(a)explain how to measure k and resolution.

(b)state three method for measuring ${}^{{\mathbf{t}}_{\mathbf{m}}}$in reversed-phase chromatography.

(c)state three method for measuring ${}^{{\mathbf{t}}_{\mathbf{m}}}$in hydrophilic interaction liquid chromatography.

(d)Estimate ${}^{{\mathbf{t}}_{\mathbf{m}}}$for ${}^{\mathbf{15}\mathbf{\times }\mathbf{0}\mathbf{.}\mathbf{46}}$column containing ${}^{\mathbf{5}\mathbf{-}\mathbf{\mu m}}$particles operating at a flow rate of ${}^{\mathbf{1}\mathbf{.}\mathbf{5}\mathbf{mL}\mathbf{/}\mathbf{min}}$Estimate ${}^{{\mathbf{t}}_{\mathbf{m}}}$if the particle size were ${}^{\mathbf{3}\mathbf{.}\mathbf{5}\mathbf{-}\mathbf{\mu m}}$ instead.

We can measure by measuring the retention time.

a) how to measure k and resolution.

We can measure by measuring the retention time for the peak of interest ${}^{\left(t_r\right)}$and the elution time for an unretained solute ${}^{\left(t_m\right)}$ .

Then we calculate using the formula:

$\mathbf{k}\mathbf{=}\frac{{\mathbf{t}}_{\mathbf{r}}\mathbf{-}{\mathbf{t}}_{\mathbf{m}}}{{\mathbf{t}}_{\mathbf{m}}}$

The resolution between neighboring peaks can be calculated dividing differences in their retention time by their average width at the baseline

$\mathbf{resolution}\mathbf{=}\frac{{\mathbf{\Delta t}}_{\mathbf{r}}}{{\mathbf{w}}_{\mathbf{av}}}$

b)state three method for measuring

The three methods for measuring${}^{{\mathbf{t}}_{\mathbf{m}}}$ in reversed-phase chromatography are:

measuring ${}^{{\mathbf{t}}_{\mathbf{m}}}$by running the unretained solutes uracil or${}^{{\mathbf{NaNO}}_{\mathbf{3}}}$

${}^{{\mathbf{t}}_{\mathbf{m}}}$is the time when the first baseline disturbance is observed we can use formula

${\mathbf{t}}_{\mathbf{m}}\mathbf{=}\frac{\mathbf{L}\mathbf{.}{{\mathbf{d}}^{\mathbf{2}}}_{\mathbf{c}}}{\mathbf{2}\mathbf{F}}$

Where the L is column length${}^{{\mathbf{d}}_{\mathbf{c}}}$ , is column diameter, and F is flow rate.

c)state three method for measuring

The three methods for measuring${}^{{\mathbf{t}}_{\mathbf{m}}}$in hydrophilic interaction liquid chromatography are:

${}^{{\mathbf{t}}_{\mathbf{m}}}$can be measured using toluene (detected at ${}^{\mathbf{215}}$nm)

${}^{{\mathbf{t}}_{\mathbf{m}}}$is the time when the first baseline disturbance is observed we can use formula:

${\mathbf{t}}_{\mathbf{m}}\mathbf{=}\frac{\mathbf{L}\mathbf{.}{{\mathbf{d}}^{\mathbf{2}}}_{\mathbf{c}}}{\mathbf{2}\mathbf{F}}$

d ) estimate column counting

The for ${}^{{\mathbf{t}}_{\mathbf{m}}}$${}^{\mathbf{\mu m}}$particle is:

$$\begin{gathered} {\mathbf{t}}_{\mathbf{m}}\mathbf{=}\frac{\mathbf{15}\mathbf{cm}\mathbf{.}\mathbf{}{\left(0.46\mathrm{cm}\right)}^{\mathbf{2}}}{\mathbf{2}\mathbf{.}\mathbf{1}\mathbf{.}\mathbf{5}\mathbf{mL}\mathbf{/}\mathbf{min}} \\ {\mathbf{t}}_{\mathbf{m}}\mathbf{=}\mathbf{1}\mathbf{.}\mathbf{1}\mathbf{min} \end{gathered}$$

The for ${}^{\mathbf{3}\mathbf{.}\mathbf{5}\mathbf{\mu m}}$particle is the same because ${}^{{\mathbf{t}}_{\mathbf{m}}}$does not depends on particle size.

Hence,

a) We can measure by measuring the retention time for the peak of interest ${}^{\left(t_r\right)}$and the elution time for an unretained solutelocalid="1655035932587" ${}^{\left(t_m\right)}$.

Then we calculate using the formula:

$\mathbf{k}\mathbf{=}\frac{{\mathbf{t}}_{\mathbf{r}}\mathbf{-}{\mathbf{t}}_{\mathbf{m}}}{{\mathbf{t}}_{\mathbf{m}}}$

b) The three methods for measuring ${}^{{\mathbf{t}}_{\mathbf{m}}}$in reversed-phase chromatography are:

measuring ${}^{{\mathbf{t}}_{\mathbf{m}}}$by running the unretained solutes uracil or${}^{{\mathbf{NaNO}}_{\mathbf{3}}}$

${}^{{\mathbf{t}}_{\mathbf{m}}}$is the time when the first baseline disturbance is observed we can use formula

${\mathbf{t}}_{\mathbf{m}}\mathbf{=}\frac{\mathbf{L}\mathbf{.}{{\mathbf{d}}^{\mathbf{2}}}_{\mathbf{c}}}{\mathbf{2}\mathbf{F}}$

Where the L is column length${}^{{\mathbf{d}}_{\mathbf{c}}}$, is column diameter, and F is flow rate.

c) The three methods for measuring${}^{{\mathbf{t}}_{\mathbf{m}}}$in hydrophilic interaction liquid chromatography are:

${}^{{\mathbf{t}}_{\mathbf{m}}}$can be measured using toluene (detected at ${}^{\mathbf{215}}$nm)

${}^{{\mathbf{t}}_{\mathbf{m}}}$is the time when the first baseline disturbance is observed we can use formula:

${\mathbf{t}}_{\mathbf{m}}\mathbf{=}\frac{\mathbf{L}\mathbf{.}{{\mathbf{d}}^{\mathbf{2}}}_{\mathbf{c}}}{\mathbf{2}\mathbf{F}}$

d)${}^{{\mathbf{t}}_{\mathbf{m}}\mathbf{=}\mathbf{1}\mathbf{.}\mathbf{1}\mathbf{min}}$