ASTM D7220-22

Standard Test Method for Sulfur in Automotive, Heating, and Jet Fuels by Monochromatic Energy Dispersive X-ray Fluorescence Spectrometry

SIGNIFICANCE AND USE
5.1 This test method provides measurement of total sulfur in automotive, No. 2 heating, and jet fuels with a minimum of sample preparation. A typical analysis time is 180 s to 360 s per sample.  
5.2 The quality of automotive, No. 2 heating, and jet fuel can be related to the amount of sulfur present. Knowledge of sulfur concentration is necessary for processing purposes. There are also regulations promulgated in federal, state, and local agencies that restrict the amount of sulfur present in some fuel.  
5.3 If this test method is applied to petroleum materials with matrices significantly different from the calibration materials specified in this test method, the cautions and recommendations in Section 6 should be observed when interpreting the results.
SCOPE
1.1 This test method specifies an energy-dispersive X-ray fluorescence (EDXRF) method for the determination of total sulfur in automotive, No. 2 heating, and jet fuels with a concentration range of 3 mg/kg to 942 mg/kg.  
1.1.1 The pooled limit of quantitation of this test method as obtained by statistical analysis of inter laboratory test results is 3 mg/kg sulfur.  
1.1.2 This test method is applicable to gasoline, oxygen enriched gasoline (RFG), diesel, diesel/biodiesel blends containing up to twenty volume percent biodiesel, kerosene, jet fuel, jet fuel/biodiesel blends containing up to five volume percent biodiesel and No. 2 home heating oil.  
1.2 A fundamental assumption in this test method is that the standard and sample matrix is well matched. Matrix mismatch can be caused by C/H ratio differences between samples and standards or by the presence of other heteroatoms.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3.1 The preferred concentration units are mg/kg sulfur.  
1.4 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.  
1.5 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-Oct-2022
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.03 - Elemental Analysis

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 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 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 D6300-19a - 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 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
• Refers: ASTM D6300-14a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Jun-2014
• Refers: ASTM D6300-14 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-May-2014
• Refers: ASTM D6300-13a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Dec-2013
• 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 D6300-13 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 15-Jul-2013

Overview

ASTM D7220-22 is the standard test method for determining total sulfur content in automotive fuel, No. 2 heating oil, and jet fuels using monochromatic energy dispersive X-ray fluorescence (EDXRF) spectrometry. Developed by ASTM International, this method provides a precise, efficient analysis with minimal sample preparation. It is applicable to gasoline, diesel, diesel/biodiesel blends (up to 20% biodiesel), oxygen-enriched gasoline, kerosene, jet fuel (including up to 5% biodiesel blends), and No. 2 home heating oil, across a sulfur concentration range of 3 mg/kg to 942 mg/kg.

This standard supports fuel quality assurance and compliance with environmental regulations that restrict sulfur content in fuels.

Key Topics

• Total Sulfur Determination: Measures total sulfur content in automotive, heating, and aviation fuels, essential for quality control and regulatory compliance.
• EDXRF Spectrometry: Utilizes monochromatic X-ray excitation for rapid, accurate sulfur measurement with typical analysis times between 180 - 360 seconds per sample.
• Sample Matrix Matching: Emphasizes the importance of matching the matrix of calibration standards and test samples to ensure accurate results.
• Applicable Fuels: Covers a broad scope including gasoline, diesel, blends containing biodiesel, kerosene, and jet fuel.
• Precision and Bias: Demonstrates high repeatability and reproducibility, critical for laboratory quality assurance.
• Safety and Handling: Highlights the need for safe laboratory practices, especially regarding X-ray radiation and flammable reagents.

Applications

ASTM D7220-22 is widely used across the petroleum and energy industries for:

• Fuel Quality Control: Monitoring sulfur levels ensures compliance with specifications that impact engine performance and emissions.
• Regulatory Compliance: Supports adherence to federal, state, and local regulations on sulfur content, limiting atmospheric emissions of SOx from combustion.
• Production and Blending: Used in refineries and blending facilities to certify product batches and optimize process conditions.
• Research and Development: Provides a reliable test for laboratories and R&D centers investigating new fuel formulations, including those with renewable components.
• Environmental Monitoring: Contributes to verifying low-sulfur requirements for cleaner-burning fuels mandated by environmental authorities.

