ISO/FDIS 20846

Petroleum and related products — Determination of sulfur content of automotive fuels — Ultraviolet fluorescence method

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 3,7 % (m/m) oxygen [including those blended with ethanol up to about 10 % (V/V)], — diesel fuels, including those containing up to about 30 % (V/V) 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). 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 document. 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 document, "% (m/m)" and "% (V/V)" are used to represent the mass fraction, w, and the volume fraction, φ, 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 Nitrogen interference can occur, see 6.5 for further guidance.

Produits pétroliers et connexes — Détermination de la teneur en soufre des carburants pour automobiles — Méthode par fluorescence ultraviolette

Le présent document spécifie une méthode par fluorescence ultra-violette (FUV) pour le dosage du soufre dans les produits suivants: — ceux dont la teneur en soufre est comprise dans l'intervalle de 3 à 500 mg/kg: — les essences automobiles contenant jusqu'à 3,7 % (m/m) en oxygène [les mélanges avec de l'éthanol jusqu'à environ 10 % (V/V) inclus], — les carburants diesel, dont ceux contenant jusqu'à 30 % (V/V) d'esters méthyliques d'acides gras. — ceux dont la teneur en soufre est comprise dans l'intervalle de 3 à 45 mg/kg: — les carburants synthétiques, tels que les huiles végétales hydrogénées (HVO) et les carburants liquides produits à partir de gaz («gas to liquid», GTL). D'autres produits peuvent être analysés et d'autres teneurs en soufre peuvent être déterminées suivant cette méthode, cependant, il n'a pas été établi de données de fidélité pour des produits autres que les carburants pour automobiles et pour des résultats en dehors de la gamme spécifiée pour le présent document. Les halogènes, à des concentrations supérieures à environ 3 500 mg/kg, interfèrent. NOTE 1 Certains catalyseurs utilisés dans le raffinage chimique et pétrolier peuvent être pollués lorsque des composés soufrés sont présents en trace dans les charges. NOTE 2 Cette méthode peut être utilisée pour déterminer la teneur en soufre des charges et peut aussi être utilisée pour contrôler la teneur en soufre des effluents. NOTE 3 Pour les besoins du présent document, «% (m/m)» et «% (V/V)» sont utilisés pour désigner respectivement la fraction massique, w, et la fraction volumique, φ, d'un produit. NOTE 4 Le facteur de conversion des sulfates dans l'éthanol n'est pas le même que celui des composés organiques sulfurés dans l'éthanol. Ils sont cependant proches. NOTE 5 Une interférence avec l'azote peut avoir lieu, voir 6.5 pour plus de précisions.

General Information

• Status: Not Published
• ICS: 75.160.20 - Liquid fuels
• ICS: 75.160.30 - Gaseous fuels
• Technical Committee: ISO/TC 28 - Petroleum and related products, fuels and lubricants from natural or synthetic sources
• Drafting Committee: ISO/TC 28 - Petroleum and related products, fuels and lubricants from natural or synthetic sources
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 03-Apr-2026
• Completion Date: 03-Apr-2026

Relations

• Consolidates: FprEN ISO 20846 - Petroleum and related products - Determination of sulfur content of automotive fuels - Ultraviolet fluorescence method (ISO/FDIS 20846:2026)
• Effective Date: 12-Feb-2026
• Revises: ISO 20846:2019 - Petroleum products — Determination of sulfur content of automotive fuels — Ultraviolet fluorescence method
• Effective Date: 22-Jul-2023

Overview

ISO/FDIS 20846:2026 establishes a standardized ultraviolet (UV) fluorescence test method for determining the sulfur content in a wide range of automotive fuels and related petroleum products. Developed by the International Organization for Standardization (ISO), this standard supports global efforts to monitor and control sulfur content as part of environmental and product quality initiatives. The method applies to:

• Motor gasolines (including those blended with up to 10% ethanol)
• Diesel fuels (including those with biodiesel blends up to 50% and pure FAME)
• Synthetic fuels such as hydrotreated vegetable oil (HVO) and gas-to-liquid (GTL) products

The UV fluorescence approach ensures reliable sulfur analysis in samples with sulfur content ranging from 3 mg/kg to 500 mg/kg, supporting regulatory compliance and quality assurance within the petroleum sector.

