2.4. Preparation of the mobile phaseA 0.02 M phosphate buffer at pH 2.7 was prepared using dis-odium hydrogen phosphate and orthophosphoric acid. This wasthen eluted together with acetonitrile to make up a mobile phaseof buffer and acetonitrile 77:23 (v/v). Liquids used for the mobilephase were kept in amber glass bottles. Fresh buffer was prepareddaily.