ASTM D8368-22a

Standard Test Method for Determination of Totals of Aromatic, Polyaromatic and Fatty Acid Methyl Esters (FAME) Content of Diesel Fuel Using Gas Chromatography with Vacuum Ultraviolet Absorption Spectroscopy Detection (GC-VUV)

SIGNIFICANCE AND USE
5.1 The determination of group type composition of diesel fuel is useful for evaluating quality and expected performance. Aromatics and polyaromatics, in particular, are related to combustion characteristics, cetane number, energy content, lubricity, water solubility and exhaust emissions.  
5.1.1 Aromatic hydrocarbon type analysis may be useful for evaluating refinery processes.  
5.1.2 The ability to determine aromatics content in the presence of FAME may be useful to users of diesel fuel.
SCOPE
1.1 This test method covers a standard procedure for the determination of group type totals of aromatic, polyaromatic, and FAME content in diesel fuel using gas chromatography and vacuum ultraviolet absorption spectroscopy detection (GC-VUV).  
1.1.1 Polyaromatic totals are the result of the summation of diaromatic and tri-plus aromatic group types. Aromatics are the summation of monoaromatic and polyaromatic group types. FAME content is the result of summation of individual fatty acid methyl esters.  
1.1.2 This test method is applicable for renewable diesel fuels from hydrotreated vegetable oil (HVO) or animal fat, gas to liquid (GTL) diesel, light cycle oil, wide boiling range aromatic solvents and biodiesel blends.  
1.2 Concentrations of group type totals are determined by percent mass or percent volume. The applicable working ranges are as follows:    
Total Aromatics %Volume  
0.088 to 77.000  
Total Aromatics %Mass  
0.104 to 79.451    
MonoAromatics %Mass  
0.076 to 67.848    
Diaromatics %Mass  
0.027 to 34.812    
Tri-plus aromatics %Mass  
0.45 to 6.77    
PAH %Mass  
0.028 to 41.586    
FAME %Volume  
1.08 to 21.67  
1.3 Diesel fuel containing biodiesel, (FAME, that is, fatty acid methyl esters including soy methyl esters, rapeseed methylesters, tallow methylesters and canola methylesters) can be analyzed by this test method. The FAME component completely elutes from the analytical column independent of feedstock.  
1.4 Individual hydrocarbon components are not reported by this test method; however, any individual component determinations are included in the appropriate summation of the totals of aromatic, polyaromatic, monoaromatic, diaromatic, tri-plus aromatic, or FAME groups.  
1.4.1 Individual components are typically not baseline-separated by the procedure described in this test method. The coelutions are resolved at the detector using VUV absorbance spectra and deconvolution algorithms.  
1.5 This test method may apply to other hydrocarbon streams boiling between heptane (98 °C) and triacontane (450 °C), but has not been extensively tested for such applications.  
1.6 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.7 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.  
1.8 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: 30-Sep-2022
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0L - Gas Chromatography Methods

Relations

• 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 D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• 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 D6792-23c - Standard Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
• Effective Date: 01-Nov-2023
• Refers: ASTM D6792-23b - Standard Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
• Effective Date: 01-Oct-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-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 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 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 D6300-16 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Apr-2016
• Refers: ASTM D4307-99(2015) - Standard Practice for Preparation of Liquid Blends for Use as Analytical Standards
• Effective Date: 01-Oct-2015
• Refers: ASTM D6300-15 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Jun-2015
• Refers: ASTM D6300-14ae1 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Jun-2014

Overview

ASTM D8368-22a is a standard developed by ASTM International outlining a method for determining the total content of aromatics, polyaromatics, and fatty acid methyl esters (FAME) in diesel fuels. This test method employs Gas Chromatography combined with Vacuum Ultraviolet Absorption Spectroscopy Detection (GC-VUV). The standard is critical for laboratories and fuel industry professionals seeking reliable, accurate analysis of diesel fuel quality, especially with the increasing presence of renewable and biodiesel components in the fuel supply.

Determining these group types is vital due to their significant influence on diesel performance, combustion characteristics, emissions, and fuel stability. The method applies to a wide variety of diesel products, including traditional petroleum diesel, renewable diesel (such as hydrotreated vegetable oil), gas-to-liquid (GTL) diesel, aromatic solvents, and biodiesel blends.

Key Topics

• Diesel Fuel Composition Analysis: The standard addresses the measurement of total aromatics (summed monoaromatics and polyaromatics), diaromatics, tri-plus aromatics, and FAMEs (including soy methyl, rapeseed methyl, tallow methyl, and canola methyl esters).
• GC-VUV Technique: Utilizes specialized detectors to differentiate and quantify overlapping hydrocarbon groups, providing high specificity and reliability even when individual components are not baseline-separated.
• Group-Type Determination: Allows reporting by both percent mass and percent volume across working ranges suited to a broad spectrum of diesel and biodiesel formulations.
• Applicability: Suitable for various fuel matrices, such as renewable diesel, light cycle oil, and blends containing biodiesel. The method may also be adapted for other hydrocarbons with boiling ranges between heptane and triacontane, pending further validation.
• Quality Assurance: Emphasizes the significance of accurate calibration, validation mixtures, quality control samples, and adherence to recommended equipment and settings to ensure measurement precision and reproducibility.

Applications

Practical uses of ASTM D8368-22a include:

• Fuel Quality Evaluation: Identifying aromatic and FAME content helps assess and certify diesel fuel for commercial or regulatory purposes, directly impacting combustion efficiency, lubricity, and emissions.
• Refining Process Control: Aromatic hydrocarbon type analysis is useful for monitoring and optimizing refinery operations.
• Renewable Fuel Blending: As regulation and market demands drive higher biodiesel and renewable content, the ability to accurately determine both aromatic and FAME content ensures compliance and product performance.
• Emissions and Compliance: Provides vital data for industries monitoring exhaust emissions, cetane number, and energy content in light of tightening environmental standards.
• Research and Development: Supports labs and technical bodies developing next-generation diesel fuels with tailored performance characteristics.

Related Standards

Professionals using ASTM D8368-22a should also be familiar with these relevant ASTM standards:

• ASTM D4057 - Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4175 - Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• ASTM D4307 - Practice for Preparation of Liquid Blends for Use as Analytical Standards
• ASTM D6299 - Statistical Quality Assurance and Control Charting Techniques
• ASTM D6300 - Determination of Precision and Bias Data for Use in Test Methods
• ASTM D6730 - Determination of Individual Components in Spark Ignition Engine Fuels by Capillary Gas Chromatography
• ASTM D6792 - Quality Management Systems in Testing Laboratories
• ASTM D7372 - Analysis and Interpretation of Proficiency Test Program Results

ASTM D8368-22a aligns with global standardization principles, promoting consistent, high-quality testing practices in the fuel industry. Its application ensures accuracy in the determination of aromatics and FAME content, supporting regulatory compliance, operational efficiency, and environmental stewardship.

