An optimized SPE-UPLC-MS/MS method for simultaneous quantification of 11 tetracyclines in dairy products

The global rise in antibiotic use, particularly tetracyclines (TCs) in animal husbandry, poses significant risks to food safety and public health due to residual accumulation and bacterial resistance. Existing detection methods for TCs in dairy products often lack efficiency, sensitivity, or the capability for simultaneous multi-residue analysis. Developing a rapid, precise, and cost-effective method to monitor TCs in compliance with international maximum residue limits remains an urgent need.

We developed a streamlined approach integrating a three-step purification process (PRiME HLB cartridges) with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The method utilizes 0.1 mol L^-1 Na₂EDTA-McIlvaine buffer for extraction, achieving 83.11-107.61% recovery rates with < 5.43% relative standard deviation (RSD). Optimized chromatographic separation on a bridged ethyl-siloxane and silica hybrid (BEH) C₁₈ column enabled simultaneous detection of 11 TCs (including parent compounds and metabolites) within 9 min. Sensitivity was exceptional, with limits of detection and limits of quantification of 0.02-0.83 μg kg^-1 and 0.07-2.78 μg kg^-1, respectively. Intra-/inter-day precision (RSD 3.03-9.33%) and compliance with European Union/Food and Drug Administration (EU/FDA) were validated using real milk and milk powder samples.

This method combines rapid sample preparation with UPLC-MS/MS for simultaneous quantification of 11 TCs in dairy products. Its high accuracy, sensitivity, and compliance with global regulatory standards make it indispensable for large-scale food safety monitoring, effectively addressing antibiotic residue risks and supporting international trade harmonization. © 2025 Society of Chemical Industry.