A versatile reversed-phase liquid chromatography charged aerosol detection method for streamlined monitoring of QS-21 content and stability in liposomal adjuvant formulations.

Caleb Kinsey; Rodell C Barrientos; Mayank Bhavsar; Heather Wang; Malini Mukherjee; Emmanuel Appiah-Amponsah; Erik L Regalado

doi:10.1016/j.jchromb.2026.125220

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A versatile reversed-phase liquid chromatography charged aerosol detection method for streamlined monitoring of QS-21 content and stability in liposomal adjuvant formulations.

Caleb Kinsey·Rodell C Barrientos·Mayank Bhavsar·Heather Wang·Malini Mukherjee·Emmanuel Appiah-Amponsah·Erik L Regalado

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Abstract

Identifying and quantifying an active adjuvant along with its degradants in drug formulations is essential for ensuring the safety and efficacy of the drug product. QS-21 is a potent adjuvant that is being evaluated in several clinical trials and is currently formulated in licensed vaccines that protect against shingles, malaria, and RSV. In aqueous environments, QS-21 is subject to hydrolytic degradation that is influenced by pH and temperature, resulting in the formation of a degradant known as QS-21 Hydrolyzed Product, QS-21 HP, which can occur during manufacturing and/or prolonged storage. The intact QS-21 and QS-21 HP induce distinct immune response profiles, making it critical to monitor the degradation of QS-21 in vaccine adjuvant formulations. To date, there has been a paucity of reliable assays for QS-21, its isomers, and degradant QS-21 HP in liposomal adjuvant formulations available that can be transferred seamlessly in quality control (QC) environments. Herein, we introduce a simple and QC-friendly liquid chromatography coupled to a charged aerosol detector (LC-CAD) enabled by stationary phase screening combined with in silico method development optimization. The method exploits 2.7 μm fused-core phenyl hexyl particles, ensuring its versatility in standard and ultra-high pressure LC systems. This approach demonstrates a high correlation between predicted retention time (RT) and experimental outcomes with overall ∆RT < 4%. In addition, this assay shows great linearity, precision, specificity, and accuracy to advance process development characterization of new vaccine formulations.

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Liposomes Chromatography, Reverse-Phase Reproducibility of Results Aerosols Saponins Drug Stability Adjuvants, Immunologic Limit of Detection Linear Models Adjuvant Chromatography In silico modeling Phenyl–hexyl QS-21 Journal Article

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Caleb Kinsey, Rodell C Barrientos, Mayank Bhavsar, Heather Wang, Malini Mukherjee, Emmanuel Appiah-Amponsah, Erik L Regalado. 2026-07-21. A versatile reversed-phase liquid chromatography charged aerosol detection method for streamlined monitoring of QS-21 content and stability in liposomal adjuvant formulations.. https://doi.org/10.1016/j.jchromb.2026.125220

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