EN ISO 20846:2011

SLOVENSKI STANDARD
01-december-2011
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SIST EN ISO 20846:2004
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Petroleum products - Determination of sulfur content of automotive fuels - Ultraviolet
fluorescence method (ISO 20846:2011)
Mineralölerzeugnisse - Bestimmung des Schwefelgehaltes von Kraftstoffen für
Kraftfahrzeuge - Ultraviolettfluoreszenz- Verfahren (ISO 20846:2011)
Produits pétroliers - Détermination de la teneur en soufre des carburants pour
automobiles - Méthode par fluorescence ultraviolette (ISO 20846:2011)
Ta slovenski standard je istoveten z: EN ISO 20846:2011
ICS:
75.160.20 7HNRþDJRULYD Liquid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 20846
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2011
ICS 75.160.30; 75.160.20 Supersedes EN ISO 20846:2004
English Version
Petroleum products - Determination of sulfur content of
automotive fuels - Ultraviolet fluorescence method (ISO
20846:2011)
Produits pétroliers - Détermination de la teneur en soufre Mineralölerzeugnisse - Bestimmung des Schwefelgehaltes
des carburants pour automobiles - Méthode par von Kraftstoffen für Kraftfahrzeuge - Ultraviolettfluoreszenz-
fluorescence ultraviolette (ISO 20846:2011) Verfahren (ISO 20846:2011)
This European Standard was approved by CEN on 30 September 2011.

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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20846:2011: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 20846:2011) has been prepared by Technical Committee ISO/TC 28 "Petroleum
products and lubricants" in collaboration 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 April 2012, and conflicting national standards shall be withdrawn at the
latest by April 2012.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 20846:2004.
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, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 20846:2011 has been approved by CEN as a EN ISO 20846:2011 without any modification.

INTERNATIONAL ISO
STANDARD 20846
Second edition
2011-10-01
Petroleum products — Determination
of sulfur content of automotive fuels —
Ultraviolet fluorescence method
Produits pétroliers — Détermination de la teneur en soufre des
carburants pour automobiles — Méthode par fluorescence ultraviolette
Reference number
ISO 20846:2011(E)
©
ISO 2011
ISO 20846:2011(E)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2011 – All rights reserved

ISO 20846:2011(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Principle . 1
4 Reagents and materials . 2
5 Apparatus . 3
6 Sampling . 5
7 Apparatus preparation . 5
8 Apparatus calibration and verification . 5
8.1 Multi-point calibration . 5
8.2 One-point calibration . 7
8.3 Verification . 8
9 Procedure . 8
10 Calculation . 9
10.1 Using multi-point calibration . 9
10.2 Using one-point calibration . 9
10.3 Calculation .10
11 Expression of results .10
12 Precision .10
12.1 General .10
12.2 Repeatability, r .10
12.3 Reproducibility, R . 11
13 Test report . 11
Bibliography .12
ISO 20846:2011(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 20846 was prepared by Technical Committee ISO/TC 28, Petroleum products and lubricants.
This second edition cancels and replaces the first edition (ISO 20846:2004), which has been technically revised.
iv © ISO 2011 – All rights reserved

INTERNATIONAL STANDARD ISO 20846:2011(E)
Petroleum products — Determination of sulfur content of
automotive fuels — Ultraviolet fluorescence method
WARNING — The use of this International Standard may involve hazardous materials, operations and
equipment. This International Standard does not purport to address all of the safety problems associated
with its use. It is the responsibility of the user of this International Standard to establish appropriate
safety and health practices and determine the applicability of regulatory limitations prior to use.
1 Scope
This International Standard specifies an ultraviolet (UV) fluorescence test method for the determination of the
sulfur content of motor gasolines containing up to 3,7 % (m/m) oxygen [including those blended with ethanol up
to about 10 % (V/V)], and of diesel fuels, including those containing up to about 10 % (V/V) fatty acid methylester
(FAME), having sulfur contents in the range 3 mg/kg to 500 mg/kg. Other products 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 International
Standard. Halogens interfere with this detection technique at concentrations above approximately 3 500 mg/kg.
NOTE 1 Some process catalysts used in petroleum and chemical refining can be poisoned when trace amounts of
sulfur-bearing materials are contained in the feedstocks.
NOTE 2 This test method can be used to determine sulfur in process feeds and can also be used to control sulfur in effluents.
NOTE 3 For the purposes of this International Standard, the terms “% (m/m)” and “% (V/V)” are used to represent the
mass fraction and the volume fraction of a material respectively.
NOTE 4 Sulfate species in ethanol do not have the same conversion factor of organic sulfur in ethanol. Nevertheless,
sulfates have a conversion factor close to that of organic sulfur.
NOTE 5 It is preferable to check the nitrogen interference and to take it into account, especially when sulfur content is
measured on diesel blended with cetane improver containing nitrogen. For example, alkyl nitrate, as 2-ethyl hexyl nitrate
(EHN), added as cetane improver to diesel fuel shows an enhancing effect on sulfur content that can range from 0 to
1,7 mg/kg when 2 000 mg/kg EHN is added to diesel fuel containing 10 mg/kg sulfur.
2 Normative references
The following referenced documents are indispensable for the application 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, Petroleum 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 and petroleum products — Determination of density — Oscillating U-tube method
3 Principle
A hydrocarbon sample is injected into a UV fluorescence detector. The sample 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

