(d) Two pharmaceutical compounds are separated using reversed phase liquid chromatography (RPLC): a weak base, loratidine ( pKa 5.3), and tolbutamide a weak acid ( pKa 5.4). The mobile phase was made using an aqueous buffer: methanol 45:55v/v and the buffer was adjusted to pH3.0. (i) State which compound will elute first and explain your reasoning. (ii) What factors should be considered when choosing a suitable buffer. Give an example of a suitable buffer in this case