manual of methods for determining micronutrients in fortified foods
manual of methods for determining micronutrients in fortified foods
manual of methods for determining micronutrients in fortified foods
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VI. Procedure<br />
1. Place the filter paper over the watch glass<br />
2. Wet the surface <strong>of</strong> the filter paper with the solution <strong>of</strong> potassium thiocyanate. Let the liquid penetrate<br />
the paper fibers.<br />
3. Us<strong>in</strong>g a hand sieve, sift portion <strong>of</strong> the flour sample <strong>in</strong> order to load a th<strong>in</strong> layer over the entire wet area.<br />
Shake <strong>of</strong>f or scrape <strong>of</strong>f any excess flour.<br />
4. Add a little more <strong>of</strong> the acidic solution <strong>of</strong> potassium thiocyanate over the flour layer.<br />
5. Add small amounts <strong>of</strong> the H 2<br />
O 2<br />
-solution. Let it stand <strong>for</strong> a few m<strong>in</strong>utes <strong>for</strong> the reaction to occur (oxidation<br />
<strong>of</strong> any <strong>for</strong>m <strong>of</strong> iron to iron(III)). Red spots <strong>in</strong>dicate the presence <strong>of</strong> added iron from any source.<br />
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