ASTM D5974-20

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of the standard as published by ASTM is to be considered the official document.
Designation: D5974 − 15 D5974 − 20
Standard Test Methods for
Fatty and Rosin Acids in Tall Oil Fractionation Products by
Capillary Gas Chromatography
This standard is issued under the fixed designation D5974; 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
1.1 These test methods cover the determination of the amounts of the individual fatty acids and rosin acids in fractionated tall oil
products, using capillary gas chromatographic separation of the volatile methyl esters of these acids.
1.2 Four methods for forming the methyl esters, and two methods for determining the amounts of the individual fatty acids and
rosin acids are described.
1.2.1 The classic method for the formation of methyl esters is through the use of diazomethane, but diazomethane is a hazardous
and toxic material, and so is no longer the preferred reagent. The use of diazomethane is detailed in the Appendix. Methyl esters
may be formed through the use of tetramethylammonium hydroxide (TMAH), trimethylphenylammonium hydroxide (TMPAH),
or N,N-dimethylformamide dimethyl acetal (DMF-DMA).
1.2.2 The two methods for determining the amount of the individual fatty acids and rosin acids are the “internal standard” method,
which yields absolute values, and the “area percent” method, which yields relative values.
1.3 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
D509 Test Methods of Sampling and Grading Rosin
D804 Terminology Relating to Pine Chemicals, Including Tall Oil and Related Products
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Significance and Use
3.1 Tall oil fractionated products derived from tall oil are important commercial materials, primarily composed of fatty acids and
These test methods are under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and are the direct responsibility of
Subcommittee D01.34 on Pine Chemicals and Hydrocarbon Resins.
Current edition approved July 1, 2015Sept. 1, 2020. Published August 2015September 2020. Originally approved in 1996. Last previous edition approved in 20102015
as D5974 – 00 (2010).D5974 – 15. DOI: 10.1520/D5974-15.10.1520/D5974-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5974 − 20
rosin acids, but also containing some neutral material (see Terminology D804). For many applications, it is necessary to know the
level of the individual fatty acids and rosin acids present in these products. Gas chromatography has proven to be a useful tool
for such determinations (see Test Methods D509), and capillary chromatography, described in these test methods, is considered to
be the most effective gas chromatographic technique currently available. In particular situations, other techniques may be more
suitable than gas chromatography. For example, the presence of fatty acid esters in the sample would result in transesterification
during the derivatization step that may affect the results.
3.2 Due to hydrogen bonding, unmodified tall oil fatty acids and rosin acids cannot be volatilized at atmospheric pressure without
undergoing decomposition. So, it is necessary to convert the free acids to the more volatile and more stable methyl esters, prior
to chromatographic separation.
3.3 These test methods describe four ways to prepare methyl esters. The classic method is through the use of diazomethane, but
diazomethane is a hazardous and toxic material, and so is no longer the preferred agent. The use of diazomethane is detailed in
Appendix X1.
3.3.1 TMAH causes isomerization of a sample’s di- and polyunsaturated fatty acids, when it is used in even a slight excess. This
leads to inaccurate results for the individual fatty acid components. TMAH should be used for materials containing only rosin
acids, or when the identification or quantitation of individual fatty acid components is not important.
3.3.2 TMPAH is the recommended methylating agent when the identification or quantitation of individual di- and polyunsaturated
fatty acids is required. TMPAH produces results that are very similar to those of diazomethane, but without the hazards that are
associated with diazomethane. A considerable excess of TMPAH may cause isomerization of conjugated compounds similar to that
encountered with TMAH.
3.3.3 DMF-DMA gives results comparable to TMPAH and is easy and safe to use. However, the reagent is moisture sensitive,
requiring samples to be free of any significant levels of water.
3.4 Two test methods for calculating the amounts of the individual fatty acid and rosin acid methyl esters are included in these
test methods. When the actual weight percentage of a given compound is required, the “internal standard” method must be used.
This method involves adding a known amount of an internal standard to a known amount of test material, and comparing the area
of the peak associated with the internal standard with the area of the peak of the individual fatty acid or rosin acid methyl esters.
The “area percent” method will give the relative amount of each component, by comparing the area of the appropriate peak to the
total area of all peaks. Non-eluting compounds will lead to erroneous (absolute) results with this method.
PREPARATION OF METHYL ESTERS
NOTE 1—Any of these three methods can be used, with the choice being dependent on the factors mentioned in 3.3.
4. Conversion By Means of Tetramethylammonium Hydroxide (TMAH)
4.1 Apparatus:
4.1.1 Standard Laboratory Equipment.
4.2 Reagents and Materials:
4.2.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society , where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
4.2.2 Tetramethylammonium Hydroxide Solution, 24 % in methanol, CAS No. 75-59-2.
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC),
Rockville, MD.
