EN ISO 20846:2026

• Abstract:

  This document specifies an ultraviolet (UV) fluorescence test method for the determination of the sulfur content of the following products:; having sulfur contents in the range 3 mg/kg to 500 mg/kg:; motor gasolines containing up to a mass fraction of 3,7 % (3,7 % (m/m)) of oxygen [including those blended with a volume fraction of ethanol up to about 10 % (10 % (V/V))];; diesel fuels, including those containing up to a volume fraction of about 50 % of fatty acid methyl ester (FAME);; having sulfur contents in the range of 3 mg/kg to 45 mg/kg:; synthetic fuels, such as hydrotreated vegetable oil (HVO) and gas to liquid (GTL);; having sulfur contents in the range of 3 mg/kg to 30 mg/kg:; neat FAME (B100) and diesel fuels containing volume fraction of more than 50 % of FAME.; Other products (for example process feeds and effluents) can be analysed and other sulfur contents can be determined according to this test method, however, no precision data for products other than automotive fuels and for results outside the specified range have been established for this document. Halogens interfere with this detection technique at concentrations above approximately 3 500 mg/kg.

• Status: Published
• Publication Date: 28-Jul-2026
• ICS: 75.160.20 - Liquid fuels
• ICS: 75.160.30 - Gaseous fuels
• Technical Committee: CEN/TC 19 - Petroleum products, lubricants and related products
• Drafting Committee: CEN/TC 19/WG 27 - Elemental analysis of petroleum and related products
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 29-Jul-2026
• Completion Date: 29-Jul-2026
• Ref Project: SIST EN ISO 20846:2026 - Petroleum and related products - Determination of sulfur content of automotive fuels - Ultraviolet fluorescence method (ISO 20846:2026)

• Replaces: EN ISO 20846:2019 - Petroleum products - Determination of sulfur content of automotive fuels - Ultraviolet fluorescence method (ISO 20846:2019)
• Effective Date: 26-Jul-2023
• Refers: ISO 12185:2024 - Crude petroleum, petroleum products and related products — Determination of density — Laboratory density meter with an oscillating U-tube sensor
• Effective Date: 02-Sep-2026
• Refers: ISO 3171:1988 - Petroleum liquids — Automatic pipeline sampling
• Effective Date: 02-Sep-2026
• Refers: ISO 3675:1998 - Crude petroleum and liquid petroleum products — Laboratory determination of density — Hydrometer method
• Effective Date: 02-Sep-2026
• Refers: ISO 1042:1998 - Laboratory glassware — One-mark volumetric flasks
• Effective Date: 02-Sep-2026
• Refers: ISO 3170:2025 - Hydrocarbon Liquids — Manual sampling
• Effective Date: 02-Sep-2026
• Referred By: CEN/TR 17103:2017 - Fast pyrolysis bio-oil for stationary internal combustion engines - Quality determination
• Effective Date: 05-Aug-2026
• Referred By: EN 16900:2017 - Fast pyrolysis bio-oils for industrial boilers - Requirements and test methods
• Effective Date: 05-Aug-2026
• Referred By: CEN/TS 15940:2012 - Automotive fuels - Paraffinic diesel fuel from synthesis or hydrotreatment - Requirements and test methods
• Effective Date: 05-Aug-2026
• Referred By: CEN/TS 18227:2025 - Automotive fuels - E20 petrol - Requirements and test methods
• Effective Date: 05-Aug-2026
• Consolidated By: ISO 20846:2026 - Petroleum and related products — Determination of sulfur content of automotive fuels — Ultraviolet fluorescence method
• Effective Date: 12-Feb-2026

Overview

EN ISO 20846:2026 is an international standard developed by CEN, specifying a test method for the determination of sulfur content in petroleum and related products, with a focus on automotive fuels. Using the ultraviolet (UV) fluorescence method, this standard provides a reliable approach for measuring sulfur levels in a variety of fuel types, including motor gasoline, diesel, synthetic fuels, and pure biodiesel (FAME). This method enables quality control in fuel production, ensuring compliance with regulatory sulfur limits and supporting efforts to minimize sulfur-related emissions for environmental and engine protections.

