Ultrafast quantification of β-lactam antibiotics in human plasma using UPLC-MS/MS.

There is an increasing interest in monitoring plasma concentrations of β-lactam antibiotics. The objective of this work was to develop and validate a fast ultra-performance liquid chromatographic method with tandem mass spectrometric detection (UPLC-MS/MS) for simultaneous quantification of amoxicillin, cefuroxime, ceftazidime, meropenem and piperacillin with minimal turn around time. Sample clean-up included protein precipitation with acetonitrile containing 5 deuterated internal standards, and subsequent dilution of the supernatant with water after centrifugation. Runtime was only 2.5 min. Chromatographic separation was performed on a Waters Acquity UPLC system using a BEH C18 column (1.7 μm, 100 mm × 2.1 mm) applying a binary gradient elution of water and methanol both containing 0.1% formic acid and 2 mmol/L ammonium acetate on a Water TQD instrument in MRM mode. All compounds were detected in electrospray positive ion mode and could be quantified between 1 and 100 mg/L for amoxicillin and cefuroxime, between 0.5 and 80 mg/L for meropenem and ceftazidime, and between 1 and 150 mg/L for piperacillin. The method was validated in terms of precision, accuracy, linearity, matrix effect and recovery and has been compared to a previously published UPLC-MS/MS method.