ASTM D5768-02(2022)

Standard Test Method for Determination of Iodine Value of Tall Oil Fatty Acids

SIGNIFICANCE AND USE
3.1 The iodine value of a fatty acid product is a measure of the unsaturated fatty acid content of that product and consequently a measure of the ease of oxidation or drying capacity of that fatty acid product.  
3.2 This test method measures the unsaturation as iodine value by addition of an iodine/chlorine reagent. The amount of reagent absorbed is determined by back titrating the excess reagent and comparing it to a blank determination.  
3.3 In samples containing conjugated double bonds, the iodine value obtained is empirical since the reagent does not react stoichiometrically with conjugated unsaturation. Where no conjugation is present, the iodine value obtained is a measure of the total unsaturation. By using proper specimen weights, the empirical values obtained are useful for comparative purposes.  
3.4 This test method was developed in order to replace the hazardous solvent, carbon tetrachloride, used in Test Method D1959 with the less hazardous and more available solvents, iso-octane and cyclohexane. As data on the satisfactory use of other solvents becomes available, this test method will be amended to include those solvents.  
3.5 This test method should have applicability to fatty acids and oils other than tall oil fatty acid but that possibility has not been investigated.
SCOPE
1.1 This test method covers the Wijs procedure for determination of unsaturation (iodine value) of tall oil fatty acids.  
1.2 Iodine value is a measure of the unsaturation of oils and fatty acids and is expressed in terms of the number of centigrams of iodine per gram of sample (weight percent of absorbed iodine).  
1.3 When this test method is used to determine the iodine value of fatty acids having conjugated systems, the result is not a measure of total unsaturated, but rather is an empirical value that affords a comparison of unsaturation. Total unsaturation of conjugated systems may be measured in accordance with Test Method D1541.  
1.4 The test method described here is not reliable for tall oil fatty acids containing an appreciable quantity of rosin.  
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.6 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.  
1.7 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: 30-Nov-2022
• ICS: 87.060.20 - Binders
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.34 - Pine Chemicals and Hydrocarbon Resins

Relations

• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM E177-10 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2010
• Refers: ASTM E177-08 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2008
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM E177-06b - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 15-Nov-2006
• Refers: ASTM E177-06a - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2006
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM E691-05 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2005
• Refers: ASTM E177-04e1 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2004
• Refers: ASTM E177-06 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2004
• Refers: ASTM E177-04 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2004
• Refers: ASTM E177-90a(2002) - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 10-Jan-2002

Overview

ASTM D5768-02(2022) is the internationally recognized Standard Test Method for Determination of Iodine Value of Tall Oil Fatty Acids. Published by ASTM International, this standard focuses on measuring the degree of unsaturation in tall oil fatty acids (TOFA) using the Wijs method. The iodine value obtained through this test indicates the concentration of unsaturated fatty acids, which is a critical parameter for assessing the ease of oxidation and drying capacity of the product. The method enhances laboratory safety by substituting hazardous carbon tetrachloride with less hazardous solvents such as iso-octane and cyclohexane.

Key Topics

• Purpose of Iodine Value: The iodine value measures the unsaturated fatty acid content, offering insight into oxidation stability and comparative drying properties of fatty acid products.
• Wijs Procedure: The test employs an iodine/chlorine reagent (Wijs solution), quantifying unsaturation by titration. The amount of reagent absorbed indicates the iodine value, expressed in centigrams of iodine per gram of sample.
• Empirical Values: For samples containing conjugated double bonds, the resulting iodine value is empirical rather than stoichiometric, enabling comparative analysis instead of direct measurement of total unsaturation.
• Sample and Solvent Considerations: The method is accurate for tall oil fatty acids without significant rosin content and may have applicability to other fatty acids, although this has not been fully evaluated.
• Safety and Regulatory Compliance: The standard emphasizes the importance of laboratory safety, encouraging users to determine appropriate safety measures and ensure compliance with relevant regulations when handling hazardous reagents.

Applications

The ASTM D5768-02(2022) test method is widely used in:

• Chemical and Petrochemical Industries: For the quality control and specification of tall oil fatty acids used in the manufacture of coatings, detergents, soaps, and lubricants.
• Paints and Varnishes Production: Since the drying capacity is linked to the degree of unsaturation, the iodine value is essential for selecting fatty acids with optimal drying performance.
• Comparative Analysis: Facilitates the comparison of different fatty acid batches or sources by empirical measurement of unsaturation, crucial for procurement and specification purposes.
• Research and Product Development: The data generated by this method inform the development of new formulations requiring specific unsaturation profiles.

