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Purpose: You will use the technique of paper chromatography to compare lipstick from 3 suspects to lipstick found at the crime scene


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Whose Lipstick?

A lab on chromatography of lipstick


Purpose: You will use the technique of paper chromatography to compare lipstick from 3 suspects to lipstick found at the crime scene.
Case: Mr. Sternman was found dead in his apartment. Mr. Sternman was a very unpopular man who had managed to make enemies of everyone he knew. Even his own family found him to be a bully. He had stolen from his own wife and daughter. He had been exiled from his house a year ago for these reasons. At the time of his death, he was living in an apartment downtown. On the afternoon that he was found dead in his apartment, he had had a meeting earlier in the day with his attorney, Ms. Justice.
He also hated house cleaning and his apartment was in shambles most of the time. On the day that his body was found, one scene in the apartment was notable because it was so unusual. The dining room table was laid out with a fresh tablecloth and silver candelabra. Two cups of coffee, two napkins and a plate of cookies were on the table. One of the napkins contained a smear of lipstick.
In this case, you are to analyze the lipstick that was found on the napkin and compare it with the lipstick of the only three women who were known to have visited Mr. Sternman’s apartment: his wife ( Mrs. Sternman); his daughter (Miss Sternman) and his attorney (Ms. Justice).


Prelab questions:


  1. We have done chromatography before…what did we use it for?

2.

Using the diagram above as a reminder, how will you calculate the retention factor for each sample of lipstick?


  1. How will calculating the R value help you determine the “culprit”?

Procedure:

  1. Obtain a piece of chromatography paper containing a lipstick sample from the crime scene, the daughter, the wife and the attorney. Make sure each strip is labeled.

  2. Mark the starting position of the lipstick with a pencil before placing the strip in the acetone.

  3. Place the strips in the acetone and allow the separation to occur for about 15 minutes.

  4. Remove the strips and immediately measure the distance that the acetone moved up the paper. This is the solvent front.

  5. Also measure the distance each component of the lipsticks moved up the paper. Some lipsticks have only two or three components…and some have more and some have less.

  6. In the space below, sketch all the chromatograms with their measurements.

7. Determine the R value for each lipstick component of all samples. Enter all values in the data table below. Also below these directions you will find a sample chromatogram and the equation needed!



Postlab questions


  1. In this experiment, what is the purpose of acetone?



  1. Do you think we could use water instead of acetone? Why or why not?



  1. According to the results, who drank coffee with Mr. Sternman before he was killed?

4. Do you think the discovery of this person’s lipstick in Mr. Sternman’s apartment is enough evidence to link that person with the crime? Why or why not?


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