허승희 (충남대학교 약학대학)

김형민 (충남대학교 약학대학)

허승희 (충남대학교 약학대학)

김형민 (충남대학교 약학대학)

 Oxolinic acid is a quinolone-class antibacterial agent which is used as a bactericide to control bacterial diseases in crops. To ensure safety, pesticide residues must be monitored under the Positive List System (PLS), which applies a uniform maximum residue limit (MRL) to pesticides without an established MRL. However, the existing method has limitations in sensitivity and selectivity for quantifying oxolinic acid at trace levels in complex herbal matrices. Therefore, in this study, a more sensitive and selective LC–MS/MS-based analytical method was developed for the determination of oxolinic acid residues in herbal medicines. Sample preparation was performed using a QuEChERS-based approach, and PSA and C18 sorbents were used for purification to minimize matrix interferences. Quantitative analysis was performed by LC–MS/MS under ESI mode. The method was validated according to CODEX guidelines for four representative herbal medicines (Glycyrrhiza uralensis, Astragalus membranaceus, Paeonia lactiflora and Rehmannia glutinosa). Linearity (R² ≥ 0.98), recovery (70–120%), and precision (RSD ≤ 20%) all satisfied the acceptance criteria within the concentration range of  0.01–0.5 mg/kg. This method provides improved sensitivity, selectivity, and reliability for the determination of oxolinic acid residues, and is expected to contribute to more accurate residue monitoring of herbal medicines under the PLS. This research was supported by a grant (25202MFDS005) from Ministry of Food and Drug Safety in 2026.​