Optimized ELSD Workflow for Improved Detection of Lipid Nanoparticle Components

Significance of the topic

Lipid nanoparticles are central to the delivery of gene and nucleic acid therapeutics, enabling stability, targeted cellular uptake and enhanced bioavailability. Reliable analytical methods are essential to monitor LNP composition and purity during development and manufacturing.

Objectives and study overview

This work aimed to systematically refine an evaporative light scattering detection (ELSD) workflow for the routine analysis of four key lipid components in LNP formulations. The goal was to maximize detector sensitivity and signal‐to‐noise ratio without extending analysis time or increasing sample use.

Methodology and instrumentation

The study involved three optimization levels:

• Sample solvent: testing methanol/water ratios (40–100% MeOH).
• LC separation: evaluating column length (50 vs 100 mm), gradient slopes (6, 10, 12 min) and mobile phase composition (up to 50% IPA).
• ELSD parameters: varying drift tube temperature, nebulizer power and nitrogen gas pressure.

Instrumentation:

• ACQUITY UPLC system with ACQUITY UPLC Evaporative Light Scattering Detector
• ACQUITY Premier CSH Phenyl-Hexyl column (1.7 µm, 2.1×50 mm)
• Empower 3 chromatography software

Main results and discussion

Sample solvent optimization identified 90/10 MeOH/water as yielding the highest peak areas for all lipids. Shallow gradients and longer columns improved resolution but broadened the PEGylated lipid peak. Introducing 10–25% IPA in mobile phase B sharpened the PEG signal and resolved cholesterol and PEG in a 6 min run. ELSD parameter tuning showed:

• Optimal drift tube temperature at 48 °C.
• Nebulizer power of 80% balanced intensity and noise.
• Lower carrier gas pressure (20 psi) enhanced signal‐to‐noise ratios.

Overall, optimized settings delivered up to 13-fold increase in peak intensity and up to 9-fold improvement in signal‐to‐noise across all four lipids.

Benefits and practical applications of the method

• Enhanced sensitivity and lower limits of detection for routine LNP monitoring.
• Maintained fast throughput and minimal sample consumption.
• Universal detection of non-chromophoric lipids without derivatization.

Future trends and potential applications

Further advances may include integration with mass spectrometry for structural confirmation, adaptation to charged aerosol detection, automation of parameter screening, and extension to other lipid-based drug delivery systems.

Conclusion

This systematic optimization of solvent, chromatographic and ELSD parameters provides a robust, high-sensitivity workflow for routine analysis of LNP components. Labs can apply these guidelines to improve confidence in lipid quantitation without compromising throughput.

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