Key Benefits

• Minimal Sample Preparation: Streamlines laboratory workflow and reduces analysis times.
• Broad Applicability: Suitable for a range of modern and legacy fuel types, including those with renewable additives.
• Consistent Results: High precision ensures reliable, repeatable sulfur analysis critical for quality management and regulatory reporting.

Related Standards

For effective sampling, calibration, and data quality assurance, the following standards are commonly referenced alongside ASTM D7220-22:

• ASTM D4057 - Manual Sampling of Petroleum and Petroleum Products
• ASTM D4177 - Automatic Sampling of Petroleum and Petroleum Products
• ASTM D6299 - Statistical Quality Assurance for Analytical Measurement Systems
• ASTM D6300 - Determination of Precision and Bias Data for Petroleum Products
• ASTM E29 - Use of Significant Digits in Test Data

These standards support robust implementation of ASTM D7220-22, ensuring best practices in laboratory measurement, calibration, and data integrity.

---

Keywords: ASTM D7220, sulfur in fuels, EDXRF spectrometry, petroleum product testing, fuel quality, sulfur determination, compliance, automotive fuel, jet fuel, diesel, heating oil, energy dispersive X-ray fluorescence.

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: D7220 − 22
Standard Test Method for
Sulfur in Automotive, Heating, and Jet Fuels by
Monochromatic Energy Dispersive X-ray Fluorescence
Spectrometry
This standard is issued under the fixed designation D7220; 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* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method specifies an energy-dispersive X-ray
D4057 Practice for Manual Sampling of Petroleum and
fluorescence (EDXRF) method for the determination of total
Petroleum Products
sulfur in automotive, No. 2 heating, and jet fuels with a
D4177 Practice for Automatic Sampling of Petroleum and
concentration range of 3 mg⁄kg to 942 mg⁄kg.
Petroleum Products
1.1.1 The pooled limit of quantitation of this test method as
D6299 Practice for Applying Statistical Quality Assurance
obtained by statistical analysis of inter laboratory test results is
and Control Charting Techniques to Evaluate Analytical
3 mg⁄kg sulfur.
Measurement System Performance
1.1.2 This test method is applicable to gasoline, oxygen
D6300 Practice for Determination of Precision and Bias
enriched gasoline (RFG), diesel, diesel/biodiesel blends con-
Data for Use in Test Methods for Petroleum Products,
taining up to twenty volume percent biodiesel, kerosene, jet
Liquid Fuels, and Lubricants
fuel, jet fuel/biodiesel blends containing up to five volume
E29 Practice for Using Significant Digits in Test Data to
percent biodiesel and No. 2 home heating oil.
Determine Conformance with Specifications
1.2 Afundamental assumption in this test method is that the
standard and sample matrix is well matched. Matrix mismatch
3. Terminology
can be caused by C/H ratio differences between samples and
3.1 Definitions:
standards or by the presence of other heteroatoms.
3.1.1 monochromatic X-radiation, n—an incident X-ray
beam on a sample having a selected photon energy with a
1.3 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this narrow energy bandwidth of 65 % relative to the selected
energy.
standard.
3.1.1.1 Discussion—Monochromatic X-ray radiation in
1.3.1 The preferred concentration units are mg/kg sulfur.
EDXRFinstrumentationcanbeobtainedbyusingBraggoptics
1.4 This standard does not purport to address all of the
(at an angle ofè=45 6 5°, in the low energy range). Bragg
safety concerns, if any, associated with its use. It is the
optics (monochromators) create very intense mono-energetic
responsibility of the user of this standard to establish appro-
radiation. A combination of a selected X-ray tube (typically a
priate safety, health, and environmental practices and deter-
Pd or Ag anode) with a highly ordered pyrolytic graphite
mine the applicability of regulatory limitations prior to use.
(HOPG) Bragg optic can be used to create monochromatic
1.5 This international standard was developed in accor-
radiation of the characteristic radiation of the anode material of
dance with internationally recognized principles on standard-
the X-ray tube. The use of such radiation for sample excitation
ization established in the Decision on Principles for the
resultsinincreasedsensitivityforthedeterminationofsulfurin
Development of International Standards, Guides and Recom-
petroleum products.
mendations issued by the World Trade Organization Technical
3.2 Abbreviations:
Barriers to Trade (TBT) Committee.
3.2.1 DBS—actual mass of Di-n-butyl sulfide, g
3.2.2 Kcps—kilo-counts per second.
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 D02.03 on Elemental Analysis. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2022. Published November 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2006. Last previous edition approved in 2017 as D7220 – 12 (2017). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D7220-22. 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
D7220 − 22
3.2.3 EDXRF—Energy dispersive X-ray spectrometry 6.3 In general, petroleum materials with compositions that
varyfromthecalibrationsamplesasspecifiedinSection 11can