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: D8368 − 22a
Standard Test Method for
Determination of Totals of Aromatic, Polyaromatic and Fatty
Acid Methyl Esters (FAME) Content of Diesel Fuel Using
Gas Chromatography with Vacuum Ultraviolet Absorption
Spectroscopy Detection (GC-VUV)
This standard is issued under the fixed designation D8368; 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* of aromatic, polyaromatic, monoaromatic, diaromatic, tri-plus
aromatic, or FAME groups.
1.1 This test method covers a standard procedure for the
1.4.1 Individual components are typically not baseline-
determination of group type totals of aromatic, polyaromatic,
separated by the procedure described in this test method. The
and FAME content in diesel fuel using gas chromatography
coelutions are resolved at the detector using VUV absorbance
andvacuumultravioletabsorptionspectroscopydetection(GC-
spectra and deconvolution algorithms.
VUV).
1.1.1 Polyaromatic totals are the result of the summation of 1.5 This test method may apply to other hydrocarbon
diaromaticandtri-plusaromaticgrouptypes.Aromaticsarethe streams boiling between heptane (98 °C) and triacontane
summation of monoaromatic and polyaromatic group types. (450 °C), but has not been extensively tested for such applica-
FAME content is the result of summation of individual fatty tions.
acid methyl esters.
1.6 Units—The values stated in SI units are to be regarded
1.1.2 This test method is applicable for renewable diesel
as standard. No other units of measurement are included in this
fuels from hydrotreated vegetable oil (HVO) or animal fat, gas
standard.
to liquid (GTL) diesel, light cycle oil, wide boiling range
1.7 This standard does not purport to address all of the
aromatic solvents and biodiesel blends.
safety concerns, if any, associated with its use. It is the
1.2 Concentrations of group type totals are determined by
responsibility of the user of this standard to establish appro-
percent mass or percent volume. The applicable working
priate safety, health, and environmental practices and deter-
ranges are as follows:
mine the applicability of regulatory limitations prior to use.
Total Aromatics %Volume 0.088 to 77.000
1.8 This international standard was developed in accor-
Total Aromatics %Mass 0.104 to 79.451
dance with internationally recognized principles on standard-
MonoAromatics %Mass 0.076 to 67.848
ization established in the Decision on Principles for the
Diaromatics %Mass 0.027 to 34.812
Tri-plus aromatics %Mass 0.45 to 6.77
Development of International Standards, Guides and Recom-
PAH %Mass 0.028 to 41.586
mendations issued by the World Trade Organization Technical
FAME %Volume 1.08 to 21.67
Barriers to Trade (TBT) Committee.
1.3 Diesel fuel containing biodiesel, (FAME, that is, fatty
acid methyl esters including soy methyl esters, rapeseed
2. Referenced Documents
methylesters, tallow methylesters and canola methylesters) can
2.1 ASTM Standards:
be analyzed by this test method. The FAME component
D4057 Practice for Manual Sampling of Petroleum and
completely elutes from the analytical column independent of
Petroleum Products
feedstock.
D4175 Terminology Relating to Petroleum Products, Liquid
1.4 Individual hydrocarbon components are not reported by
Fuels, and Lubricants
this test method; however, any individual component determi-
D4307 Practice for Preparation of Liquid Blends for Use as
nations are included in the appropriate summation of the totals
Analytical Standards
D6299 Practice for Applying Statistical Quality Assurance
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 D02.04.0L on Gas Chromatography Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2022. Published November 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2021. Last previous edition approved in 2022 as D8368 – 22. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D8368-22A. 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
D8368 − 22a
and Control Charting Techniques to Evaluate Analytical 3.2.5 tri plus aromatic hydrocarbons, n—hydrocarbon com-
Measurement System Performance pounds containing three aromatic rings; this group includes
D6300 Practice for Determination of Precision and Bias phenanthrene, anthracene and alkylated derivatives of these
Data for Use in Test Methods for Petroleum Products, hydrocarbons.
Liquid Fuels, and Lubricants
3.3 Abbreviations:
D6730 Test Method for Determination of Individual Com-
3.3.1 ARV—accepted reference value
ponents in Spark Ignition Engine Fuels by 100-Metre
3.3.2 AU—absorbance units
Capillary (with Precolumn) High-Resolution Gas Chro-
3.3.3 GC-VUV—gaschromatographywithvacuumultravio-
matography
let absorption spectroscopy detection
D6792 Practice for Quality Management Systems in Petro-
leum Products, Liquid Fuels, and Lubricants Testing
3.3.4 LTL—lower95 %confidence/99 %coveragetolerance
Laboratories
level
D7372 Guide for Analysis and Interpretation of Proficiency
3.3.5 PAH—polyaromatic hydrocarbons
Test Program Results
3.3.6 RI—retention index
3. Terminology
3.3.7 RRF—relative response factor
3.1 Definitions: 3.3.8 UTL—upper 95 % confidence/99 % coverage toler-
3.1.1 For definitions of terms used in this test method, refer ance level
to Terminology D4175.
3.1.2 integration filter, n—a mathematical operation per- 4. Summary of Test Method
formed on an absorbance spectrum for the purpose of convert-
4.1 A sample is introduced to a gas chromatographic (GC)
ing the spectrum to a single-valued response suitable for
system. After volatilization, the effluent is introduced onto a
representation in a two-dimensional chromatogram plot.
GC column for separation, and then detected by a vacuum
3,4
3.1.3 library reference spectrum, n—an absorbance spec-
ultraviolet absorption spectroscopy detector. The separation
trum representation of a molecular species stored in a library
isaccomplishedusinga30 m,nonpolarphasecapillarycolumn
database and used for identification of a compound/compound
and a moderately fast temperature ramp (typical operating
class or deconvolution of multiple coeluting compounds.
parametersofthistestmethodaregiveninTable1).Coelutions
are resolved by the detector using vacuum ultraviolet absor-
3.1.4 response area, n—generally refers to a response
bance spectra and deconvolution.
summed over a given time interval and has units of absorbance
units (AU).
4.2 Total response areas are determined for sequential time
3.1.4.1 Discussion—A time factor necessary to convert a
intervals over the entire chromatogram. The calculation of the
response area to a true mathematical area cancels out of all
results is based on the deconvoluted response areas of each of
critical calculations and is omitted.
the classes of saturate, aromatic, monoaromatic, diaromatic,
tri-plus aromatic, and fatty acid methyl esters. The total
3.2 Definitions of Terms Specific to This Standard:
aromatics class includes the summation of monoaromatics,
3.2.1 diaromatic hydrocarbons, n—hydrocarbon com-
diaromatics, and tri-plus aromatics. The total polyaromatics
pounds containing two aromatic rings; this group includes
class includes a summation of the diaromatics and tri-plus
naphthalene, biphenyls, acenaphthene, acenaphthylene and
aromatics. The percent mass concentrations are calculated
alkylated derivatives of these hydrocarbons.
from the response areas using specific component or class and
