Extraction of Iron from Oat Meal
Iron is an important nutrient for plants
and animals. Iron is a major component of the pigment called “heme”
which acts as oxygen carriers in the human body. Deficiency in iron
leads to anemia. The greatest need for iron
is during growth or periods of blood loss. Young children, adolescents
and pregnant women have increased needs for iron because of the growth
processes during these periods. In order to make up for the
regular iron loss, iron has to be supplemented in the regular diet
through food. The measurement of iron in food stuff is for great
Since iron in most food
products is at trace levels, its analysis is relatively complicated.
Typically the metal is first extracted using a solvent (acid or
chelating agent) and then analyzed. The objective of this experiment is
to extract iron from food using conventional method such as hot plate
and then compare it to microwave. The experiment involves acid
extraction and the estimation of extraction efficiency.
1% Potassium Thiocyanate (KSCN) was prepared by
dissolving 1.0 g of potassium thiocyanate in 100 ml of 10% nitric acid solution.
10mg/ml Iron (III) Chloride stock solution was prepared by dissolving10g of Iron
(III) Chloride Hexahydrate in 1litre of 10% nitric acid solution. Five dilute
standards of 0.2, 0.4, 0.6, 0.8, and 1.0 mg/mL were then prepared from the stock
A measured volume 50mlof 10% nitric acid
solution was added to 10g of oatmeal (from Grocery store) and heated on a hot
plate until the oatmeal dissolved. The time taken for the extraction reaction to
go to completion was recorded. The solution was then filtered and 0.1ml of 1%
KSCN was added to the filtrate forming a blood red colored complex represented
by equation 5. The absorbance of the colored complex was measured at 450 nm on a
UV spectrometer. The process was repeated in a microwave oven to compare the
extraction efficiency. The change in color is show in the figure 11.
Fe3+ (aq.) + 3SCN-(aq.)
Fe (SCN) 3 (aq.)
Formation of ferric thiocyanate complex.
A calibration curves was generated by successive
dilution of standard 10% nitric acid, and 0.1 mL of 1% KSCN solution was added
to the dilute standards and their absorbance measured at 450nm on a
UV-spectrometer using 10% nitric acid solution as a blank. Absorbance was
plotted against the concentration of standards and is presented in figure 12.
(a) (b) (c)
Represents the iron extracted from oats before the formation of the color
(b) Along with the formation of color
complex. (c) Represents the extracted iron with and without color complex.
Results and Discussion
The iron is extracted from oat meal by acid extraction
method, which dissolves the oat meal on heating. The filtrate separated from the
extract forms color complexes with potassium thiocyanate solution, which is
analyzed using a UV- Spectrometer.
Figure 12 represents the calibration curve
obtained by plotting the absorbance of known concentrations. The concentration
of iron extracted from oat meal is interpreted from the standard graph. The
efficiency of extraction through microwave oven and conventional method of
heating was compared by the amount of iron extracted and the time taken for the
Figure 12. Calibration curve
for iron content determination.
The energy consumed
and the concentration of iron extracted by different heating methods.
Power Rating (KJ/min)
Actual Energy Consumed (KJ)
Amount of Iron present (mg/g)
Difference in Calculated and Recorded Values:
Energy = Power x Time
Energy Consumed = 51.0 KJ/min x
Hot Plate: Energy
Consumed= 51.9 KJ/min x 15 min
The percentage of error for
microwave oven is,
and the percentage of error
for hot plate is,
Therefore, the percentage of energy saved by the microwave oven
over the conventional oven as recorded by the power meter is,
From the results it is evident that though
the hotplate took five times as much time to complete extraction, a slightly
higher concentration of iron was extracted in the microwave process translating
to about 77% energy saving. The direct heating capability of microwaves can be
credited with the superior heating and extraction efficiency.