ASTM D5554-95(2001)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D5554–95 (Reapproved 2001)
Standard Test Method for
Determination of the Iodine Value of Fats and Oils
This standard is issued under the fixed designation D 5554; 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 KMnO shall be added. The pink color shall not be entirely
discharged within 2 h.
1.1 This test method covers the determination of the iodine
3.6 Potassium Iodide, A.C.S. grade.
value of fats and oils.
3.7 Chlorine, 99.8 %. Satisfactory commercial grades are
1.2 The values stated in SI units are to be regarded as the
available in cylinders, but this gas must be dried by passing
standard. The values given in parentheses are for information
through sulfuric acid (sp. gr. 1.84) before introducing into the
only.
iodine solution.
1.3 This standard does not purport to address all of the
3.7.1 Chlorine may be prepared by allowing hydrochloric
safety concerns, if any, associated with its use. It is the
acid (sp. gr. 1.19) to drop onto potassium permanganate or on
responsibility of the user of this standard to establish appro-
a mixture of potassium permanganate and manganese dioxide.
priate safety and health practices and determine the applica-
The gas thus generated shall be led through a glass tube into
bility of regulatory limitations prior to use.
sulfuric acid (sp. gr. 1.84) and then into the iodine solution.
2. Significance and Use
3.8 Carbon Tetrachloride, A.C.S. grade.
3.9 Hydrochloric Acid, A.C.S. grade, sp. gr. 1.19.
2.1 This test method is intended for the determination of the
3.10 Soluble Starch, of suitable sensitivity.
iodine value of fats and oils that do not contain conjugated
3.10.1 The test for starch sensitivity shall be made by
doublebonds.Theiodinevalueisameasureoftheunsaturation
adding, while stirring, 200 mLof boiling water to a paste made
of fats and oils and is expressed in terms of the number of
with1gof starch in a small amount of water. After placing 5
centigrams of iodine absorbed per gram of sample.
mL of this solution in 100 mL of water, add 0.05 mL of 0.1 N
3. Apparatus and Reagents
iodine solution. The deep blue color produced must be dis-
charged by 0.05 mL of 0.1 N sodium thiosulfate.
3.1 Glass-Stoppered Bottles or Wide Mouth Erlenmeyer
3.11 Potassium Dichromate, A.C.S. grade, shall be finely
Flasks, 500 mL. Wide mouth bottles or flasks are essential if
ground and dried to constant weight at about 110°C before
stirring is done by mechanical means.
using. (A standard sample of potassium dichromate with a
3.2 Glass-Stoppered Volumetric Flasks, conforming to
certificate of analysis may be obtained from NIST. This
NIST tolerances and accurately calibrated to contain 1000
sample is strongly recommended as the primary standard for
mL.
this test method. The dichromate should be treated as directed
3.3 Pipette,20mL.
in the certificate of analysis accompanying the sample.)
3.4 Two Pipettes, 25 mL. One pipette is reserved for use
3.12 Sodium Thiosulfate—(Na S O ·5H O), A.C.S. grade.
with the standard potassium dichromate solution and shall
2 2 3 2
3.13 Iodine, A.C.S. grade.
conform to NIST tolerances and be calibrated to deliver 25
3.14 Potassium Iodide Solution, prepared by dissolving 150
mL.
g in distilled water and making up to 1 L.
3.5 Glacial Acetic Acid, A.C.S. grade. The permanganate
3.15 Starch Indicator Solution, shall be prepared by making
test shall be applied to be sure that this specification is met.
a homogeneous paste of 10 g of soluble starch in cold distilled
3.5.1 Two millilitres of the glacial acetic acid shall be
water and adding to this 1 L of boiling distilled water with
diluted with 10 mL of distilled water and 0.1 mL of 0.1 N
rapid stirring; cool. Salicylic acid (1.25 g/L) shall be added to
preserve the indicator. If long storage is required, the solution
This test method is under the jurisdiction ofASTM Committee D31 on Leather
shall be kept in a refrigerator at 4 to 10°C (40 to 50°F). Fresh
and is the direct responsibility of Subcommittee D31.08 on Fats and Oils. This test
indicator shall be prepared when the end-point of the titration
method was developed in cooperation with the American Leather Chemists Assn.
from blue to colorless fails to be sharp.
(Method H 32-1957).
Current edition approved May 15, 1995. Published July 1995. Originally
3.16 Standard Potassium Dichromate Solution, 0.1 N, shall
published as D 5554 – 94. Last previous edition D 5554 – 94.
be prepared by dissolving 4.9035 g of finely ground and dried
Available from National Institute of Standards and Technology, (NIST),
potassium dichromate in distilled water in the 1000 mL
Gaithersburg, MD 20899.
volumetric flask and making to volume at 25°C.
WijsSolution(IodineMonochlorideSolution)maybepurchasedcommercially.
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D5554
TABLE 1 Guide for Selecting Sample Size
3.17 Sodium Thiosulfate Solution, 0.1 N, prepared by dis-
solving 24.8 g of sodium thiosulfate in distilled water and Sample Weight, g
Weighing
Iodine Value
diluting to 1 L. Accuracy, g
100 % Excess 150 % Excess
3.17.1 StandardizationoftheThiosulfate—Pipette 25 mL
...