Sigma-Aldrich Integrated Chiral Services

Significance of the Topic

Chiral purity is critical in pharmaceutical research and production to ensure efficacy and safety of enantiomeric compounds. Sigma-Aldrich’s integrated chiral services streamline enantiomeric separation from discovery through commercial manufacture.

Study Objectives and Overview

This whitepaper outlines the consolidation of chiral screening, preparative separation, and crystallisation capabilities at the Cambridge, UK facility. It presents the SAFC Pharmorphix platform and the workflow for chiral method development and scale-up purification using chromatography and diastereomeric salt resolution.

Methodology and Instrumentation

The platform combines:

• Chiral chromatographic screening by HPLC (reversed-phase, polar organic, normal phase) and GC (cyclodextrin-based phases) with LC-MS compatibility.
• Preparative chiral HPLC and SMB (simulated moving bed) for scales from milligrams to multi-kilograms under cGMP.
• Diastereomeric salt formation using a library of >150 resolving agents and diverse solvents.
• Single crystal and powder X-ray diffraction, DSC, TGA, hot-stage microscopy, variable temperature XRPD.
• Physicochemical profiling: pKa, logP/D, intrinsic dissolution, solubility studies.
• Crystallisation reactors (250 mL to 7.5 L) and parallel blocks with turbidity probes.

Main Results and Discussion

Automated primary column screening delivers an 80 % success rate within five days. Verification on secondary systems ensures robustness. A case study on racemic mandelic acid illustrates dual pathways:

• Chiral HPLC separation on cellulose DMP column achieved baseline resolution at ambient temperature.
• Resolution via diastereomeric salt with (R)-phenylglycinol produced a hydrated conglomerate, confirmed by SC-XRD, XRPD, DSC, TGA, and VT-XRPD.
• Scale-up and recrystallisation afforded (R)-mandelic acid with > 95 % ee using optimized solvent volumes.

Benefits and Practical Applications

The integrated workflow supports rapid analytical method development, flexible purification strategies from research to kilo-scale, and comprehensive solid-state characterisation. This enables efficient selection of drug candidates with optimal enantiomeric purity and physicochemical properties.

Future Trends and Opportunities

Emerging directions include automated high-throughput screening, in silico prediction tools for chiral interactions, expansion of novel chiral stationary phases, and intensified continuous separation processes for sustainable manufacturing.

Conclusion

Sigma-Aldrich’s consolidated chiral services offer end-to-end solutions for enantiomeric analysis and purification, accelerating pharmaceutical development and ensuring compliance with regulatory standards.

References

• Kennedy, DDT 2:436-444 (1997)