Step 1. Make sure that you have a good TLC run with proper separation as previously described. Clearly mark the extent of the solvent absorbtion up the plate. This will be the dM reference point used in the R_f calculations.

Step 2. Mark the area of greatest compound density in each sample spot that traveled up the plate. The traveled spot ideally should be the same shape as the original spot, but oftentimes one will encounter tailing. Remember to choose the reference point as the most dense area of spotting.

Step 3. Carefully measure the distances between the baseline where the original spotting was made and the traveled spots. The ratio of these measurements to the overall distance travelled by the solvent (dM) is known as the Retardation Factor (Rf).

R_f of compound A = dA/dM

R_f of compound B = dB/dM

R_f of component 1 of compound C = dC1/dM

R_f of component 2 of compound C = dC2/dM

OTHER TIPS:

• Try to choose your solvents so that your Rf values are not very close to unity. Rf values close to unity indicate that your analyte has traveled to near the end of the plate (assuming your solvent front also neared the end of the plate). Coming to the end of the plate means that you are running out of room, thus your spot might not have had the chance to separate out into even more composite substances. We don't want to miss any possible analyte components!