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4.2.3 Tetramethylammonium Hydroxide Solution, 6 % (v/v) in methanol. Dilute 25 mL of the reagent described in 4.2.2 with 75
mL of methanol.
4.2.4 Phenolphthalein Solution, 1 % (w/v) in methanol.
4.2.5 Diethyl Ether, anhydrous.
4.2.6 Methanol, anhydrous.
4.2.7 Acetic Acid, 5 % volume/volume (v/v) in methanol.
4.2.8 Toluene, optional.
4.3 Procedure:
4.3.1 Dissolve the sample from 9.2.2 or 17.1 in 0.5 to 3.0 mL of a 50:50 ether/methanol mixture, add 2 to 3 drops of
phenolphthalein indicator solution, and titrate to a pH of 7.8 to 8.1 or to the very first permanent pink color, with the 6 % solution
of TMAH. If the solution is overtitrated, it can be back titrated with the acetic acid in methanol solution to the end point. When
the solution is injected into the heated injection port of the chromatograph, the tetramethylammonium salts are pyrolyzed to methyl
esters.
NOTE 2—For solid rosin, or other samples that are difficult to dissolve, 2 to 3 drops of toluene may be added to the vial prior to the addition of TMAH,
to assist in dissolving the sample.
5. Conversion By Means of Trimethylphenylammonium Hydroxide (TMPAH)
5.1 Apparatus:
5.1.1 Standard Laboratory Equipment.
5.2 Reagents and Materials:
5.2.1 Purity of Reagents, see 4.2.1.
5.2.2 Trimethylphenylammonium Hydroxide Solution, 0.2 M or 0.1 M in methanol, CAS No. 1899-02-1.
5.2.3 Diethyl Ether, anhydrous.
5.2.4 Methanol, anhydrous.
5.2.5 Toluene, optional.
5.3 Procedure:
5.3.1 Add 0.5 to 3.0 mL of a 50:50 ether/methanol, to the sample from 9.2.2 or 17.1. Add 2 to 3 drops of phenolphthalein indicator
solution and titrate to the very first permanent pink color with the TMPAH in methanol solution. When the solution is injected into
the heated injection port of the chromatograph, the trimethylphenylammonium salts are pyrolyzed to their respective methyl esters.
NOTE 3—For solid rosin, or other samples that are difficult to dissolve, 2 to 3 drops of toluene may be added to the vial prior to the addition of TMPAH,
to assist in dissolving the sample.
6. Conversion by Means of N,N-Dimethylformamide Dimethyl Acetal (DMF-DMA)
6.1 Apparatus:
6.1.1 Standard Laboratory Equipment.
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6.2 Reagents and Materials:
6.2.1 Purity of Reagents, see 4.2.1.
6.2.2 N,N-Dimethylformamide dimethyl acetal (DMF-DMA), CAS No. 4637-24-5.
6.2.3 Methanol, anhydrous.
6.2.4 Toluene.
6.3 Procedure:
6.3.1 Place the sample from 9.2.2 or 17.1 in an appropriate anhydrous vial, and dissolve with approximately 0.5 mL of either
methanol or toluene. Add approximately 1 mL of DMF-DMA, mix well, and maintain the sample at 30–40°C for 15 minutes.
INTERNAL STANDARD METHOD
7. Apparatus
7.1 Gas Chromatograph—An instrument equipped with a flame ionization detector (FID) that can be operated at conditions given
in 10.1.
7.2 Column—A high resolution column between 15 and 60 m in length, up to 0.53 mm internal diameter, with a 0.20-μm film
thickness of biscyanopropylsiloxane type liquid phase. The recommended referee column is 30 m in length, 0.32 mm internal
diameter, with a 0.20-μm film thickness, and provides separations equivalent or better than that displayed in Fig. 1.
NOTE 4—When using this method for referee purposes, verify that the resolution is adequate and comparable to that shown in Fig. 1.
7.3 Analytical Balance, accurate to 0.1 mg.
NOTE 1—Labeled peaks are eluted as methyl esters.
FIG. 1 Typical Chromatogram of Distilled Tall Oil
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8. Reagents and Materials
8.1 Purity of Reagents, see 4.2.1.
8.2 Myristic Acid (Internal Standard),99 % pure.
NOTE 5—A higher molecular-weight saturated fatty acid that elutes as a methyl ester later in the chromatogram may be used in place of, or in addition
to myristic acid, provided that the alternative internal standard peak does not coelute with sample component peaks.
8.3 Stearic Acid, Oleic Acid, Linoleic Aci
...