Key Topics

ISO/FDIS 20846 addresses several essential areas for laboratories and fuel producers:

• Sampling and sample handling: Guidance for obtaining, preserving, and preparing representative samples to ensure accurate measurement.
• Apparatus and calibration: Requirements for UV fluorescence detectors, combustion tubes, syringes, flow controllers, and calibration methods to achieve precise sulfur quantification.
• Reagents and standards: Preparation and use of high-purity gases, solvents such as toluene or isooctane, and traceable sulfur compounds for stock and calibration solutions.
• Test method principles: Combustion of samples in an oxygen-rich environment to convert sulfur to SO₂, followed by detection using UV fluorescence emission.
• Quality control: Recommendations for quality control samples and traceable reference materials to confirm system performance and data accuracy.
• Interferences and limitations: Acknowledgement of factors such as halogens, nitrogen, and specific solvent or sample characteristics that may impact measurement.
• Reporting and precision: Procedures for data calculation, reporting results, and understanding the repeatability and reproducibility of test outcomes.

Applications

The UV fluorescence method defined by ISO/FDIS 20846 is essential for:

• Regulatory compliance: Meeting government and environmental agency requirements for fuel sulfur content, supporting cleaner emissions and improved air quality.
• Product quality control: Verifying sulfur concentrations in finished fuels, process feeds, and fuel blends, including ethanol-containing gasolines and high-biodiesel diesel blends.
• Process monitoring: Tracking sulfur levels in refinery streams and process effluents to safeguard catalysts, optimize refining operations, and minimize contamination risk.
• Research and development: Enabling manufacturers and laboratories to analyze new fuel types, including synthetic and renewable fuels, with confidence in sulfur content data.

This standard is widely adopted in refineries, independent testing labs, fuel distribution networks, and research institutions focused on petroleum quality assurance.

Related Standards

ISO/FDIS 20846 complements and references several key international standards:

• 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
• ISO 12185: Crude petroleum, petroleum products and related products - Determination of density by oscillating U-tube

Organizations implementing ISO/FDIS 20846 may also utilize these companion standards to ensure robust sampling, preparation, and analytical procedures for sulfur content determination and fuel quality control.

By following this standard, stakeholders in the petroleum and fuel industries ensure consistent, accurate, and internationally recognized measurement of sulfur content using the advanced UV fluorescence method. This supports product quality, regulatory adherence, and the transition to cleaner fuel technologies.

Standards Content (Sample)

FINAL DRAFT
International
Standard
ISO/TC 28
Petroleum and related products —
Secretariat: NEN
Determination of sulfur content
Voting begins on:
of automotive fuels — Ultraviolet
2026-04-03
fluorescence method
Voting terminates on:
2026-05-29
Produits pétroliers et connexes — Détermination de la teneur
en soufre des carburants pour automobiles — Méthode par
fluorescence ultraviolette
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/CEN PARALLEL PROCESSING LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 28
Petroleum and related products —
Secretariat: NEN
Determination of sulfur content
Voting begins on:
of automotive fuels — Ultraviolet
fluorescence method
Voting terminates on:
Produits pétroliers et connexes — Détermination de la teneur
en soufre des carburants pour automobiles — Méthode par
fluorescence ultraviolette
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
© ISO 2026
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
IN ADDITION TO THEIR EVALUATION AS
be reproduced or utilized otherwise in any fo
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ISO /TC 28
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Date: 2026-02-1603-19
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Petroleum and related products — Determination of sulfur content
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of automotive fuels — Ultraviolet fluorescence method
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St l D fi iti
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All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
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Published in Switzerland.
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ii © ISO 2025 2026 – All rights reserved
ii
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Contents
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 . 4
5.8 Quartz wool . 4
6 Apparatus . 4
7 Sampling and sample handling . 6
8 Apparatus preparation . 6
9 Apparatus calibration and verification. 6
9.1 Multi-point calibration . 6
9.2 Single point calibration . 8
9.3 Verification . 9
10 Procedure . 9
11 Calculation . 10
11.1 Using multi-point calibration . 10
11.2 Using one-point calibration . 11
11.3 Calculation . 11
12 Expression of results . 11
13 Precision . 11
13.1 General. 11
13.2 Repeatability, r . 12
13.3 Reproducibility, R . 12
13.4 Precision estimates . 12
14 Test report . 13
Bibliography . 14

