WHEAT FLOUR FORTIFICATION WITH IRON - Idpas.org
WHEAT FLOUR FORTIFICATION WITH IRON - Idpas.org
WHEAT FLOUR FORTIFICATION WITH IRON - Idpas.org
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Appendix 3.7<br />
Spectrophotometric analysis for quantitative<br />
determination of iron in foods<br />
INCAP method VI<br />
INCAP, Chemistry and Biochemistry Laboratory<br />
Revision No. 3; April, 1997<br />
To analyze in<strong>org</strong>anic iron in foods, the <strong>org</strong>anic material is first combusted by ashing. The resultant<br />
ash is then solubilized and iron reduced to the ferrous form by adding hydroxylamine. The ferrous<br />
iron is determined spectrophotometrically after forming a colored complex with any of the<br />
following chromogens: α,α-dipyridyl (2,2'-bipyridine), bathophenanthroline (4,7-diphenyl-1,10-<br />
phenanthroline-disulfonic acid), or ferrozine (3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-<br />
triazine. The absorption maxima of the colored solution is 521 nm for dipyridyl, 535 nm for<br />
bathophenanthroline, and 562 nm for ferrozine. The reaction leading to the formation of the color is<br />
sensitive to pH, thus the pH of the solution is maintained through the addition of 2M sodium acetate<br />
buffer.<br />
I. Materials<br />
Volumetric flask, 1 L<br />
Volumetric flasks, 250 mL<br />
Volumetric flasks, 100 mL<br />
Volumetric flasks, 25 mL<br />
Beakers, 250 mL<br />
Manual volumetric pipettes (200-1000 mL)<br />
Porcelain crucibles<br />
Watch glasses<br />
Pipette tips<br />
Graduated tubes<br />
Tips for ‘blue’ pipettes<br />
Test tubes, 10 mL<br />
II. Equipment<br />
Vortex mixer<br />
Analytical balance<br />
Spectrophotometer (521, 535, or 562 nm)<br />
Hot plate<br />
Muffle furnace<br />
Eppendorf pipette (100 and 500 mL)<br />
III. Reagents<br />
Sodium acetate (CH 3<br />
COONa.3H 2<br />
O), 99%, Fe
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