Question

Explain what a theoretical plate is. What is the relationship between the number of theoretical plates and resolution? How is theoretical plate height related to resolution? Now quantitatively, answer the following question: how many theoretical plates, N, must a packed column have to achieve a resolution of 1.5 between 2 peaks that elute at 5.42 minutes and 5.63 minutes. At a resolution of 1.5 are these peaks considered resolved?

Answer 1

Theoretical plate: A theoretical plate in many separation processes is a hypothetical zone or stage in which two phases, i.e. the liquid and vapor phases of a substance, exist in an equilibrium.

The relationship between the number of theoretical plates (N) and resolution (R):

R = (1/4) * (N)^1/2 * {( - 1)/} * {k/(1 + k)}

Where, = separation factor and k = retention factor

Relation of the theretical plate height to the resolution:

The height of theoretical plate can be calculated by H = L/N, where L = length of column used

This ratio gives information about the resolution.

Finally, Yes, at a resolution of 1.5 the given peaks are considered resolved.