1.1 本试验方法涵盖了测定妥尔油脂肪酸不饱和度（碘值）的Wijs程序。 1.2 碘值是油和脂肪酸不饱和度的量度，用每克样品中碘的百分含量（吸收碘的重量百分比）表示。 1.3 当该试验方法用于测定具有共轭体系的脂肪酸的碘值时，结果不是总不饱和的测量值，而是提供不饱和比较的经验值。可根据试验方法测量共轭体系的总不饱和度 第1541页 . 1.4 本文描述的测试方法对于含有大量松香的妥尔油脂肪酸不可靠。 1.5 以国际单位制表示的数值应视为标准。括号中给出的值仅供参考。 1.6 本标准并不旨在解决与其使用相关的所有安全问题（如有）。 本标准的使用者有责任在使用前建立适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《国际标准、指南和建议制定原则决定》中确立的国际公认标准化原则制定的。 =====意义和用途====== 3.1 脂肪酸产品的碘值是该产品的不饱和脂肪酸含量的量度，因此是该脂肪酸产品易氧化性或干燥能力的量度。 3.2 本试验方法通过添加碘/氯试剂测量碘值的不饱和度。通过反向滴定过量的试剂并将其与空白测定进行比较来确定吸收的试剂量。 3.3 在含有共轭双键的样品中，获得的碘值是经验值，因为试剂不会与共轭不饱和度发生化学计量反应。如果不存在共轭，则获得的碘值是总不饱和度的量度。通过使用适当的试样重量，获得的经验值可用于比较目的。 3.4 本试验方法旨在替代试验方法中使用的危险溶剂四氯化碳 1959年 使用危险性较低且可用的溶剂异辛烷和环己烷。随着其他溶剂令人满意使用的数据可用，本试验方法将进行修改，以包括这些溶剂。 3.5 该试验方法应适用于脂肪酸和除妥尔油脂肪酸以外的油，但尚未研究其可能性。

1.1 This test method covers the Wijs procedure for determination of unsaturation (iodine value) of tall oil fatty acids. 1.2 Iodine value is a measure of the unsaturation of oils and fatty acids and is expressed in terms of the number of centigrams of iodine per gram of sample (weight percent of absorbed iodine). 1.3 When this test method is used to determine the iodine value of fatty acids having conjugated systems, the result is not a measure of total unsaturated, but rather is an empirical value that affords a comparison of unsaturation. Total unsaturation of conjugated systems may be measured in accordance with Test Method D1541 . 1.4 The test method described here is not reliable for tall oil fatty acids containing an appreciable quantity of rosin. 1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.6 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. 1.7 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. ====== Significance And Use ====== 3.1 The iodine value of a fatty acid product is a measure of the unsaturated fatty acid content of that product and consequently a measure of the ease of oxidation or drying capacity of that fatty acid product. 3.2 This test method measures the unsaturation as iodine value by addition of an iodine/chlorine reagent. The amount of reagent absorbed is determined by back titrating the excess reagent and comparing it to a blank determination. 3.3 In samples containing conjugated double bonds, the iodine value obtained is empirical since the reagent does not react stoichiometrically with conjugated unsaturation. Where no conjugation is present, the iodine value obtained is a measure of the total unsaturation. By using proper specimen weights, the empirical values obtained are useful for comparative purposes. 3.4 This test method was developed in order to replace the hazardous solvent, carbon tetrachloride, used in Test Method D1959 with the less hazardous and more available solvents, iso-octane and cyclohexane. As data on the satisfactory use of other solvents becomes available, this test method will be amended to include those solvents. 3.5 This test method should have applicability to fatty acids and oils other than tall oil fatty acid but that possibility has not been investigated.