Exploring the Effects of Optically Active Solvents in Chiral Chromatography on Polysaccharide-Based Columns

Area of Science:

• Analytical Chemistry
• Chromatography
• Organic Chemistry

Background:

• Chiral liquid chromatography (LC) relies on mobile phase modifiers to tune chiral selectivity.
• Optically active solvents offer a novel approach to enhance chiral recognition.
• Biobased solvents like l-ethyl lactate (LEL) present sustainable alternatives.

Purpose of the Study:

• To investigate the effectiveness of l-ethyl lactate (LEL) as a mobile-phase modifier in chiral LC.
• To compare LEL's performance against common achiral solvents like acetonitrile (ACN) and methanol (MeOH).
• To explore the impact of chiral solvent interactions on enantioseparations.

Main Methods:

• Reversed-phase LC (RPLC) chiral separations were performed using LEL as a partial or complete replacement for ACN and MeOH.
• Various conditions were tested on polysaccharide columns.
• The influence of d-ethyl lactate (DEL) was compared with LEL to study chiral interactions.

Main Results:

• LEL demonstrated distinct chiral selectivity, improving resolution for 8 out of 16 test compounds.
• LEL showed better performance with ACN than MeOH, likely due to methanol's protic nature.
• LEL exhibited steeper increases in chiral resolution at lower temperatures compared to ACN and showed good compatibility with salt additives.

Conclusions:

• Optically active l-ethyl lactate (LEL) is a viable and effective mobile-phase modifier for chiral LC.
• LEL offers unique selectivity and can simplify chiral screening platforms, promoting greener analytical methods.
• Chiral interactions between solvents and analytes significantly influence enantioseparations, as shown by comparing LEL and DEL.