Retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a...

The reproducibility of the separation of basic drugs on silica columns has been tested in a collaborative study between nine laboratories. The results from the different laboratories were very similar. Various methods of recording the retention properties of the drugs were compared with reference to their reproducibility and ability to discriminate between different compounds. Relative retention times, relative capacity factors, and corrected capacity factors were much better than retention times and capacity factors, although all the methods suffered from large errors with weakly retained compounds. All the work was carried out using a single batch of silica to avoid variations due to the stationary phase.