3.2.4 PTFE—Polytetrafluorethylene
be analyzed with standards made from base materials that are
3.2.5 SDBS—mass % of sulfur in Di-n-butyl sulfide, typi-
of the same or similar composition. Thus a gasoline may be
cally 21.91 %
simulated by mixing isooctane and toluene in a ratio that
3.2.6 SStd—mg/kg sulfur in the calibration standard
approximates the expected aromatic content of the samples to
be analyzed. Standards made from this simulated gasoline can
3.2.7 SStock—mg/kg of sulfur in the stock standard
produce results that are more accurate than results obtained
3.2.8 STK—actual mass of stock standard, g
using white oil standards.
4. Summary of Test Method
7. Apparatus
4.1 ThesampleisplacedinthemonochromaticX-raybeam,
7.1 Monochromatic X-ray Fluorescence Analyzer—A
and the peak area of the sulfur Kα line at 2.307 keV is
Monochromatic Excitation Energy Dispersive XRF spectrom-
measured. The background spectrum, measured with a sulfur
eter may be used if its design incorporates as a minimum, the
free white oil or other matrix matching blank sample (see 8.4)
following features:
is adapted to the measured spectrum using adjustment regions
7.1.1 Source of X-ray Excitation, X-ray end window tube
following the instrument manufacturer’s instructions and then
with Ag or Pd anode, in combination with HOPG Bragg
subtracted from the measured spectrum. The resultant net
monochromating X-ray optics. The monochromator must pro-
counting rate is then compared to a previously prepared
duce monochromatic Ag or Pd L radiation. Other anode
calibration curve or equation to obtain the concentration of
materialsandmonochromatorsmaybeutilized,howeverstated
sulfur in mg/kg. (Warning—Exposure to excessive quantities
precision and bias may not apply.
of X-radiation is injurious to health.The operator needs to take
7.1.2 Sample Cell, providing a sample depth of at least
appropriate actions to avoid exposing any part of their body,
7 mm and equipped with replaceable X-ray transparent film
not only to primary X-rays, but also to secondary or scattered
window.
radiation that might be present.The X-ray spectrometer should
7.1.3 X-ray Detector, with a resolution value not to exceed
be operated in accordance with the regulations governing the
175 eV at 5.9 Kcps (10 000 cps). A Si drift chamber has been
use of ionizing radiation.)
found suitable for use. Using a detection system with this
minimum spectral resolution has been shown to eliminate the
5. Significance and Use
potential effect of interference from chlorine on sulfur should
5.1 Thistestmethodprovidesmeasurementoftotalsulfurin
either salt contamination, or chlorine from other sources (for
automotive, No. 2 heating, and jet fuels with a minimum of
example, recycled vegetable oils) occur.
samplepreparation.Atypicalanalysistimeis180 sto360 sper
7.1.4 He-flush, the system must allow flushing of the optical
sample.
pathwithhelium(see8.6).Alternatively,avacuumof ≤4.0 kPa
5.2 The quality of automotive, No. 2 heating, and jet fuel
(≤30.4 Torr) is applied to the optical path.
can be related to the amount of sulfur present. Knowledge of
7.1.5 Signal Conditioning and Data Handling Electronics,
sulfur concentration is necessary for processing purposes.
including the functions of X-ray intensity counting, spectra
There are also regulations promulgated in federal, state, and
handling by background subtraction and deconvolution, calcu-
localagenciesthatrestricttheamountofsulfurpresentinsome
lation of overlap corrections and conversion of sulfur X-ray
fuel.
intensity into mg/kg sulfur concentration.
5.3 Ifthistestmethodisappliedtopetroleummaterialswith
8. Reagents and Materials
matrices significantly different from the calibration materials
8.1 Purity of Reagents —Reagent grade chemicals shall be
specified in this test method, the cautions and recommenda-
used in all tests. Unless otherwise indicated, it is intended that
tions in Section 6 should be observed when interpreting the
all reagents conform to the specifications of the Committee on
results.
Analytical Reagents of the American Chemical Society where
6. Interferences such specifications are available. Other grades may be used,
provided it is first ascertained that the reagent is of sufficiently
6.1 When the elemental composition (excluding sulfur) of
high purity to permit its use without lessening the accuracy of
samples differs significantly from the standards, errors in the
the determination.
sulfur determination can result. For example, differences in the
carbon-hydrogen ratio of sample and calibration standards 8.2 Di-n-butyl Sulfide—A high-purity standard with a certi-
introduce errors in the determination. fied analysis for sulfur content. Use the certified sulfur content
when calculating the exact concentrations of the calibration
6.2 M-85 and M-100 are fuels containing 85 % and 100 %
methanol, respectively. They have a high oxygen content
leading to significant absorption of sulfur Kα radiation. Such
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
fuels can, however, be analyzed using this test method pro-
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
vided either that correction factors are applied to the results
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
(when calibrating with white oils) or that the calibration