Limitations

• The method is not reliable for samples with significant rosin content, and results for fatty acids with conjugated double bonds are for comparative use only.
• Applicability to oils and fatty acids beyond tall oil fatty acid has not been comprehensively determined.

Related Standards

Users may also consider the following related ASTM standards for complementary or alternative methods:

• ASTM D1193: Specification for Reagent Water, ensuring the purity of reagents used.
• ASTM E177: Practice for Use of the Terms Precision and Bias in ASTM Test Methods.
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method.
• Withdrawn Standards (for reference only):
  • ASTM D1541: Test Method for Total Iodine Value of Drying Oils and Their Derivatives.
  • ASTM D1959: Test Method for Iodine Value of Drying Oils and Fatty Acids.

Practical Value

By using ASTM D5768-02(2022), laboratories and manufacturers gain:

• Consistent Measurement of Unsaturation: Ensures reliable and reproducible iodine value determination across different labs.
• Improved Safety: Substitutes less hazardous solvents for carbon tetrachloride, aligning laboratory practices with current safety standards.
• Quality Control: Enables precise monitoring and control of raw material properties, contributing to the production of high-quality end products.
• Regulatory and Market Acceptance: Adherence to an international ASTM standard facilitates regulatory compliance and market acceptance in global supply chains.

Keywords: iodine value, tall oil fatty acids, ASTM D5768, unsaturation, fatty acid testing, Wijs method, cyclohexane, iso-octane, quality control, standard test method.

