Kinetic and thermodynamic studies of moxifloxacin hydrolysis in the presence and absence of metal ions in acidic solutions.

Chromatographic and densitometric method for determination of moxifloxacin in the presence of products of acidic hydrolysis was developed. The established method had suitable specificity, precision, good accuracy, and high sensitivity. In addition, stability of moxifloxacin in acidic solutions at temperature 90 degrees C and 110 degrees C in the presence and absence of metal ions, such as Cu(II), Fe(III), Zn(II), and Al(III) was studied. It was proved that decomposition of moxifloxacin proceeds according to kinetics of the first-order reaction and is dependent on temperature, incubation time and the type of the metal ion. Based on the calculated kinetic (k, t0, and t0.5) and thermodynamic (Ea) parameters, it was observed that among studied ions the highest effect on decomposition process of moxifloxacin had Cu(II) ions. The liquid chromatography coupled with mass spectrometry detection (LC-MS) and proton nuclear magnetic resonance (1H NMR) techniques have been used to identify degradation products for the compound.