Robotic-assisted magnetic dispersive solid-phase extraction coupled with UHPLC-MS/MS for antibiotic analysis in...

Trace-level antibiotic analysis in aqueous matrices requires large-volume enrichment to achieve adequate sensitivity, yet conventional SPE procedures are often time-consuming. While MSPE offers an attractive alternative owing to its operational simplicity, it remains limited by the lack of readily implementable and effective operational strategies for large-volume sample enrichment. Here, we developed a robotic-assisted MSPE coupled with UHPLC-MS/MS for high-throughput antibiotic analysis in aqueous matrices. The two-step procedure involves manual extraction of antibiotics from 100 mL of water using porous polymer magnetic beads, followed by bead collection with a magnetic ball to convert the dispersed format into a robot-compatible one. The automated detection system then automatically performs post-extraction processing and UHPLC-MS/MS analysis, achieving an instrumental throughput of 6 samples/h. By automating post-extraction operations and chromatographic injection, the method reduces manual workload and minimizes operator exposure to organic solvents. After optimization, the method achieved limits of detection of 0.6-1.3 ng/L for all 18 target antibiotics in blank river water. Humic acid at 2.5 mg/L had negligible effects, and spiked river-water recoveries were 78.3-106.2%. Compared with conventional SPE, the proposed method achieves a 60% reduction in sample pretreatment time at the same theoretical enrichment factor (50-fold), offering a practical workflow for routine antibiotic monitoring.