3.2.2 monoaromatic hydrocarbons, n—hydrocarbon com-
carbon number based relative response factors. The volume
pounds containing one aromatic ring; including benzene,
percent concentrations are calculated from the mass concen-
alkylsubstituted benzenes, indans, tetralins, alkyl-substituted
trations by applying specific component or class and carbon
indans, and alkyl-substituted tetralins.
number based density values. The mass and volume percent
3.2.3 polyaromatic hydrocarbons, n—all hydrocarbon com-
calculations are software automated, whereby the RRFs and
pounds containing two or more aromatic rings, including
densities are a function of elution time in a static database
diaromatics and tri plus aromatics.
library.
3.2.4 relative response factor, n—in vacuum ultraviolet
NOTE 1—Appendix X1 and Appendix X2 provide further RRF details.
spectroscopy, the relative response factor for a given com-
pound is calculated from the compound’s absorption cross
section (expressed in cm /molecule) and methane’s cross
The sole source of supply of the apparatus known to the committee at this time
section.
is VUV-Analytics, Cedar Park, Texas. If you are aware of alternative suppliers,
3.2.4.1 Discussion—The absorption cross section is aver-
please provide this information to ASTM International Headquarters. Your com-
aged over the 125 nm to 240 nm wavelength region.
ments will receive careful consideration at a meeting of the responsible technical
3.2.4.2 Discussion—A compound’s relative response factor
committee, which you may attend.
The vacuum ultraviolet absorption apparatus is covered by a patent. Interested
is a function of the type and number of chemical bonds.
parties are invited to submit information regarding the identification of an
3.2.4.3 Discussion—A compound’s relative response factor
alternative(s) to this patented item to the ASTM International Headquarters. Your
is relative to the response of methane, which is taken to have
comments will receive careful consideration at a meeting of the responsible
a relative response factor of 1. technical committee, which you may attend.
D8368 − 22a
TABLE 1 Typical Instrument Settings
7.6 Vacuum Ultraviolet Absorption Spectroscopy Detector,
Column Dimensions Capillary, 30 m × 0.25 mm ID × capable of measuring 125 nm to 240 nm absorbance spectra
0.25 µm film thickness
with a wavelength resolution of 1 nm or better.
A
Column phase Nonpolar (for example, 100 %
7.6.1 The detector shall be able to interface with a gas
dimethyl polysiloxane)
Injector temperature 300 °C chromatographic system and measure an eluent with a scan
B
Injection volume 1.0 µL
frequency of at least 5 Hz with a baseline peak-to-peak noise
B
Split ratio 100:1
width over a 10 s interval no greater than 0.002 AU when
Column flow (constant flow mode) 2.0 mL ⁄min
Oven initial temperature 50 °C
averaged over the following wavelength regions: 125 nm to
Initial hold time 0.1 min
240 nm, 170 nm to 200 nm, 125 nm to 160 nm, and 0.001 AU
Oven ramp 15 °C ⁄min
when averaged over the 140 nm to 160 nm wavelength region.
Final oven temperature 260 °C
Final hold time 10.9 min
7.6.2 The detector shall be equipped with a shutter or
Detector makeup gas pressure as per manufacturer’s instructions
equivalent mechanism that allows the detector array to be
(gauge)
blocked from the light source in order to perform a “dark”
Data scan rate 7.0 Hz
Detector flow cell temperature 275 °C
measurement of electronic noise level.
Transfer line temperature 275 °C
7.6.3 Thedetectorshallbeequippedwithaflowcellcapable
A
Columns with low bleed phases such as MS grade have been successfully used
of being heated to at least 275 °C.
for this application (see 11.6).
B 7.6.4 The detector shall have an independently controlled
Other injection volumes and split ratios may be used to achieve the required
naphthalene response (see 13.2). makeup gas capability, capable of providing up to 5 mL⁄min
additional flow of nitrogen, helium, or argon to the flow cell.
5. Significance and Use
7.7 Data Processing System,capableofstoringandprocess-
5.1 The determination of group type composition of diesel ing absorbance scan data and corresponding time. Data pro-
fuel is useful for evaluating quality and expected performance. cessing system shall include a database library of vacuum
Aromatics and polyaromatics, in particular, are related to ultraviolet absorption reference spectra, compound class
combustion characteristics, cetane number, energy content, information, carbon number, density, and approximate reten-
lubricity, water solubility and exhaust emissions.
tion index values. Data processing system shall also store
5.1.1 Aromatic hydrocarbon type analysis may be useful for relative response factors for each hydrocarbon class in addition
evaluating refinery processes. to relative response factors for individually reported com-
pounds.
5.1.2 The ability to determine aromatics content in the
presence of FAME may be useful to users of diesel fuel. 7.7.1 Data processing system shall be capable of imple-
menting equations and fit procedures that result in deconvolu-
tion of absorbance spectra that contain contributions from
6. Interferences
multiple species.
6.1 Interferenceswiththistestmethod,ifany,havenotbeen
7.7.2 Data processing system shall be capable of binning
determined.
and storing response contributions from each deconvolution
analysis and reporting a combined total response at the end of
7. Apparatus
the analysis.
7.1 Gas Chromatograph, equipped with automated oven
7.7.3 Data processing system shall be capable of imple-
temperature control and split/splitless inlet.
menting equations to convert response areas to percent mass
7.1.1 Flow Controllers—The gas chromatograph must be and further convert percent mass to percent volume.
equipped with mass flow controllers capable of maintaining
8. Reagents and Materials
carrier gas flow constant to 61 % over the full operating
temperature range of the column. The inlet pressure of the
8.1 Purity of Reagents—Reagent grade chemicals shall be
carrier gas supplied to the gas chromatograph must be at least
used in all tests. Unless otherwise indicated, it is intended that
485 kPa.This will ensure that the minimum pressure needed to
all reagents shall conform to the specifications of the commit-
compensate for the increase in column back-pressure as the
tee on Analytical Reagents of the American Chemical Society
column temperature is maintained.
where such specifications are available. Other grades may be
7.1.2 It is highly recommended that the gas chromatograph
used, provided it is first ascertained that the reagent is of
is equipped with an autosampler. All statistical data were
sufficiently high purity to permit its use without lessening the
obtained using a GC equipped with an autosampler.
accuracy of the determination.
7.2 Carrier Gas, for gas chromatograph: Helium (see 8.2).
8.2 Helium carrier gas for gas chromatograph, 99.999 %
pure.
7.3 Purge/Makeup Gas, for detector: helium, nitrogen, or
argon (see 8.3).
7.4 Oxygen, Water, Hydrocarbon Filters, to further purify
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
GC carrier gas and detector purge/makeup gas.
Standard-Grade Reference Materials, American Chemical Society, Washington,
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
7.5 Capillary Analytical Column, nonpolar (for example,
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
