ASTM D5558-95(2011)
(Test Method)Standard Test Method for Determination of the Saponification Value of Fats and Oils
Standard Test Method for Determination of the Saponification Value of Fats and Oils
SIGNIFICANCE AND USE
This test method is intended for use in the determination of the saponification value of fats and oils used in the manufacture of fat liquors for the purpose of quality assurance.
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 standard. No other units of measurement are included in this 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.
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Designation:D5558 −95 (Reapproved 2011)
Standard Test Method for
Determination of the Saponification Value of Fats and Oils
This standard is issued under the fixed designation D5558; 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 temperature below 15.5°C (60°F) while the alkali is being
dissolved. This solution should remain clear.
1.1 This test method covers the determination of the saponi-
fication value of fats and oils.
4. Procedure
1.2 The values stated in SI units are to be regarded as
4.1 Melt the sample, if not already liquid, and filter through
standard. No other units of measurement are included in this
filter paper to remove any impurities and the last traces of
standard.
moisture. The sample must be completely dry.
1.3 This standard does not purport to address all of the
4.2 Accurately weigh a sample, of such size (usually 4 to 5
safety concerns, if any, associated with its use. It is the
g) that the back titration is 45 to 55 % of the blank, and 50 mL
responsibility of the user of this standard to establish appro-
of the alcoholic KOH is added with a pipette, allowing the
priate safety and health practices and determine the applica-
pipette to drain for a definite period of time.
bility of regulatory limitations prior to use.
4.2.1 Prepare a blank determination and conduct simultane-
ously with the sample.
2. Significance and Use
4.3 Connect air condensers to the flask and boil the solution
2.1 This test method is intended for use in the determination
gently but steadily until the sample is completely saponified.
of the saponification value of fats and oils used in the
This usually requires approximately 1 h for normal samples.
manufacture of fat liquors for the purpose of quality assurance.
Take care that the vapor ring in the condenser does not rise to
the top of the condenser or there may be some loss.
3. Apparatus and Reagents
NOTE 1—Some samples particularly difficult to saponify may require
3.1 Erlenmeyer Flasks, Corning alkali resistant, Kimble
more than 1 h. This can only be determined by trial. Clarity and
resistant, or equivalent, 250 or 300 mL.
homogeneity of the test solution are partial indicators of the complete
saponification, but they are not necessarily absolute criteria.
3.2 Air Condensers, minimum length 650 mm.
4.4 After the flask and condenser have cooled somewhat,
3.3 Water Bath or a Hot Plate, with variable heat control.
but not sufficiently to jell the contents, wash down the inside of
3.4 Hydrochloric Acid, 0.5 N, accurately standardized.
the condenser with a little distilled water. Then disconnect the
flask, add approximately 1 mL of indicator, and titrate the
3.5 Alcoholic Potassium Hydroxide, added to a 2-L flask
solution with 0.5 N HCl until the pink color has just disap-
from 1 to 1.5 L of 95 % ethyl alcohol (U.S.S.D. Formula 3A
peared.
is permitted) and a few grams (5 to 10 g) of potassium
hydroxide. After boiling under a refl
...
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