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Date Submitted: 01/29/2013 10:52 PM
Name: X
Chemistry 213 – Section A02
Potassium Determination in Bananas by Atomic Absorption
Abstract: The theme and objective of this experiment was to determine the amount of potassium in a
Chiquita TM banana using Atomic Absorption (AAS). To accomplish this, potassium was extracted from a
banana using a 120mL mortar and pestle. Potassium exists in ionic form in bananas initially therefore
the simple addition of water will aid in extracting the ion. Hydrochloric acid was added as well to attract
the potassium ions (the potassium is attracted to the negative chloride ions). By adding these two things
in conjunction with rigorous shaking, the potassium containing supernatant was filtered out, obtained,
and diluted for measurement. A series of potassium standards were prepared as well. Simple dilution
factors were calculated to create seven standards (1ppm‐7ppm) from a 100ppm K+ Stock solution. These
standards were measured in the AAS machine to create a calibration curve that was utilized in
quantitatively determining the amount of potassium in bananas. The unknown banana solution was
then measured in the AAS, and from the absorbance of the measurement the concentration was
obtained using the calibration curve. In‐order to eliminate any chemical interference, standard addition
was performed. This was done by adding a known amount of standard to unknown potassium solutions
to account for the interference, and then running them through the AAS machine. The results were then
compared to the calibration curve previously made in order to calculate the amount of potassium that
exists without interference. This step was necessary to obtain accurate potassium amounts. The motive ...