dimethyl polysiloxane) phase, dimensions 30 m length,
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
0.25 mm internal diameter, 0.25 µm film thickness. copeial Convention, Inc. (USPC), Rockville, MD.
D8368 − 22a
NOTE 2—VUVCSD S1 is one of the samples included in the ILS for the
8.3 Nitrogen, helium, or argon purge/makeup gas for
determination of method precision.
vacuum ultraviolet absorption spectroscopy detector, 99.999 %
pure.
9. Hazards
8.4 Methylenechloride,reagentgrade,usedasasolventtest
9.1 Many of the compounds in diesel fuel or other test
sample and GC rinse solvent. (Warning—Toxic material. May
samples used in this test method are toxic, flammable, or both.
be combustible at high temperatures.)
Safety and sample-handling procedures appropriate for work-
8.5 Asystem validation mixture that complies with Practice
ing with such materials shall be in place before attempting to
D4307, having the components and approximate concentra-
use this test method.
tions given in Table 2. The concentrations of the prepared
system validation mixture should be close to those in Table 2
10. Sampling
and shall otherwise be accurately known.
10.1 Refer to Practice D4057 for guidelines on obtaining
8.5.1 The components of the system validation mixture may
samples.
be modified to include other components of particular rel-
evance to this test method.
11. Preparation of Apparatus
8.5.2 The components of the system validation mixture
11.1 Ensure that all gas connections are properly made,
must include linear alkanes in a continuous series from C7 to
without leaks.
C30 at the nominal concentrations in Table 2.
8.5.2.1 The system validation mixture is used to determine
11.2 Install oxygen, moisture, and hydrocarbon filters in gas
a retention time marker list (see 12.1 and 12.2).
lines upstream of GC and detector. Maintain gas filters as
8.5.2.2 The system validation mixture is used to determine
instructed by manufacturer.
split linearity (see 13.4).
11.3 Install the 30 m column in the GC inlet. Condition the
8.6 Aquality control (QC) sample, similar in characteristics
column according to the column manufacturer’s recommenda-
to samples that are to be routinely analyzed such as diesel fuel
tions prior to installation in the detector.
or biodiesel blend. See Section 18 Quality Control Monitoring.
11.4 Perform maintenance on the GC as suggested by
8.7 Check standard VUVCSD S1, with accepted reference
manufacturer, such as replacing septum and liner.
values (ARV) and tolerance limits as listed in Table 3.
11.5 Configure the injector, carrier gas, and other GC
parameters according to Table 1.
Available from Spectrum Quality Standards, 17360 Groeschke Rd., Houston, 11.6 Inject the solvent test sample defined in 8.4 and run the
TX 77084, https://spectrumstandards.com.
apparatus through a full oven ramp and cool-down cycle.
Repeat.
TABLE 2 System Validation Mixture
11.6.1 Assess the baseline on either a solvent test sample or
Component Concentration (percent mass)
a system validation mixture (see 8.5) run. The average absor-
Hexane 0.25
bance value (125 nm to 240 nm) of at least a 0.1 min section of
Heptane 0.25
the baseline near the end of the oven ramp shall be no more
Octane 0.25
Nonane 0.25 than 60.0035 AU of the average value (125 nm to 240 nm) of
Decane 0.25
the initial 0.5 min to 1.0 min range.
Undecane 0.25
Dodecane 0.25
Tridecane 0.25 12. Calibration and Standardization
Tetradecane 0.25
12.1 On installation of apparatus, after significant mainte-
Pentadecane 0.25
Hexadecane 0.25
nance of GC-VUV apparatus, or after a significant method
Hexadecanoic methyl ester C16:0 0.25
change, establish a retention index file. Run the system
Heptadecane 0.25
validationmixture(see8.5)usingthesameflowconditionsand
Octadecane 0.25
Linoleic acid methyl ester C18:2 0.25
oven ramp profile as measured samples (see Table 1 for
Nonadecane 0.25
recommended run conditions). Record the retention times of
Eicosane 0.25
C7 through C30 linear alkanes. These will serve as retention
Heneicosane 0.25
Docosane 0.25
time markers.
Tricosane 0.25
12.1.1 Significant method changes include changing the
Tetracosane 0.25
GC, column type, make-up gas pressure, or oven ramp profile.
Pentacosane 0.25
Hexacosane 0.25
Significant maintenance of the apparatus includes changing or
Heptacosane 0.25
trimming the analytical column.
Octacosane 0.25
Nonacosane 0.25
12.2 A list of retention times and retention indices for the
Triacontane 0.25
linear alkanes is used to estimate elution times of other
Naphthalene 0.25
2-Methylnaphthalene 0.25 compounds in the VUV library according to an interpolation
1,2,4-Trimethylbenzene 0.25
scheme. The retention index scheme sets the linear alkane
Phenanthrene 0.25
retention indices to multiples of 100 according to carbon
Methylene Chloride Balance
number: nonane RI = 900, decane RI = 1000, etc. Once
D8368 − 22a
A
TABLE 3 Check Sample VUVCSD S1 95 % Confidence/99 % Coverage Tolerance Intervals
Aromatics ARV LTL UTL
Total Aromatics %Volume 23.349 22.259 24.439
Total Aromatics %Mass 25.224 24.035 26.413
Monoaromatics %Mass 23.282 22.348 24.216
Diaromatics %Mass 1.466 1.302 1.631
Tri-plus aromatics %Mass 0.47 0.03 0.90
FAME %Volume 5.06 4.22 5.90
PAH %Mass 1.930 1.587 2.273
A
Consensus results for Check Sample VUVCSD S1 obtained from 21 laboratories in 2021. Supporting data have been filed at ASTM International Headquarters and may
be obtained by requesting Research Report RR:D02-2027. Contact ASTM Customer Service at [e-mail].
TABLE 5 Relative Response Factors for Specific Individual
updated, the same retention time marker list is used for all
Compounds and Compound Groups
subsequent measurements until the next modification or main-
Compound Relative Response Factor
tenance of the GC-VUV instrumentation.
Toluene 0.267
Ethylbenzene 0.284
12.3 The conversion from response areas to percent mass
Xylenes 0.284
uses class-based relative response factors. The relative re-
1,2,4-trimethylbenzene 0.279
sponse factors account for the differing areal response per unit
Naphthalene 0.198
Methylnaphthalenes 0.202
mass for the various hydrocarbon classes.
Phenanthrene 0.231
12.4 For the purpose of this calculation, the response at a
given elution time refers to the absorbance averaged over the
125 nm to 240 nm wavelength region.The response area refers
to the sum of the response over all detector scans within a
given time region.Atrue area can be generated by multiplying
13.2.1 Otherwise adjust the detector make-up gas pressure
this quantity by the time interval between scans. However, this
in 0.14 kPa increments and reanalyze the system validation
step is unnecessary when the scan rate is kept constant
mixture, checking the naphthalene response until it is in the
throughout a given measurement. For the purposes of this test
specified range. Increasing the detector make-up gas pressure
method, the response area is taken to be a sum having units of
willdecreasethenaphthaleneresponse.Donotadjustthemake
absorbance units.
up gas pressure to less than 1.0 kPa or to more than 4.1 kPa.
12.5 The response factors are relative to the response of 13.2.2 If the detector make-up gas pressure has been
methane, which is taken to have a relative response factor of 1. changed, reanalyze the retention index sample (see 12.1 and
12.2) and establish a new retention index file. Adjusting the
12.6 Relative response factor ranges used to obtain the
