Enhancing Achiral Purification Workflows in Drug Discovery with Open-Access SFC-MS Purification Platform

Importance of the Topic

This work addresses a key challenge in drug discovery: rapid and reliable purification of small-molecule candidates. Supercritical fluid chromatography coupled with mass spectrometry (SFC-MS) offers high separation efficiency, lower solvent usage and accelerated throughput compared to conventional liquid chromatography. Automating scale up from analytical screening to preparative purification broadens accessibility and consistency, reducing operator variability and resource consumption.

Objectives and Study Overview

The study aimed to develop an open-access, automated SFC-MS platform that recommends optimal columns and gradient conditions to seamlessly transition from screening to preparative purification. Three achiral columns (PolyVP, PBr and Diol II) were evaluated for their retention selectivity across seven model pharmaceuticals. The goal was to demonstrate a scale-up algorithm that simplifies method transfer and maintains high purity in diverse compound mixtures.

Experimental Methods and Instrumentation

The workflow comprises two main steps:

• Screening: small-scale analytical SFC-MS runs on columns with different stationary phases to identify the best separation.
• Scale-up: automated generation of preparative gradient conditions using a linear algorithm correlating analytical retention times to initial solvent composition.

Key features include fixed gradient duration, on-column dilution injection for larger sample loads and open-access software control to ensure reproducibility.

Used Instrumentation

• Analytical SFC-MS system: Shimadzu Nexera UC with Shim-pack UC-PolyVP, PBr and Diol II (50 × 3.0 mm, 3 µm).
• Preparative SFC system: Shimadzu Nexera UC Prep with corresponding preparative columns (250 × 20 mm, 5 µm).
• MS detectors: Dual ESI/APCI (DUIS) in positive mode, scan m/z 150–1000, nitrogen nebulizing and drying gases, 200–450 °C interface temperatures.

Main Findings and Discussion

The scale-up algorithm produced linear correlations between analytical retention time and initial fraction of co-solvent B for each column. PolyVP and Diol II required two-segment models, while PBr followed a single linear fit (R² > 0.97). Model mixtures of low-molecular-weight drugs achieved >95% purity under automated conditions. The on-column dilution method enabled injection volumes up to 1500 µL without loss of peak shape or resolution, demonstrating robust preparative performance even for closely eluting analytes.

Practical Benefits and Applications

• Consistent high-purity output regardless of operator skill.
• Significant reduction in organic solvent consumption.
• Accelerated method development by combining screening and scale up in one software environment.
• Applicability to diverse small-molecule drug candidates and early-stage library purification.

Future Trends and Potential Uses

Advances may include integration of machine-learning models to predict column selectivity, further miniaturization of preparative hardware and expansion to chiral separations. Coupling real-time mass spectral feedback for dynamic gradient adjustment could further streamline workflows. Open-access platforms will likely drive broader adoption across academic and industrial laboratories.

Conclusion

The developed open-access SFC-MS purification platform successfully automates scale-up from analytical screening to preparative runs. The combination of systematic column selection, a validated scale-up algorithm and on-column dilution injection yields high-purity compounds with reduced solvent use. By lowering technical barriers, this approach supports faster and more sustainable drug discovery.