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iii
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Foreword Formatted: Adjust space between Latin and Asian text,
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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).
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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
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
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www.iso.org/iso/foreword.htmlwww.iso.org/iso/foreword.html.
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This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels and
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lubricants from natural or synthetic sources, in collaboration with the European Committee for Standardization Adjust space between Asian text and numbers
(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
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CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 20846:2019), which has been technically
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revised.
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The main changes are as follows:— :
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— the extension of the application scope to include higher blends of biodiesel (FAME) from 50 % up to neat
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FAME (B100);
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stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
— — further instructions regarding the (validity of the) multi-point calibration have been implemented.
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Any feedback or questions on this document should be directed to the user’s national standards body. A
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complete listing of these bodies can be found at www.iso.org/members.htmlwww.iso.org/members.html.
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iv © ISO 2025 2026 – All rights reserved
iv
Final DRAFT International Standard ISO/FDIS 20846:2026(en)

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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.
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This document does not purport to address all of the safety problems associated with its use. It is the
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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:
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— — motor gasolines containing up to a mass fraction of 3,7 % (3,7 % (m/m) ))) of oxygen
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
[including those blended with a volume fraction of ethanol up to about 10 % (10 % (V/V) )],))]; 3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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— — diesel fuels, including those containing up to a volume fraction of about 50 % of fatty acid
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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);
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— — having sulfur contents in the range of 3 mg/kg to 30 mg/kg:
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— — neat FAME (B100) and diesel fuels containing volume fraction of more than 50 % of FAME.
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Other products (for example process feeds and effluents) can be analysed and other sulfur contents can be
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determined according to this test method, however, no precision data for products other than automotive
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fuels and for results outside the specified range have been established for this document. Halogens interfere
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with this detection technique at concentrations above approximately 3 500 mg/kg.
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
2 Normative references
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The following documents are referred to in the text in such a way that some or all of their content constitutes
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requirements of this document. For dated references, only the edition cited applies. For undated references,
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the latest edition of the referenced document (including any amendments) applies.
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ISO 1042, Laboratory glassware — One-mark volumetric flasks
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ISO 3170, Hydrocarbon Liquids — Manual sampling
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ISO 3171, Petroleum liquids — Automatic pipeline sampling
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ISO 3675, Crude petroleum and liquid petroleum products — Laboratory determination of density —
Hydrometer method
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ISO 12185, Crude petroleum, petroleum products and related products — Determination of density —
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Laboratory density meter with an oscillating U-tube sensor
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3 Terms and definitions
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ISO and IEC maintain terminology databases for use in standardization at the following addresses:
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— — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
Kingdom)
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— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
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4 Principle
Kingdom)
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A hydrocarbon sample is either directly injected or placed in a sample boat. Then, it enters a high temperature
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combustion tube (1 000 °C to 1 100 °C), where the sulfur is oxidized to sulfur dioxide (SO ) in an oxygen-rich
Kingdom)
atmosphere. Water produced during the sample combustion is removed and the sample combustion gases are
exposed to UV light. The SO2 absorbs the energy from the UV light and is converted to excited sulfur dioxide Formatted: Adjust space between Latin and Asian text,