Key Topics

The standard covers the following essential topics:

• Product Applicability:
  • Motor gasoline with up to 3.7% oxygen, including ethanol blends up to 10% (v/v)
  • Diesel fuels with up to 50% FAME (biodiesel)
  • Synthetic fuels (such as hydrotreated vegetable oil (HVO) and gas-to-liquid (GTL) fuels)
  • Neat FAME (B100) and diesel with >50% FAME content
• Sulfur Content Ranges:
  • 3 mg/kg to 500 mg/kg: Motor gasolines and diesel fuels
  • 3 mg/kg to 45 mg/kg: Synthetic fuels
  • 3 mg/kg to 30 mg/kg: Neat FAME and high FAME blends
• Test Principle:
  • Samples are combusted in an oxygen-rich atmosphere; sulfur is converted to sulfur dioxide (SO₂), which is exposed to UV light, causing fluorescence proportional to the sulfur quantity.
• Calibration and Verification:
  • Methods for multi-point and one-point calibration
  • Use of certified reference materials and quality control samples
• Precision and Interference:
  • Guidance on test precision and control limitations, particularly regarding halogen interference at high concentrations

Applications

Implementing EN ISO 20846:2026 delivers value across several sectors:

• Refineries & Fuel Producers: Ensures automotive fuels meet legal sulfur content requirements, critical for market access and environmental compliance.
• Testing Laboratories: Supports accurate sulfur analysis in routine quality control and research, with defined calibration procedures and precision criteria.
• Regulatory Authorities: Provides a globally recognized reference for sulfur content verification in automotive fuels, essential for emissions regulation enforcement.
• Automotive Industry: Enables engine manufacturers and stakeholders to verify fuel compliance, minimizing risk of catalyst poisoning and extending the life of emission control systems.

The UV fluorescence method is particularly suited to automated laboratory environments, offering high reproducibility and sensitivity across a broad range of fuel types and blends. It is not only applicable to automotive fuels but can be adapted for other petroleum products, provided some performance limitations are acknowledged.

Related Standards

For comprehensive testing and sampling of petroleum and related products, the following standards are referenced in EN ISO 20846:2026:

• ISO 1042: Laboratory glassware - One-mark volumetric flasks
• ISO 3170: Hydrocarbon liquids - Manual sampling
• ISO 3171: Petroleum liquids - Automatic pipeline sampling
• ISO 3675: Crude petroleum and liquid petroleum products - Density determination by hydrometer
• ISO 12185: Density determination using an oscillating U-tube
• ISO 4259-1: Precision of measurement methods and results

These related standards ensure the quality and traceability of laboratory analyses, supporting consistency in international fuel testing and trade.

---

By following EN ISO 20846:2026, organizations involved in fuel production, analysis, and regulation gain an authoritative framework for determining sulfur content, improving product reliability, environmental performance, and regulatory alignment in the petroleum sector.

SLOVENSKI STANDARD
01-september-2026
Nadomešča:
SIST EN ISO 20846:2019
Naftni in sorodni proizvodi - Določanje žvepla v gorivih za motorna vozila -
Ultravijolična fluorescenčna metoda (ISO 20846:2026)
Petroleum and related products - Determination of sulfur content of automotive fuels -
Ultraviolet fluorescence method (ISO 20846:2026)
Mineralölerzeugnisse - Bestimmung des Schwefelgehaltes von Kraftstoffen -
Ultraviolettfluoreszenz-Verfahren (ISO 20846:2026)
Produits pétroliers et connexes - Détermination de la teneur en soufre des carburants
pour automobiles - Méthode par fluorescence ultraviolette (ISO 20846:2026)
Ta slovenski standard je istoveten z: EN ISO 20846:2026
ICS:
75.160.20 Tekoča goriva Liquid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 20846
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2026
EUROPÄISCHE NORM
ICS 75.160.20; 75.160.30 Supersedes EN ISO 20846:2019
English Version
Petroleum and related products - Determination of sulfur
content of automotive fuels - Ultraviolet fluorescence
method (ISO 20846:2026)
Produits pétroliers et connexes - Détermination de la Mineralölerzeugnisse - Bestimmung des
teneur en soufre des carburants pour automobiles - Schwefelgehaltes von Kraftstoffen -
Méthode par fluorescence ultraviolette (ISO Ultraviolettfluoreszenz-Verfahren (ISO 20846:2026)
20846:2026)
This European Standard was approved by CEN on 1 July 2026.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20846:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 20846:2026) has been prepared by Technical Committee ISO/TC 28 "Petroleum
and related products, fuels and lubricants from natural or synthetic sources" in collaboration with
Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related products of
petroleum, synthetic and biological origin” the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2027, and conflicting national standards shall
be withdrawn at the latest by January 2027.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 20846:2019.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 20846:2026 has been approved by CEN as EN ISO 20846:2026 without any modification.

