Background At present, no generally accepted standard methods are available for detection of β-lactam antibiotics in water, while conventional methods are polluting, harmful, and timeconsuming. Rapid and effective detection methods are therefore warranted in handling public health emergencies.
Objective This study aims to establish a rapid method for detecting six β-lactam antibiotic residues in source water by ultra high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS), including amoxicillin, ceftazidime, cefaclor, cephradine, phenoxymethylpenicillin potassium, and cloxacillin.
Methods Matrix effects were evaluated with relative response value. The best storage conditions were determined by comparing the stability of β-lactam drugs in source water at different temperatures combined with different storage time. Water samples were filtered through a 0.22 μm rated microporous membrane using large volume injection, and then separated on Kinetex 2.6 μm C18 column with gradient elution using mobile phase of 0.1% formic acid and 0.1% acetonitrile. Electrospray ionization in positive mode and multiple reaction monitoring mode were used for detection.
Results Matrix effect interference was compensated by matrix curve. The water samples were stored at 4℃ and analyzed within 24 h to avoid degradation of target chemicals. The six β-lactam antibiotics showed good linear relationships in designed ranges. The limits of detection (S/N=3) were 4-7 ng/L, the limits of quantification (S/N=10) were 10-20ng/L, the adding standard recoveries were 84.8%-99.6%, and the relative standard deviations were all less than 15.6% or equal to (n=6).
Conclusion The method is featured with simplified pre-treatment process and meets the requirement of simultaneously detecting six β-lactam antibiotic residues in source water in case of emergency events.
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