Chiral Analysis of Sodium Lactate with Agilent InfinityLab Poroshell 120 Chiral-T Columns

Significance of the Topic

The enantioselective analysis of small molecules is critical in pharmaceutical development and quality control. Over half of current therapeutics are chiral, and many are administered as racemic mixtures with distinct biological activities for each enantiomer. Fast, sensitive, and robust methods for resolving enantiomers are essential to ensure safety, efficacy, and regulatory compliance.

Objectives and Study Overview

This study demonstrates a method for separating sodium lactate enantiomers on an Agilent InfinityLab Poroshell 120 Chiral-T column. Key goals include evaluating mobile phase composition, optimizing resolution and peak shape, and confirming compatibility with evaporative light scattering detection.

Methodology and Instrumentation

A reversed-phase approach was employed using methanol with low concentrations of ammonium salts. Initial screening tested 0.2% ammonium formate, 0.2% ammonium acetate, and alternatives in methanol to identify optimal conditions. The column temperature was maintained at 30 °C, flow rate at 0.5 mL/min, and injection volume at 1 µL.

Used Instrumentation

• Agilent 1290 Infinity LC System with low-dispersion tubing
• Agilent 1290 Flexible Pump (G7104A)
• Agilent 1290 High Performance Autosampler (G4226A) with ultralow-dispersion capillaries
• Agilent Multicolumn Thermostat (G7116B)
• Agilent 1290 ELSD II (G7102A) configured at 30 °C evaporator and nebulizer temperatures
• InfinityLab Poroshell 120 Chiral-T column, 4.6 × 100 mm, 2.7 µm
• Agilent OpenLab CDS software, version C.01.07

Key Results and Discussion

Screening revealed that 0.2% ammonium formate produced poor peak shape for the sodium D,L-lactate racemate, while switching to 0.2% ammonium acetate yielded sharp, well-resolved peaks for both enantiomers and an additional sodium peak. Lowering ammonium acetate concentration increased retention of the sodium peak without improving resolution. Injection of sodium chloride identified the late-eluting peak as sodium. The separation mechanism involves polar ionic interactions with the teicoplanin-based glycopeptide selector phase.

Benefits and Practical Applications of the Method

• Rapid separation with resolution suitable for routine analysis
• Compatibility with reversed-phase solvents common in LC laboratories
• Resistance of covalently bonded glycopeptide CSP to a wide range of mobile phase additives
• Sensitivity with ELSD detection for non-UV-active analytes

Future Trends and Opportunities

Further development may include coupling with mass spectrometry for increased specificity, application to other small chiral ions, and transfer of methods to supercritical fluid chromatography for faster run times. Exploration of alternative glycopeptide selectors and greener mobile phase additives may enhance selectivity and sustainability.

Conclusion

The Agilent InfinityLab Poroshell 120 Chiral-T column provides a robust, MS-compatible method for separating sodium lactate enantiomers. Optimization of mobile phase composition with ammonium acetate yields excellent peak shape and resolution, supporting its use in pharmaceutical and biochemical analysis.

References

• Bonner, W. A. Parity Violation and the Evolution of Biomolecular Homochirality. Chirality 2000, 114.
• Agilent Technologies. Put InfinityLab Poroshell 120 Chiral Innovation to Work for Your Challenging Separations. Application Compendium, Publication Number 5991-8450EN, 2017.