International
Standard
ISO 20846
Fourth edition
Petroleum and related products —
2026-07
Determination of sulfur content
of automotive fuels — Ultraviolet
fluorescence method
Produits pétroliers et connexes — Détermination de la teneur
en soufre des carburants pour automobiles — Méthode par
fluorescence ultraviolette
Reference number
ISO 20846:2026(en) © ISO 2026
ISO 20846:2026(en)
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 20846:2026(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 2
5 Reagents and materials . 2
5.1 Inert gas .2
5.2 Oxygen .2
5.3 Solvent .2
5.4 Sulfur compounds .2
5.5 Sulfur stock solution . .3
5.6 Calibration standards .3
5.7 Quality control samples .3
5.8 Quartz wool .4
6 Apparatus . 4
7 Sampling and sample handling . 5
8 Apparatus preparation . 5
9 Apparatus calibration and verification . 6
9.1 Multi-point calibration .6
9.2 Single point calibration .8
9.3 Verification . .8
10 Procedure . 9
11 Calculation . 9
11.1 Using multi-point calibration.9
11.2 Using one-point calibration .10
11.3 Calculation .10
12 Expression of results .11
13 Precision .11
13.1 General .11
13.2 Repeatability, r.11
13.3 Reproducibility, R .11
13.4 Precision estimates . 12
14 Test report .12
Bibliography .13

iii
ISO 20846:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels and
lubricants from natural or synthetic sources, in collaboration with the European Committee for Standardization
(CEN) Technical Committee CEN/TC 19, Gaseous and liquid fuels, lubricants and related products of petroleum,
synthetic and biological origin, in accordance with the Agreement on technical cooperation between ISO and
CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 20846:2019), which has been technically
revised.
The main changes are as follows:
— the extension of the application scope to include higher blends of biodiesel (FAME) from 50 % up to neat
FAME (B100);
— further instructions regarding the (validity of the) multi-point calibration have been implemented.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
International Standard ISO 20846:2026(en)
Petroleum and related products — Determination of sulfur
content of automotive fuels — Ultraviolet fluorescence
method
WARNING — The use of this document can involve hazardous materials, operations and equipment.
This document does not purport to address all of the safety problems associated with its use. It is
the responsibility of users of this document to take appropriate measures to ensure the safety and
health of personnel prior to application of the document and fulfil other applicable requirements for
this purpose.
1 Scope
This document specifies an ultraviolet (UV) fluorescence test method for the determination of the sulfur
content of the following products:
— having sulfur contents in the range 3 mg/kg to 500 mg/kg:
— motor gasolines containing up to a mass fraction of 3,7 % (3,7 % (m/m)) of oxygen [including those
blended with a volume fraction of ethanol up to about 10 % (10 % (V/V))];
— diesel fuels, including those containing up to a volume fraction of about 50 % of fatty acid methyl
ester (FAME);
— having sulfur contents in the range of 3 mg/kg to 45 mg/kg:
— synthetic fuels, such as hydrotreated vegetable oil (HVO) and gas to liquid (GTL);
— having sulfur contents in the range of 3 mg/kg to 30 mg/kg:
— neat FAME (B100) and diesel fuels containing volume fraction of more than 50 % of FAME.
Other products (for example process feeds and effluents) can be analysed and other sulfur contents can be
determined according to this test method, however, no precision data for products other than automotive
fuels and for results outside the specified range have been established for this document. Halogens interfere
with this detection technique at concentrations above approximately 3 500 mg/kg.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3170, Hydrocarbon Liquids — Manual sampling
ISO 3171, Petroleum liquids — Automatic pipeline sampling
ISO 3675, Crude petroleum and liquid petroleum products — Laboratory determination of density — Hydrometer
method
ISO 12185, Crude petroleum, petroleum products and related products — Determination of density —
Laboratory density meter with an oscillating U-tube sensor

