Chapter 23, Problem 23.19P

(a)

Interpretation Introduction

Interpretation:

Migration time and peak width of $\text{C}{\text{l}}^{-}$ in the figure has to be measured and number of theoretical plates has to be calculated.

Concept Introduction:

Number of theoretical plates for $\text{C}{\text{l}}^{-}$ is calculated by the equation as follows:

    $\text{N}=\frac{\text{5}\text{.5}{\text{t}}_{\text{r}}^{\text{2}}}{{\left({\text{W}}_{\frac{1}{2}}\right)}^2}$

Here, $\text{N}$ is the number of theoretical plates.

${\text{t}}_{\text{r}}$ is the migration time.

${\text{W}}_{\frac{1}{2}}$ is the width at the half peak height.

(b)

Interpretation Introduction

Interpretation:

Plate height for $\text{C}{\text{l}}^{-}$ has to be calculated.

Concept Introduction:

The peak height is calculated from number of theoretical plate as follows:

    $\text{H}=\frac{\text{L}}{\text{N}}$

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

$\text{L}$ is the length of the column.

$\text{N}$ is the number of theoretical plate.

(c)

Interpretation Introduction

Interpretation:

Reason behind the negative response in analysis has to be explained.

Concept Introduction:

The relation between the absorbance and concentration of the analyte is calculated from the Lambert Beer’s law as follows:

    $\text{A}=\left(\text{ε}\right)\left(\text{c}\right)\left(\text{l}\right)$

Here, $\text{A}$ is the absorbance.

$\text{ε}$ is the molar absorption coefficient.

$\text{c}$ is the concentration of analyte.

$\text{l}$ is the optical path length.

Indirect spectrophotometric analysis is concerned with the measurement of the decolorization of a colored system. In this analysis the lowest relative error can be achieved at low absorbance reading and the precision is increased, if the reading is taken against a partly decolorized standard.

Indirect detection measures strong signal from the background electrolyte and a weak signal from analyte.