Examining Elements in CerealsA Real World ProjectBy Nicole Dixon and Amanda Lagace

Purpose The purpose of our experiment was to analyze the mineral

content in cereal products in order to make a comparison to the reported values. The content analyses of sodium, potassium, magnesium, calcium, copper, iron, and zinc were performed by the ICP-OES, and the analyses of iron and zinc were performed again using the AA. We analyzed the content using a calibration curve made from standards of various concentrations, and the cereal products we analyzed were Cheerios, Total, Oatmeal Crisp, and Cocoa Puffs.

Method•We began this procedure by creating 1L of 0.1M nitric acid to use as a solvent.

•We then created standards for the experiment. We made standards from the sodium, potassium, magnesium, calcium, copper, iron, and zinc stock solutions in concentrations of 10ppm, 20ppm, 30ppm, 40ppm, and 50ppm in 100mL volumetric flasks with nitric acid. We also set aside a blank of nitric acid for analysis.

•We then created our cereal samples for analysis. We first crushed 0.1g of cereal with a mortar and pestle and dissolved it in 100mL of nitric acid. We used a stir plate for several minutes in order to dissolve most of the sample. What could not be dissolved we filtered out of the solution with filter paper.

•We ran the blank, standards, and samples on the ICP for the presence of the seven elements. We used the information from the standard to create a calibration curve in order to determine the concentration of the elements in the samples.

•We then ran the blank, standards, and samples on the AA for the presence of zinc and iron, using the information from the standards again to create a calibration curve to determine the sample concentrations.

•We used the concentration determined by experimentation to compare to the reported values on the cereal boxes and we calculated the percent difference between the two.

Data

Cereal Samples Massed Out

Cheerios 0.101 g

Total 0.1064 g

Oatmeal Crisp 0.1012 g

Cocoa Puffs 0.1016 g

Data-AAAA Data

Sample Absorbance10 ppm 0.20920 ppm 0.42530 ppm 0.64040 ppm 0.88250 ppm 0.850

Oatmeal Crisp 0.162Cheerios 0.260

Total 0.021Cocoa Puffs 0.019

Sample Absorbance10 ppm 0.61020 ppm 1.80530 ppm 1.86040 ppm 1.88850 ppm 1.917

Oatmeal Crisp 1.732Cheerios 0.183

Total 0.080Cocoa Puffs 0.117

IronZinc

Iron:

Zinc

AA Calibration Curves

5 10 15 20 25 30 35 40 45 50 550

0.5

1f(x) = 0.01739 x + 0.0795000000000001R² = 0.924460477838903

Absorbance vs. Con-centration

Iron

Concentration (ppm)

Concentr

ati

on

5 10 15 20 25 30 35 40 45 50 550

0.51

1.52

2.5

f(x) = 0.02697 x + 0.8069R² = 0.571895181770579

Absorbance vs. Concen-tration

Zinc

Concentration (ppm)

Absorb

ance

Data-ICP

Sample Ca Int. (c/s) Cu Int. (c/s) Fe Int. (c/s) K Int. (c/s) Mg Int. (c/s) Na Int. (c/s) Zn Int. (c/s)

10 ppm 2975345 28152 34371 463324 401600 1172474 420913

20 ppm 4993901 63703 71769 894113 689372 2144804 603284

30 ppm 7341610 96232 109049 1353595 1051647 3381446 767545

40 ppm 9354119 122977 141546 1556369 1221686 4200734 837377

50 ppm N/A 143857 184411 1908458 1495157 5395084 907003

Oatmeal Crisp 620447 486.01 3596.0 139844 55575 742545 11474

Cheerios 1408208 240.00 1890.9 286040 64344 870787 4006.0

Total 10086059 186.06 3185.2 166009 72996 897222 4970.9

Cocoa Puffs 1432715 140.70 1288.6 122246 37250 896478 2056.0

ICP Calibration Curves

5 10 15 20 25 30 35 40 45 50 550

2000000

4000000

6000000

8000000

10000000f(x) = 214840.31 x + 795236R² = 0.9990442795859

Intensity vs. Concentration Calcium

Concentration (ppm)

Inte

nsit

y (

c/s

)

5 10 15 20 25 30 35 40 45 50 550

50000

100000

150000

200000

f(x) = 2906.84 x + 3778.99999999999R² = 0.989572013716158

Intensity vs. Concentration Copper

Concentration (ppm)

Inte

nsit

y (

c/s

)

ICP Calibration Curves (cont)

5 10 15 20 25 30 35 40 45 50 550

50000

100000

150000

200000

f(x) = 3698.57 x − 2727.90000000001R² = 0.998590545617477

Intensity vs. ConcentrationIron

Concentration (ppm)

Inte

nsit

y

(c/s

)

5 10 15 20 25 30 35 40 45 50 550

500000

1000000

1500000

2000000

2500000

f(x) = 35525.24 x + 169414.6R² = 0.983990457552598

Intensity vs. ConcentrationPotassium

Concentration (ppm)