ISO 20846:2011(E)
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 by a
2 2 2
photomultiplier tube and the resulting signal is a measure of the sulfur contained in the sample.
4 Reagents and materials
4.1 Inert gas, argon or helium, high purity grade with a minimum purity of 99,998 % (V/V).
4.2 Oxygen, high purity grade with a minimum purity of 99,75 % (V/V).
CAUTION — Vigorously accelerates combustion.
4.3 Solvent
4.3.1 General
Use either that specified in 4.3.2 or 4.3.3, 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, use of a solvent with non-detectable sulfur contamination relative to the unknown sample makes
the blank correction unnecessary.
4.3.2 Toluene, reagent grade.
4.3.3 Isooctane, reagent grade.
CAUTION — Flammable solvents.
4.4 Sulfur compounds
4.4.1 General
Compounds with a minimum purity of 99 % (m/m). Examples are given in 4.4.2 to 4.4.4. Where the purity of
these compounds is less than 99 % (m/m), the concentrations and nature of all impurities shall be established.
NOTE A correction for chemical impurity can be applied when the sulfur content is known with accuracy.
Certified reference materials (CRM) from accredited suppliers are suitable alternatives to the compounds listed
in 4.4.2 to 4.4.4.
4.4.2 Dibenzothiophene (DBT), of molecular mass 184,26, with a nominal sulfur content of 17,399 % (m/m).
4.4.3 Dibutyl sulfide (DBS), of molecular mass 146,29, with a nominal sulfur content of 21,915 % (m/m).
4.4.4 Thionaphthene (Benzothiophene) (TNA), of molecular mass 134,20, with a nominal sulfur content of
23,890 % (m/m).
4.5 Sulfur stock solution
Prepare a stock solution of approximately 1 000 mg/l sulfur content by accurately weighing the appropriate
quantity of sulfur compound (4.4) in a volumetric flask (5.9). Ensure complete dissolution with solvent (4.3).
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 (4.4) in a
volumetric flask (5.9) and reweighing the volumetric flask once it has been filled to the mark with the solvent
(4.3). Take precautions to ensure that evaporation of the solvent and/or sulfur compounds is not causing
weighing errors.
2 © ISO 2011 – All rights reserved

ISO 20846:2011(E)
The appropriate mass of sulfur compound described in 4.4.2 to 4.4.4 to add to the 100 ml flask is 0,574 8 g
(DBT), 0,456 3 g (DBS) and 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.
4.6 Calibration standards
Prepare the calibration standards by dilution of the stock solution (4.5) with the selected solvent (4.3).
Calculate the exact sulfur content of each calibration standard.
Calibration standards with a known sulfur concentration, in milligrams per litre, (or content, in milligrams per
kilogram) can be obtained with a volume/volume dilution (or mass/mass dilution, respectively) of the stock
solution at 1 000 mg/l (or 1 000 mg/kg respectively). Other practices are possible, but those mentioned above
avoid any density correction.
New calibration standards should be prepared on a regular basis, depending upon the frequency of use and
age. When stored at low temperature, typically in a refrigerator, the calibration standards with a sulfur content
above 30 mg/kg (or mg/l) have a shelf life of at least one month. Below this sulfur content (30 mg/kg), the shelf
life should be reduced.
4.7 Quality control samples
Quality control samples are stable samples representative of the materials be
...