1. The linear regression evaluation for the calibration plots showed a very good linear relationship (r = 0.999) inside the concentration variety 0.041?.240 mg mL-1. The technique demonstrated great precision (1.14?.96 RSD) and recovery (99.60?01.90 ). The limits of detection and quantitation had been 9.69 and 29.36 lg mL-1, respectively. The evaluation of tebipenem reactivity was supported by quantum chemical calculations based around the density functional theory (DFT). The analysis on the electron density in the HOMO and LUMO ofPublished in the unique paper collection Advances in Chromatography and Electrophoresis Chiranal 2012 with guest editor Jan Petr. J. Cielecka-Piontek ( ) ?P. Zalewski ?M. Paczkowska Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Poznan University of Healthcare Sciences, Grunwaldzka 6, ?60-780 Poznan, Poland e-mail: [email protected] B. Barszcz ?K. Lewandowska Department of Molecular Crystals, Institute of Molecular Physics Polish Academy Sciences, Smoluchowskiego 17, ?60-179 Poznan, Polandtebipenem recommended the possibility of electron transport inside the molecule throughout the degradation of bi-cyclic 4:5 fused penem rings. Key phrases Column liquid chromatography ?Pressure degradation research ?HOMO UMO ?Intramolecular charge transfer ?TebipenemIntroduction Tebipenem is the active form of tebipenem pivoxil, a novel oral carbapenem antibiotic which has been authorized for the remedy of bacterial diseases triggered by G-positive and G-negative bacteria in pediatric patients [1]. Tebipenem similarly to other CH3 carbapenems contains the bi-cyclic four:five fused b-lactam and pyrrolidine rings, a trans-1hydroxyethyl substituent at C-6 in addition to a methyl group at C-4. The presence of a 1-[(1,3-thiazolin-2-yl)azetidin-3-yl]thio substituent at C-2 will be the differentiating feature from the molecule which influences the antibacterial activity of tebipenem and may influence its chemical stability [2]. Within a molecule of tebipenem, similarly to other carbapenem analogs, the important instability of the b-lactam ring is a consequence of your presence of a bi-cyclic four:5 fused ring, represented by the fusion on the b-lactam ring as well as the pyrrolidine moiety [3]. During the degradation of carbapenems according to pressure components (solvents, pH, drug concentration, temperature, time) and their chemical structures, numerous degradation items are formed [4].152835-00-2 web Study reports deliver only data on antibacterial efficiency, crystallographic structures of tebipenem complexed with penicillin-binding proteins, and pharmacokinetic parameters [5?].Price of Oxetane-2-carboxylic acid Towards the greatest of our knowledge, no LC system for the determination of tebipenem in theJ.PMID:24856309 Cielecka-Piontek et al.presence of its degradation items in the pharmaceutical matrix has so far been reported. The International Conference on Harmonization (ICH) recommendations need the improvement of stability-indicating methods (SIAMs) for drug assays in stability tests. SIAMs ought to be suitable for drug determination through hydrolysis (at several pH), oxidation, photolysis, and thermal degradation [9]. Throughout stability research, the prediction from the pathways of degradation and locations in molecules that are more susceptible to degradation can by supported by quantumchemical calculations [10]. That is definitely in particular important for stability studies of novel compounds when the main analytical tools are chromatographic procedures. Additionally, the analysis of electron density on the HOMO along with the LUMO shows location of electrons, consequently gives an i.