Pham Van ToiKhanh V. DoanNgo Ngọc Quang MinhPham Nguyen PhuongMenno D. de JongH. Rogier van DoornThomas PouplinUCLMahidol UniversityNuffield Department of Clinical MedicineAmsterdam UMC - University of AmsterdamTan Tao UniversityChildren's Hospital 12020-01-272020-01-272020-01-01Biomedical Chromatography. Vol.34, No.1 (2020)10990801026938792-s2.0-85075006039https://repository.li.mahidol.ac.th/handle/20.500.14594/49562© 2019 Oxford University Clinical Research Unit. Biomedical Chromatography published by John Wiley & Sons Ltd. In this study, we developed and validated two reliable high-performance liquid chromatography (HPLC) methods for the qualitative detection of six oral β-lactams, which are commonly used in pediatric patients with acute respiratory infections (ARIs). Two distinct reverse-phase chromatographic separations of six β-lactams were obtained. Four β-lactams (cefadroxil, cephalexin, cefaclor and cefixime) in urine were separated using a gradient program with a mobile phase consisting of K2HPO4 buffer (20 mm, pH 2.8) and acetonitrile on a LichroCART 250 × 4.6 mm, Purospher STAR C18 end-capped (5 μm) column. Two remained β-lactams (amoxicillin and cefuroxime) were analyzed using a gradient elution with the mobile phase containing K2HPO4 buffer (20 mm, pH 3.0) and acetonitrile on a LichroCart® Purospher Star C8 end-capped column (5 μm, 125 × 4.6 mm). Good linearity within the range of 0.3–30 μg/ml for cefadroxil, cephalexin, cefaclor and cefixime, and 0.2–20 μg/ml for amoxicillin and cefuroxime, was attained. The precisions were <14%. The accuracies ranged from 85.87 to 102.8%. The two validated methods were then applied to determine these six antibiotics in 553 urine samples of pediatric patients with ARIs. As a result, 32.2% were positive with one or more of six tested β-lactams. Cefixime was the most commonly detected agent, accounting for 9.8% of enrolled patients.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyChemistryPharmacology, Toxicology and PharmaceuticsArticleSCOPUS10.1002/bmc.4699