Chapter 22, Problem 22.2P

(a)

Interpretation Introduction

Interpretation:

Reason behind increase in plate height at very high and low flow rate for $\text{5}\text{μm}$ and $\text{3}\text{.5}\text{μm}$ particle size has to be explained.

Concept Introduction:

Plate height 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 eddy diffusion constant.

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

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

$\text{u}$ is flow rate.

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

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

The term $\text{C}$ is mass transfer constant and it is related to linear velocity and square of the particle size.

(b)

Interpretation Introduction

Interpretation:

Reason behind the not increase in plate height at very high and low flow rate for $1.8\text{μm}$ particle size has to be explained.

Concept Introduction:

Refer to part (a).