MODEL-BUILDING FOR THE PREDICTION OF INITIAL CHROMATOGRAPHIC CONDITIONS IN PHARMACEUTICAL ANALYSIS USING REVERSED-PHASE LIQUID-CHROMATOGRAPHY

The development of a first guess expert system in HPLC requires a rough estimate of retention properties. This paper investigates the extent to which the simplest possible descriptor, namely the total number of carbons in a molecule, can be used. For this purpose, experimental data acquired after investigation of this parameter on the retention behaviour of various acidic, basic and neutral compounds, for a mobile phase composed of methanol-phosphate buffer and a LiChrosorb CN column, were employed. The usefulness of the descriptor log P (calculated according to Rekker's fragment system) was also studied. Similar models were derived for both descriptors. Subsequently these models were used for the selection of initial chromatographic conditions. Both models were compared through a PRESS value. The regression equation including the descriptor log P was found to be more appropriate for the present purpose.