GUESSmix-guided optimization of elution-extrusion counter-current separations

Area of Science:

• Chromatographic separation techniques
• Natural product chemistry
• Analytical chemistry

Background:

• Rational optimization strategies are essential for chromatographic separations.
• Counter-current separations (CS) require parameter manipulation after solvent system selection.
• Elution-extrusion counter-current chromatography (EECCC) is a recently introduced CS methodology.

Purpose of the Study:

• To assess optimization strategies for counter-current separations using a defined natural product mixture (GUESSmix).
• To investigate the effects of operational parameters on the elution and extrusion stages of EECCC.
• To evaluate the utility of K-based reciprocal symmetry plots (ReS and ReSS) for analyzing CS experiments.

Main Methods:

• Utilized a 21-component natural product mixture (GUESSmix) in a hexane/ethyl acetate/methanol/water solvent system.
• Investigated operational parameters including temperature, flow rate, revolution speed, sample loading, rotation direction, and injection timing in EECCC.
• Employed K-based reciprocal symmetry plots (ReS and ReSS) to analyze chromatograms and compare experimental results.

Main Results:

• The GUESSmix proved effective for comparing retention volumes, resolution, K-values, peak shapes, and extrusion characteristics in CS.
• EECCC demonstrated robustness, with performance influenced by temperature, rpm, flow rate, sample loading, rotation direction, and injection timing.
• ReS[S] chromatograms facilitated systematic study of CS parameters, offering advantages over traditional retention time or volume plots.

Conclusions:

• EECCC is a versatile and robust counter-current separation technique.
• Systematic optimization of EECCC operational parameters significantly enhances separation efficiency.
• K-based reciprocal symmetry plots are valuable tools for the systematic study and optimization of counter-current chromatography.