supporting data (obtained in a comparison study of Test Methods D1319 and D5186) have been filed at ASTM International Headquarters and may be obtained by
requesting Research Report RR:D02-1276. Contact ASTM Customer Service at [e-mail].
ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference Materials, American Chemical Society, Washington, DC. For
suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and
the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
D5186 − 22
6 on Reference Materials in Practice D6299. Alternatively, samples subjected to round robin may be used as check standards. It
is important that the standard deviation of the values of the laboratory exchange program not be statistically greater than the
reproducibility for the test method.
7.5 Hydrogen—Hydrogen of high quality (hydrocarbon-free) is used as the fuel for the flame ionization detector. (Warning—
Hydrogen is usually supplied under high pressure and is extremely flammable.)
7.6 Performance Mixture—A quantitative mixture of approximately 75 % by mass hexadecane (n-C ), 20 % by mass toluene, 3
% by mass tetralin (1,2,3,4-tetrahydronaphthalene), and 2 % by mass naphthalene is used for performance checks.
7.7 Quality Control Sample—A homogeneous material having similar physical and chemical properties to the samples to be
analyzed. The choice of such material should be guided by Section 6 on Reference Materials in Practice D6299. Examples of such
material can be motor diesel fuel or other typical samples containing aromatics and polynuclear aromatics similar to the samples
to be analyzed.
8. Preparation of Apparatus
8.1 Install the SFC instrumentation in accordance with the manufacturer’s instructions. System operating conditions will depend
upon the column used and optimization of performance. If the performance characteristics in terms of retention and resolution,
specified in 8.2, are not achieved, modify the temperature, pressure, or mobile phase flow rate to achieve compliance. A column
of low activity may be reactivated by solvent rinsing using established liquid chromatography activation techniques.
NOTE 1—This temperature can be increased (up to 40 °C) if the resolution between the monoaromatics and polynuclear aromatics is not satisfactory.
Lower temperatures are suggested to improve resolution between nonaromatics and monoaromatics.
8.2 System Performance:
8.2.1 Resolution—Analyze the performance mixture prepared in 7.6. The resolution between the nonaromatics and monoaromatics
(R ) must be at least four and resolution between the monoaromatics and polynuclear aromatics (R ) must be at least two when
NM MD
calculated in accordance with the following equations:
23 t 2 t
~ !
2 1
R 5 (1)
NM
1.699 3 y 1y
~ !
2 1
23 t 2 t
~ !
4 3
R 5 (2)
MD
1.699 3 y 1y
~ 4 3!
where:
t = time for the n-C peak apex, s,
1 16
t = time for the toluene peak apex, s,
t = time for the tetralin peak apex, s,
t = time for the naphthalene peak apex, s,
y = peak width at half height of n-C peak, s,
1 16
y = peak width at half height of toluene, s,
y = peak width at half height of tetralin, s, and
y = peak width at half height of naphthalene, s.
8.2.2 Retention Time Reproducibility—Repeated injections of the performance mixture must show a retention time repeatability
(maximum difference between duplicate runs) of not more than 0.5 % for n-C and toluene peaks.
8.2.3 Detector Accuracy Test—This test method assumes that the FID response approximates the theoretical unit carbon response.
To verify this assumption, analyze the performance mixture and calculate the response factors, relative to hexadecane (RRF ), for
i
each of the components in the performance mix, using the following equations:
A
i
RF 5 (3)
i
M
i
RF
i
RRF 5 (4)
i
RF
C16
D5186 − 22
TABLE 1 Theoretical Response Factors
Component Carbon Number Molecular Mass RRF
theo
Toluene 7 92.13 1.075
Tetralin 10 132.2 1.070
Naphthalene 10 128.2 1.104
where:
A = Component i in performance mix, % by area,
i
M = Component i in performance mix, known % by mass,
i
RF = response factor of Component i,
i
RF = response factor of hexadecane in performance mix, and
C16
RRF = relative response factor of Component i.
i
These values can then be compared to the theoretical response factor for each component in the performance mix as calculated
by the following equation:
12.01 3n 226.4
RRF 5 3 (5)
S D
...