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Analysis of the Chromatogram:
XXXXXXXXXXStaple the chromatogram to your report sheet. On it, use a pencil to show:
SOLVENT FRONT Draw a line on the topmost wet edge.
SOLVENT FRONT MEASUREMENT Record the distance from the origin to the solvent front in cm. This number
should be the same for the entire chromatogram unless it ascended unevenly.
SPOT Each colored spot has a leading edge and an extended tail. Place a dot on this
leading edge. Some samples will have one spot while others will have two.
SPOT MEASUREMENT Measure the distance in centimeters from the ORIGIN to each SPOT.
RETENTION FACTOR (Rf) Calculate the Rf of each spot.
XXXXXXXXXXOn the picture of the chromatogram below, transfer the Rf for each spot for all 10 samples.
XXXXXXXXXXExamine the Rf of the spots from samples
#1-4. Each spot is made up of one FD&C dye.
Match the dye to the Rf and summarize it in the
table. Since Red 40, for example, is found in both
samples #1 and #2, you will need to average the Rf.
XXXXXXXXXXAnswer the questions about samples #5 - #10.
Sample #5 (neon pink) contains ________.
XXXXXXXXXXa. Red XXXXXXXXXXb. Red XXXXXXXXXXc. Blue XXXXXXXXXXd. Yellow XXXXXXXXXXe. more than one of these
Sample #6 (neon purple) is made up of ________ dyes.
XXXXXXXXXXa. one XXXXXXXXXXb. two XXXXXXXXXXc. three XXXXXXXXXXd. four
Sample #7 (neon blue) contains ________.
XXXXXXXXXXa. Red XXXXXXXXXXb. Red XXXXXXXXXXc. Blue XXXXXXXXXXd. Yellow XXXXXXXXXXe. more than one of these
Sample #8 (neon green) is made up of ________ dyes.
XXXXXXXXXXa. one XXXXXXXXXXb. two XXXXXXXXXXc. three XXXXXXXXXXd. four
For Sample #9 what type of Gatorade or Kool-Aid did you use? What FD&C dyes are present? What data
lead to your conclusion?
Write one sentence that summarizes the dye(s) present in your food sample, #10.
FD&C Dye Identity Rf
Red 40
Red 3
Blue 1
Yellow 5
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#9: What FD&C dyes are present are in sample 9? Explain your reasoning. Your explanation
should be concise, but complete (what were all the things you considered to come to your
conclusion?)
#10: Sample 10 for this student was a marker. If you think any of the known dyes are in that
sample, state which dyes and why (as above). If you don’t think any of the dyes are present,
why not?
#11: So why are we doing this lab? First, it’s pretty ‐ a lot of chemistry actually isn’t so colorful,
so this is a nice exception. Secondly, the dyes are traveling based on size and polarity, a
concept you learned about recently in lecture and your previous lab
Look at the structures of Red 40, Blue 1, and Yellow 5 on page 2. The solvent is less polar than
the chromatography paper, so the more polar a dye is the less it moves (due to its stronger
attraction to the stationary paper than the mobile solvent). If you want more background on
the theory, see this video: https:
www.youtube.com/watch?v=gFw2WOC2mcU
Did the dyes in this experiment move as you would expect based on their polarity/charge?
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