Objective To develop a fully automated method combining solid-phase extraction with ultra-high performance liquid chromatography tandem mass spectrometry for the determination of 52 types of antibiotics in drinking water.

Methods The water samples were adjusted to pH 2 using phosphoric acid. The antibiotics in the water samples were enriched and purified through solid-phase extraction membrane. Subsequently, the samples underwent two elutions with 10 mL of 5% ammonia methanol, followed by nitrogen-assisted drying to near-dryness. Finally, the volume was adjusted to 1 mL using a 5% methanol aqueous solution for analysis purposes. Separation was achieved using an ACQUITY UPLC BEH C18 chromatographic column (2.1×100 mm, 1.7 μm). A mobile phase consisting of a gradient elution system comprising of 0.1% formic acid-water-0.1% formic acid methanol was employed for this purpose. Mass spectrometry utilized positive ion scan multiple reaction monitoring (MRM) mode.

Results Within the range of 0.1 – 100 μg/L, all regression equations obtained for the 52 target analytes exhibited satisfactory linear relationships. The method detection limit ranged from 0.1 to 0.6 ng/L, while the recovery rate varied between 65.1% and 133.3%. Additionally, the relative standard deviation (RSD) ranged from 3.1% to 20.5%.

Conclusion The established method is a simple, rapid, and highly accurate and precise approach for the simultaneous detection of 52 types of antibiotics in drinking water.