detector make-up gas pressure will change retention times.
precisiondatainthistestmethodaregiveninTable4andTable
Reanalyze the system validation mixture (see 8.5) and verify
5.Therelativeresponsefactor(s)usedwithineachtimeinterval
the total response for naphthalene (see 13.2).
are fixed and invariable and are determined by the defined
software algorithms.
13.3 The system validation mixture (see 8.5) serves as a
verification of the analytical system.
12.7 Relative response factors may alternatively be refined
13.3.1 System Accuracy—The system validation mixture
or determined as described in Appendix X1; however, preci-
percent by mass results for individual components shall be
sion may be affected.
within 610 % relative of the certified concentration values.
13. Pre-Measurement Validation
13.4 Split Linearity—The experimentally determined ratio
13.1 Before proceeding with measurements or after a sig- of C30 to C7 shall be within 610 % relative of each of the
nificant change or maintenance of the apparatus, the proce-
certified percent by masses in the system validation mixture.
dures in Section 11 should have been completed, and a For example; the lower limit of this ratio is [0.9 multiplied by
retention index file generated or verified following the proce-
the certified percent by mass C30] divided by [1.1 multiplied
dure in 12.1 and 12.2. by the certified percent by mass C7].
13.4.1 If the split linearity results are unacceptable, verify
13.2 Verify that the total response for naphthalene is 3.25 6
that the inlet seals, liner, and column position are designed to
0.25 in the system validation mixture (see 8.5).
minimize split inlet mass discrimination. A GC inlet liner
packed with deactivated glass wool is recommended.
TABLE 4 Relative Response Factors for Bulk Group Types
A
13.5 Analyze the quality control sample defined in 8.6.
Group Type Relative Response Factor Range
Saturates 0.587 – 0.796
13.6 If the specifications in 13.3 or control limits in 13.5 are
Monoaromatics 0.267 – 0.540
Diaromatics 0.190 – 0.254
not met, verify the functionality of all GC-VUV components,
Tri-plus aromatics 0.213 – 0.262
validityofretentiontimemarkerlist,andvalidity/qualityofthe
FAMEs 0.454 – 0.825
QC or system validation mixture, or both. Repeat setup
A
A compound’s relative response factor is a function of the type and number of
methodology in Sections 11, 12, and 13 as necessary to ensure
chemical bonds. See Appendix X2.
specifications in 13.3 and 13.5 are met before proceeding.
D8368 − 22a
13.7 It is strongly recommended that the system validation value from the total absorbance and library reference spectra
mixture and or the QC sample be run with every subsequent used in subsequent fits for that time slice.
batch of 20 samples.
15.3.2 Calculate the average retention index of the time
sliceusingtheaverageelutiontimeofthetimesliceandthelist
14. Procedure of retention time markers. A linear interpolation scheme is
sufficient.
14.1 Inject the sample into the GC injector port.Typical GC
15.3.3 Construct a list consisting of all compounds in the
method and detector conditions are given in Table 1.
VUV reference library within 6RI window of the average
14.2 The system shall record a dark scan immediately after
retention index of the time slice.
start.
15.3.4 Perform a tiered search on the total absorbance
14.3 The system shall record a reference scan immediately
spectrum, drawing from the constructed list of compounds:
after the dark scan.
15.3.4.1 Construct Eq A2.1 (see Annex A2) assuming a
14.3.1 The reference scan refers to an initial detector scan
single component contributes to the total absorbance. Select a
used as a reference to convert subsequent detector scans to
compound from the list and assign its library reference
absorbancescans,andisdefinedinAnnexA1.Itisnotalibrary
spectrum to A in Eq A2.1. Fit the total absorbance to Eq
1,ref
reference spectrum.
A2.1 using general linear least squares. Calculate a metric,
such as the chi-squared statistic:
14.4 The system shall record 125 nm to 240 nm absorbance
N
spectra and time of scan for each detector scan. Conversion of
1 1
2 2
x 5 A 2 A (1)
~ !
recorded intensity data to absorbance is given in Annex A1. 2
( i,meas i,calc
N σ
i21 i
14.5 At the end of the GC run, the data collection shall
where:
automatically stop. From this point up to and including the
N = the number of data points in an absorbance spec-
reporting of the measurement results, the apparatus automati-
trum fit,
cally controls all operations.
A = the measured total absorbance at data point i,
i,meas
14.5.1 Process the recorded absorbance spectra in order to
A = the calculated total absorbance at data point i, and
i,calc
obtain response areas for each of the hydrocarbon classes and
σ = the uncertainty of measured data point i, expressed
i
individual compounds being monitored.
as a standard deviation.
14.5.2 Calculate percent mass for each hydrocarbon group;
If the uncertainty in the measured data have not been
saturates, aromatics, monoaromatics, diaromatics, tri plus
estimated, theσ may be set to 1. Normalization by the number
i
aromatics, and FAME.
of data points, N, is also optional.
14.5.3 Calculate percent volume results from the percent
15.3.4.2 Repeat the fit for each compound in the list and
mass results and class/compound densities.
retain the fit yielding the best chi-square value, along with the
best-fit compound’s fit value f .
15. Calculation
15.3.4.3 Construct Eq A2.1 assuming two compounds con-
NOTE 3—See pertinent information on modeling absorbance data in
Annex A2. tribute to the total absorbance spectrum. Populate A and
1,ref
A in Eq A2.1 with library reference spectra for each
15.1 Divide the measured chromatogram into time slices of 2,ref
possible pair of compounds from the compound list. Fit the
a given width, ∆t. Define the following parameters:
total absorbance to Eq A2.1 for each pair. Retain the pair
15.1.1 A retention index (RI) window,
resulting in the best chi-squared value along with their fit
15.1.2 A chi-squared iteration threshold, expressed as a
values, f and f . Compare the chi-squared value from the best
percentage, 1 2
two-component fit to the chi-squared value from the best
15.1.3 An R threshold,
one-component fit. If the percent improvement of the chi-
15.1.4 A saturation threshold, and
squared value for the best two-component fit over the best
15.1.5 An initial background time region (optional).
one-component fit is greater than the chi-squared iteration
15.2 If an initial background time region is defined, calcu-
threshold, retain the two-component result. Otherwise, reject
lateabackgroundspectrumfromtheaverageoftheabsorbance
the two-component result and retain the one-component result.
scans over the background time region.
15.3.4.4 Construct Eq A2.1 assuming three compounds
15.3 Analyze each time slice using the following algorithm: contribute to the total absorbance spectrum. Populate A ,
1,ref
15.3.1 Calculate the total absorbance from the sum of the
A , and A with library reference spectra for each possible
2,ref 3,ref
absorbance scans within the time slice. triplet of compounds from the compound list. Fit the total
15.3.1.1 If a background spectrum is defined, subtract the absorbance to Eq A2.1 for each triplet. Retain the triplet
background spectrum from each of the individual absorbance resulting in the best chi-squared value along with th
...

