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TLC analysis of Midol

A student obtained a silica gel TLC plat shown in attached figure by spotting samples of Midol, caffeine and acetaminophen on the plate, then eluting with petroleum ether: chloroform
What are the Rf-values of acetaminophen and caffeine, respectively?
Based on this TLC analysis, what are the ingredients in a tablet of Midol?
What are the mobile phase and the stationary phase in this TLC experiment?
No spots were observed visually when the TLC plate was removed from the developing chamber. How might the student effect visualization of the spots?
Another student accidentally used Midol PM in her experiment and observed only one spot. Speculate as to which spot was absent and offer a possible explanation for the difference in this student's result.


Solution Preview

The Rf values need to be measured accurately with a ruler.

Rf = Distance from baseline to the center of the spot / Distance from baseline to the solvent front

If you do this correctly, it looks like the Rf value of acetaminophen should be greater than that of ...

Solution Summary

The TLC of Midol is analyzed and spots are identified.