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: D5768 − 02 (Reapproved 2022)
Standard Test Method for
Determination of Iodine Value of Tall Oil Fatty Acids
This standard is issued under the fixed designation D5768; 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 D1541 Test Method for Total Iodine Value of Drying Oils
and Their Derivatives (Withdrawn 2006)
1.1 This test method covers the Wijs procedure for deter-
D1959 Test Method for Iodine Value of Drying Oils and
mination of unsaturation (iodine value) of tall oil fatty acids.
Fatty Acids (Withdrawn 2006)
1.2 Iodine value is a measure of the unsaturation of oils and
E177 Practice for Use of the Terms Precision and Bias in
fatty acids and is expressed in terms of the number of
ASTM Test Methods
centigrams of iodine per gram of sample (weight percent of
E691 Practice for Conducting an Interlaboratory Study to
absorbed iodine).
Determine the Precision of a Test Method
1.3 When this test method is used to determine the iodine
3. Significance and Use
value of fatty acids having conjugated systems, the result is not
a measure of total unsaturated, but rather is an empirical value
3.1 The iodine value of a fatty acid product is a measure of
that affords a comparison of unsaturation.Total unsaturation of
the unsaturated fatty acid content of that product and conse-
conjugated systems may be measured in accordance with Test
quently a measure of the ease of oxidation or drying capacity
Method D1541.
of that fatty acid product.
1.4 The test method described here is not reliable for tall oil
3.2 This test method measures the unsaturation as iodine
fatty acids containing an appreciable quantity of rosin. value by addition of an iodine/chlorine reagent. The amount of
reagent absorbed is determined by back titrating the excess
1.5 The values stated in SI units are to be regarded as the
reagent and comparing it to a blank determination.
standard. The values given in parentheses are for information
only.
3.3 In samples containing conjugated double bonds, the
iodine value obtained is empirical since the reagent does not
1.6 This standard does not purport to address all of the
react stoichiometrically with conjugated unsaturation. Where
safety concerns, if any, associated with its use. It is the
no conjugation is present, the iodine value obtained is a
responsibility of the user of this standard to establish appro-
measure of the total unsaturation. By using proper specimen
priate safety, health, and environmental practices and deter-
weights, the empirical values obtained are useful for compara-
mine the applicability of regulatory limitations prior to use.
tive purposes.
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3.4 This test method was developed in order to replace the
ization established in the Decision on Principles for the
hazardous solvent, carbon tetrachloride, used in Test Method
Development of International Standards, Guides and Recom-
D1959 with the less hazardous and more available solvents,
mendations issued by the World Trade Organization Technical
iso-octane and cyclohexane. As data on the satisfactory use of
Barriers to Trade (TBT) Committee.
other solvents becomes available, this test method will be
amended to include those solvents.
2. Referenced Documents
3.5 This test method should have applicability to fatty acids
2.1 ASTM Standards:
and oils other than tall oil fatty acid but that possibility has not
D1193 Specification for Reagent Water
been investigated.
This test method is under the jurisdiction of ASTM Committee D01 on Paint 4. Apparatus
and Related Coatings, Materials, andApplications and is the direct responsibility of
4.1 Bottles—Glass-stopperedbottlesorErlenmeyerflasksof
Subcommittee D01.34 on Pine Chemicals and Hydrocarbon Resins.
Current edition approved Dec. 1, 2022. Published December 2022. Originally 250 mL capacity.
approved in 1995. Last previous edition approved in 2018 as D5768 – 02 (2018).
4.2 Pipets—20-mL and 25-mL capacity.
DOI: 10.1520/D5768-02R22.
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 last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5768 − 02 (2022)
4.3 Analytical balance constantly, until the yellow color has almost disappeared. Add
1 mL to 2 mL of starch indicator solution and continue the
5. Reagents
titration, adding the Na S O solution slowly until the blue
2 2 3
color has just disappeared. Calculate the normality, N,ofthe
5.1 Purity of Reagents—Reagent grade chemicals shall be
Na S O as follows:
2 2 3
used in all tests unless otherwise specified. Unless otherwise
indicated, it is intended that all reagents shall conform to the
N 5 A 320.39 /C (1)
~ !
Specifications of the Committee onAnalytical Reagents of the
where:
American Chemical Society, where such specifications are
A =K Cr O used, g, and
2 2 7
available. Other grades may be used provided it is first
C =Na S O solution required for titration of the K Cr O ,
2 2 3 2 2 7
ascertained that the reagent is of sufficiently high purity to
mL.
permit its use without lessening the accuracy of the determi-
nation.
5.8 Starch Indicator Solution:
5.8.1 Use soluble starch that will pass the following test for
5.2 Purity of Water—Unless otherwise indicated, references
sensitivity: Make a paste with1gof starch and a small amount
to water shall be understood to mean reagent water conforming
of cold water. Add, while stirring, 200 mL of boiling water.
to Type I of Specification D1193.
Dilute 5 mL of this solution with 100 mL of water and add
5.3 Acetic Acid (Glacial) 17.4 M—Verify the absence of
0.05 mLof0.1 Niodinesolution.Thedeepbluecolorproduced
substances reducing permanganate as follows: Dilute 2 mL of
must be discharged by 0.05 mL of 0.1 N Na S O solution.
2 2 3
the acid with 10 mL of water and add 0.1 mL of 0.1 N
5.8.2 Make a homogeneous paste of 10 g of soluble starch
potassium permanganate (KMnO ) solution. The pink color
in cold water.Add to this 1 Lof boiling water. Stir rapidly and
should not be entirely discharged at the end of 2 h.
cool. Salicylic acid (1.25 g/L) may be added to preserve the
5.4 Iso-octane or cyclohexane.
indicator. If long storage is required, keep the solution in a
refrigerator at 4 °C to 10 °C (40 °F to 50 °F). Prepare fresh
5.5 Chlorine (99.8 % Cl)—(Warning—Extremely hazard-
indicator when the end point of the titration from blue to
ous. For specific hazard information and guidance, see suppli-
colorless fails to be sharp.
er’s Material Safety Data sheets.) Commercial grades of
chlorineavailableincylindersmaybeused,providedthegasis
5.9 Wijs Solution—(Warning—Extremely hazardous. For
dried by passing through concentrated sulfuric acid (H SO ,sp
specific hazard information and guidance, see supplier’s Safety
2 4
gr1.84)beforepassingitintotheiodinesolution.Alternatively,
Data sheets.) Dissolve 13.0 g of iodine in 1 L of acetic acid.
the chlorine may be prepared by allowing concentrated hydro-
Gentle heat may be necessary to promote solution. Cool and
chloric acid (HCl, sp gr 1.19) to drop onto potassium perman-
remove a small quantity (100 mL to 200 mL) and set aside in
ganate (KMnO ) or onto a mixture of KMnO and manganese
acoolplaceforfutureuse.Passdrychlorinegasintotheiodine
4 4
dioxide (MnO ). Dry the gas thus generated by passing it
2 solution until the original titration is not quite doubled. A
through concentrated H SO .
characteristic color change takes place in the Wijs solution
2 4
when the desired amount of chlorine has been added; this may
5.6 Potassium Iodide Solution (150 g/L)—Dissolv
...