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: D8368 − 22 D8368 − 22a
Standard Test Method for
Determination of Totals of Aromatic, Polyaromatic and Fatty
Acid Methyl Esters (FAME) Content of Diesel Fuel Using
Gas Chromatography with Vacuum Ultraviolet Absorption
Spectroscopy Detection (GC-VUV)
This standard is issued under the fixed designation D8368; 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 a standard procedure for the determination of group type totals of aromatic, polyaromatic, and FAME
content in diesel fuel using gas chromatography and vacuum ultraviolet absorption spectroscopy detection (GC-VUV).
1.1.1 Polyaromatic totals are the result of the summation of diaromatic and tri-plus aromatic group types. Aromatics are the
summation of monoaromatic and polyaromatic group types. FAME content is the result of summation of individual fatty acid
methyl esters.
1.1.2 This test method is applicable for renewable diesel fuels from hydrotreated vegetable oil (HVO) or animal fat, gas to liquid
(GTL) diesel, light cycle oil, wide boiling range aromatic solvents and biodiesel blends.
1.2 Concentrations of group type totals are determined by percent mass or percent volume. The applicable working ranges are as
follows:
Total Aromatics %Volume 0.088 to 77.000
Total Aromatics %Mass 0.104 to 79.451
MonoAromatics %Mass 0.076 to 67.848
Diaromatics %Mass 0.027 to 34.812
Tri-plus aromatics %Mass 0.45 to 6.77
PAH %Mass 0.028 to 41.586
FAME %Volume 1.08 to 21.67
1.3 Diesel fuel containing biodiesel, (FAME, that is, fatty acid methyl esters including soy methyl esters, rapeseed methylesters,
tallow methylesters and canola methylesters) can be analyzed by this test method. The FAME component completely elutes from
the analytical column independent of feedstock.
1.4 Individual hydrocarbon components are not reported by this test method; however, any individual component determinations
are included in the appropriate summation of the totals of aromatic, polyaromatic, monoaromatic, diaromatic, tri-plus aromatic, or
FAME groups.
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
D02.04.0L on Gas Chromatography Methods.
Current edition approved Feb. 1, 2022Oct. 1, 2022. Published March 2022November 2022. Originally approved in 2021. Last previous edition approved in 20212022 as
D8368 – 21.D8368 – 22. DOI: 10.1520/D8368-22.10.1520/D8368-22A.
*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
D8368 − 22a
1.4.1 Individual components are typically not baseline-separated by the procedure described in this test method. The coelutions
are resolved at the detector using VUV absorbance spectra and deconvolution algorithms.
1.5 This test method may apply to other hydrocarbon streams boiling between heptane (98 °C) and triacontane (450 °C), but has
not been extensively tested for such applications.
1.6 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.7 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.
1.8 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:
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
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
D6730 Test Method for Determination of Individual Components in Spark Ignition Engine Fuels by 100-Metre Capillary (with
Precolumn) High-Resolution Gas Chromatography
D6792 Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
D7372 Guide for Analysis and Interpretation of Proficiency Test Program Results
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175.
3.1.2 integration filter, n—a mathematical operation performed on an absorbance spectrum for the purpose of converting the
spectrum to a single-valued response suitable for representation in a two-dimensional chromatogram plot.
3.1.3 library reference spectrum, n—an absorbance spectrum representation of a molecular species stored in a library database and
used for identification of a compound/compound class or deconvolution of multiple coeluting compounds.
3.1.4 response area, n—generally refers to a response summed over a given time interval and has units of absorbance units (AU).
3.1.4.1 Discussion—
A time factor necessary to convert a response area to a true mathematical area cancels out of all critical calculations and is omitted.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 diaromatic hydrocarbons, n—hydrocarbon compounds containing two aromatic rings; this group includes naphthalene,
biphenyls, acenaphthene, acenaphthylene and alkylated derivatives of these hydrocarbons.
3.2.2 monoaromatic hydrocarbons, n—hydrocarbon compounds containing one aromatic ring; including benzene, alkylsubstituted
benzenes, indans, tetralins, alkyl-substituted indans, and alkyl-substituted tetralins.
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.
D8368 − 22a
3.2.3 polyaromatic hydrocarbons, n—all hydrocarbon compounds containing two or more aromatic rings, including diaromatics
and tri plus aromatics.
3.2.4 relative response factor, n—in vacuum ultraviolet spectroscopy, the relative response factor for a given compound is
calculated from the compound’s absorption cross section (expressed in cm /molecule) and methane’s cross section.
3.2.4.1 Discussion—
The absorption cross section is averaged over the 125 nm to 240 nm wavelength region.
3.2.4.2 Discussion—
A compound’s relative response factor is a function of the type and number of chemical bonds.
3.2.4.3 Discussion—
A compound’s relative response factor is relative to the response of methane, which is taken to have a relative response factor of
1.
3.2.5 tri plus aromatic hydrocarbons, n—hydrocarbon compounds containing three aromatic rings; this group includes
phenanthrene, anthracene and alkylated derivatives of these hydrocarbons.
3.3 Abbreviations:
3.3.1 ARV—accepted reference value
3.3.2 AU—absorbance units
3.3.3 GC-VUV—gas chromatography with vacuum ultraviolet absorption spectroscopy detection
3.3.4 LTL—lower 95 % confidence/99 % coverage tolerance level
3.3.5 PAH—polyaromatic hydrocarbons
3.3.6 RI—retention index
3.3.7 RRF—relative response factor
3.3.8 UTL—upper 95 % confidence/99 % coverage tolerance level
4. Summary of Test Method
4.1 A sample is introduced to a gas chromatographic (GC) system. After volatilization, the effluent is introduced onto a GC column
3,4
for separation, and then detected by a vacuum ultraviolet absorption spectroscopy detector. The separation is accomplished using
a 30 m, nonpolar phase capillary column and a moderately fast temperature ramp (typical operating parameters of this test method
are given in Table 1). Coelutions are resolved by the detector using vacuum ultraviolet absorbance spectra and deconvolution.
4.2 Total response areas are determined for sequential time intervals over the entire chromatogram. The calculation of the results
is based on the determination of the total deconvoluted response areas of each of the classes of saturate, aromatic, monoaromatic,
diaromatic, tri-plus aromatic, and fatty acid methyl ester compounds. esters. The total aromatics class includes the summation of
monoaromatics, diaromatics, and tri-plus aromatics. The total polyaromatics class includes a summation of the diaromatics and
tri-plus aromatics. The percent mass concentrations are calculated from the response areas using specific component or class and
The sole source of supply of the apparatus known to the committee at this time is VUV-Analytics, Cedar Park, Texas. If you are aware of alternative suppliers, please
provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which
you may attend.
The vacuum ultraviolet absorption apparatus is covered by a patent. Interested parties are invited to submit information regarding the identification of an alternative(s)
to this patented item to the ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which
you may attend.
The vacuum ultraviolet absorption apparatus is covered by a patent. Interested parties are invited to submit information regarding the identification of an alternative(s)
to this patented item to the ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which
you may attend.
D8368 − 22a
carbon number based relative response factors, as appropriate. factors. The volume percent concentrations are calculated from the
mass concentrations by applying specific component or class and carbon number based density values as appropriate.values. The
mass
and volume percent calculations are software automated, whereby the RRFs and densities are a function of elution time in a static
database library.
NOTE 1—Appendix X1 and Appendix X2 provide further RRF details.
TABLE 1 Typical Instrument Settings
Column Dimensions Capillary, 30 m × 0.25 mm ID × 0.25 μm film thickness
A
Column phase Nonpolar (for example, 100 % dimethyl polysiloxane)
Injector temperature 250 °C
Injector temperature 300 °C
B
Injection volume 1.0 μL
B
Split ratio 100:1
Column flow (constant flow mode) 2.0 mL ⁄min
Oven initial temperature 50 °C
Initial hold time 0.1 min
Oven ramp 15 °C ⁄min
Final oven temperature 260 °C
Final hold time 10.9 min
Detector makeup gas pressure (gauge) as per manufacturer’s instructions
Data scan rate 7.0 Hz
Detector flow cell temperature 275 °C
Transfer line temperature 275 °C
A
Columns with low bleed phases such as MS grade have been successfully used for this application (see 11.6).
B
Other injection volumes and split ratios may be used to achieve the required naphthalene response (see 13.2).
