ASTM D5558-95

Standard Test Method for Determination of the Saponification Value of Fats and Oils

SCOPE
1.1 This test method covers the determination of the saponification value of fats and oils.
1.2 The values stated in SI units are to be regarded as the standard.
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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 14-May-1995
• Technical Committee: D31 - Leather
• Drafting Committee: D31.08 - Fats and Oils

Relations

• Replaced By: ASTM D5558-95(2001) - Standard Test Method for Determination of the Saponification Value of Fats and Oils
• Effective Date: 15-May-1995

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 5558 – 95
Standard Test Method for
Determination of the Saponification Value of Fats and Oils
This standard is issued under the fixed designation D 5558; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4.2 Accurately weigh a sample, of such size (usually 4 to 5
g) that the back titration is 45 to 55 % of the blank, and 50 mL
1.1 This test method covers the determination of the saponi-
of the alcoholic KOH is added with a pipette, allowing the
fication value of fats and oils.
pipette to drain for a definite period of time.
1.2 The values stated in SI units are to be regarded as the
4.2.1 Prepare a blank determination and conduct simulta-
standard.
neously with the sample.
1.3 This standard does not purport to address all of the
4.3 Connect air condensers to the flask and boil the solution
safety concerns, if any, associated with its use. It is the
gently but steadily until the sample is completely saponified.
responsibility of the user of this standard to establish appro-
This usually requires approximately 1 h for normal samples.
priate safety and health practices and determine the applica-
Take care that the vapor ring in the condenser does not rise to
bility of regulatory limitations prior to use.
the top of the condenser or there may be some loss.
2. Significance and Use
NOTE 1—Some samples particularly difficult to saponify may require
2.1 This test method is intended for use in the determination
more than 1 h. This can only be determined by trial. Clarity and
homogeneity of the test solution are partial indicators of the complete
of the saponification value of fats and oils used in the
saponification, but they are not necessarily absolute criteria.
manufacture of fat liquors for the purpose of quality assurance.
4.4 After the flask and condenser have cooled somewhat,
3. Apparatus and Reagents
but not sufficiently to jell the contents, wash down the inside of
3.1 Erlenmeyer Flasks, Corning alkali resistant, Kimble
the condenser with a little distilled water. Then disconnect the
resistant, or equivalent, 250 or 300 mL.
flask, add approximately 1 mL of indicator, and titrate the
3.2 Air Condensers, minimum length 650 mm.
solution with 0.5 N HCl until the pink color has just disap-
3.3 Water Bath or a Hot Plate, with variable heat control.
peared.
3.4 Hydrochloric Acid, 0.5 N, accurately standardized.
5. Calculation and Report
3.5 Alcoholic Potassium Hydroxide, added to a 2-L flask
from 1 to 1.5 L of 95 % ethyl alcohol (U.S.S.D. Formula 3A
5.1 Calculate the saponification number as follows:
is permitted) and a few grams (5 to 10 g) of potassium
28.05~A 2 B!
hydroxide. After boiling under a reflux condenser on a water saponification value 5 (1)
weight of sample
bath for 30 to 60 min, the alcohol shall be distilled and
collected. For the preparation of
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