Chapter 22, Problem 22.16P

Interpretation Introduction

Interpretation:

Ways to increase the resolution of chromatograph without the change in solvents or the stationary phase has to be explained.

Concept Introduction:

In chromatographic analysis, isocratic elution means the composition of mobile phase is kept constant.

Plate height of chromatogram can be calculated by van Deemter equation as follows:

    $\text{H}\approx \text{A}+\frac{\text{B}}{\text{u}}+\left(\text{C}\right)\left(\text{u}\right)$

Here, $\text{H}$ is the plate height.

$\text{A}$ term is the eddy diffusion constant.

$\text{B}$ term is the longitudinal diffusion constant.

$\text{C}$ term is the mass transfer constant.

$\text{u}$ is flow rate.

The term $\text{A}$ that is the eddy diffusion constant is related to the particle size of the packing material and consistency of the flow around the particles but it is independent of the flow rate.

The term $\text{B}$ that is the longitudinal diffusion is related to the diffusion of the analyte in mobile phase and the stationary phase.

The term $\text{C}$ is mass transfer constant that is related to the flow rate and the square of the particle size.