D8368 − 22a
5. Significance and Use
5.1 The determination of group type composition of diesel fuel is useful for evaluating quality and expected performance.
Aromatics and polyaromatics, in particular, are related to combustion characteristics, cetane number, energy content, lubricity,
water solubility and exhaust emissions.
5.1.1 Aromatic hydrocarbon type analysis may be useful for evaluating refinery processes.
5.1.2 The ability to determine aromatics content in the presence of FAME may be useful to users of diesel fuel.
6. Interferences
6.1 Interferences with this test method, if any, have not been determined.
7. Apparatus
7.1 Gas Chromatograph, equipped with automated oven temperature control and split/splitless inlet.
7.1.1 Flow Controllers—The gas chromatograph must be equipped with mass flow controllers capable of maintaining carrier gas
flow constant to 61 % over the full operating temperature range of the column. The inlet pressure of the carrier gas supplied to
the gas chromatograph must be at least 485 kPa. This will ensure that the minimum pressure needed to compensate for the increase
in column back-pressure as the column temperature is maintained.
7.1.2 It is highly recommended that the gas chromatograph is equipped with an autosampler. All statistical data were obtained
using a GC equipped with an autosampler.
7.2 Carrier Gas, for gas chromatograph: Helium (see 8.2).
7.3 Purge/Makeup Gas, for detector: helium, nitrogen, or argon (see 8.3).
7.4 Oxygen, Water, Hydrocarbon Filters, to further purify GC carrier gas and detector purge/makeup gas.
7.5 Capillary Analytical Column, nonpolar (for example, dimethyl polysiloxane) phase, dimensions 30 m length, 0.25 mm internal
diameter, 0.25 μm film thickness.
7.6 Vacuum Ultraviolet Absorption Spectroscopy Detector, capable of measuring 125 nm to 240 nm absorbance spectra with a
wavelength resolution of 1 nm or better.
7.6.1 The detector shall be able to interface with a gas chromatographic system and measure an eluent with a scan frequency of
at least 5 Hz with a baseline peak-to-peak noise width over a 10 s interval no greater than 0.002 AU when averaged over the
following wavelength regions: 125 nm to 240 nm, 170 nm to 200 nm, 125 nm to 160 nm, and 0.001 AU when averaged over the
140 nm to 160 nm wavelength region.
7.6.2 The detector shall be equipped with a shutter or equivalent mechanism that allows the detector array to be blocked from the
light source in order to perform a “dark” measurement of electronic noise level.
7.6.3 The detector shall be equipped with a flow cell capable of being heated to at least 275 °C.
7.6.4 The detector shall have an independently controlled makeup gas capability, capable of providing up to 5 mL ⁄min additional
flow of nitrogen, helium, or argon to the flow cell.
7.7 Data Processing System, capable of storing and processing absorbance scan data and corresponding time. Data processing
system shall include a database library of vacuum ultraviolet absorption reference spectra, compound class information, carbon
number, density, and approximate retention index values. Data processing system shall also store relative response factors for each
hydrocarbon class in addition to relative response factors for individually reported compounds.
D8368 − 22a
7.7.1 Data processing system shall be capable of implementing equations and fit procedures that result in deconvolution of
absorbance spectra that contain contributions from multiple species.
7.7.2 Data processing system shall be capable of binning and storing response contributions from each deconvolution analysis and
reporting a combined total response at the end of the analysis.
7.7.3 Data processing system shall be capable of implementing equations to convert response areas to percent mass and further
convert percent mass to percent volume.
8. Reagents and Materials
8.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall 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.
8.2 Helium carrier gas for gas chromatograph, 99.999 % pure.
8.3 Nitrogen, helium, or argon purge/makeup gas for vacuum ultraviolet absorption spectroscopy detector, 99.999 % pure.
8.4 Methylene chloride, reagent grade, used as a solvent test sample and GC rinse solvent. (Warning—Toxic material. May be
combustible at high temperatures.)
8.5 A system validation mixture that complies with Practice D4307, having the components and approximate concentrations given
in Table 2. The concentrations of the prepared system validation mixture should be close to those in Table 2 and shall otherwise
be accurately known.
8.5.1 The components of the system validation mixture may be modified to include other components of particular relevance to
this test method.
8.5.2 The components of the system validation mixture must include linear alkanes in a continuous series from C7 to C30 at the
nominal concentrations in Table 2.
8.5.2.1 The system validation mixture is used to determine a retention time marker list (see 12.1 and 12.2).
8.5.2.2 The system validation mixture is used to determine split linearity (see 13.4).
8.6 A quality control (QC) sample, similar in characteristics to samples that are to be routinely analyzed such as diesel fuel or
biodiesel blend. See Section 18 Quality Control Monitoring.
8.7 Check standard VUVCSD S1, with accepted reference values (ARV) and tolerance limits as listed in Table 3.
NOTE 2—VUVCSD S1 is one of the samples included in the ILS for the determination of method precision.
9. Hazards
9.1 Many of the compounds in diesel fuel or other test samples used in this test method are toxic, flammable, or both. Safety and
sample-handling procedures appropriate for working with such materials shall be in place before attempting to use this test method.
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.
Available from Spectrum Quality Standards, 17360 Groeschke Rd., Houston, TX 77084, https://spectrumstandards.com.
D8368 − 22a
TABLE 2 System Validation Mixture
Component Concentration (percent mass)
Hexane 0.25
Heptane 0.25
Octane 0.25
Nonane 0.25
Decane 0.25
Undecane 0.25
Dodecane 0.25
Tridecane 0.25
Tetradecane 0.25
Pentadecane 0.25
Hexadecane 0.25
Hexadecanoic methyl ester C16:0 0.25
Heptadecane 0.25
Octadecane 0.25
Linoleic acid methyl ester C18:2 0.25
Nonadecane 0.25
Eicosane 0.25
Heneicosane 0.25
Docosane 0.25
Tricosane 0.25
Tetracosane 0.25
Pentacosane 0.25
Hexacosane 0.25
Heptacosane 0.25
Octacosane 0.25
Nonacosane 0.25
Triacontane 0.25
Naphthalene 0.25
2-Methylnaphthalene 0.25
1,2,4-Trimethylbenzene 0.25
Phenanthrene 0.25
Methylene Chloride Balance
10. Sampling
10.1 Refer to Practice D4057 for guidelines on obtaining samples.
11. Preparation of Apparatus
11.1 Ensure that all gas connections are properly made, without leaks.
11.2 Install oxygen, moisture, and hydrocarbon filters in gas lines upstream of GC and detector. Maintain gas filters as instructed
by manufacturer.
11.3 Install the 30 m column in the GC inlet. Condition the column according to the column manufacturer’s recommendations
prior to installation in the detector.
11.4 Perform maintenance on the GC as suggested by manufacturer, such as replacing septum and liner.
11.5 Configure the injector, carrier gas, and other GC parameters according to Table 1.
11.6 Inject the solvent test sample defined in 8.4 and run the apparatus through a full oven ramp and cool-down cycle. Repeat.
11.6.1 Assess the baseline on either a solvent test sample or a system validation mixture (see 8.5) run. The average absorbance
value (125 nm to 240 nm) of at least a 0.1 min section of the baseline near the end of the oven ramp shall be no more than
60.0035 AU of the average value (125 nm to 240 nm) of the initial 0.5 min to 1.0 min range.
12. Calibration and Standardization
12.1 On installation of apparatus, after significant maintenance of GC-VUV apparatus, or after a significant method change,
D8368 − 22a
A
TABLE 3 Check Sample VUVCSD S1 95 % Confidence/99 % Coverage Tolerance Intervals
Aromatics ARV LTL UTL
Total Aromatics %Volume 23.349 22.259 24.439
Total Aromatics %Mass 25.224 24.035 26.413
Monoaromatics %Mass 23.282 22.348 24.216
Diaromatics %Mass 1.466 1.302 1.631
Tri-plus aromatics %Mass 0.47 0.03 0.90
FAME %Volume 5.06 4.22 5.90
PAH %Mass 1.930 1.587 2.273
A
Consensus results for Check Sample VUVCSD S1 obtained from 21 laboratories in 2021. Supporting data have been filed at ASTM International Headquarters and may
be obtained by requesting Research Report RR:D02-2027. Contact ASTM Customer Service at [e-mail].
establish a retention index file. Run the system validation mixture (see 8.5) using the same flow conditions and oven ramp profile
as measured samples (see Table 1 for recommended run conditions). Record the retention times of C7 through C30 linear alkanes.
These will serve as retention time markers.
12.1.1 Significant method changes include changing the GC, column type, make-up gas pressure, or oven ramp profile. Significant
maintenance of the apparatus includes changing or trimming the analytical column.
12.2 A list of retention times and retention indices for the linear alkanes is used to estimate elution times of other compounds in
the VUV library according to an interpolation scheme. The retention index scheme sets the linear alkane retention indices to
multiples of 100 according to carbon number: nonane RI = 900, decane RI = 1000, etc. Once updated, the same retention time
