Question

A student is comparing two samples of crystalline organic solids. A TLC analysis shows a single spot for each sample and the co-spot with the same Rf value. Which of the following would provide the most conclusive evidence that the two samples are the same compound?
-rerun the TLC using more developing solvent
-rerun the TLC on a longer TLC plate
-Perform a mixture melting point
-mix the substances and run the TLC as a single spot

Answer 1

Answer:

Rerun the TLC using more developing solvent

Explanation:

The TLC principle envolves the interaction of the samples with the solvent and the stationary phase.

For the solvent you are using at the moment, the interaction with the sample may be very similar for both cases depending with the polarity, what could indicate an equal value.

If you develops a new solvent with a different polarity, you can see if the samples are the same compound or not. Because a more polar compound will interact more with the stationary phase and a more non-polar compound will interact more with the solvent.