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
standards are prepared to match the matrix of the sample. copeial Convention, Inc. (USPC), Rockville, MD.
D7220 − 22
standards (see 11.1). (Warning—Di-n-butyl sulfide is both 9.2 Whenreusablesamplecellsareused,cleananddrycells
flammable and toxic.) before each use. Disposable sample cells shall not be reused.
For each sample, an unused piece of X-ray film is required for
NOTE 1—It is essential to know the concentration of sulfur in the
di-n-butyl sulfide, not the purity, since impurities may also be sulfur
the sample cell. Avoid touching the inside of the sample cell,
containing compounds.
the portion of the window film in the cell, or the instrument
8.3 Drift Correction Monitor(s) (Optional)—Several differ- window that is exposed to X-rays. Oil from fingerprints can
affect the reading when determining low levels of sulfur.
ent materials have been found to be suitable for use as drift
correction monitors. Examples of sulfur containing materials WrinklesinthefilmwillaffecttheintensityofthesulfurX-rays
transmitted. Therefore, it is essential that the film be taut and
that have been found to be suitable include a renewable liquid
petroleum material or a fused glass disk. The monitor’s count clean to ensure reliable results. When handling the window
film, avoid touching the central part (the part that actually
rate, in combination with count time, shall be sufficient to give
arelativecountingerroroflessthan1 %.Thecountrateforthe forms the optical window) as this can lead to contamination
from sweat, grease, or other petrochemical products. Similarly,
monitor sample is determined during calibration (see 11.4) and
again at the time of analysis (see 12.1). These counting rates discard any film that has been exposed to the atmosphere (for
example, hanging outside of the film roll dispensing box).
are used to calculate a drift correction factor (see 13.1).
Also, when opening a new roll of film, discard the first metre,
8.3.1 Drift correction is usually implemented automatically
since some films are packaged in plastic bags that contain
in software, although the calculation can readily be done
sulfur. The analyzer may need recalibration if the type or
manually. For X-ray instruments that are highly stable, the
thickness of the window film is changed.After the sample cell
magnitude of the drift correction factor may not differ signifi-
is filled, make a small vent hole in the lid of the sample cell.
cantly from unity.
Place the sample in the cell using techniques consistent with
8.4 White Oil (Light Paraffın Oil) or Matrix-Matching
good practice for the particular instrument being used. Al-
Blank Sample, with a certified content of less than 0.2 mg⁄kg
though sulfur radiation will emerge from only a small distance
sulfur.Ifonlyonematrixistobeanalyzed(forexample,diesel)
into the sample, scatter from the sample cell and the sample
accuracy of results may be improved by using a matrix
canvary.Laboratorypersonnelshallensurethatthesamplecell
matched diluent. In these cases, the matrix matched diluent
is filled above a minimum depth, beyond which additional
should match approximately the C/H ratio and oxygen content
sample does not significantly affect the count rate. Generally,
of the material to be analyzed.
fill the sample cell to a minimum of three-fourths of the cell’s
capacity.
8.5 X-ray Transparent Film—Any film that resists attack by
the sample, is free of sulfur, and is sufficiently X-ray transpar-
9.3 Consider sample reactivity, volatility and level of sulfur
ent can be used, with film thickness of between 2 µm to 6 µm.
to be determined when preparing multiple samples for analysis
Filmscanincludepolyester,polypropylene,polycarbonate,and
orwhenanauto-samplerisutilized.Examples,analyzevolatile
polyimide.Typicallypolycarbonatewithathicknessof5 µmto
samples, such as gasoline or samples with low (< 50 mg/kg)
6 µm is used. However, samples of high aromatic content can
sulfur content directly after the sample cell is sealed (see 9.2).
dissolve polyester and polycarbonate films. It is important that
Follow recommendations to utilize techniques consistent with
samples, standards, and blanks be measured using the same
good practice for the sulfur concentration range, sample matrix
batch of film to avoid bias.
type, sample cell, window film and the apparatus being used
(see 8.5, 8.7, 9.2, 9.4, and 9.5).
8.6 Helium Gas, minimum purity 99.9 %.
9.4 If the instrument is equipped with a replaceable
8.7 Sample Cells, compatible with the sample and the
secondary/safety window, take steps to ensure there is no
geometry requirements of the spectrometer. Disposable cells
cross-contamination. Follow manufacturer’s recommendations
are recommended.
to periodically clean the window surface. Replace the window
8.8 Calibration Check Samples, portions of one or more
if it is torn, contaminated by spillage or wrinkled. When
liquid petroleum or product standards of known sulfur content
changing the window, follow the precautions given in 9.2.
and not used in the generation of the calibration curve. The
9.5 Impurities or thickness variations, which may affect the
check samples shall be used to determine the accuracy of the
determina
...

