title: Determination of chromatographic dissociation constants of some carbapenem group antibiotics and quantification of these compounds in human urine.
abstract: The dissociation constant values (s (s) pKa ) of some carbapenem group drugs (ertapenem, meropenem, doripenem) in different percentages of methanol-water binary mixtures (18, 20 and 22%, v/v) were determined from the mobile phase pH dependence of their retention factor. Evaluation of these data was performed using the NLREG program. From calculated pKa values, the aqueous pKa values of these subtances were calculated by different approaches. Moreover, the correlation established between retention factor and the pH of the water-methanol mobile phase was used to determine the optimum separation conditions. In order to validate the optimized conditions, these drugs were studied in human urine. The chromatographic separation was realized using a Gemini NX C18 column (250 × 4.6 mm i.d., 5 µm particles) and UV detector set at 220 and 295 nm.
authors.affiliation: Department of Chemistry, Faculty of Science and Literature, Süleyman Demirel University, 32260, Isparta, Turkey.
authors.forename: Ebru
authors.initials: E
authors.lastname: Çubuk Demiralay
authors.forename: Duygu
authors.initials: D
authors.lastname: Koç
authors.forename: Y Doğan
authors.initials: YD
authors.lastname: Daldal
authors.forename: Güleren
authors.initials: G
authors.lastname: Alsancak
authors.forename: Sibel A
authors.initials: SA
authors.lastname: Ozkan
mesh_terms: D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics / Q000652:urine*; D015780:Carbapenems / Q000493:pharmacokinetics / Q000652:urine*; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007700:Kinetics
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems
keywords: Carbapenem group; aqueous pKa values; human urine; internal standard; method optimization; nonlinear regression