1107LWK4PatelR

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Feb 20, 2024

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Group 5, Riya Patel, 02/16/2022, Colorimetric Assays Qualitative Analysis Report INTRODUCTION: Colorimetric assays are tests that result in a color change that occurs when one reagent, is added to another substance and it contains a specific compound that results in a molecular change, causing an altered color to be seen. In this experiment, we tested three different reagents to determine the presence of macromolecules such as sugar, starch, and protein. As a group, we used Lugol’s reagent to determine starch, Benedict’s reagent to determine sugar, and Biuret’s reagent to determine protein. Therefore, we outlined a way to test the supplements to conclude the appearance of the compounds in each solution in order to get our results. METHODS: For the completion of this experiment, we needed five different test tubes for each test, which is fifteen total test tubes. Benedict’s reagent was the first test we concluded to determine the existence of sugar. We then labeled five test tubes for this experiment, tube one had supplement one, tube two had supplement two, tube three had supplement three, tube four had positive control, and tube five had negative control. After that was all labeled, we added .5 milliliters of Benedict’s reagent to each tube except the negative control. Next, we added 2.5 milliliters of each supplement to its corresponding tubes. Then, we added stock sugar to the positive control and added Benedict’s reagent. Lastly, after combining the supplement and the reagent, we heated up the five test tubes in the water bath for four to seven minutes. The second test we did was Biuret’s reagent to determine the existence of protein. We created five test tubes and labeled them as, tube one had supplement one, tube two had supplement two, tube three had supplement three, tube four had positive control, and tube five had negative control. Next, we added 1 milliliter of Biuret’s reagent to each tube except the negative control. After, we added 2.5 milliliters of each supplement into its respective tubes. Lastly, we added the protein into the positive control. For the last experiment, which is Lugol’s reagent, we tested to determine the presence of starch. We labeled the five test tubes, the exact same as the other two, which was that tube one had supplement one, tube two had supplement two, tube three had supplement three, tube four had positive control, and tube five had negative control. Following that step, we added .5 milliliters of Lugol’s reagent to each test tube except for the negative control tube. Next, we added 2.5 milliliters of each supplement into its specific test tubes. After all that was added, we added starch into the positive control.

RESULTS: TEST ONE: Benedict’s reagent This was the result after completing test one, Benedict’s reagent. We concluded that Supplement 3 was the one that contained the presence of sugar. TEST TWO: Biuret’s reagent Seen above, is our test results gathered from test two, Biuret’s reagent. We found that Supplement 2 was the one that contained a presence of proteins in that solution.

TEST THREE: Lugol’s reagent In the picture above, was the result for test three, Lugol’s reagent. It is shown that we have acquired Supplement 1 as the one that determined the presence of starch in that solution. CONCLUSION: However, we came across some limitations that could have possibly affected the experiment. One limitation we observed was that we did not repeat the steps multiple times, therefore meaning the results might have come back different from what we concluded. Also, another limitation we established was the time frame while conducting these experiments. For example, when we heated up test one, Benedict’s reagent, there was a wide interval of time which could have partaken a potential limitation. After finishing the experiments for each test, we concluded that we could correctly run tests to determine the presence of compounds, and this test was known as colorimetric assays. This experiment was a representation of how the three different reagents, Lugol’s, Benedict’s, and Biuret’s, changed the supplements of each test by color due to its specific category. It also helped us understand the process of how it could be used to find other compounds in different solutions.

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REFERENCES: LaMotte, B. (2020, March 23). Colorimetric testing . LaMotte Company. Retrieved February 22, 2022, from https://lamotte.com/technical-tips/post/colorimetric-testing