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: D7220 − 12 (Reapproved 2017) D7220 − 22
Standard Test Method for
Sulfur in Automotive, Heating, and Jet Fuels by
Monochromatic Energy Dispersive X-ray Fluorescence
Spectrometry
This standard is issued under the fixed designation D7220; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This test method specifies an energy-dispersive X-ray fluorescence (EDXRF) method for the determination of total sulfur in
automotive, No. 2 heating, and jet fuels with a concentration range of 3 mg ⁄kg to 942 mg ⁄kg.
1.1.1 The pooled limit of quantitation of this test method as obtained by statistical analysis of inter laboratory test results is
3 mg ⁄kg sulfur.
1.1.2 This test method is applicable to gasoline, oxygen enriched gasoline (RFG), diesel, diesel/biodiesel blends containing up to
twenty volume percent biodiesel, kerosene, jet fuel, jet fuel/biodiesel blends containing up to five volume percent biodiesel and
No. 2 home heating oil.
1.2 A fundamental assumption in this test method is that the standard and sample matrix is well matched. Matrix mismatch can
be caused by C/H ratio differences between samples and standards or by the presence of other heteroatoms.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3.1 The preferred concentration units are mg/kg sulfur.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 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
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
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
D02.03 on Elemental Analysis.
Current edition approved May 1, 2017Nov. 1, 2022. Published July 2017November 2022. Originally approved in 2006. Last previous edition approved in 20122017 as
D7220 – 12.D7220 – 12 (2017). DOI: 10.1520/D7220-12R17.10.1520/D7220-22.
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
D7220 − 22
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
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
3. Terminology
3.1 Definitions:
3.1.1 monochromatic X-radiation, n—an incident X-ray beam on a sample having a selected photon energy with a narrow energy
bandwidth of 65 % relative to the selected energy.
3.1.1.1 Discussion—
Monochromatic X-ray radiation in EDXRF instrumentation can be obtained by using Bragg optics (at an angle of è = 45 6 5°,
in the low energy range). Bragg optics (monochromators) create very intense mono-energetic radiation. A combination of a selected
X-ray tube (typically a Pd or Ag anode) with a highly ordered pyrolytic graphite (HOPG) Bragg optic can be used to create
monochromatic radiation of the characteristic radiation of the anode material of the X-ray tube. The use of such radiation for
sample excitation results in increased sensitivity for the determination of sulfur in petroleum products.
3.2 Abbreviations:
3.2.1 DBS—actual mass of Di-n-butyl sulfide, g
3.2.2 Kcps—kilo-counts per second.
3.2.3 EDXRF—Energy dispersive X-ray spectrometry
3.2.4 PTFE—Polytetrafluorethylene
3.2.5 SDBS—mass % of sulfur in Di-n-butyl sulfide, typically 21.91 %
3.2.6 SStd—mg/kg sulfur in the calibration standard
3.2.7 SStock—mg/kg of sulfur in the stock standard
3.2.8 STK—actual mass of stock standard, g
4. Summary of Test Method
4.1 The sample is placed in the monochromatic X-ray beam, and the peak area of the sulfur Kα line at 2.307 keV is measured.
The background spectrum, measured with a sulfur free white oil or other matrix matching blank sample (see 8.4) is adapted to the
measured spectrum using adjustment regions following the instrument manufacturer’s instructions and then subtracted from the
measured spectrum. The resultant net counting rate is then compared to a previously prepared calibration curve or equation to
obtain the concentration of sulfur in mg/kg. (Warning—Exposure to excessive quantities of X-radiation is injurious to health. The
operator needs to take appropriate actions to avoid exposing any part of their body, not only to primary X-rays, but also to
secondary or scattered radiation that might be present. The X-ray spectrometer should be operated in accordance with the
regulations governing the use of ionizing radiation.)
5. Significance and Use
5.1 This test method provides measurement of total sulfur in automotive, No. 2 heating, and jet fuels with a minimum of sample
preparation. A typical analysis time is 180 s to 360 s per sample.
