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Feasible oxidative degradates separation with instant quantification of two non-classical β-lactams by derivative UV spectrophotometry and TLC densitometry

A. M. El-Kosasy, O. Abdel-Aziz, Rania M. Youssif, and N. N. Salama

Analytical Pharmaceutical Chemistry Department, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt



Received: 23 June 2019  Accepted: 2 May 2020


The present paper focuses on the study of stability of two non-classical β-lactam drugs, namely meropenem (MP) and ertapenem (EP) that are highly susceptible to degradation. We proposed two facile and accurate derivative UV spectrophotometric and TLC densitometric methods for fast separation of MP and EP from their oxidative degradates. Firstly, first derivative (D1) and derivative ratio (DR1) techniques were successfully implemented at 325, 324 nm and 322, 320 nm, respectively. Secondly, TLC densitometry was apparently applied at 254 nm, utilizing 2-propanol–methanol–water as a developing system. Oxidative degradation is elucidated by infrared and mass spectrometry. Both developed methodologies aided to determine MP and EP in pure forms, prepared mixtures with oxidative degradates and pharmaceutical vials. Validation was performed in accordance with USP guidelines. Despite both derivative techniques attained the same sensitivity, DR1 method advantageously improved the selectivity by tenfold than D1. All methods considered stability, indicating to oxidative degradation. Statistical comparison and single-way ANOVA emphasized insignificant differences among suggested methods with other referenced ones. Multiple privileges were encountered in UV spectrophotometric and TLC densitometric methods because no sophisticated handling, minimal solvent consumption, no prior separation stages, easiness and wide implementation in QC laboratories of limited budget levels.

Keywords: Meropenem; Ertapenem; Derivative UV spectrophotometry; TLC densitometry; Oxidative degradation; Stability studies

Full paper is available at

DOI: 10.1007/s11696-020-01181-7


Chemical Papers 74 (10) 3557–3567 (2020)

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