Science Buddies: "Ask an Expert"

Hi!

I am doing a project about iodine deficiency in the area of Ireland that I live in. I want to test different foods for levels of iodine, but I'm not sure how to do this. It would be an invaluable area of my project. Do you know of a way that I could test food for levels of iodine myself to make it easier for people to track their daily iodine intake?

Please reply ASAP

Many thanks

Hello!
I like your project idea - sounds cool! Often scientists who perform nutrition and exposure studies face the same challenge that you face - how to quantify nutrient content in foods and resulting exposure. This is also an issue for contaminants in food.

One option you may or may not have considered is to obtain previous data on nutrient content in foods. These can be obtained by keyword searches on the web and on google scholar (www.scholar.google.com). E.g., check out Tables 3.3 and 3.4 (and elsewhere) of the following report which I found from a web search on :
http://nora.nerc.ac.uk/8354/1/CR03084N.pdf

For confirming whether table salt contains iodine, the following experiment is available on Science Buddies:
https://www.sciencebuddies.org/science- ... ml#summary
I don't know about other foods, though...

Cheers
Ben

Hi Ben,

Thanks for that information, I definitely use it in my project thanks for all your help

Have you ever heard of the iodine test for starch? A common school lab experiment involves exposing iodine solution to a food sample. If the sample contains starch, the sample will turn black-blue. In contrast, protein will remain brown, which is the same color as the iodine solution. Maybe if you expose your samples to starch, they will turn black-blue if they contain iodine. You can find a similar procedure from the study A field study for detecting iodide enriched salt by J.P. Dustin and J.P. Ecoffey.

Okay, thanks I'll have a look for that and try it out. Thank you

Hi,

Using the starch-iodine test to detect iodine is a great idea, but I am wondering whether it is sensitive enough.

I was curious which foods have the most iodine and how much, and what I found was that dairy products and shellfish are fairly high, and of course seaweed and iodized salt: http://www.livestrong.com/article/29195 ... und-dairy/

An 8 oz glass of milk [236 mL] has 56 micrograms (ug) of iodine which would mean a concentration of 0.24 ug/mL. I looked up the sensitivity of the starch-iodine test and it is quite sensitive, at least for the tri-iodide form of iodine--http://en.wikipedia.org/wiki/Starch_indicator

The Wiki said the sensitivity was 0.00002 M or 20 uM iodine. I did a calculation to determine the lowest concentration of iodine detectable and got 2.5 ug/ml. Assuming my math is correct [not always a good assumption!] that might mean that the starch-iodine test wouldn't be sensitive enough for some foods. You could try the starch-iodine reagent with different solutions of iodized salt where you know the concentration of iodine to get an idea how low a concentration you can detect, then try it with some milk.

I hope this helps. I don't know any other method for iodine detection that you would be able to do in a high school lab.

Good luck

I'll run it by my teacher and see if he thinks we could try it out thanks