Quantification of Iron in Total Cereal
Aidan O’Neill
Mark Paradzinsky
Chem 1035, Experiment 9, 11/25/2018
Honor Code Signature: Aidan O’Neill
Abstract
In this experiment the claim that Total Cereal has the daily serving of iron is tested. The selling
point of Total Cereal is that it has the daily serving of iron in a single serving of the cereal. The results
were found by grinding 10 gm of Total Cereal and mixed with water to extract the iron from the sample.
Then the iron was placed in a boiling bath with HCl and diluted with 2 drops of 6 M HCl, 0.5 mL of
hydroxylamine-HCl, 6 drops of 2 M sodium acetate, 1 mL of 0.1% 2,2-dipyridyl solution and DI water.
The diluted sample was then tested using an Atomic Absorbance Instrument along with five other control
samples to compare it to. The results show that there is 1.594 g of iron in a serving of total cereal. This
was found using the dilution formula and the formula given by the trendline. This is less than the
recommended daily amount by almost 7 g and not enough for an average adult making Total Cereal’s
claim false. It would suffice for a newborn and this is likely how Total Cereal is able to make this claim.
I. Introduction
This experiment Would most likely be used by the Food and Drug Association to find the exact
concentrations of ingredients in products. Or anyone who is curious of what exactly they are eating.
Knowing the exact amount of minerals that you consume on a daily basis is a good base for a diet or
healthy eating. This information is also relevant to people with allergies as not everyone is 100% allergic
to certain things. For example, you can become sick after consuming a certain amount of diary but not be
lactose intolerant if diary bothers you. For others they may have iron rich blood and need to monitor their
iron intake. In this experiment the dilution formula is used: M1V1=M2V2. First the final
concentration/diluted had to be determined using the formula found in the trendline. Because the solution
was diluted several times, the dilution formula goes through several iterations to find the initial mass of
the iron in the cereal. If the final concentration was used to find the initial mass without going through
several iterations, the mass of iron found would be incorrect as it would be based off the wrong dilution.
The dilution formula can be is used to convert between known and unknown masses and volumes as it
was in this experiment.
II. Experimental
The experiment was started by grinding 10 gm of Total Cereal with an electric grinder. The cereal
powder was then added to a 150 mL beaker along with enough water to make brown watery solution.
Then it was stirred for ten minutes in a magnetic stir plate, allowing for some of the metal to be seen on
the stir bar. The leftover cereal mush was disposed of and the stir bar was rinsed with DI water. After this
the stir bar was placed in a test tube with 6 mL of 6 M HCl. The test tube was then placed in a boiling
water bath over a Bunsen Burner for 10 minutes. The clear color of the HCl slowly turned green over the
ten-minute boiling bath. The stir bar was then removed, and the liquid poured into a 100 mL volumetric
flask and diluted to 100 mL with DI water. 2 mL of this solution was then put into a 10 mL volumetric
flask using a pipet along with 2 drops of 6 M HCl, 0.5 mL of hydroxylamine-HCl, 6 drops of 2 M sodium
acetate, 1 mL of 0.1% 2,2-dipyridyl solution and then diluted to 10 mL with DI water. The Atomic
Absorbance Instrument was then used to measure the absorbance of 1, 2, 4, 5 and 8 ppm solutions at 522
nm. Using the same settings on the Atomic Absorbance Instrument, the Total Cereal sample was then
tested.
III. Results/Discussion
Table 1
Concentration (ppm)
1
2
4
5
8
Sample
Absorption
0.0343
0.0721
0.1350
0.1616
0.2909
0.1095
This table shows the level of absorption of the five base concentrations and the concentration of the iron
sample from the cereal found by the Atomic Absorption Instrument.
Figure 1
Absorption vs Concentration
0.35
0.3
y = 0.0359x - 0.005
R² = 0.9925
Absorbtion
0.25
0.2
0.15
0.1
0.05
0
0
1
2
3
4
5
6
7
8
9
Concentration (ppm)
This figure shows the trendline of the absorption values of the baseline samples. As the concentration
increases so does the absorption of the samples meaning there is a positive correlation between the two.
As shown by Figure 1 the absorption increased as concentration increased indicating a positive
correlation. The Total Cereal iron sample was found to be somewhere in between the 4 ppm and 2 ppm
concentrations, the lower end of the scale in terms of iron concentration. The R2 value was 0.9925,
meaning it was almost a straight line. This showss that the Atomic Absorption Instrument was accurate in
its readings and was calibrated correctly. Any sources of error had to have been human error. There were
several dilutions in this lab, meaning there were several opportunities for a slightly incorrect
measurement. An inaccurate measurement at the beginning of the experiment would have greater effects
on the resulting concentration than if the error occurred later in the experiment. To minimize this,
volumetric flasks were used throughout the experiment because the are the most accurate of the glassware
due to their small diameter necks1. As stated earlier, it was observed that the solution of the iron and 6 mL
of HCl turned a light shade of green while it was in the boiling bath. It was also observed that the flame of
the Atomic Absorption Instrument darkened as the concentration (ppm) increased.
The concentration of iron in Total Cereal was found starting with the equation found in the
trendline:
𝑦 = 0.0359𝑥 − 0.005
0.1095 = 0.0359𝑥 − 0.005
𝑥 = 3.189 ppm
The dilution formula was then used twice to find the mass of iron:
M1V1 = M2V2
M1 × 0.002𝐿 = 3.189𝑝𝑝𝑚 × 0.01𝐿
M1 = 15.947 ppm
M1× 0.006𝐿 = 15.947𝑝𝑝𝑚 × 0.1𝐿
M1 = 265.78 ppm
Mass Fe = 265.78𝑝𝑝𝑚 × 0.006𝐿
Mass Fe = 1.594 mg
According to the NIH, the DRI for iron of an average adult is between 8 and 27 mg depending on
gender and age2. The value found in the cereal is far less than what is recommended for an adult by
almost 7 mg for the lowest amount. The statement that this cereal is 100% of your daily iron intake is
false unless it was being eaten by a child of less than 6 months who only requires 0.27 mg of iron2. This is
likely how the manufacturer can advertise the cereal as such; it meets one of the standards.
IV. Conclusion
From the results it was concluded that Total Cereal does not have the daily dosage of iron for an
average adult. It would meet the daily requirements of a newborn, but that is unlikely the target audience
of this cereal. Based on these findings further research could be done to find the percentages of the other
elements as it is possible that they are falsely labeled in addition to the iron. The future experiment would
be very similar to this one using the Atomic Absorption Instrument and involving several dilutions to
calculate the percentage of the element.
Supplementary Questions
The DRI of iron is 8 mg for a 19 to 50-year-old man and 18 mg for a 19 to 50-year-old woman2.
0.001594𝑔
𝑥
=
30𝑔
18.5𝑔
x = 0.000983g
There is 0.000983 g of iron in an 18.5 g sample of Total Cereal.
References
(1)
Walker, J. Volumetric Glassware. Nature 1929, 123 (3102), 561–561.
(2)
Siu, A. L. Screening for Iron Deficiency Anemia and Iron Supplementation in Pregnant Women to
Improve Maternal Health and Birth Outcomes: U.S. Preventive Services Task Force
Recommendation Statement. Annals of Internal Medicine. October 6, 2015, pp 529–536.