ASTM D5554-15(R2021) pdf free download

ASTM D5554-15(R2021) pdf free download.Standard Test Method for Determination of the Iodine Value of Fats and Oils
1. Scope
1.1 This test method covers the determination of the iodine 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Significance and Use
2.1 This test method is intended for the determination ofthe iodine value of fats and oils that do not contain conjugated double bonds. The iodine value is a measure ofthe unsaturation of fats and oils and is expressed in terms of the number of centigrams of iodine absorbed per gram of sample.
3. Apparatus and Reagents
3.1 Glass-Stoppered Bottles or Wide Mouth Erlenmeyer Flasks, 500 mL. Wide mouth bottles or flasks are essential if stirring is done by mechanical means. 3.2 Glass-Stoppered Volumetric Flasks, conforming to NIST tolerances 2 and accurately calibrated to contain 1000 mL. 3.3 Pipette, 20 mL. 3.4 Two Pipettes, 25 mL. One pipette is reserved for use with the standard potassium dichromate solution and shall conform to NIST tolerances 2 and be calibrated to deliver 25 mL. 3.5 Glacial Acetic Acid, A.C.S. grade. The permanganate test shall be applied to be sure that this specification is met. 3.5.1 Two millilitres of the glacial acetic acid shall be diluted with 10 mL of distilled water and 0.1 mL of 0.1 N KMnO 4 shall be added. The pink color shall not be entirely discharged within 2 h. 3.6 Potassium Iodide, A.C.S. grade. 3.7 Chlorine, 99.8 %. Satisfactory commercial grades are available in cylinders, but this gas must be dried by passing through sulfuric acid (sp. gr. 1.84) before introducing into the iodine solution. 3.7.1 Chlorine may be prepared by allowing hydrochloric acid (sp. gr. 1.19) to drop onto potassium permanganate or on a mixture of potassium permanganate and manganese dioxide. The gas thus generated shall be led through a glass tube into sulfuric acid (sp. gr. 1.84) and then into the iodine solution. 3.8 Carbon Tetrachloride, A.C.S. grade. (Warning— Carbon Tetrachloride is a known carcinogen. It is toxic by inhalation, ingestion and skin absorption. Always handle Car- bon Tetrachloride inside a fume hood. Use only with adequate ventilation.) 3.9 Cyclohexane 3 , A.C.S. grade. 3.10 Reagent for Diluting Sample—Prepare by mixing fresh cyclohexane and glacial acetic acid, 1:1, v/v. (After mixing, verify the absence of oxidizable matter in the reagent by shaking 10 mL of the reagent with 1 mL of saturated aqueous potassium dichromate solution and 2 mL of concentrated sulfuric acid: no green coloration should appear. A green coloration indicates presence of oxidizable matter.3.17 Starch Indicator Solution, shall be prepared by making a homogeneous paste of 10 g of soluble starch in cold distilled water and adding to this 1 L of boiling distilled water with rapid stirring; cool. Salicylic acid (1.25 g/L) shall be added to preserve the indicator. If long storage is required, the solution shall be kept in a refrigerator at 4 °C to 10 °C (40 °F to 50 °F). Fresh indicator shall be prepared when the end-point of the titration from blue to colorless fails to be sharp. 3.18 Standard Potassium Dichromate Solution, 0.1 N, shall be prepared by dissolving 4.9035 g of finely ground and dried potassium dichromate in distilled water in the 1000 mL volumetric flask and making to volume at 25 °C. 3.19 Sodium Thiosulfate Solution, 0.1 N, prepared by dis- solving 24.8 g of sodium thiosulfate in distilled water and diluting to 1 L. 3.19.1 Standardization ofthe Thiosulfate—Pipette 25 mL of the standard dichromate solution into Erlenmeyer flask or bottle. Add 5 mL of hydrochloric acid, 10 mL of potassium iodide solution and rotate to mix. Allow to stand for 5 min and then add 100 mL of distilled water. Titrate with sodium thiosulfate solution, shaking continuously, until the yellow color has almost disappeared. Add 1 mL to 2 mL of indicator and continue titration, adding the thiosulfate solution slowly, until the blue color has just disappeared. The strength of the sodium thiosulfate solution is expressed in terms of its normal- ity.