Inte

nsit

y (

c/s

)

ICP Calibration Curves (cont)

5 10 15 20 25 30 35 40 45 50 550

500000

1000000

1500000

2000000

f(x) = 27194.28 x + 156064R² = 0.98918451728549

Intensity vs. Concentration Magnesium

Concentration (ppm)

Inte

nsit

y (

c/s

)

5 10 15 20 25 30 35 40 45 50 550

1000000

2000000

3000000

4000000

5000000

6000000

f(x) = 105011.5 x + 108563.4R² = 0.997077768333118

Intensity vs. ConcentrationSodium

Concentration (ppm)

Inte

nsit

y (

c/s

)

ICP Calibration Curves (cont)

5 10 15 20 25 30 35 40 45 50 550

200000

400000

600000

800000

1000000f(x) = 12062.73 x + 345342.5R² = 0.949381779414573

Intensity vs. ConcentrationZinc

Concentration (ppm)

Inte

nsit

y (

c/s

)

Even More DataCheerios Total Oatmeal Crisp Cocoa Puffs

Sodium 160mg 140mg 125mg 150mgPotassium 170mg 90mg 190mg 70mgCalcium 100mg 1000mg 20mg 100mgIron 6.75mg 15mg 7.5mg 3.75mgZinc 3.75mg 15mg Not reported 3.75mgMagnesium 35mg 21mg 35mg 14mgCopper Not reported Not reported Not reported 0.04mg

Reported values of elements in one serving of each cereal product:

Cheerios Total Oatmeal Crisp Cocoa PuffsSodium 5.771ppm 4.965ppm 2.108ppm 5.644ppmPotassium 6.132ppm 3.192ppm 3.205ppm 2.634ppmCalcium 3.607ppm 35.467ppm 0.3373ppm 3.763ppmIron 0.2435ppm 0.532ppm 0.1265ppm 0.1411ppmZinc 0.3527ppm 0.532ppm 0.5903ppm 0.1411ppmMagnesium 1.2625ppm 0.7448ppm Not reported 0.5268ppmCopper Not reported Not reported Not reported 0.0015ppm

Calculated theoretical values of elements in 0.1g of cereal in 100mL of solvent based on reported values

Sample Calculations

Example Calculations of Theoretical Values:

Calculations UsedICP (Calibration Curves from Instrument

Na y= 108758x + 51823.3

K y= 44295.1x + 2010.58

Ca y= 246238x + 67399.6

Fe y= 3423.14x + 242.967

Mg y= 37115.8x + 2944.18

Zn y= 24438.6x + 171.203

Cu y= 2809.82x + 64.584

AA (Calibration Curves from Excel)

Fe y= 0.0124x + 0.0795

Zn y= 0.027x + 0.8069

ResultsCheerios – ICP

Element Concentration (ppm)

% Difference

Na 7.5301 30.48%

K 6.4122 4.57%

Ca 5.4452 50.96%

Fe 0.4814 97.70%

Mg 1.6543 31.03%

Zn 0.1569 55.51%

Cu 0.0625 ---

Cheerios – AA

Element Concentration (ppm)

% Difference

Fe 1.546 338.33%

Zn 12.5483 5053.05%

ResultsTotal - ICP

Element Concentration (ppm)

% Difference

Na 7.7732 56.56%

K 3.7024 15.52%

Ca 40.6869 14.72%

Fe 0.8595 61.56%

Mg 1.8874 153.41%

Zn 0.1964 63.08%

Cu 0.0432 ---

Total - AA

Element Concentration (ppm)

% Difference

Fe .6759 27.05%

Zn 1.0135 90.51%

ResultsOatmeal Crisp - ICP

Element Concentration (ppm)

% Difference

Na 6.3510 201.28%

K 3.1117 2.911%

Ca 2.2460 565.88%

Fe 0.9795 674.31%

Mg 1.4180 140.22%

Zn 0.4625 ---

Cu 0.14998 ---

Oatmeal Crisp - AA

Element Concentration (ppm)

% Difference

Fe 14.633 6080.63%

Zn 7.8185 ---

ResultsCocoa Puffs - ICP

Element Concentration (ppm)

% Difference

Na 7.7664 24.38%

K 2.7144 3.05%

Ca 5.5447 47.35%

Fe 0.3055 116.51%

Mg 0.9243 75.46%

Zn 0.0771 45.36%

Cu 0.0271 170.04%

Cocoa Puffs - AA

Element Concentration (ppm)

% Difference

Fe 0.9885 600.57%

Zn 0.9170 549.9%

Conclusions The best results came from Potassium. The cereal with the lowest percent

differences overall was Cheerios. The cereal with the worst numbers

was Oatmeal Crisp. The worst results elementally was iron. Most of the elements with higher

percent differences were those with lower reported concentrations in the cereals.

What Went Wrong (Possibly)Dissolving the flaky cereals. Filtering the cereals. Concentrations of standards.Low concentration of cereal in

the samples. (Used 0.1g in 100 mL)

Difference between ICP and AA.