Simulated-moving-bed chromatography (SMB) has been increasingly applied for enantioseparations in all production scales, from laboratory to pilot to production scale. Product quality control is mandatory for this type of chromatographic separation, and this requires robust on-line monitoring of absolute enantiomer concentrations.

In this work, an on-line monitoring system consisting of a high-speed HPLC setup with UV detection is used to monitor the concentration profiles of the two enantiomers. This monitoring scheme does not require the use of a polarimeter. The high-speed HPLC column is packed with the same stationary phase as that used in the preparative unit, but with smaller particle size to achieve lower retention times. By selecting an appropriate particle size, the monitoring scheme can achieve a sampling rate faster than the dynamics of the preparative unit.

The model system selected is the separation of binaphthol enantiomers on cellulose tris-(3,5-dimethylphenylcarbamate) using isopropanol as eluent.