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News|Videos|October 9, 2026
HILIC VS RP: Separating Impurities in Fatty-Acid-Conjugated siRNAs (Part 1)
Author(s)Martina Lioi
Martina Lioi pairs IP-HILIC and RP to map impurities in fatty acid–linked siRNAs
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At ISC 2026 in Prague, Czech Republic, a session on the analysis of nucleic acids and oligonucleotides featured Martina Lioi of Novartis Pharma AG, Switzerland, who spoke on "Expanding the Analytical Toolbox: Denaturing Ion-Pair HILIC and RP Approaches for Impurity Characterization of Fatty Acid-Conjugated siRNAs."1 Lioi highlighted chromatographic approaches for characterizing impurities in fatty acid–conjugated small interfering RNAs (siRNAs), in which the added hydrophobic lipid component introduces structural and chromatographic complexity beyond that of conventional oligonucleotides.
Her group evaluated a denaturing ion-pair form of hydrophilic interaction liquid chromatography (HILIC), known as IP-HILIC, alongside reversed-phase (RP) approaches to obtain complementary separation mechanisms, using both to examine closely related impurities and product variants of the conjugated siRNA. According to Lioi, the work makes the case for using more than one chromatographic mode when analyzing modified nucleic acid therapeutics: ion-pair reversed-phase chromatography remains the standard for denaturing oligonucleotide analysis, while HILIC and related approaches can add different selectivity and reveal additional product-related species.
Lioi spoke to LCGC International about her work. Here, she discusses what analytical challenges with fatty-acid-conjugated siRNAs motivated her to investigate HILIC and RP approaches, as well as additional information HILIC provided compared with RP.
Reference
- Lioi, M. Expanding the Analytical Toolbox: Denaturing Ion-Pair HILIC and RP Approaches for Impurity Characterization of Fatty Acid-Conjugated siRNAs. Presented at ISC 2026, in Prague, Czech Republic.
https://www.czech-in.org/cmPortalv15/Searchable/isc26/config/normal#!sessionschedule (accessed 2026-09-18).
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