Dietary Supplements Lab Report

Title:
Determining which organic molecules are present in a series of unknown dietary supplements ● Introduction:
Our main objective was to find out if the dietary supplements that claimed to be providing high levels of proteins contained fillers such as starch and sugar. We developed and carried out tests to determine which organic molecules were present in a series of unknown supplements. This is important because it is important to know what is in the food you eat for yourself and not always reply on the vague claims that companies make about their products.
● Description:
Knowing that sugars react to a Benedict’s reagent, proteins will react to a Biuret reagent, and starch will react to a Lugol’s reagent, we will be able to test the presence
of each of those three macromolecules by observing if they react the same way in each of the three stock solutions in the same way they reacted to their each of their corresponding reagent.
Initially, we tested each reagent in the stock solution by positive control to prove their indicator. To positively test each solution, we first obtained 5 mL of each stock solution (protein, sugar, and starch). Then, we added 1 mL of the Lugol reagent in the starch solution and observed and noted the reaction. Similarly, we added 2 mL of the
Biuret reagent in the protein solution and observed and noted the reaction. Lastly, we added 1 mL of the Benedict’s reagent in the sugar solution then heated the reaction to
65 degrees celsius for 4-7 minutes for the full color change and then observed and noted the reaction.
For all three reactions, cover each test tube with parafilm after adding the reagent to mix the solution and the reagent together before observing the reaction.
To negatively test each solution, we obtained 5 mL of each stock solution
(protein, sugar, and starch) and added 1 mL of water in each solution and observed and noted each reaction.
To test which macromolecules are in each of the three unknown stock solution, obtain 6, 5 mL sample of each unknown stock solution(3 for each trial). You should have
18 solution samples in total. Label which tubes correspond to which unknown. First, place 1 mL of the Lugol reagent in two of the samples of each unknown. Cover the test tubes with para film and mix well. Observe the color change and report the results. Next, place 2 mL of Biuret reagent in two of the samples of each unknown. Cover the test tubes with para film and mix well. Observe the color change and report the results.
Lastly, place 1 mL of Benedict’s reagent in two of the sample of each unknown. Heat
Benedict’s reaction to 65 degrees celsius for 4-5 minutes for full color change. Cover the test tubes with para film and mix well. Observe the color change and report the
results.
Compare the color changes observed in each reaction (if any) to the color changes of the positive controls.
From the comparison, decipher how prominent is each macromolecule is in each unknown based on pigmentation.
● Conclusion:
After running through the experiment, we concluded that unknown solution 1 contains starch since it reacted in a similar way in comparison to the positive control.
Also, we concluded that there are traces of sugar since it also reacted to the Benedict’s solution, but not as strongly as it did with the positive control. In unknown solution 2,
we observed that there are traces of proteins as well as sugars since it reacted to the Biuret and Benedict's reagents. For unknown solution 3, we concluded that it contains starch and glucose but very little protein since it was not as pigmented of a color in comparison to the color change we obtained in our positive indicator outcomes.
Since the syringes we used to obtain 5 mL of each solution varied, human error could have arisen and would have therefore affected our outcome because different ratios of solution and reagent would lead to different pigmentations of color changes. In addition, human error of not being consistent with the mixing of the solution could have yielded different outcomes than what we should have observed. However, since we ran the experiment through two trials, we could have accounted for some of those sources of
errors.