(SO *). The fluorescence emitted from the excited SO * as it returns to a stable state SO is detected by a Adjust space between Asian text and numbers
2 2 2
photomultiplier tube and the resulting signal is a measure of the sulfur contained in the sample.
5 Reagents and materials
5.1 5.1 Inert gas
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Use argon or helium, high purity grade with a minimum purity of 99,998 % by volume.
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+ 2.8 cm + 3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3
5.2 5.2 Oxygen
cm + 7 cm
Use high purity grade with a minimum purity of 99,75 % by volume.
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WARNING — Oxygen vigorously accelerates combustion.
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5.3 5.3 Solvent
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+ 2.8 cm + 3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3
Use either that specified in a) or b), or a solvent similar to that occurring in the sample under analysis.
cm + 7 cm
Correction for sulfur contribution from solvents used in standard preparation and sample dilution is required.
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Alternatively, a solvent with non-detectable sulfur contamination relative to the unknown sample can be used,
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NOTE Non-detectable is in general considered to be below 0,5 mg/kg for regular samples, though solvents with
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< < 0,05 mg/kg of sulfur are readily available.
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a) a) Toluene, reagent grade.
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b) b) Isooctane, reagent grade.
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WARNING — Flammable solvents.
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5.4 5.4 Sulfur compounds
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Compounds with a minimum purity of 99 % by mass shall be used. Examples are given in a) to d). Where the
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purity of these compounds is less than 99 % by mass, the concentrations and nature of all impurities shall be
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established.
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2 © ISO 2025 2026 – All rights reserved
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NOTE 1 A correction for chemical impurity can be applied when the sulfur content is known with accuracy.
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[3][3]
NOTE 2 Certified reference materials (CRM) produced in accordance with ISO 17034 are suitable alternatives to Adjust space between Asian text and numbers, Tab
the compounds listed in a) to d). stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
a) a) Dibenzothiophene (DBT), of molar mass 184,26 g/mol, with a nominal sulfur content of 17,399 % mass
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fraction.
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b) b) Dibutyl sulfide (DBS), of molar mass 146,29 g/mol, with a nominal sulfur content of 21,915 % mass
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fraction.
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c) c) Dibutyl disulfide (DBDS), of molar mass 178,36 g/mol, with a nominal sulfur content of 35,950 % mass
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fraction.
d) d) Thionaphthene (benzothiophene) (TNA), of molar mass 134,20 g/mol, with a nominal sulfur content
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of 23,890 % mass fraction.
5.5 5.5 Sulfur stock solution
Prepare a stock solution of approximately 1 000 mg/l sulfur content by accurately weighing the appropriate
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quantity of sulfur compound (5.4)(5.4) in a volumetric flask (6.9).(6.9). Ensure complete dissolution with
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solvent (5.3).(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)(5.4) in a volumetric flask (6.9)(6.9) and reweighing the volumetric flask once it has
been filled to the mark with the solvent (5.3).(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 5.4.25.4 a) to 5.4.5 to addd) that shall be added to the
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100 ml flask is :
— 0,574 8 g (DBT),
— 0,456 3 g (DBS),
— 0,2781278 1 g (DBDS) and ),
— 0,418 6 g (TNA).
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NOTE The shelf life of the stock solution is approximately three months when stored at low temperature, typically
numbers
in a refrigerator.
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5.6 5.6 Calibration standards
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Prepare the calibration standards by dilution of the stock solution (5.5)(5.5) with the selected solvent
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(5.3).(5.3).
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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
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kilogram) can be obtained with a volume/volume dilution (or mass/mass by volume (dilution by mass,
respectively) of the stock solution at 1 000 mg/l (or 1 000 mg/kg respectively). Other practices are possible, Formatted: FooterCentered, Left, Space Before: 0 pt,
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but those mentioned above avoid any density correction.
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New calibration standards should be prepared on a regular basis, depending upon the frequency of use and
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age. When stored at low temperature, typically in a refrigerator, the calibration standards with a sulfur content
Tab stops: Not at 17.2 cm
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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.
5.7 5.7 Quality control samples
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Quality control samples are stable samples representative of the materials being analysed, which have a sulfur
numbers, Tab stops: Not at 0.7 cm + 1.4 cm + 2.1 cm
content that is known by this test method over a substantial period of time. Alternatively, there are standard
+ 2.8 cm + 3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3
