Determination of 18 antibiotics in urine using LC-QqQ-MS/MS

A determination method to identify and quantify 18 multi-class antibiotics in urine was developed using liquid chromatography triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS). Targeted antibiotics were extracted using preliminary dilution followed by d-SPE extraction. Specificity and selectivity, linearity, LOD and LOQ, accuracy, and precision were validated. LOQ of the majority of targeted compounds ranged from 0.3-7.5 μg/L. Excellent recovery in the range of 73-136% was achieved for most antibiotics, except macrolides whose recovery were of 52-78%. High precision was obtained with coefficients of variation (CV) less than 20%. All compounds were clearly separated and detected after a total run time of 15 min. Following development and validation, the method was applied to real urine samples where five out of 18 antibiotics were detected and high precision with CV less than 15% was obtained. The method was validated to be capable of quantifying antibiotics in urine for applications in supervision of antibiotics consumption or in pharmacokinetic studies.