marker list is used for all subsequent measurements until the next modification or maintenance of the GC-VUV instrumentation.
12.3 The conversion from response areas to percent mass uses class-based relative response factors. The relative response factors
account for the differing areal response per unit mass for the various hydrocarbon classes.
12.4 For the purpose of this calculation, the response at a given elution time refers to the absorbance averaged over the 125 nm
to 240 nm wavelength region. The response area refers to the sum of the response over all detector scans within a given time
region. A true area can be generated by multiplying this quantity by the time interval between scans. However, this step is
unnecessary when the scan rate is kept constant throughout a given measurement. For the purposes of this test method, the response
area is taken to be a sum having units of absorbance units.
12.5 The response factors are relative to the response of methane, which is taken to have a relative response factor of 1.
12.6 Examples of relative response factors Relative response factor ranges used to obtain the precision data in this test method
are given in Table 4 and Table 5, and are suitable for use with this test method. The relative response factor(s) used within each
time interval are fixed and invariable and are determined by the defined software algorithms.
12.7 Relative response factors may alternatively be refined or determined as described in Appendix X1.; however, precision may
be affected.
13. Pre-Measurement Validation
13.1 Before proceeding with measurements or after a significant change or maintenance of the apparatus, the procedures in Section
11 should have been completed, and a retention index file generated or verified following the procedure in 12.1 and 12.2.
TABLE 4 Relative Response Factors for Bulk Hydrocarbon
ClassesGroup Types
A
Hydrocarbon Class Relative Response Factor C7 to C30
A
Group Type Relative Response Factor Range
Saturates 0.587 – 0.796
Monoaromatics 0.267 – 0.540
Diaromatics 0.190 – 0.254
Tri-plus aromatics 0.213 – 0.262
FAMEs 0.454 – 0.825
A
A compound’s relative response factor is a function of the type and number of
chemical bonds. See Appendix X2.
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TABLE 5 Relative Response Factors for Specific Individual
Compounds and Compound Groups
Compound Relative Response Factor
Toluene 0.267
Ethylbenzene 0.284
Xylenes 0.284
1,2,4-trimethylbenzene 0.279
Naphthalene 0.198
Methylnaphthalenes 0.202
Phenanthrene 0.231
13.2 Verify that the total response for naphthalene is 3.25 6 0.25 in the system validation mixture (see 8.5).
13.2.1 Otherwise adjust the detector make-up gas pressure in 0.14 kPa increments and reanalyze the system validation mixture,
checking the naphthalene response until it is in the specified range. Increasing the detector make-up gas pressure will decrease the
naphthalene response. Do not adjust the make up gas pressure to less than 1.0 kPa or to more than 4.1 kPa.
13.2.2 If the detector make-up gas pressure has been changed, reanalyze the retention index sample (see 12.1 and 12.2) and
establish a new retention index file. Adjusting the detector make-up gas pressure will change retention times. Reanalyze the system
validation mixture (see 8.5) and verify the total response for naphthalene (see 13.2).
13.3 The system validation mixture (see 8.5) serves as a verification of the analytical system.
13.3.1 System Accuracy—The system validation mixture percent by mass results for individual components shall be within 610 %
relative of the certified concentration values.
13.4 Split Linearity—The experimentally determined ratio of C30 to C7 shall be within 610 % relative of each of the certified
percent by masses in the system validation mixture. For example; the lower limit of this ratio is [0.9 multiplied by the certified
percent by mass C30] divided by [1.1 multiplied by the certified percent by mass C7].
13.4.1 If the split linearity results are unacceptable, verify that the inlet seals, liner, and column position are designed to minimize
split inlet mass discrimination. A GC inlet liner packed with deactivated glass wool is recommended.
13.5 Analyze the quality control sample defined in 8.6.
13.6 If the specifications in 13.3 or control limits in 13.5 are not met, verify the functionality of all GC-VUV components, validity
of retention time marker list, and validity/quality of the QC or system validation mixture, or both. Repeat setup methodology in
Sections 11, 12, and 13 as necessary to ensure specifications in 13.3 and 13.5 are met before proceeding.
13.7 It is strongly recommended that the system validation mixture and or the QC sample be run with every subsequent batch of
20 samples.
14. Procedure
14.1 Inject the sample into the GC injector port. Typical GC method and detector conditions are given in Table 1.
14.2 The system shall record a dark scan immediately after start.
14.3 The system shall record a reference scan immediately after the dark scan.
14.3.1 The reference scan refers to an initial detector scan used as a reference to convert subsequent detector scans to absorbance
scans, and is defined in Annex A1. It is not a library reference spectrum.
14.4 The system shall record 125 nm to 240 nm absorbance spectra and time of scan for each detector scan. Conversion of
recorded intensity data to absorbance is given in Annex A1.
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14.5 At the end of the GC run, the data collection shall automatically stop, and the recorded absorbance spectra processed in order
to obtain response areas for each of the hydrocarbon classes and individual compounds being monitored.stop. From this point up
to and including the reporting of the measurement results, the apparatus automatically controls all operations.
14.5.1 Process the recorded absorbance spectra in order to obtain response areas for each of the hydrocarbon classes and individual
compounds being monitored.
14.5.2 Calculate percent mass for each hydrocarbon group; saturates, aromatics, monoaromatics, diaromatics, tri plus aromatics,
and FAME.
14.5.3 Calculate percent volume results from the percent mass results and class/compound densities.
15. Calculation
NOTE 3—See pertinent information on modeling absorbance data in Annex A2.
15.1 Divide the measured chromatogram into time slices of a given width, Δt. Define the following parameters:
15.1.1 A retention index (RI) window,
15.1.2 A chi-squared iteration threshold, expressed as a percentage,
15.1.3 An R threshold,
15.1.4 A saturation threshold, and
15.1.5 An initial background time region (optional).
15.2 If an initial background time region is defined, calculate a background spectrum from the average of the absorbance scans
over the background time region.
15.3 Analyze each time slice using the following algorithm:
15.3.1 Calculate the total absorbance from the sum of the absorbance scans within the time slice.
15.3.1.1 If a background spectrum is defined, subtract the background spectrum from each of the individual absorbance spectra
within the time slice. Sum the resulting background-subtracted spectra to obtain the total absorbance spectrum for the time slice.
15.3.1.2 If the absorbance value at a given wavelength exceeds the saturation threshold for any of the absorbance scans within
the time slice, remove the data at that wavelength value from the total absorbance and library reference spectra used in subsequent
fits for that time slice.
15.3.2 Calculate the average retention index of the time slice using the average elution time of the time slice and the list of
retention time markers. A linear interpolation scheme is sufficient.
15.3.3 Construct a list consisting of all compounds in the VUV reference library within 6RI window of the average retention
index of the time slice.
15.3.4 Perform a tiered search on the total absorbance spectrum, drawing from the constructed list of compounds:
15.3.4.1 Construct Eq A2.1 (see Annex A2) assuming a single component contributes to the total absorbance. Select a compound
from the list and assign its library reference spectrum to A in Eq A2.1. Fit the total absorbance to Eq A2.1 using general linear
1,ref
least squares. Calculate a metric, such as the chi-squared statistic:
N
1 1
2 2
x 5 ~A 2 A ! (1)
( 2 i,meas i,calc
N σ
i21
i
D8368 − 22a
where:
N = the number of data points in an absorbance spectrum fit,
A = the measured total absorbance at data point i,
i,meas
A = the calculated total absorbance at data point i, and
i,calc
σ = the uncertainty of measured data point i, expressed as a standard deviation.
i
If the uncertainty in the measured data have not been estimated, the σ may be set to 1. Normalization by the number of data
i
points, N, is also optional.
15.3.4.2 Repeat the fit for each compound in the list and retain the fit yielding the best chi-square value, along with the best-fit
compound’s fit value f .
15.3.4.3 Construct Eq A2.1 assuming two compounds contribute to the total absorbance spectrum. Populate A and A in Eq
1,ref 2,ref
A2.1 with library reference spectra for each possible pair of compounds from the compound list. Fit the total absorbance to Eq
A2.1 for each pair. Retain the pair resulting in the best chi-squared value along with their fit values, f and f . Compare the
1 2
chi-sq
...