HILIC-like separation on a base-deactivated C18 column for ion-pair-free LC–MS/MS analysis of 16 aminoglycosides in foods

First demonstration of C18-column HILIC-like separation for aminoglycosides. • Hydrophilic retention via water layer & vicinal silanols on base-deactivated silica. • Tandem WCX-C18 SPE protocol developed for effective matrix cleanup. • Robust, MS-compatible, practical monitoring of aminoglycoside residues in foods. An LC–MS/MS method was developed for the simultaneous determination of 16 aminoglycosides (AGs) in pork, chicken, milk, and eggs using a conventional Hypersil base-deactivated silica (BDS) C 18 column operated under HILIC-like conditions. Unlike typical C 18 -based methods that rely on ion-pairing reagents in the LC mobile phase, separation was achieved with an ion-pair-free mobile phase consisting only of 0.1% formic acid and acetonitrile under gradient elution. Column comparison, aqueous-fraction experiments, and SRM 870 probe testing indicated a mixed retention mechanism involving hydrophilic partitioning into a water-enriched interfacial layer and reversible interactions with accessible residual silanol sites. Because the method prioritizes MS compatibility and reproducible multi-residue quantification, compound-specific MRM transitions and matrix-matched calibration were used to ensure selectivity and quantitative reliability. The method showed good linearity (R² > 0.99), satisfactory accuracy (71.2–99.8%) with reported standard deviations, acceptable precision (CV ≤ 11.3%), and low detection limits (LODs 3–15 μg/kg; LOQs 10–50 μg/kg). Overall, this work demonstrates that a conventional C 18 column can exhibit pronounced hydrophilic selectivity under high-organic conditions, offering a practical, MS-friendly alternative for aminoglycoside residue analysis and informing future stationary-phase development for hydrophilic separations.