ASTM D1240-24

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
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Designation: D1240 − 14 (Reapproved 2018) D1240 − 24
Standard Test Methods for
Rosin Acids Content of Pine Chemicals, Including Rosin,
Tall Oil, and Related Products
This standard is issued under the fixed designation D1240; 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 rosin acids in tall oil, tall oil fatty acid, tall oil rosin, and other pine chemicals
products.
1.2 These test methods may not be applicable to adducts or derivatives of rosin, fatty acid, or other pine chemicals products.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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.
1.5 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:
D1585D664 Test Methods for Fatty Acids Content of Pine Chemicals, Including Rosin, Tall Oil, and Related ProductsMethod
for Acid Number of Petroleum Products by Potentiometric Titration
D7795 Test Method for Acidity in Ethanol and Ethanol Blends by Titration
E70 Test Method for pH of Aqueous Solutions With the Glass Electrode
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Summary of Test Method
3.1 The rosin acids content is determined by one of two procedures; by selective esterification of fatty acids to form methyl esters
followed by titration of the unreacted rosin acids, by selective esterification of fatty acids to form butylmethyl esters followed by
titration of the unreacted rosin acids.
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 June 1, 2018Feb. 1, 2024. Published June 2018February 2024. Originally approved in 1952. Last previous edition approved in 20142018 as
D1240 – 14.D1240 – 14 (2018). DOI: 10.1520/D1240-14R18.10.1520/D1240-24.
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
D1240 − 24
4. Significance and Use
4.1 This is a revision of the method for measuring rosin acids content combines the three major ways of determining the rosin
acids content of pine chemicals products into a single method.
4.1.1 For materials containing less than 15 % rosin, the modified Glidden procedure has gained acceptance. For materials
containing more than 15 % rosin the modified Wolfe Method is preferred. The modified Wolfe and modified Glidden procedures
differ only in their details. They have been combined here into a single procedure. This procedure can be run using either a
potentiometer or an internal indicator to determine the end point of the titration. Use of a potentiometer is preferred and is the
referee method. Use of an internal indicator is the principal alternative method. They will be referred to as the Potentiometric
Method and the Internal Indicator Method.
5. Reagents
5.1 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.
5.2 Unless otherwise indicated, references to water shall be understood to mean deionized or distilled water.
6. Preparation of Sample
6.1 Homogeneous liquid materials may be used without further preparation.
6.2 Nonhomogeneous liquid materials should be heated until they are homogeneous, then a portion taken for analysis.
6.3 Solid samples are subject to surface oxidation which may affect the results. Prepare the sample for analysis by chipping small
pieces from a freshly exposed surface of a lump or lumps and crush to a coarse powder to facilitate weighing and solution. Prepare
fresh on the same day, prior to weighing, in order to avoid changes due to surface oxidation of crushed rosin on exposure to the
air.
ROSIN ACIDS CONTENT BY THE POTENTIOMETRIC METHOD
(Referee Method)
7. Scope
7.1 This test method covers the determination of rosin acids content of tall oil rosin, tall oil fatty acid, and other pine chemicals
products, where the most reproducible results are desired. By using the potentiometric inflection end points, the error due to
colorimetric end points is avoided.
8. Summary of Test Method
8.1 A sample is refluxed with methyl sulfuric acid to esterify the fatty acids. The rosin acids and sulfuric acid are then titrated
potentiometrically, and either with a use of pH meter or an automatic titrator and the rosin acids content calculated from the
difference between the two inflection points obtained.
9. Apparatus
9.1 pH Meter—An indicating potentiometer having a limit of error not greater than 60.1 pH over a range from pH 1 to pH 13,
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. PharmaceuticalPharmacopeial Convention, Inc.
(USPC), Rockville, MD.
D1240 − 24
using an alkali-resistant glass electrodecombination electrode (Note 1 and a saturated calomel half-cell. The ). The pH meter shall
conform to the requirements of Test Method E70. Alternatively, an automatic potentiometric titrator may be used.used as described
in Test Method D7795.
