Effect of selected metal ions on the photodegradation of ciprofloxacin in the solid phase.

The photodegradation of ciprofloxacin in the solid phase was investigated by using the chromatographic-densitometric method in the presence and absence of selected metal ions. It was shown that both ion concentration and ion type have an effect on the degradation process that leads to the generation of 2 new products with R(f) values of approximately 0.45 and 0.56, which are different from the R(f) of approximately 0.68 for ciprofloxacin. It was found that CU2+ and Fe3+ ions have the strongest effect on ciprofloxacin photodegradation compared with photodegradation carried out without these ions and also with photodegradations carried out in the presence of Zn2+, Cr3+, Ni2+, and Co2+ ions. To identify the photodegradation products, we used amine-specific chromatographic reactions, UV spectra recorded directly from the chromatograms, and proton nuclear magnetic resonance and IR spectroscopic methods. The chemical structures of the degradation products were found to be 7-[(2-aminoethyl)amino]-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-quinoline-3-carboxylic acid and 7-amino-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid.