In: Chemistry
Rf Values
When comparing the Rf values of the organic compounds to those of authentic samples, there is a limitation of TLC comparison.
Why do Rf values not provide definitive proof of identity?
Rf value does not provide complete idea about the identitiy of the unknown compound because two different samples may have nearly same Rf values due to interaction of the samples with each other and the concentration of the component in the sample will both effect the Rf value.
Under identical conditions, two different compounds may have different Rf values and same compounds will have same Rf values. However, comparison of an unknown sample with authentic samples can provide an insight to the identitiy of the compound. Thus analytical techniques like IR, NMR should be used to confirm the identity of the compound