NOTE 1—A combination electrode will be used as the referee method and the saturated calomel half cell will be used as an alternative electrode for this
method.
9.2 Potentiometric Titrator—Automatic titration systems capable of adding fixed increments of titrant at fixed time intervals
(monotonic) or variable titrant increments with electrode stability between increment additions (dynamic) with endpoint seeking
capabilities as prescribed in the method. At the very least, the automatic titration system shall meet the performance and
specification requirements as warranted by the manufacturer, as described in Test Method D7795.
9.3 Combination Electrodes—Sensing electrodes may have the Ag/AgCl reference electrode built into the same electrode body,
which offers the convenience of working with and maintaining only one electrode. The combination electrode shall have a sleeve
junction on the reference compartment and shall use an inert ethanol electrolyte, for example, 1M–3M LiCl in ethanol. These
combination electrodes shall have the same response or better response than a dual electrode system. They shall have removable
sleeves for easy rinsing and addition of electrolyte, as described in Test Method D664.
9.3.1 Preparation of Electrodes—When a Ag/AgCl reference electrode is used for the titration and it contains an electrolyte which
is not 1M–3M LiCl in ethanol, replace the electrolyte. Drain the electrolyte from the electrode, wash away all the salt (if present)
with water and then rinse with ethanol. Rinse several times with the LiCl electrolyte solution. Finally, replace the sleeve and fill
the electrode with the LiCl electrolyte to the filling hole. When refitting the sleeve, ensure that there will be a free flow of
electrolyte into the system. A combination electrode shall be prepared in the same manner. The electrolyte in a combination
electrode can be removed with the aid of a vacuum suction.
9.3.2 Testing of Electrodes—Test the meter-electrode combination when first put into use, or when new electrodes are installed,
and retest at intervals thereafter. Rinse the electrodes with solvent then with water, and dip them into a pH 4 aqueous buffer
solution. Read the mV value after stirring 1 min. Remove the electrodes and rinse with water. Dip the electrodes into a pH 7
aqueous buffer. Read the mV value after stirring 1 min. Calculate the mV difference. A good electrode system will have a difference
of at least 162 mV (20 °C to 25 °C). If the difference is less than 162 mV, lift the sleeve of the electrode and ensure electrolyte
flow. Repeat the measurements. If the difference is still less than 162 mV, clean or replace the electrode(s).
9.3.3 When the sensing electrode and the reference electrode are separate, one pair of electrodes shall be considered as one unit.
If one or the other is changed, it shall be considered as different pair and shall be retested.
9.3.4 Maintenance and Storage of Electrodes—Cleaning the electrodes thoroughly, keeping the ground-glass joint free of foreign
materials, and regular testing of the electrodes are very important in obtaining repeatable potentials, since contamination may
introduce uncertain erratic and unnoticeable liquid contact potentials. While this is of secondary importance when end points are
chosen from inflection points in the titration curve, it may be quite serious when end points are chosen at arbitrarily fixed cell
potentials.
9.3.5 Clean the glass electrode at frequent intervals based on use and type of samples being analyzed (not less than once every
week during continual use) by immersing in nonchromium containing, strongly oxidizing cleaning solution. The reference
electrode shall be cleaned periodically when in use or when a new electrode is installed. Drain the reference electrode at least once
each week and refill with the fresh LiCl electrolyte as far as the filling hole. Ensure that there are no air bubbles in the electrode
liquid. If air bubbles are observed, hold the electrode in a vertical position and gently tap it to release the bubbles. Always maintain
the electrolyte level in the reference electrode above that of the liquid in the titration beaker or vessel.
9.4 Stirrer, magnetic, equipped with poly(tetrafluoroethylene)-coated stir bar.
9.5 Buret, 50-mL50 mL capacity, w
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