$($i$)$ Discuss the significance of pH investigations during the method development

process for reversed phase liquid chromatography, referencing the data in the

graph below. Use the information from the graph below to:

$$ explain the retention profiles of the four pharmaceutical drugs.

$$ identify the most suitable mobile phase pH which will give the best separation

of the four analytes and justify your reasoning.

$$ give an example of a suitable buffer to use with a RPLC mobile phase$($i$)$ Discuss the significance of $pH$ investigations during the method development

process for reversed phase liquid chromatography, referencing the data in the

graph below. Use the information from the graph below to:

explain the retention profiles of the four pharmaceutical drugs.

identify the most suitable mobile phase $pH$ which will give the best separation

of the four analytes and justify your reasoning.

give an example of a suitable buffer to use with a RPLC mobile phase

Retention Factor $($k$)$ Vs pH of mobile phase

naproxen

$--0--$ amphetamime

ephedrine

heptanophenone