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Topic: Iodine Value, Varying Sample Weights  (Read 1342 times)

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Offline beanfiend98

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Iodine Value, Varying Sample Weights
« on: November 12, 2021, 09:00:33 AM »
I've recently started performing an iodine value titration for fatty acids, specifically following AOCS's Wijs Method (Tg 1a-64).  According to this method, it recommends adding varying oil sample amounts depending on expected iodine value.  For example: adding 0.1954-0.2442g when IV=130 or adding 0.3175-0.3969 when IV=80.  I've attached a picture of the table.

I've looked at other methods online and this doesn't seem to be consistent across methods: some say to add 10g or 100g no matter the sample. 

I'm wondering if anyone can explain why this might be? I haven't been able to find explanations in my method or the others.  I would have thought that in most cases, especially where you're unsure of the IV, a consistent sample weight would be the way to go.

Offline Borek

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Re: Iodine Value, Varying Sample Weights
« Reply #1 on: November 12, 2021, 02:02:07 PM »
Most likely they suggest different amounts of acids to force optimal use of titre volume (about 80-90% of the burette volume).
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