ISO 20846:2026(en)
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
A hydrocarbon sample is either directly injected or placed in a sample boat. Then, it enters a high temperature
combustion tube (1 000 °C to 1 100 °C), where the sulfur is oxidized to sulfur dioxide (SO ) in an oxygen-rich
atmosphere. Water produced during the sample combustion is removed and the sample combustion gases
are exposed to UV light. The SO absorbs the energy from the UV light and is converted to excited sulfur
dioxide (SO *). The fluorescence emitted from the excited SO * as it returns to a stable state SO is detected
2 2 2
by a photomultiplier tube and the resulting signal is a measure of the sulfur contained in the sample.
5 Reagents and materials
5.1 Inert gas
Use argon or helium, high purity grade with a minimum purity of 99,998 % by volume.
5.2 Oxygen
Use high purity grade with a minimum purity of 99,75 % by volume.
WARNING — Oxygen vigorously accelerates combustion.
5.3 Solvent
Use either that specified in a) or b), or a solvent similar to that occurring in the sample under analysis.
Correction for sulfur contribution from solvents used in standard preparation and sample dilution is
required. Alternatively, a solvent with non-detectable sulfur contamination relative to the unknown sample
can be used, making the blank correction unnecessary.
NOTE Non-detectable is in general considered to be below 0,5 mg/kg for regular samples, though solvents
with < 0,05 mg/kg of sulfur are readily available.
a) Toluene, reagent grade.
b) Isooctane, reagent grade.
WARNING — Flammable solvents.
5.4 Sulfur compounds
Compounds with a minimum purity of 99 % by mass shall be used. Examples are given in a) to d). Where the
purity of these compounds is less than 99 % by mass, the concentrations and nature of all impurities shall be
established.
NOTE 1 A correction for chemical impurity can be applied when the sulfur content is known with accuracy.
[3]
NOTE 2 Certified reference materials (CRM) produced in accordance with ISO 17034 are suitable alternatives to
the compounds listed in a) to d).

ISO 20846:2026(en)
a) Dibenzothiophene (DBT), of molar mass 184,26 g/mol, with a nominal sulfur content of 17,399 % mass
fraction.
b) Dibutyl sulfide (DBS), of molar mass 146,29 g/mol, with a nominal sulfur content of 21,915 % mass
fraction.
c) Dibutyl disulfide (DBDS), of molar mass 178,36 g/mol, with a nominal sulfur content of 35,950 % mass
fraction.
d) Thionaphthene (benzothiophene) (TNA), of molar mass 134,20 g/mol, with a nominal sulfur content of
23,890 % mass fraction.
5.5 Sulfur stock solution
Prepare a stock solution of approximately 1 000 mg/l sulfur content by accurately weighing the appropriate
quantity of sulfur compound (5.4) in a volumetric flask (6.9). Ensure complete dissolution with solvent (5.3).
Calculate the exact sulfur concentration of the stock solution to the nearest 1 mg/l. This stock solution is
used for the preparation of calibration standards. As an alternative procedure, a sulfur stock solution of
approximately 1 000 mg/kg can be prepared by accurately weighing the appropriate quantity of sulfur
compound (5.4) in a volumetric flask (6.9) and reweighing the volumetric flask once it has been filled to the
mark with the solvent (5.3). Take precautions to ensure that evaporation of either the solvent or the sulfur
compounds, or both, are not causing weighing errors.
The appropriate mass of sulfur compound described in 5.4 a) to d) that shall be added to the 100 ml flask is:
— 0,574 8 g (DBT),
— 0,456 3 g (DBS),
— 0,278 1 g (DBDS),
— 0,418 6 g (TNA).
NOTE The shelf life of the stock solution is approximately three months when stored at low temperature, typically
in a refrigerator.
5.6 Calibration standards
Prepare the calibration standards by dilution of the stock solution (5.5) with the selected solvent (5.3).
Calculate the exact sulfur content of each calibration standard.
Calibration standards with a known
...