气相色谱法计算油脂碘价

1．主题内容与适用范围SCOPE

适用于甘三酯、脂肪酸和他们的氢化产品（参阅注3）。

Applicable to triglycerides and free fatty acids and their hydrogenated products(see Notes,3).

2．参考标准REFERENCE STANDARD

AOCS Recommended Practice Cd1c-85

3．定义DEFINITION

直接从脂肪酸组分计算而的食用油测定碘价的方法（参阅注1、2）.

This method determines the iodine value for edible oils directly from fatty acid compositions(see Notes,1 and2).

4．仪器、设备APPARATUS

气相色谱:使用正规的脂肪酸组分检测方法.例如：AOCS Ce1-62、AOCS Ce1c-89等。

Gas chromatograph,to provide FAC by accepted validated methodology,e.g.,AOCS Ce1-62,AOCS Ce 1c-89,etc.

5．程序PROCEDURE

选择被相关机构认可的正规脂肪酸组分的检测方法.Proceed as directed in the accepted validated method of choice.

测定混合脂肪酸或油脂的脂肪酸组分.Determine the fatty acid composition of the oil or fatty acid mixture. 6．计算CALCULATIONS(see Notes,4)

甘三酯triglycerides,

IV=C16:1%×0.950+C18:1%×0.860+C18:2%×1.732+C18:3%×2.616+C20:1%×0.785+C22:1%×0.723

脂肪酸free fatty acid,

IV=C16:1%×0.9976+C18:1%×0.8986+C18:2%×1.810+C18:3%×2.735+C20:1%×0.8175+C22:1%×0.7497

注NOTES

1.虽然这个程序得到IV,不是一个快速法,但是我们可以通过一次分析得出两个我们需要的结果（FAC和IV）.

While this procedure provides an IV,it isn’t intended to be a rapid method,but rather gives2results from 1analysis.

2.1994年,AOCS协会讨论了这些公式中用于计算的系数,并且那时决定不需要做任何的改变.

In1994,the AOCS Uniform Methods Committee reviewed the factors used in the calculations and concluded that no changes were necessary at that time.

3.对于不皂化物含量大于0.5%的油(例如,鱼油),这个计算结果可能偏低.

For oils with an unsaponifiable content greater than0.5%(e.g.,fish oils),the calculation tends to be low.

4.低IV的原料计算结果偏低.The calculation tends to be low for materials with low iodine value.

5.对于没有甘三酯的液体原料的气相色谱检测脂肪酸组分，例如部分的甘油的酯、山梨醇的酯、山梨聚糖的酯、甘油等等，计算的碘价将是部分酯的脂肪酸计算的碘价.为了获的没有脂肪酸的多羟基化合物部分酯的实际碘价,应使用韦氏碘价方法.因为羟基化合物稀释的影响，韦氏方法测出的IV将比气相色谱计算的的低.

Calculated IV based on GC fatty acid composition of non-triglyceride lipid mate rials such as partial esters of glycerol,partial esters of sorbitol/sorbitan/isosorbide esters,partial esters of poly oxyethylene sorbitol/sorbitan/isosorbide or glycerol,etc.will provide the calculated IV of only the fatty acids used to prepare the partial esters.To obtain the actual IV of partial esters with nonfatty acid polyol diluents,the chlorinated Wijs Reagent IV method should be used.IV values of partial esters via the Wijs method are lower than those obtained by GC because of the dilution effect of the polyol material.