Parallel SFC/MS‐MUX screening to assess enantiomeric purity

Abstract

Enantiomeric excess (ee) was evaluated for two internally synthesized compound libraries using a high-throughput automated, intelligent four-channel parallel supercritical fluid chromatography/mass spectrometry system equipped with a multiplexed ion source interface (SFC/MS-MUX). The two libraries contained compounds spanning a wide range of enantiomeric ratios with structurally diverse chemical scaffolds and stereogenic centers. The system analyzed each sample simultaneously against four chiral columns using up to six organic modifiers. Enhancements to our previously published parallel supercritical fluid chromatography/mass spectrometry system were implemented to address the challenges associated with automated trace enantiomer identification and quantitation. A reversal of enantiomer elution order was observed for several samples across multiple CSPs and modifiers. The relationship between elution order and % ee accuracy is presented for compounds exhibiting high, middle and low % ee values. Despite incidences in which the minor enantiomer eluted prior to the major enantiomer with less than baseline resolution, the overall % ee was in agreement with separations in which full baseline resolution was achieved. The methods presented here demonstrate the value and utility of high-throughput ee determinations to support drug discovery and development programs.

Chiral Recognition Mechanism: Practical Considerations for Pharmaceutical Analysis of Chiral Compounds

“…In recent years, due to several admired features such as fast and high-efficient enantioseparation, short method development cycle resulting from fast column equilibrium and simple mobile-phase compositions, and great preparative potential, chiral SFC using the same packed columns as HPLC has gained increasing popularity as the preferred technology for high-throughput chiral analysis and accessing large quantities of pure enantiomers in drug discovery [149,[151][152][153]. However, chiral SFC is much less influential in pharmaceutical development.…”

“…In drug discovery and process, a high-throughput chiral method is required to accommodate huge sample volume and large numbers of novel chemical entities. Consequently, chiral SFC separation becomes advantageous due to its fast method development, high separation efficiency, and short analysis time [149,[151][152][153]. In early stage of pharmaceutical development, there is more flexibility in selecting chiral columns and separation technologies, and it is not unusual to adapt the method developed in drug discovery or process department.…”

“…Indeed, the chiral recognition process is sensitive not only to the structures of both analyte and CSPs but also to the mobile-phase conditions. Currently, a practical approach that is widely utilized in pharmaceutical industry, particularly in drug discovery, is to screen a small set of selected CSPs which have demonstrated a broad enantioselectivity [149][150][151][152][153][156][157][158][159][160][161][162][163][164][165][166]. The implementation of new technologies, such as automated systems [156,157], multiple-column parallel screening stations [156,157], mobile-phase gradient [152,153,[158][159][160][161], and SFC [149,[151][152][153], has significantly accelerated the process of chiral column selection and makes it possible to develop and optimize chiral separation within a day [157].…”

Advances in High Throughput Supercritical Fluid Chromatography

“…Although a fully integrated single instrument or software approach seems beneficial, severe disruptions occur when the instrument stops or malfunctions, causing potentially lengthy process interruptions and downtime. [62][63][64] Having redundancy within the system or duplication of instruments allows for facile rerouting of samples to maintain continuity and throughput without sacrificing data quality. For instance, utilization of centralized database servers, which connect multiple sites within an organization, is a risk; when the server fails, all sites are adversely affected.…”

Separation of Chiral Compounds on Polysaccharide Columns

“…As with the other techniques, a large increase in sample throughput is realized using this approach. The technique was also adapted for rapid determination of the enantiomeric excess of each enantiomeric pair in two large compound libraries [216].…”