Question

For a TLC lab,the stationary phase is the mixture of isopropanol and ammonia or the mixture of hexane,ethyl acetate and ethanol, the stationary phase is silica gel. text some dyes and drugs.

which one of the two mobile phases is the more polar? Actualy I need two pieces of evidence... I think the polar one should be the isopropanol and ammonia because it moves slower. Can you help me come up another reason? Thank you~

Answer 1

For a TLC lab,the stationary phase

I think you mean the mobile phase?

is the mixture of isopropanol and ammonia or the mixture of hexane,ethyl acetate and ethanol, the stationary phase is silica gel. text some dyes and drugs.

The isopropanol and ammonia solvent mix is the more polar. Probably the easiest is think which solvent mix is likely to be the more water soluble. Another test is which solvent is most likely to dissolve a polar compound.

The speed of the solvent front up the TLC plate is governed by a number of things, not least of which is the viscosity of the solvent mixture, and so is not a good key to solvent polarity.