materials with a certified value commercially available. Prior to use, ensure that the material is within its shelf
cm + 7 cm
life.
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5.8 5.8 Quartz wool
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Follow the manufacturer's recommendations.
numbers, Tab stops: Not at 0.7 cm + 1.4 cm + 2.1 cm
+ 2.8 cm + 3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3
6 Apparatus
cm + 7 cm
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Figure 1Figure 1 illustrates the basic pieces of the ultraviolet fluorescence equipment.
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numbers
Key
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1 UV source
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2 photomultiplier stops: Not at 0.7 cm + 1.4 cm + 2.8 cm + 3.5 cm +
4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
3 output signal
4 furnace (6.1)(6.1)
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5 oxygen input
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6 inert gas input
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7 gases output
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4 © ISO 2025 2026 – All rights reserved
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8 vapour drier (6.4)(6.4)
9 quartz tube
10 microlitre syringe
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Figure 1 — Synopsis of the apparatus Formatted
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6.1 6.1 Furnace, comprising a device capable of maintaining a temperature sufficient to pyrolyze all
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of the sample and oxidize all sulfur to sulfur dioxide (SO2).
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It can be set either in a horizontal or vertical position.
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6.2 6.2 Combustion tube, of quartz, constructed to allow the direct injection of the sample into the
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heated oxidation zone of the furnace (6.1).(6.1).
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The combustion tube shall have side arms for the introduction of oxygen and carrier gas. The oxidation section
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shall be large enough to ensure complete combustion of the sample. It can be set either in a horizontal or
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6.3 6.3 Flow controllers, capable of maintaining a constant supply of oxygen and carrier gas.
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6.4 6.4 Vapour drier, capable of removing water vapour formed during combustion prior to
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measurement by the detector (6.5).(6.5).
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6.5 6.5 UV fluorescence detector, selective and quantitative, capable of measuring light emitted
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from the fluorescence of sulfur dioxide by UV light.
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WARNING — Exposure to excessive quantities of UV light is injurious to health. Operators should avoid
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exposing any part of their body, especially his/herthe eyes, not only to direct UV light, but also to
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secondary or scattered radiation that can be present.
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It is recommended to verify that the nitrogen interference has been compensated for. If in doubt check with Formatted
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the manufacturer.
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NOTE 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
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containing 10 mg/kg of sulfur.
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6.6 6.6 Microlitre syringe, capable of accurately delivering between 5 µl to 50 µl quantities.
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Follow the manufacturer’s instructions for determining the length of the needle required. For vertical
injection, syringes with a polytetrafluoroethylene (PTFE) plunger are recommended. Formatted
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6.7 6.7 Sample inlet system, either positioned vertically or horizontally.
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It shall consist of a direct injection inlet system capable of allowing the quantitative delivery of the material to
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be analysed into an inlet carrier stream which directs the sample into the oxidation zone at a controlled and
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repeatable rate. A syringe drive mechanism, which discharges the sample from the microlitre syringe
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(6.6)(6.6) at a constant rate of approximately 1 µl/s maximum, is required. .
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Boat injection systems may be used if they meet the performance requirements of Clause 13.Clause 13.
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6.8 6.8 Balance, capable of weighing to the nearest 0,1 mg.
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6.9 6.9 Volumetric flasks, Class A one-mark volumetric flasks, which shall conform to ISO 1042, of
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appropriate capacities, including 100 ml, for the preparation of sulfur stock solution (5.5)(5.5) and .
calibration standards (5.6).(5.6).
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7 Sampling and sample handling .
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7.1 7.1 Unless otherwise specified, obtain the laboratory sample by the procedures described in
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ISO 3170 for manual sampling, or ISO 3171 for automatic pipeline sampling. To preserve volatile
components found in some samples, keep samples at as low a temperature as is practicable and do not Formatted
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uncover samples any longer than necessary.
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Samples should be analy
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