5.2 The quality of automotive, No. 2 heating, and jet fuel can be related to the amount of sulfur present. Knowledge of sulfur
concentration is necessary for processing purposes. There are also regulations promulgated in federal, state, and local agencies that
restrict the amount of sulfur present in some fuel.
D7220 − 22
5.3 If this test method is applied to petroleum materials with matrices significantly different from the calibration materials
specified in this test method, the cautions and recommendations in Section 6 should be observed when interpreting the results.
6. Interferences
6.1 When the elemental composition (excluding sulfur) of samples differs significantly from the standards, errors in the sulfur
determination can result. For example, differences in the carbon-hydrogen ratio of sample and calibration standards introduce
errors in the determination.
6.2 M-85 and M-100 are fuels containing 85 % and 100 % methanol, respectively. They have a high oxygen content leading to
significant absorption of sulfur Kα radiation. Such fuels can, however, be analyzed using this test method provided either that
correction factors are applied to the results (when calibrating with white oils) or that the calibration standards are prepared to match
the matrix of the sample.
6.3 In general, petroleum materials with compositions that vary from the calibration samples as specified in Section 11 can be
analyzed with standards made from base materials that are of the same or similar composition. Thus a gasoline may be simulated
by mixing isooctane and toluene in a ratio that approximates the expected aromatic content of the samples to be analyzed.
Standards made from this simulated gasoline can produce results that are more accurate than results obtained using white oil
standards.
7. Apparatus
7.1 Monochromatic X-ray Fluorescence Analyzer—A Monochromatic Excitation Energy Dispersive XRF spectrometer may be
used if its design incorporates as a minimum, the following features:
7.1.1 Source of X-ray Excitation, X-ray end window tube with Ag or Pd anode, in combination with HOPG Bragg
monochromating X-ray optics. The monochromator must produce monochromatic Ag or Pd L radiation. Other anode materials and
monochromators may be utilized, however stated precision and bias may not apply.
7.1.2 Sample Cell, providing a sample depth of at least 4 mm7 mm and equipped with replaceable X-ray transparent film window.
7.1.3 X-ray Detector, with a resolution value not to exceed 175 eV at 5.9 Kcps (10 000 cps). A Si drift chamber has been found
suitable for use. Using a detection system with this minimum spectral resolution has been shown to eliminate the potential effect
of interference from chlorine on sulfur should either salt contamination, or chlorine from other sources (for example, recycled
vegetable oils) occur.
7.1.4 He-flush, the system must allow flushing of the optical path with helium (see 8.6). Alternatively, a vacuum of ≤4.0 kPa
(≤30.4 Torr) is applied to the optical path.
7.1.5 Signal Conditioning and Data Handling Electronics, including the functions of X-ray intensity counting, spectra handling
by background subtraction and deconvolution, calculation of overlap corrections and conversion of sulfur X-ray intensity into
mg/kg sulfur concentration.
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 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.
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For Suggestionssuggestions on the testing of reagents not listed by the American Chemical Society, see
AnnualAnalar 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.
D7220 − 22
8.2 Di-n-butyl Sulfide—aA high-purity standard with a certified analysis for sulfur content. Use the certified sulfur content when
calculating the exact concentrations of the calibration standards (see 11.1). (Warning—Di-n-butyl sulfide is both flammable and
toxic.)
NOTE 1—It is essential to know the concentration of sulfur in the di-n-butyl sulfide, not the purity, since impurities may also be sulfur containing
compounds.
8.3 Drift Correction Monitor(s) (Optional)—Several different materials have been found to be suitable for use as drift correction
monitors. Examples of sulfur containing materials that have been found to be suitable include a renewable liquid petroleum
material or a fused glass disk. The monitor’s count rate, in combination with count time, shall be sufficient to give a relative
