Improvements in the determination of penicillin analogues by HPLC separation and laser-based polarimetric detection

The combination of HPLC separation and laser-based polarimetric detection is shown to provide unique advantages when applied to the study of penicillin analogues. The mass delectability for penicillin G is 5 ng with this system, which is an order-of-magnitude improvement over other techniques. More importantly, the polarimetric system can provide specific rotation information about eluting species. Individual specific rotations are reported for the (10R)- and (10S)-epimers of both carbenicillin and ticarcillin. These results demonstrate the sensitivity of specific rotation to the arrangement of atoms at or near the chiral centre, suggesting that specific rotation may be used to identify closely related penicillin analogues.