ISO/TR 5756

• Abstract:

  This Technical Report presents information on volumetric practices used to estimate ethanol and hydrocarbon content in blends of fuel ethanol and gasoline. The practices are based on phase separation induced by a sodium chloride (NaCl) solution, allowing approximate observation of hydrocarbon fraction and aqueous fraction. The approaches described are intended for informational purposes only.

• Status: Not Published
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: ISO/TC 28/SC 7 - Liquid Biofuels
• Drafting Committee: ISO/TC 28/SC 7/WG 4 - Ethanol test methods
• Current Stage: 6000 - International Standard under publication
• Start Date: 30-Jul-2026
• Completion Date: 26-Sep-2026

Overview

ISO/TR 5756: Petroleum and related products, fuels and lubricants from natural or synthetic sources - Overview of volumetric practices for estimating hydrocarbon and ethanol content in fuel ethanol and gasoline blends is a Technical Report developed by ISO. This document provides an overview of commonly observed volumetric practices used for the rapid estimation of hydrocarbon (gasoline) and ethanol content in blends of fuel ethanol and gasoline. The report is based on the principle of inducing phase separation in the blend with a sodium chloride (NaCl) solution, allowing users to visually approximate the volume of hydrocarbon (organic) and aqueous (ethanol-rich) fractions.

This overview offers practical insights for laboratory technicians, fuel station operators, and quality assurance personnel looking for basic, rapid screening methods. The approaches described are intended for information only and are not designed to serve as definitive or highly precise analytical methods.

Key Topics

• Volumetric Estimation Practices: Guidance on simple volume-based methods to estimate the ethanol and hydrocarbon content in blended fuels.
• Phase Separation Using NaCl Solution: Description of the use of sodium chloride solution to induce clear separation between aqueous and organic phases in the sample.
• Apparatus and Procedure: Use of a graduated measuring cylinder (typically 100 mL capacity) with stepwise addition of fuel blend and NaCl solution.
• Observational Method: Instructions for visual identification and measurement of the two phases after gentle inversion and settling.
• Interpretation of Results: Guidelines for relating measured phase volumes to approximate content of hydrocarbon and ethanol.
• Limitations: Explanation of the interpretive, approximate nature of these practices and potential interference from other fuel components.

Applications

ISO/TR 5756 has practical applications, including:

• Laboratory Screening: Laboratories can use the described method as a quick check for general estimation of ethanol and hydrocarbon balance in gasoline-ethanol blends.
• Fuel Quality Checks at Gas Stations: Service stations or distributors may employ this simple practice for routine on-site assessments where swift observations are needed.
• Educational and Training Purposes: The procedure provides a straightforward demonstration for training personnel in basic fuel blend analysis techniques.
• Informational Reference: Acts as a supplementary resource for organizations seeking to understand the limitations and utility of basic volumetric estimation, complementing more precise analytical approaches.
• Supporting Compliance Awareness: While not suitable for regulatory auditing, these practices enhance awareness of blend composition within the framework of fuel quality and conformity.

Note: The NaCl-induced phase separation technique outlined in this ISO Technical Report offers rapid, approximate results and is not a substitute for laboratory-grade analytical testing when high accuracy is required or for official certification purposes.

Related Standards

For those involved in fuel analysis and quality assurance, the following international standards and technical reports may provide relevant and complementary guidance:

• ISO 4257: Petroleum products - Determination of water content - Dean and Stark method
• ISO 3675: Crude petroleum and liquid petroleum products - Laboratory determination of density - Hydrometer method
• ISO 22854: Liquid petroleum products - Determination of hydrocarbon types and oxygenates in automotive-motor gasoline and in ethanol (E85) automotive fuel - Multidimensional gas chromatography method
• ASTM D4815: Standard Test Method for Determination of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C1 to C4 Alcohols in Gasoline by Gas Chromatography

For further information and access to the official documents, visit ISO.org or consult national standards organizations.

Keywords: ISO/TR 5756, fuel ethanol, gasoline blends, volumetric practices, hydrocarbon content estimation, ethanol content, sodium chloride solution, phase separation, fuel analysis, petroleum standards, ISO standards.

Disclaimer: The methods described in ISO/TR 5756 are for informational purposes only. For official compliance and certification, refer to validated test methods provided in applicable international or national standards.

FINAL DRAFT
Technical
Report
ISO/DTR 5756
ISO/TC 28/SC 7
Petroleum and related products,
Secretariat: ABNT
fuels and lubricants from natural
Voting begins on:
or synthetic sources — Overview of
2026-06-03
volumetric practices for estimating
Voting terminates on:
hydrocarbon and ethanol content in
2026-07-29
fuel ethanol and gasoline blends
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
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
ISO/DTR 5756:2026(en) © ISO 2026

FINAL DRAFT
ISO/DTR 5756:2026(en)
Technical
Report
ISO/DTR 5756
ISO/TC 28/SC 7
Petroleum and related products,
Secretariat: ABNT
fuels and lubricants from natural
Voting begins on:
or synthetic sources — Overview of
volumetric practices for estimating
Voting terminates on:
hydrocarbon and ethanol content in
fuel ethanol and gasoline blends
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.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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 Reference number
ISO/DTR 5756:2026(en) © ISO 2026

ii
ISO/DTR 5756:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle observed in practice . 1
5 Description of reported practice . 2
6 Interpretation of results as reported in practice . 3
7 Observations and limitations . . 4

iii
ISO/DTR 5756:2026(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, Pe
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ISO/CD TRDTR 5756:2026(en)
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: + 41 22 749 01 11
E-mail: [e-mail]
Formatted: German (Germany)
Website: www.iso.org
Formatted: German (Germany)
Published in Switzerland
Formatted: German (Germany)
ii
ISO/CD TRDTR 5756:2026(en)
Contents
Foreword . iii
Introduction . iii
Scope . iii
Normative references . iii
Terms and definitions . iii
Principle observed in practice . iii
Description of reported practice . iii
Interpretation of results as reported in practice . iii
Observations and limitations . iii
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle observed in practice . 1
5 Description of reported practice . 2
6 Interpretation of results as reported in practice . 3
7 Observations and limitations . 4

iii
ISO/CD TRDTR 5756:2026(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 1Part 1. In particular, the different approval criteria needed for the different
types of ISO documentsdocument should be noted. This document was drafted in accordance with the editorial
rules of the ISO/IEC DirectivesIEC Directives, Part 2Part 2 (see www.iso.org/directives).
Attention is drawnISO draws attention to the possibility that some of the elementsimplementation of this
document may beinvolve the subjectuse 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. Details of any patent rights identified during the development of the
document will be in the Introduction and/or on the ISO list of patent declarations received (see
www.iso.org/patents).
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 produc
...