counting error of less than 1 %. The count rate for the monitor sample is determined during calibration (see 11.4) and again at the
time of analysis (see 12.1). These counting rates are used to calculate a drift correction factor (see 13.1).
8.3.1 Drift correction is usually implemented automatically in software, although the calculation can readily be done manually.
For X-ray instruments that are highly stable, the magnitude of the drift correction factor may not differ significantly from unity.
8.4 White Oil (Light Paraffın Oil) or Matrix-Matching Blank Sample, with a certified content of less than 0.2 mg ⁄kg sulfur. If only
one matrix is to be analyzed (for example, diesel) accuracy of results may be improved by using a matrix matched diluent. In these
cases, the matrix matched diluent should match approximately the C/H ratio and oxygen content of the material to be analyzed.
8.5 X-ray Transparent Film—Any film that resists attack by the sample, is free of sulfur, and is sufficiently X-ray transparent can
be used, with film thickness of between 2 μm to 6 μm. Films can include polyester, polypropylene, polycarbonate, and polyimide.
Typically polycarbonate with a thickness of 5 μm to 6 μm is used. However, samples of high aromatic content can dissolve
polyester and polycarbonate films. It is important that samples, standards, and blanks be measured using the same batch of film
to avoid bias.
8.6 Helium Gas, minimum purity 99.9 %.
8.7 Sample Cells, compatible with the sample and the geometry requirements of the spectrometer. Disposable cells are
recommended.
8.8 Calibration Check Samples, portions of one or more liquid petroleum or product standards of known sulfur content and not
used in the generation of the calibration curve. The check samples shall be used to determine the accuracy of the initial calibration
(see 11.5).
8.9 Quality Control Samples, stable petroleum or product samples representative of the samples of interest that are run on a regular
basis to verify that the system is in statistical control.
NOTE 2—Verification of system control through the use of QC samples and control charting is highly recommended. It is recognized that QC procedures
are the province of the individual laboratory. Suitable QC samples can often be prepared by combining retains of typical samples.
9. Sampling, Test Specimens, and Test Units
9.1 Samples shall be taken in accordance with the instructions in Practices D4057 or D4177 when applicable.
9.2 When reusable sample cells are used, clean and dry cells before each use. Disposable sample cells shall not be reused. For
each sample, an unused piece of X-ray film is required for the sample cell. Avoid touching the inside of the sample cell, the portion
of the window film in the cell, or the instrument window that is exposed to X-rays. Oil from fingerprints can affect the reading
when determining low levels of sulfur. Wrinkles in the film will affect the intensity of the sulfur X-rays transmitted. Therefore, it
is essential that the film be taut and clean to ensure reliable results. When handling the window film, avoid touching the central
part (the part that actually forms the optical window) as this can lead to contamination from sweat, grease, or other petrochemical
products. Similarly, discard any film that has been exposed to the atmosphere (for example, hanging outside of the film roll
dispensing box). Also, when opening a new roll of film, discard the first metre, since some films are packaged in plastic bags that
contain sulfur. The analyzer may need recalibration if the type or thickness of the window film is changed. After the sample cell
is filled, make a small vent hole in the lid of the sample cell. Place the sample in the cell using techniques consistent with good
D7220 − 22
TABLE 1 Nominal Composition of Stock Standard
Mass of White Oil or Mass of
Sulfur Content,
Matrix-Matching Blank, Di-n-butyl Sulfide,
mg/kg
g g
2498 197.72 2.28
practice for the particular instrument being used. Although sulfur radiation will emerge from only a small distance into the sample,
scatter from the sample cell and the sample can vary. Laboratory personnel shall ensure that the sample cell is filled above a
minimum depth, beyond which additional sample does not significantly affect the count rate. Generally, fill the sample cell to a
minimum of three-fourths of the cell’s capacity.
9.3 Consider sampl
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